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• Does my fat-client application belong in the MVC pattern?

  - by boatingcow

  The web-based application I’m currently working on is growing arms and legs! It’s basically an administration system which helps users to keep track of bookings, user accounts, invoicing etc. It can also be accessed via a couple of different websites using a fairly crude API. The fat-client design loosely follows the MVC pattern (or perhaps MVP) with a php/MySQL backend, Front Controller, several dissimilar Page Controllers, a liberal smattering of object-oriented and procedural Models, a confusing bunch of Views and templates, some JavaScripts, CSS files and Flash objects. The programmer in me is a big fan of the principle of “Separation of Concerns” and on that note, I’m currently trying to figure out the best way to separate and combine the various concerns as the project grows and more people contribute to it. The problem we’re facing is that although JavaScript (or Flash with ActionScript) is normally written with the template, hence part of the View and decoupled from the Controller and Model, we find that it actually encompasses the entire MVC pattern... Swap an image with an onmouseover event - that’s Behaviour. Render a datagrid - we’re manipulating the View. Send the result of reordering a list via AJAX - now we’re in Control. Check a form field to see if an email address is in a valid format - we’re consulting the Model. Is it wise to let the database people write up the validation Model with jQuery? Can the php programmers write the necessary Control structures in JavaScript? Can the web designers really write a functional AJAX form for their View? Should there be a JavaScript overlord for every project? If the MVC pattern could be applied to the people instead of the code, we would end up with this: Model - the database boffins - “SELECT * FROM mind WHERE interested IS NULL” Control - pesky programmers - “class Something extends NothingAbstractClass{…}” View - traditionally the domain of the graphic/web designer - “” …and a new layer: Behaviour - interaction and feedback designer - “CSS3 is the new black…” So, we’re refactoring and I’d like to stick to best practice design, but I’m not sure how to proceed. I don’t want to reinvent the wheel, so would anyone have any hints or tips as to what pattern I should be looking at or any code samples from someone who’s already done the dirty work? As the programmer guy, how can I rewrite the app for backend and front end whilst keeping the two separate? And before you ask, yes I’ve looked at Zend, CodeIgnitor, Symfony, etc., and no, they don’t seem to cross the boundary between server logic and client logic!

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• jQuery tools modal overlay display problem in IE6-8

  - by Michael Stone

  I'm trying to enable the overlay to be modal. It works perfectly fine in FireFox, but the window object is behind the mask when it becomes modal. This prevents any interaction with it and the page is actually useless. I've tried debugging this for a while and can't figure it out. Here is a link to the example on their site: http://flowplayer.org/tools/demos/overlay/modal-dialog.html $.fn.cfwindow = function(btnEvent,modal,draggable){ //error checking if(btnEvent == ""){ alert('Error in window :\n Please provide an id that instantiates the window. '); } if(!modal && !draggable){ $('#'+btnEvent+'[rel]').overlay(); $('#content_overlay').css('cursor','default'); } if(!modal && draggable){ $('#'+btnEvent+'[rel]').overlay(); $('#content_overlay').css('cursor','move'); $('#custom').draggable(); } if(modal){ $('#'+btnEvent+'[rel]').overlay({ // some mask tweaks suitable for modal dialogs mask: { color: '#646464', loadSpeed: 200, opacity: 0.6 }, closeOnClick: false }); $('#content_overlay').css('cursor','default'); //$('#custom').addClass('modal'); } }; That's what I'm referencing when I call through: <script type="text/javascript"> $(document).ready(function(){ $(document).pngFix(); var modal = <cfoutput>#attributes.modal#; var drag = #attributes.draggable#; var btn = '#attributes.selector#'; var src = '#attributes.source#'; var wid = '#attributes.width#'; $('##custom').width(parseInt(wid)); $('div##load_content').load(src); $('##custom').cfwindow(btn,modal,drag,wid); }); </script> CSS for the modal: <style type="text/css"> .modal { display:none; text-align:left; background-color:#FFFFFF; -moz-border-radius:6px; -webkit-border-radius:6px; } </style> Exclude the and the additional pound signs, IE. "##". Screen shot of the problem: http://twitpic.com/1tak06 Note: IE6 and IE8 have the same problem. Any help would be appreciated.

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• What's the best way to structure this Linq-to-Events Drag & Drop code?

  - by Rob Fonseca-Ensor

  I am trying to handle a drag & drop interaction, which involves mouse down, mouse move, and mouse up. Here is a simplified repro of my solution that: on mouse down, creates an ellipse and adds it to a canvas on mouse move, repositions the ellipse to follow the mouse on mouse up, changes the colour of the canvas so that it's obvious which one you're dragging. var mouseDown = Observable.FromEvent<MouseButtonEventArgs>(canvas, "MouseLeftButtonDown"); var mouseUp = Observable.FromEvent<MouseButtonEventArgs>(canvas, "MouseLeftButtonUp"); var mouseMove = Observable.FromEvent<MouseEventArgs>(canvas, "MouseMove"); Ellipse ellipse = null; var q = from start in mouseDown.Do(x => { // handle mousedown by creating a red ellipse, // adding it to the canvas at the right position ellipse = new Ellipse() { Width = 10, Height = 10, Fill = Brushes.Red }; Point position = x.EventArgs.GetPosition(canvas); Canvas.SetLeft(ellipse, position.X); Canvas.SetTop(ellipse, position.Y); canvas.Children.Add(ellipse); }) from delta in mouseMove.Until(mouseUp.Do(x => { // handle mouse up by making the ellipse green ellipse.Fill = Brushes.Green; })) select delta; q.Subscribe(x => { // handle mouse move by repositioning ellipse Point position = x.EventArgs.GetPosition(canvas); Canvas.SetLeft(ellipse, position.X); Canvas.SetTop(ellipse, position.Y); }); the XAML is simply <Canvas x:Name="canvas"/> There's a few things I don't like about this code, and I need help refactoring it :) First of all: the mousedown and mouseup callbacks are specified as side effects. If two subscriptions are made to q, they will happen twice. Second, the mouseup callback is specified before the mousemove callback. This makes it a bit hard to read. Thirdly, the reference to the ellipse seems to be in a silly place. If there's two subscriptions, that variable reference will get overwritten quite quickly. I'm sure that there should be some way we can leverage the let keyword to introduce a variable to the linq expression that will mean the correct ellipse reference is available to both the mouse move and mouse up handlers How would you write this code?

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• Why does one loop take longer to detect a shared memory update than another loop?

  - by Joseph Garvin

  I've written a 'server' program that writes to shared memory, and a client program that reads from the memory. The server has different 'channels' that it can be writing to, which are just different linked lists that it's appending items too. The client is interested in some of the linked lists, and wants to read every node that's added to those lists as it comes in, with the minimum latency possible. I have 2 approaches for the client: For each linked list, the client keeps a 'bookmark' pointer to keep its place within the linked list. It round robins the linked lists, iterating through all of them over and over (it loops forever), moving each bookmark one node forward each time if it can. Whether it can is determined by the value of a 'next' member of the node. If it's non-null, then jumping to the next node is safe (the server switches it from null to non-null atomically). This approach works OK, but if there are a lot of lists to iterate over, and only a few of them are receiving updates, the latency gets bad. The server gives each list a unique ID. Each time the server appends an item to a list, it also appends the ID number of the list to a master 'update list'. The client only keeps one bookmark, a bookmark into the update list. It endlessly checks if the bookmark's next pointer is non-null ( while(node->next_ == NULL) {} ), if so moves ahead, reads the ID given, and then processes the new node on the linked list that has that ID. This, in theory, should handle large numbers of lists much better, because the client doesn't have to iterate over all of them each time. When I benchmarked the latency of both approaches (using gettimeofday), to my surprise #2 was terrible. The first approach, for a small number of linked lists, would often be under 20us of latency. The second approach would have small spats of low latencies but often be between 4,000-7,000us! Through inserting gettimeofday's here and there, I've determined that all of the added latency in approach #2 is spent in the loop repeatedly checking if the next pointer is non-null. This is puzzling to me; it's as if the change in one process is taking longer to 'publish' to the second process with the second approach. I assume there's some sort of cache interaction going on I don't understand. What's going on?

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• Richfaces modal panel and a4j:keepAlive

  - by mykola

  Hello! I've got unexpected problems with richfaces (3.3.2) modal panel. When i try to open it, browser opens two panels instead of one: one is in the center, another is in the upper left corner. Besides, no fading happens. Also i have three modes: view, edit, new - and when i open my panel it should show either "Create new..." or "Edit..." in the header and actually it shows but not in the header as the latter isn't rendered at all though it should, because i set proper mode in action before opening this modal panel. Besides it works fine on all other pages i've made and there are tens of such pages in my application. I can't understand what's wrong here. The only way to fix it is to remove <a4j:keepAlive/> from the page that is very strange, imho. I'm not sure if code will be usefull here as it works fine everywhere in my application but this only case. So if you put it on your page it will probably work without problems. My only question is: are there any hidden or rare problems in interaction of these two elements (<rich:modalPanel> and <a4j:keepAlive>)? Or shall i spent another two or three days searching for some wrong comma, parenthesis or whatever in my code? :) For most curious. Panel itself: <!-- there's no outer form --> <rich:modalPanel id="panel" autosized="true" minWidth="300" minHeight="200"> <f:facet name="header"> <h:panelGroup id="panelHeader"> <h:outputText value="#{msg.new_smth}" rendered="#{MbSmth.newMode}"/> <h:outputText value="#{msg.edit_smth}" rendered="#{MbSmth.editMode}"/> </h:panelGroup> </f:facet> <h:panelGroup id="panelDiv"> <h:form > <!-- fields and buttons --> </h:form> </h:panelGroup> </rich:modalPanel> One of the buttons that open panel: <a4j:commandButton id="addBtn" reRender="panelHeader, panelDiv" value="#{form.add}" oncomplete="#{rich:component('panel')}.show()" action="#{MbSmth.add}" image="create.gif"/> Action invoked on button click: public void add() { curMode = NEW_MODE; // initial mode is VIEW_MODE newSmth = new Smth(); } Mode check: public boolean isNewMode() { return curMode == NEW_MODE; } public boolean isEditMode() { return curMode == EDIT_MODE; }

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• Routed Command Question

  - by Andrew

  I'd like to implement a custom command to capture a Backspace key gesture inside of a textbox, but I don't know how. I wrote a test program in order to understand what's going on, but the behaviour of the program is rather confusing. Basically, I just need to be able to handle the Backspace key gesture via wpf commands while keyboard focus is in the textbox, and without disrupting the normal behaviour of the Backspace key within the textbox. Here's the xaml for the main window and the corresponding code-behind, too (note that I created a second command for the Enter key, just to compare its behaviour to that of the Backspace key): <Window x:Class="WpfApplication1.Window1" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="Window1" Height="300" Width="300"> <Grid> <TextBox Margin="44,54,44,128" Name="textBox1" /> </Grid> </Window> And here's the corresponding code-behind: using System.Windows; using System.Windows.Input; namespace WpfApplication1 { /// <summary> /// Interaction logic for EntryListView.xaml /// </summary> public partial class Window1 : Window { public static RoutedCommand EnterCommand = new RoutedCommand(); public static RoutedCommand BackspaceCommand = new RoutedCommand(); public Window1() { InitializeComponent(); CommandBinding cb1 = new CommandBinding(EnterCommand, EnterExecuted, EnterCanExecute); CommandBinding cb2 = new CommandBinding(BackspaceCommand, BackspaceExecuted, BackspaceCanExecute); this.CommandBindings.Add(cb1); this.CommandBindings.Add(cb2); KeyGesture kg1 = new KeyGesture(Key.Enter); KeyGesture kg2 = new KeyGesture(Key.Back); InputBinding ib1 = new InputBinding(EnterCommand, kg1); InputBinding ib2 = new InputBinding(BackspaceCommand, kg2); this.InputBindings.Add(ib1); this.InputBindings.Add(ib2); } #region Command Handlers private void EnterCanExecute(object sender, CanExecuteRoutedEventArgs e) { MessageBox.Show("Inside EnterCanExecute Method."); e.CanExecute = true; } private void EnterExecuted(object sender, ExecutedRoutedEventArgs e) { MessageBox.Show("Inside EnterExecuted Method."); e.Handled = true; } private void BackspaceCanExecute(object sender, CanExecuteRoutedEventArgs e) { MessageBox.Show("Inside BackspaceCanExecute Method."); e.Handled = true; } private void BackspaceExecuted(object sender, ExecutedRoutedEventArgs e) { MessageBox.Show("Inside BackspaceExecuted Method."); e.Handled = true; } #endregion Command Handlers } } Any help would be very much appreciated. Thanks! Andrew

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• Best Practice: Legitimate Cross-Site Scripting

  - by Ryan

  While cross-site scripting is generally regarded as negative, I've run into several situations where it's necessary. I was recently working within the confines of a very limiting content management system. I needed to include database code within the page, but the hosting server didn't have anything usable available. I set up a couple barebones scripts on my own server, originally thinking that I could use AJAX to import the contents of my scripts directly into the template of the CMS (thus retaining dynamic images, menu items, CSS, etc.). I was wrong. Due to the limitations of XMLHttpRequest objects, it's not possible to grab content from a different domain. So I thought "iFrame" - even though I'm not a fan of frames, I thought that I could create a frame that matched the width and height of the content, so that it would appear native. Again, I was blocked by cross-site scripting "protections." While I could indeed load a remote file into the iFrame, I couldn't execute JavaScript to modify its size on either the host page or inside the loaded page. In this particular scenario, I wasn't able to point a subdomain to my server. I also couldn't create a script on the CMS server that could proxy content from my server, so my last thought was to use a remote JavaScript. A remote JavaScript works. It breaks when the user has JavaScript disabled, which is a downside; but it works. The "problem" I was having with using a remote JavaScript was that I had to use the JS function document.write() to output any content. Any output that isn't JS causes script errors. In addition to using document.write() for every line, you also have to ensure that the content is escaped - or else you end up with more script errors. My solution was as follows: My script received a GET parameter ("page") and then looked for the file ({$page}.php), and read the contents into a variable. However, I had to use awkward buffering techniques in order to actually execute the included scripts (for things like database interaction) then strip the final content of all line break characters ("\n") followed by escaping all required characters. The end result is that my original script (which outputs JavaScript) accesses seemingly "standard" scripts on my server and converts their standard output to JavaScript for displaying within the CMS template. While this solution works, it seems like there may be a better way to accomplish the same thing. What is the best way to make cross-site scripting work specifically for the purpose of including content from a completely different domain?

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• Best Practices / Patterns for Enterprise Protection/Remediation of SSNs (Social Security Numbers)

  - by Erik Neu

  I am interested in hearing about enterprise solutions for SSN handling. (I looked pretty hard for any pre-existing post on SO, including reviewing the terriffic SO automated "Related Questions" list, and did not find anything, so hopefully this is not a repeat.) First, I think it is important to enumerate the reasons systems/databases use SSNs: (note—these are reasons for de facto current state—I understand that many of them are not good reasons) Required for Interaction with External Entities. This is the most valid case—where external entities your system interfaces with require an SSN. This would typically be government, tax and financial. SSN is used to ensure system-wide uniqueness. SSN has become the default foreign key used internally within the enterprise, to perform cross-system joins. SSN is used for user authentication (e.g., log-on) The enterprise solution that seems optimum to me is to create a single SSN repository that is accessed by all applications needing to look up SSN info. This repository substitutes a globally unique, random 9-digit number (ASN) for the true SSN. I see many benefits to this approach. First of all, it is obviously highly backwards-compatible—all your systems "just" have to go through a major, synchronized, one-time data-cleansing exercise, where they replace the real SSN with the alternate ASN. Also, it is centralized, so it minimizes the scope for inspection and compliance. (Obviously, as a negative, it also creates a single point of failure.) This approach would solve issues 2 and 3, without ever requiring lookups to get the real SSN. For issue #1, authorized systems could provide an ASN, and be returned the real SSN. This would of course be done over secure connections, and the requesting systems would never persist the full SSN. Also, if the requesting system only needs the last 4 digits of the SSN, then that is all that would ever be passed. Issue #4 could be handled the same way as issue #1, though obviously the best thing would be to move away from having users supply an SSN for log-on. There are a couple of papers on this: UC Berkely: http://bit.ly/bdZPjQ Oracle Vault: bit.ly/cikbi1

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• PHP MVC Principles

  - by George

  I'm not using an off-the-shelf framework and don't particularly want to (nor d I want to go into the reasons why...). Anyway, onto my question(s), I hope it make sense.... I'm trying to get my head around what should go in the model and what should go in the controller. Originally I had the impression that a model class should represent an actual object (eg - a car from the cars table of a database) and model properties should mirror the database fields. However I'm now getting the feeling that I've got the wrong idea - should an instance of a model class represent an actual item, or should it contain a number of methods for doing stuff - sometimes to one car or sometimes to multiple cars based on my example earlier. For example I want to get all the cars from a the database and show them in the view. Am I right in think it should be along the lines of this? Controller File function list() { $cars = $this->model->get_all(); $this->view->add($cars); $this->view->render('cars-list'); } Model File function get_all() { // Use a database interaction class that I've written $cars = Database::select(); return $cars; } Now, if the car had a "status" field that was stored as an integer in the database and I wanted to change that to a string, where should that be done? By looping the SQL results array in the get_all() method in the model? Also, where should form validation live? I have written a validation class that works a little like this: $validator = new Validator(); $validator->check('field_name', 'required'); If the check fails, it adds an error message to the array in the Validator. This array of error messages would then get passed to the view. Should the use of my validator class go in model or the controller? Thanks in advance for for any help anyone can offer. If you know of any links to a simple MVC example / open source application that deals with basic CRUD, they would be much appreciated.

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• Advice for Architecture Design Logic for software application

  - by Prasad

  Hi, I have a framework of basic to complex set of objects/classes (C++) running into around 500. With some rules and regulations - all these objects can communicate with each other and hence can cover most of the common queries in the domain. My Dream: I want to provide these objects as icons/glyphs (as I learnt recently) on a workspace. All these objects can be dragged/dropped into the workspace. They have to communicate only through their methods(interface) and in addition to few iterative and conditional statements. All these objects are arranged finally to execute a protocol/workflow/dataflow/process. After drawing the flow, the user clicks the Execute/run button. All the user interaction should be multi-touch enabled. The best way to show my dream is : Jeff Han's Multitouch Video. consider Jeff is playing with my objects instead of the google maps. :-) it should be like playing a jigsaw puzzle. Objective: how can I achieve the following while working on this final product: a) the development should be flexible to enable provision for web services b) the development should enable easy web application development c) The development should enable client-server architecture - d) further it should also enable mouse based drag/drop desktop application like Adobe programs etc. I mean to say: I want to economize on investments. Now I list my efforts till now in design : a) Created an Editor (VB) where the user writes (manually) the object / class code b) On Run/Execute, the code is copied into a main() function and passed to interpreter. c) Catch the output and show it in the console. The interpreter can be separated to become a server and the Editor can become the client. This needs lot of standard client-server architecture work. But some how I am not comfortable in the tightness of this system. Without interpreter is there much faster and better embeddable solution to this? - other than writing a special compiler for these objects. Recently learned about AXIS-C++ can help me - looks like - a friend suggested. Is that the way to go ? Here are my questions: (pl. consider me a self taught programmer and NOT my domain) a) From the stage of C++ objects to multi-touch product, how can I make sure I will develop the parallel product/service models as well.? What should be architecture aspects I should consider ? b) What technologies are best suited for this? c) If I am thinking of moving to Cloud Computing, how difficult/ how redundant / how unnecessary my efforts will be ? d) How much time in months would it take to get the first beta ? I take the liberty to ask if any of the experts here are interested in this project, please email me: [email protected] Thank you for any help. Looking forward.

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• DriverManager always returns my custom driver regardless of the connection URL

  - by JGB146

  I am writing a driver to act as a wrapper around two separate MySQL connections (to distributed databases). Basically, the goal is to enable interaction with my driver for all applications instead of requiring the application to sort out which database holds the desired data. Most of the code for this is in place, but I'm having a problem in that when I attempt to create connections via the MySQL Driver, the DriverManager is returning an instance of my driver instead of the MySQL Driver. I'd appreciate any tips on what could be causing this and what could be done to fix it! Below is a few relevant snippets of code. I can provide more, but there's a lot, so I'd need to know what else you want to see. First, from MyDriver.java: public MyDriver() throws SQLException { DriverManager.registerDriver(this); } public Connection connect(String url, Properties info) throws SQLException { try { return new MyConnection(info); } catch (Exception e) { return null; } } public boolean acceptsURL(String url) throws SQLException { if (url.contains("jdbc:jgb://")) { return true; } return false; } It is my understanding that this acceptsURL function will dictate whether or not the DriverManager deems my driver a suitable fit for a given URL. Hence it should only be passing connections from my driver if the URL contains "jdbc:jgb://" right? Here's code from MyConnection.java: Connection c1 = null; Connection c2 = null; /** *Constructors */ public DDBSConnection (Properties info) throws SQLException, Exception { info.list(System.out); //included for testing Class.forName("com.mysql.jdbc.Driver").newInstance(); String url1 = "jdbc:mysql://server1.com/jgb"; String url2 = "jdbc:mysql://server2.com/jgb"; this.c1 = DriverManager.getConnection( url1, info.getProperty("username"), info.getProperty("password")); this.c2 = DriverManager.getConnection( url2, info.getProperty("username"), info.getProperty("password")); } And this tells me two things. First, the info.list() call confirms that the correct user and password are being sent. Second, because we enter an infinite loop, we see that the DriverManager is providing new instances of my connection as matches for the mysql URLs instead of the desired mysql driver/connection. FWIW, I have separately tested implementations that go straight to the mysql driver using this exact syntax (al beit only one at a time), and was able to successfully interact with each database individually from a test application outside of my driver.

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• adding child nodes to a treeview control in wpf,c#

  - by ebhakt

  Hi , i have implemented a treeview control on a buttonclick event like this: using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Windows; using System.Windows.Controls; using System.Windows.Data; using System.Windows.Documents; using System.Windows.Input; using System.Windows.Media; using System.Windows.Media.Imaging; using System.Windows.Navigation; using System.Windows.Shapes; using System.Collections.ObjectModel; namespace TaxonomyTreeview { /// /// Interaction logic for Window1.xaml /// public partial class Window1 : Window { ObservableCollection _TaxonomyCollection = new ObservableCollection(); public Window1() { InitializeComponent(); } private void Window_Loaded(object sender, RoutedEventArgs e) { } public ObservableCollection<TaxonomyData> TaxonomyCollection { get { return _TaxonomyCollection; } } private void SelectedTaxonomyChanged(object sender, RoutedPropertyChangedEventArgs<Object> e) { TaxonomyData taxo = taxonomytree.SelectedItem as TaxonomyData; if (taxo != null) { MessageBox.Show("" + taxo.Tid); } } public class TaxonomyData { private string _name; private string _tid; public string Tid { get { return _tid; } set { _tid = value; } } public string Name { get { return _name; } set { _name = value; } } public TaxonomyData(string name, string tid) { Name = name; Tid = tid; } } private void populate_Click(object sender, RoutedEventArgs e) { taxonomytree.Items.Clear(); TaxonomyCollection.Add(new TaxonomyData("Taxonomy1", "1")); taxonomytree.Items.Add(TaxonomyCollection[0]); } } } The xaml code is : <TextBox Height="23" Margin="20,9,0,0" Name="startvid" VerticalAlignment="Top" HorizontalAlignment="Left" Width="120" /> <TextBox Height="23" Margin="165,9,151,0" Name="endvid" VerticalAlignment="Top" /> <Button Height="23.78" HorizontalAlignment="Right" Margin="0,8.22,11,0" Name="populate" VerticalAlignment="Top" Width="115" Click="populate_Click">Populate</Button> <TreeView HorizontalAlignment="Left" Margin="20,53,0,144" Width="120" Name="taxonomytree" ItemsSource="{Binding Window1.TaxonomyCollection}" SelectedItemChanged="SelectedTaxonomyChanged"> <TreeView.ItemTemplate> <DataTemplate> <TextBlock Text="{Binding Path=Name}" /> </DataTemplate> </TreeView.ItemTemplate> </TreeView> </Grid> As i want to display, the structure in a hierarchy , i want to know what is the best method to add a child node to this Please help

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• Programming graphics and sound on PC - Total newbie questions, and lots of them!

  - by Russel

  Hello, This isn't exactly specifically a programming question (or is it?) but I was wondering: How are graphics and sound processed from code and output by the PC? My guess for graphics: There is some reserved memory space somewhere that holds exactly enough room for a frame of graphics output for your monitor. IE: 800 x 600, 24 bit color mode == 800x600x3 = ~1.4MB memory space Between each refresh, the program writes video data to this space. This action is completed before the monitor refresh. Assume a simple 2D game: the graphics data is stored in machine code as many bytes representing color values. Depending on what the program(s) being run instruct the PC, the processor reads the appropriate data and writes it to the memory space. When it is time for the monitor to refresh, it reads from each memory space byte-for-byte and activates hardware depending on those values for each color element of each pixel. All of this of course happens crazy-fast, and repeats x times a second, x being the monitor's refresh rate. I've simplified my own likely-incorrect explanation by avoiding talk of double buffering, etc Here are my questions: a) How close is the above guess (the three steps)? b) How could one incorporate graphics in pure C++ code? I assume the practical thing that everyone does is use a graphics library (SDL, OpenGL, etc), but, for example, how do these libraries accomplish what they do? Would manual inclusion of graphics in pure C++ code (say, a 2D spite) involve creating a two-dimensional array of bit values (or three dimensional to include multiple RGB values per pixel)? Is this how it would be done waaay back in the day? c) Also, continuing from above, do libraries such as SDL etc that use bitmaps actual just build the bitmap/etc files into machine code of the executable and use them as though they were build in the same matter mentioned in question b above? d) In my hypothetical step 3 above, is there any registers involved? Like, could you write some byte value to some register to output a single color of one byte on the screen? Or is it purely dedicated memory space (=RAM) + hardware interaction? e) Finally, how is all of this done for sound? (I have no idea :) )

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• Reading Metadata property of GifBitmapDecoder...why is it null?

  - by David

  How can I read the delay, left and top offset data for each frame of a gif? I've gotten this far. Load the Gif var myGif = new GifBitmapDecoder(uri, BitmapCreateOptions.PreservePixelFormat, BitmapCacheOption.OnLoad); Get a frame var frame = myGif.Frames[i]; From MSDN: Native Image Format Metadata Queries read (ushort)Metadata.GetQuery("/grctlext/Delay"), (ushort)Metadata.GetQuery("/imgdesc/Left"), (ushort)Metadata.GetQuery("/imgdesc/Top") But two things don't work. First the Metadata property of both the gif and the frame are always null, even if I try different animated gif files. Second, the Metadata property of the frame doesn't seem to have a GetQuery method. How do I run these queries, what did I miss? Edit: Here is sample code that gives me null metadata. Using a fresh install of VS2010 Premium, on a fresh WPF application. The image file is the one in the comments. using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Windows; using System.Windows.Controls; using System.Windows.Data; using System.Windows.Documents; using System.Windows.Input; using System.Windows.Media; using System.Windows.Media.Imaging; using System.Windows.Navigation; using System.Windows.Shapes; namespace WpfApplication1 { /// <summary> /// Interaction logic for MainWindow.xaml /// </summary> public partial class MainWindow : Window { public MainWindow() { InitializeComponent(); var uri = new Uri(@"c:\b-414328-animated_gif_.gif"); var myGif = new GifBitmapDecoder(uri, BitmapCreateOptions.PreservePixelFormat, BitmapCacheOption.OnLoad); var frame = myGif.Frames[0]; Title = ""; Title += "Global Metadata is null: " + (myGif.Metadata == null).ToString(); Title += "; Frame Metadata is null: " + (frame.Metadata == null).ToString(); // Crash due to null metadata //var frameData = (BitmapMetadata)frame.Metadata; //var rate = (ushort)frameData.GetQuery("/grctlext/Delay"); } } }

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• Can you help me optimize this code for finding factors of a number? I'm brushing up on my math progr

  - by Sergio Tapia

  I've never really bothered with math programming, but today I've decided to give it a shot. Here's my code and it's working as intended: using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Windows; using System.Windows.Controls; using System.Windows.Data; using System.Windows.Documents; using System.Windows.Input; using System.Windows.Media; using System.Windows.Media.Imaging; using System.Windows.Navigation; using System.Windows.Shapes; namespace PrimeFactorization { /// <summary> /// Interaction logic for MainWindow.xaml /// </summary> public partial class MainWindow : Window { public MainWindow() { InitializeComponent(); } private void btnSubmit_Click(object sender, RoutedEventArgs e) { List<int> primeFactors = FindPrimeFactors(Convert.ToInt32(txtNumber.Text)); primeFactors.Sort(); for (int i = 0; i < primeFactors.Count; i++) { listBoxFoundNumbers.Items.Add(primeFactors[i]); } } private List<int> FindPrimeFactors(int number) { List<int> factors = new List<int>(); factors.Add(1); factors.Add(number); for (int i = 2; i < number; i++) { if (number % i == 0) { int holder = number / i; //If the number is in the list, don't add it again. if (!factors.Contains(i)) { factors.Add(i); } //If the number is in the list, don't add it again. if (!factors.Contains(holder)) { factors.Add(holder); } } } return factors; } } } The only problem I can see with my code is that it will iterate through to the bitter end, even though there will definitely not be any factors. For example, imagine I wrote in 35. My loop will go up to 35 and check 24,25,26,27...etc. Not very good. What do you recommend?

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• Can I get a bitmap of an arbitrary window in another application process?

  - by Chris Farmer

  I am trying to automate a third-party Win32 application where I want to capture the graphics content of a particular window at defined time intervals. I am in the early phases of this, and I'm currently trying to use the Microsoft UI Automation API via C# to do most of the interaction between my client app and the external app. I can now get the external app to do what I want it to do, but now I want to capture the graphics from a specific window that seems to be some third-party owner-drawn control. How can I do this? The window I want to capture is the one marked by the red rectangle in this image: I have an implementation that sort of works, but it's dependent on the external app's UI being on top, and that's not guaranteed for me, so I'd prefer to find something more general. var p = Process.Start("c:\myapp.exe"); var mainForm = AutomationElement.FromHandle(p.MainWindowHandle); // "workspace" below is the window whose content I want to capture. var workspace = mainForm.FindFirst(TreeScope.Descendents, new PropertyCondition(AutomationElement.ClassNameProperty, "AfxFrameOrView70u")); var rect = (Rect) workspace.GetCurrentPropertyValue(AutomationElement.BoundingRectangleProperty); using (var bmp = new Bitmap((int)rect.Width, (int)rect.Height)) { using (var g = Graphics.FromImage(bmp)) { g.CopyFromScreen((int)rect.Left, (int)rect.Top, 0, 0, new Size((int)rect.Width, (int)rect.Height)); bmp.Save(@"c:\screenshot.png", ImageFormat.Png); } } The above works well enough when the automated app is on top, but it just blindly copies the screen in the rectangle, so my code is at the mercy of whatever happens to be running on the machine and might cover my app's window. I have read some suggestions to send the WM_PRINT message to the window. This question/answer from a few months back seemed promising, but when I use this code, I just get a white rectangle with none of my control's actual contents. var prop = (int)workspace.GetCurrentPropertyValue(AutomationElement.NativeWindowHandleProperty); var hwnd = new IntPtr(prop); using ( var bmp2 = new Bitmap((int)rect.Width, (int)rect.Height)) { using (Graphics g = Graphics.FromImage(bmp2)) { g.FillRectangle(SystemBrushes.Control, 0, 0, (int)rect.Width, (int)rect.Height); try { SendMessage(hwnd, WM_PRINT, g.GetHdc().ToInt32(), (int)(DrawingOptions.PRF_CHILDREN | DrawingOptions.PRF_CLIENT | DrawingOptions.PRF_OWNED)); } finally { g.ReleaseHdc(); } bmp2.Save(@"c:\screenshot.bmp"); } } So, first, is it even possible for me to reliably save a bitmap of a window's contents? If so, what is the best way, and what is wrong with my WM_PRINT with SendMessage attempt?

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• Can I call make runtime decided method calls in Java?

  - by Catalin Marin

  I know there is an invoke function that does the stuff, I am overall interested in the "correctness" of using such a behavior. My issue is this: I have a Service Object witch contains methods which I consider services. What I want to do is alter the behavior of those services without later intrusion. For example: class MyService { public ServiceResponse ServeMeDonuts() { do stuff... return new ServiceResponse(); } after 2 months I find out that I need to offer the same service to a new client app and I also need to do certain extra stuff like setting a flag, or make or updating certain data, or encode the response differently. What I can do is pop it up and throw down some IFs. In my opinion this is not good as it means interaction with tested code and may result in un wanted behaviour for the previous service clients. So I come and add something to my registry telling the system that the "NewClient" has a different behavior. So I'll do something like this: public interface Behavior { public void preExecute(); public void postExecute(); } public class BehaviorOfMyService implements Behavior{ String method; String clientType; public void BehaviorOfMyService(String method,String clientType) { this.method = method; this.clientType = clientType; } public void preExecute() { Method preCall = this.getClass().getMethod("pre" + this.method + this.clientType); if(preCall != null) { return preCall.invoke(); } return false; } ...same for postExecute(); public void preServeMeDonutsNewClient() { do the stuff... } } when the system will do something like this if(registrySaysThereIs different behavior set for this ServiceObject) { Class toBeCalled = Class.forName("BehaviorOf" + usedServiceObjectName); Object instance = toBeCalled.getConstructor().newInstance(method,client); instance.preExecute(); ....call the service... instance.postExecute(); .... } I am not particularly interested in correctness of code as in correctness of thinking and approach. Actually I have to do this in PHP, witch I see as a kind of Pop music of programming which I have to "sing" for commercial reasons, even though I play POP I really want to sing by the book, so putting aside my more or less inspired analogy I really want to know your opinion on this matter for it's practical necessity and technical approach. Thanks

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• User Control as container at design time

  - by Luca

  I'm designing a simple expander control. I've derived from UserControl, drawn inner controls, built, run; all ok. Since an inner Control is a Panel, I'd like to use it as container at design time. Indeed I've used the attributes: [Designer(typeof(ExpanderControlDesigner))] [Designer("System.Windows.Forms.Design.ParentControlDesigner, System.Design", typeof(IDesigner))] Great I say. But it isn't... The result is that I can use it as container at design time but: The added controls go back the inner controls already embedded in the user control Even if I push to top a control added at design time, at runtime it is back again on controls embedded to the user control I cannot restrict the container area at design time into a Panel area What am I missing? Here is the code for completeness... why this snippet of code is not working? [Designer(typeof(ExpanderControlDesigner))] [Designer("System.Windows.Forms.Design.ParentControlDesigner, System.Design", typeof(IDesigner))] public partial class ExpanderControl : UserControl { public ExpanderControl() { InitializeComponent(); .... [System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name = "FullTrust")] internal class ExpanderControlDesigner : ControlDesigner { private ExpanderControl MyControl; public override void Initialize(IComponent component) { base.Initialize(component); MyControl = (ExpanderControl)component; // Hook up events ISelectionService s = (ISelectionService)GetService(typeof(ISelectionService)); IComponentChangeService c = (IComponentChangeService)GetService(typeof(IComponentChangeService)); s.SelectionChanged += new EventHandler(OnSelectionChanged); c.ComponentRemoving += new ComponentEventHandler(OnComponentRemoving); } private void OnSelectionChanged(object sender, System.EventArgs e) { } private void OnComponentRemoving(object sender, ComponentEventArgs e) { } protected override void Dispose(bool disposing) { ISelectionService s = (ISelectionService)GetService(typeof(ISelectionService)); IComponentChangeService c = (IComponentChangeService)GetService(typeof(IComponentChangeService)); // Unhook events s.SelectionChanged -= new EventHandler(OnSelectionChanged); c.ComponentRemoving -= new ComponentEventHandler(OnComponentRemoving); base.Dispose(disposing); } public override System.ComponentModel.Design.DesignerVerbCollection Verbs { get { DesignerVerbCollection v = new DesignerVerbCollection(); v.Add(new DesignerVerb("&asd", new EventHandler(null))); return v; } } } I've found many resources (Interaction, designed, limited area), but nothing was usefull for being operative... Actually there is a trick, since System.Windows.Forms classes can be designed (as usual) and have a correct behavior at runtime (TabControl, for example).

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• Multi-Threading Question Concerning WPF

  - by Andrew

  Hello, I'm a newbie to threading, and I don't really know how to code a particular task. I would like to handle a mouse click event on a window that will kick off a while loop in a seperate thread. This thread, which is distinct from the UI thread, should call a function in the while loop which updates a label on the window being serviced by the UI thread. The while loop should stop running when the left mouse button is no longer being pressed. All the loop does is increment a counter, and then repeatedly call the function which displays the updated value in the window. The code for the window and all of the threading is given below (I keep getting some error about STA threading, but don't know where to put the attribute). Also, I'm hoping to use this solution, if it ever works, in another project that makes asynchronous calls elsewhere to a service via wcf, so I was hoping not to make any application-wide special configurations, since I'm really new to multi-threading and am quite worried about breaking other code in a larger program... Here's what I have: <Window x:Class="WpfApplication2.MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:local="clr-namespace:WpfApplication2" Name="MyMainWindow" Title="MainWindow" Width="200" Height="150" PreviewMouseLeftButtonDown="MyMainWindow_PreviewMouseLeftButtonDown"> <Label Height="28" Name="CounterLbl" /> </Window> And here's the code-behind: using System.Windows; using System.Windows.Input; using System.Threading; namespace WpfApplication2 { /// <summary> /// Interaction logic for MainWindow.xaml /// </summary> public partial class MainWindow : Window { private int counter = 0; public MainWindow() { InitializeComponent(); } private delegate void EmptyDelegate(); private void MyMainWindow_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e) { Thread counterThread = new Thread(new ThreadStart(MyThread)); counterThread.Start(); } private void MyThread() { while (Mouse.LeftButton == MouseButtonState.Pressed) { counter++; Dispatcher.Invoke(new EmptyDelegate(UpdateLabelContents), null); } } private void UpdateLabelContents() { CounterLbl.Content = counter.ToString(); } } } Anyways, multi-threading is really new to me, and I don't have any experience implementing it, so any thoughts or suggestions are welcome! Thanks, Andrew

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• How to do a proper search with nhibernate

  - by Denis Rosca

  Hello everyone, i'm working on a small project that is supposed to allow basic searches of the database. Currently i'm using nhibernate for the database interaction. In the database i have 2 tables: Person and Address. The Person table has a many-to-one relationship with Address. The code i've come up with for doing searches is: public IList<T> GetByParameterList(List<QueryParameter> parameterList) { if (parameterList == null) { return GetAll(); } using (ISession session = NHibernateHelper.OpenSession()) { ICriteria criteria = session.CreateCriteria<T>(); foreach (QueryParameter param in parameterList) { switch (param.Constraint) { case ConstraintType.Less: criteria.Add(Expression.Lt(param.ParameterName, param.ParameterValue)); break; case ConstraintType.More: criteria.Add(Expression.Gt(param.ParameterName, param.ParameterValue)); break; case ConstraintType.LessOrEqual: criteria.Add(Expression.Le(param.ParameterName, param.ParameterValue)); break; case ConstraintType.EqualOrMore: criteria.Add(Expression.Ge(param.ParameterName, param.ParameterValue)); break; case ConstraintType.Equals: criteria.Add(Expression.Eq(param.ParameterName, param.ParameterValue)); break; case ConstraintType.Like: criteria.Add(Expression.Like(param.ParameterName, param.ParameterValue)); break; } } try { IList<T> result = criteria.List<T>(); return result; } catch { //TODO: Implement some exception handling throw; } } } The query parameter is a helper object that i use to create criterias and send it to the dal, it looks like this: public class QueryParameter { public QueryParameter(string ParameterName, Object ParameterValue, ConstraintType constraintType) { this.ParameterName = ParameterName; this.ParameterValue = ParameterValue; this.Constraint = constraintType; } public string ParameterName { get; set; } public Object ParameterValue { get; set; } public ConstraintType Constraint { get; set; } } Now this works well if i'm doing a search like FirstName = "John" , but not when i try to give a parameter like Street = "Some Street". It seems that nhibernate is looking for a street column in the Person table but not in the Address table. Any idea on how should i change my code for so i could do a proper search? Tips? Maybe some alternatives? Disclaimer: i'm kind of a noob so please be gentle ;) Thanks, Denis.

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• custom control in DataGridTemplateColumn

  - by Johnsonlu

  Hi all, I'd like to add my custom control into a template column of data grid. The custom control is very similar to a text box, but has an icon in it. The user can click the icon, and selects an item from a prompted window, then the selected item will be filled into the text box. My problem is when the text box is filled, after I click the second column, the text will disappear. If I replace the custom control with a simple text box, the result is the same. Here is the sample code: //Employee.cs using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace SimpleGridTest { public class Employee { public string Department { get; set; } public int ID { get; set; } public string Name { get; set; } } } Mainwindow.xaml <Window x:Class="SimpleGridTest.MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="MainWindow" Height="350" Width="525"> <Grid> <DataGrid x:Name="grid" Grid.Row="1" Margin="5" AutoGenerateColumns="False" RowHeight="25" RowHeaderWidth="10" ItemsSource="{Binding}" CanUserAddRows="True" CanUserSortColumns="False"> <DataGrid.Columns> <DataGridTemplateColumn Header="Department" Width="150"> <DataGridTemplateColumn.CellTemplate> <DataTemplate> <TextBox Text="{Binding Department}" /> </DataTemplate> </DataGridTemplateColumn.CellTemplate> </DataGridTemplateColumn> <DataGridTextColumn Header="ID" Binding="{Binding Path=ID}" Width="100"/> <DataGridTextColumn Header="Name" Binding="{Binding Path=Name}" Width="200"/> </DataGrid.Columns> </DataGrid> </Grid> </Window> MainWindow.xaml.cs using System.Windows; using System.Collections.ObjectModel; namespace SimpleGridTest { /// <summary> /// Interaction logic for MainWindow.xaml /// </summary> public partial class MainWindow : Window { private ObservableCollection<Employee> _employees = new ObservableCollection<Employee>(); public ObservableCollection<Employee> Employees { get { return _employees; } set { _employees = value; } } public MainWindow() { InitializeComponent(); grid.ItemsSource = Employees; } } } How can I fix this problem? Or I need to write a DataGrid***Column as DataGridTextColumn? Thanks in advance! Best Regards, Johnson

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• C# DLL Deployed in COM+. Error while accessing the methods.

  - by Dakshinamurthy

  I have the C# Dll (ABService) deployed in COM + and my os Is windows 2008. I have given the strong name for this dll and its dependent dll’s When I access the method of this dll through localhost or if I add the reference to the client project the method are executed successfully. Simply if I access the dll from the same machine with the reference it is working. So I think there is no problem with the way I deployed in the COM +. I have the doubt whether I have the problem in OS and Visual Studio 2008 combination. I have built all the dll with the Visual Studio 2008 with Target cpu as x86 and targert framework as 2.0. I have given in below the codes I have tried with and the errors. I need to create the object for the dll in server machine(64 bit) and access its method from the client(32 bit) Code : Type svr = Type.GetTypeFromProgID("ABService.Service", strserver1url[2],false); ABService.Service service1= (ABService.Service)Activator.CreateInstance(svr); strresult = service1.ExecuteService(orequest.xml); Error :{"Retrieving the COM class factory for remote component with CLSID {77BF00E0-41AC-3967-9E72-A4927CC0B880} from machine 10.105.138.64 failed due to the following error: 80040154."} Code Type svr = Type.GetTypeFromProgID("ABService.Service", strserver1url[2],true); object Service1 = null; Service1 = (ABService.Service)Activator.CreateInstance(svr, true); strresult = Convert.ToString(ReflectionHelper.Invoke(Service1, "ExecuteService", new object[] { orequest.xml })); Service1 = null; Error: Retrieving the COM class factory for remote component with CLSID {77BF00E0-41AC-3967-9E72-A4927CC0B880} from machine ftpsite failed due to the following error: 80040154. With the below code instead of C#.Net dll if i have the vb dll in Com + the method is executed successfully. Code ords = new RDS.DataSpace(); ords.InternetTimeout = 600000; object M_Service = null; ABService.Service oabservice = null; M_Service = ords.CreateObject("ABService.Service",url); strresult = Convert.ToString(ReflectionHelper.Invoke(M_Service, "ExecuteService", new object[] { orequest.xml })); Error : {"Object doesn't support this property or method 'ExecuteService'"} Code object obj=Interaction.CreateObject("ABService.Service", "10.105.138.64"); strresult = Convert.ToString(ReflectionHelper.Invoke(obj, "ExecuteService", new object[] { orequest.xml })); Error: {"Cannot create ActiveX component."} Code object obj = Activator.GetObject(typeof(ABService.Service), @"http://10.105.138.64:80/ABANET"); strresult = Convert.ToString(ReflectionHelper.Invoke(obj, "ExecuteService", new object[] { orequest.xml })); Error: InnerException {"The remote server returned an error: (405) Method Not Allowed."} System.Exception {System.Net.WebException} Message "Exception has been thrown by the target of an invocation.”

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• Any thoughts on how to create a true 'punch-out' area in a Sprite?

  - by rhtx

  I've been working on this for awhile, now. You might also call it a 'reverse mask', or an 'inverse mask'. Basically, I'm creating a view window within a display object. I need to allow objects on the stage that are under the window to be able to interact with the mouse. This is similar to a WPF question: http://stackoverflow.com/questions/740994/use-wpf-object-to-punch-hole-in-another, which has a much shorter write-up. I've got a Class called PunchOutShield, which creates a Sprite that covers the stage (or over some desired area). The Sprite's Graphics object is filled using the color and transparency of Flex's modal screen. The result is a screen that looks like the screen which appears behind a modal PopUp. PunchOutShield has a method called punch, which takes two arguments - the first is a Shape object, which defines the shape of the punch-through area; the second is a Point object, which indicates where to position the punch-through area. It took some experimenting, but I found that I can successfully create a punch-out area (i.e. - the modal screen does not display within the bounds of the given Shape). To do this, I set cacheAsBitmap to true on the Sprite that is used to create the modal screen, and also on the Shape object, which is added to the modal screen Sprite's displayList. If I set the blend mode of the Shape to ERASE, a completely transparent area is created in the modal screen. So far, great. The problem is that Shape does not subclass InteractiveObject, so there is no way to set mouseEnabled = false on it. And so, it prevents interaction between the mouse and any objects that are visible through the punch-out area. On top of that, InteractiveObject isn't available to look at, so I can't see if there is a way to borrow what it's doing to provide the mouseEnabled functionality and apply it to a subclass of Shape. I've tried using another Sprite object, rather than a Shape object, but the blending doesn't work out correctly. I'm not sure why there is a difference, but the Shape object seems to somehow combine with the parenting Sprite, allowing the ERASE blendMode to effect the desired punch-out visual appearance. It wouldn't be the end of the world if I had to draw up the screen with a series of rectangles so that the punch-out area was just simply not drawn, but that approach won't work if the punch-out area is complex. Or round. Any thoughts on this approach, or on an alternative approach?

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• User Control as container

  - by Luca

  I'm designing a simple expander control. I've derived from UserControl, drawn inner controls, built, run; all ok. Since an inner Control is a Panel, I'd like to use it as container at design time. Indeed I've used the attributes: [Designer(typeof(ExpanderControlDesigner))] [Designer("System.Windows.Forms.Design.ParentControlDesigner, System.Design", typeof(IDesigner))] Great I say. But it isn't... The result is that I can use it as container at design time but: The added controls go back the inner controls already embedded in the user control Even if I push to top a control added at design time, at runtime it is back again on controls embedded to the user control I cannot restrict the container area at design time into a Panel area What am I missing? Here is the code for completeness... why this snippet of code is not working? [Designer(typeof(ExpanderControlDesigner))] [Designer("System.Windows.Forms.Design.ParentControlDesigner, System.Design", typeof(IDesigner))] public partial class ExpanderControl : UserControl { public ExpanderControl() { InitializeComponent(); .... [System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name = "FullTrust")] internal class ExpanderControlDesigner : ControlDesigner { private ExpanderControl MyControl; public override void Initialize(IComponent component) { base.Initialize(component); MyControl = (ExpanderControl)component; // Hook up events ISelectionService s = (ISelectionService)GetService(typeof(ISelectionService)); IComponentChangeService c = (IComponentChangeService)GetService(typeof(IComponentChangeService)); s.SelectionChanged += new EventHandler(OnSelectionChanged); c.ComponentRemoving += new ComponentEventHandler(OnComponentRemoving); } private void OnSelectionChanged(object sender, System.EventArgs e) { } private void OnComponentRemoving(object sender, ComponentEventArgs e) { } protected override void Dispose(bool disposing) { ISelectionService s = (ISelectionService)GetService(typeof(ISelectionService)); IComponentChangeService c = (IComponentChangeService)GetService(typeof(IComponentChangeService)); // Unhook events s.SelectionChanged -= new EventHandler(OnSelectionChanged); c.ComponentRemoving -= new ComponentEventHandler(OnComponentRemoving); base.Dispose(disposing); } public override System.ComponentModel.Design.DesignerVerbCollection Verbs { get { DesignerVerbCollection v = new DesignerVerbCollection(); v.Add(new DesignerVerb("&asd", new EventHandler(null))); return v; } } } I've found many resources (Interaction, designed, limited area), but nothing was usefull for being operative...

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• Java DriverManager Always Assigns My Driver

  - by JGB146

  I am writing a driver to act as a wrapper around two separate MySQL connections (to distributed databases). Basically, the goal is to enable interaction with my driver for all applications instead of requiring the application to sort out which database holds the desired data. Most of the code for this is in place, but I'm having a problem in that when I attempt to create connections via the MySQL Driver, the DriverManager is returning an instance of my driver instead of the MySQL Driver. I'd appreciate any tips on what could be causing this and what could be done to fix it! Below is a few relevant snippets of code. I can provide more, but there's a lot, so I'd need to know what else you want to see. First, from MyDriver.java: public MyDriver() throws SQLException { DriverManager.registerDriver(this); } public Connection connect(String url, Properties info) throws SQLException { try { return new MyConnection(info); } catch (Exception e) { return null; } } public boolean acceptsURL(String url) throws SQLException { if (url.contains("jdbc:jgb://")) { return true; } return false; } It is my understanding that this acceptsURL function will dictate whether or not the DriverManager deems my driver a suitable fit for a given URL. Hence it should only be passing connections from my driver if the URL contains "jdbc:jgb://" right? Here's code from MyConnection.java: Connection c1 = null; Connection c2 = null; /** *Constructors */ public DDBSConnection (Properties info) throws SQLException, Exception { info.list(System.out); //included for testing Class.forName("com.mysql.jdbc.Driver").newInstance(); String url1 = "jdbc:mysql://server1.com/jgb"; String url2 = "jdbc:mysql://server2.com/jgb"; this.c1 = DriverManager.getConnection( url1, info.getProperty("username"), info.getProperty("password")); this.c2 = DriverManager.getConnection( url2, info.getProperty("username"), info.getProperty("password")); } And this tells me two things. First, the info.list() call confirms that the correct user and password are being sent. Second, because we enter an infinite loop, we see that the DriverManager is providing new instances of my connection as matches for the mysql URLs instead of the desired mysql driver/connection. FWIW, I have separately tested implementations that go straight to the mysql driver using this exact syntax (al beit only one at a time), and was able to successfully interact with each database individually from a test application outside of my driver.

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