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  • Adding a UIPickerView over a UITabBarController

    - by Kai
    I'm trying to have a UIPickerView slide from the bottom of the screen (over the top of a tab bar) but can't seem to get it to show up. The actual code for the animation is coming from one of Apple's example code projects (DateCell). I'm calling this code from the first view controller (FirstViewController.m) under the tab bar controller. - (IBAction)showModePicker:(id)sender { if (self.modePicker.superview == nil) { [self.view.window addSubview:self.modePicker]; // size up the picker view to our screen and compute the start/end frame origin for our slide up animation // // compute the start frame CGRect screenRect = [[UIScreen mainScreen] applicationFrame]; CGSize pickerSize = [self.modePicker sizeThatFits:CGSizeZero]; CGRect startRect = CGRectMake(0.0, screenRect.origin.y + screenRect.size.height, pickerSize.width, pickerSize.height); self.modePicker.frame = startRect; // compute the end frame CGRect pickerRect = CGRectMake(0.0, screenRect.origin.y + screenRect.size.height - pickerSize.height, pickerSize.width, pickerSize.height); // start the slide up animation [UIView beginAnimations:nil context:NULL]; [UIView setAnimationDuration:0.3]; // we need to perform some post operations after the animation is complete [UIView setAnimationDelegate:self]; self.modePicker.frame = pickerRect; // shrink the vertical size to make room for the picker CGRect newFrame = self.view.frame; newFrame.size.height -= self.modePicker.frame.size.height; self.view.frame = newFrame; [UIView commitAnimations]; // add the "Done" button to the nav bar self.navigationItem.rightBarButtonItem = self.doneButton; }} Whenever this action fires via a UIBarButtonItem that lives in a UINavigationBar (which is all under the FirstViewController) nothing happens. Can anyone please offer some advice?

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  • Polymorphic Numerics on .Net and In C#

    - by Bent Rasmussen
    It's a real shame that in .Net there is no polymorphism for numbers, i.e. no INumeric interface that unifies the different kinds of numerical types such as bool, byte, uint, int, etc. In the extreme one would like a complete package of abstract algebra types. Joe Duffy has an article about the issue: http://www.bluebytesoftware.com/blog/CommentView,guid,14b37ade-3110-4596-9d6e-bacdcd75baa8.aspx How would you express this in C#, in order to retrofit it, without having influence over .Net or C#? I have one idea that involves first defining one or more abstract types (interfaces such as INumeric - or more abstract than that) and then defining structs that implement these and wrap types such as int while providing operations that return the new type (e.g. Integer32 : INumeric; where addition would be defined as public Integer32 Add(Integer32 other) { return Return(Value + other.Value); } I am somewhat afraid of the execution speed of this code but at least it is abstract. No operator overloading goodness... Any other ideas? .Net doesn't look like a viable long-term platform if it cannot have this kind of abstraction I think - and be efficient about it. Abstraction is reuse.

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  • How would I go about sharing variables in a class with Lua?

    - by Nicholas Flynt
    I'm fairly new to Lua, I've been working on trying to implement Lua scripting for logic in a Game Engine I'm putting together. I've had no trouble so far getting Lua up and running through the engine, and I'm able to call Lua functions from C and C functions from Lua. The way the engine works now, each Object class contains a set of variables that the engine can quickly iterate over to draw or process for physics. While game objects all need to access and manipulate these variables in order for the Game Engine itself to see any changes, they are free to create their own variables, a Lua is exceedingly flexible about this so I don't forsee any issues. Anyway, currently the Game Engine side of things are sitting in C land, and I really want them to stay there for performance reasons. So in an ideal world, when spawning a new game object, I'd need to be able to give Lua read/write access to this standard set of variables as part of the Lua object's base class, which its game logic could then proceed to run wild with. So far, I'm keeping two separate tables of objects in place-- Lua spawns a new game object which adds itself to a numerically indexed global table of objects, and then proceeds to call a C++ function, which creates a new GameObject class and registers the Lua index (an int) with the class. So far so good, C++ functions can now see the Lua object and easily perform operations or call functions in Lua land using dostring. What I need to do now is take the C++ variables, part of the GameObject class, and expose them to Lua, and this is where google is failing me. I've encountered a very nice method here which details the process using tags, but I've read that this method is deprecated in favor of metatables. What is the ideal way to accomplish this? Is it worth the hassle of learning how to pass class definitions around using libBind or some equivalent method, or is there a simple way I can just register each variable (once, at spawn time) with the global lua object? What's the "current" best way to do this, as of Lua 5.1.4?

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  • How to record different authentication types (username / password vs token based) in audit log

    - by RM
    I have two types of users for my system, normal human users with a username / password, and delegation authorized accounts through OAuth (i.e. using a token identifier). The information that is stored for each is quite different, and are managed by different subsytems. They do however interact with the same tables / data within the system, so I need to maintain the audit trail regardless of whether human user, or token-based user modified the data. My solution at the moment is to have a table called something like AuditableIdentity, and then have the two types inheriting off that table (either in the single table, or as two seperate tables with 1 to 1 PK with AuditableIdentity. All operations would use the common AuditableIdentity PK for CreatedBy, ModifiedBy etc columns. There isn't any FK constraint on the audit columns, so any text can go in there, but I want an easy way to easily determine whether it was a human or system that made the change, and joining to the one AuditableIdentity table seems like a clean way to do that? Is there a best practice for this scenario? Is this an appropriate way of approaching the problem - or would you not bother with the common table and just rely on joins (to the two seperate un-related user / token tables) later to determine which user type matches which audit records?

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  • What is the 'page lifecycle' of an ASP.NET MVC page, compared to ASP.NET WebForms?

    - by Simon
    What is the 'page lifecycle' of an ASP.NET MVC page, compared to ASP.NET WebForms? I'm tryin to better understand this 'simple' question in order to determine whether or not existing pages I have in a (very) simple site can be easily converted from ASP.NET WebForms. Either a 'conversion' of the process below, or an alternative lifecycle would be what I'm looking for. What I'm currently doing: (yes i know that anyone capable of answering my question already knows all this -- i'm just tryin to get a comparison of the 'lifecycle' so i thought i'd start by filling in what we already all know) Rendering the page: I have a master page which contains my basic template I have content pages that give me named regions from the master page into which I put content. In an event handler for each content page I load data from the database (mostly read-only). I bind this data to ASP.NET controls representing grids, dropdowns or repeaters. This data all 'lives' inside the HTML generated. Some of it gets into ViewState (but I wont go into that too much!) I set properties or bind data to certain items like Image or TextBox controls on the page. The page gets sent to the client rendered as non-reusable HTML. I try to avoid using ViewState other than what the page needs as a minimum. Client side (not using ASP.NET AJAX): I may use JQuery and some nasty tricks to find controls on the page and perform operations on them. If the user selects from a dropdown -- a postback is generated which triggers a C# event in my codebehind. This event may go to the database, but whatever it does a completely newly generated HTML page ends up getting sent back to the client. I may use Page.Session to store key value pairs I need to reuse later So with MVC how does this 'lifecycle' change?

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  • How to highlight the button untill the next view is changed in iphone?

    - by Pugal Devan
    Hi, I am new to iphone development. I have created five buttons in the view controller. If i clicked the button it goes to the corresponding view. Now i want to display the button in highlighted state when it is clicked. It should go back to the normal state only when i click the other button.(See the image below). I have set the another image for highigthting buttons when i clicked it, but it shows that highlighted state only one sec. Now i want to display the buttons highlighted till another button is clicked. Same like a Tabbar operations.(I have used buttons instead of tabbar for my requirements). Now i have used the following code, void didLoad { [btn1 setImage:[UIImage imageNamed:@"ContentColor.png"] forState:UIControlStateHighlighted]; [btn2 setImage:[UIImage imageNamed:@"bColor.png"] forState:UIControlStateHighlighted]; [btn3 setImage:[UIImage imageNamed:@"ShColor.png"] forState:UIControlStateHighlighted]; [btn4 setImage:[UIImage imageNamed:@"PicturesColor.png"] forState:UIControlStateHighlighted]; [btn5 setImage:[UIImage imageNamed:@"infoColor.png"] forState:UIControlStateHighlighted]; } Please help me out. Thanks.

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  • DQL delete from multiple tables (doctrine)

    - by singer
    Need to perform DQL delete from multple related tables. In SQL it is something like this: DELETE r1,r2 FROM ComRealty_objects r1, com_realty_objects_phones r2 WHERE r1.id IN (10,20) AND r2.id_object IN (10,20) I need to perform this statement using DQL, but I'm stuck on this :( <?php $dql = Doctrine_Query::create() ->delete('phones, comrealtyobjects') ->from('ComRealtyObjects comrealtyobjects') ->from('ComRealtyObjectsPhones phones') ->whereIn("comrealtyobjects.id", $ids) ->whereIn("phones.id_object", $ids); echo($dql->getSqlQuery()); ?> But DQL parser gives me this result: DELETE FROM `com_realty_objects_phones`, `ComRealty_objects` WHERE (`id` IN (?) AND `id_object` IN (?)) Searching google and stack overflow I found this(useful) topic: http://stackoverflow.com/questions/2247905/what-is-the-syntax-for-a-multi-table-delete-on-a-mysql-database-using-doctrine But this is not exactly my case - there was delete from single table. If there is a way to override dql parser behaviour? Or maybe some other way to delete records from multiple tables using doctrine. Note: If you are using doctrine behaviours(Doctrine_Record_Generator) you need first to initialize those tables using Doctrine_Core::initializeModels() to perform DQL operations on them.

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  • Fast sign in C++ float...are there any platform dependencies in this code?

    - by Patrick Niedzielski
    Searching online, I have found the following routine for calculating the sign of a float in IEEE format. This could easily be extended to a double, too. // returns 1.0f for positive floats, -1.0f for negative floats, 0.0f for zero inline float fast_sign(float f) { if (((int&)f & 0x7FFFFFFF)==0) return 0.f; // test exponent & mantissa bits: is input zero? else { float r = 1.0f; (int&)r |= ((int&)f & 0x80000000); // mask sign bit in f, set it in r if necessary return r; } } (Source: ``Fast sign for 32 bit floats'', Peter Schoffhauzer) I am weary to use this routine, though, because of the bit binary operations. I need my code to work on machines with different byte orders, but I am not sure how much of this the IEEE standard specifies, as I couldn't find the most recent version, published this year. Can someone tell me if this will work, regardless of the byte order of the machine? Thanks, Patrick

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  • Writing fortran robust and "modern" code

    - by Blklight
    In some scientific environments, you often cannot go without FORTRAN as most of the developers only know that idiom, and there is lot of legacy code and related experience. And frankly, there are not many other cross-platform options for high performance programming ( C++ would do the task, but the syntax, zero-starting arrays, and pointers are too much for most engineers ;-) ). I'm a C++ guy but I'm stuck with some F90 projects. So, let's assume a new project must use FORTRAN (F90), but I want to build the most modern software architecture out of it. while being compatible with most "recent" compilers (intel ifort, but also including sun/HP/IBM own compilers) So I'm thinking of imposing: global variable forbidden, no gotos, no jump labels, "implicit none", etc. "object-oriented programming" (modules with datatypes + related subroutines) modular/reusable functions, well documented, reusable libraries assertions/preconditions/invariants (implemented using preprocessor statements) unit tests for all (most) subroutines and "objects" an intense "debug mode" (#ifdef DEBUG) with more checks and all possible Intel compiler checks possible (array bounds, subroutine interfaces, etc.) uniform and enforced legible coding style, using code processing tools C stubs/wrappers for libpthread, libDL (and eventually GPU kernels, etc.) C/C++ implementation of utility functions (strings, file operations, sockets, memory alloc/dealloc reference counting for debug mode, etc.) ( This may all seem "evident" modern programming assumptions, but in a legacy fortran world, most of these are big changes in the typical programmer workflow ) The goal with all that is to have trustworthy, maintainable and modular code. Whereas, in typical fortran, modularity is often not a primary goal, and code is trustworthy only if the original developer was very clever, and the code was not changed since then ! (i'm a bit joking here, but not much) I searched around for references about object-oriented fortran, programming-by-contract (assertions/preconditions/etc.), and found only ugly and outdated documents, syntaxes and papers done by people with no large-scale project involvement, and dead projects. Any good URL, advice, reference paper/books on the subject?

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  • Application log aggregation, management and notifications...

    - by Matthew Savage
    I'm wondering what everyone is using for logging, log management and log aggregation on their systems. I am working in a company which uses .NET for all it's applications and all systems are Windows based. Currently each application looks after its own logging and notifications of failures (e.g. if app A fails it will send out its own 'call for help' to an admin). While this current practice works its a bit hacky and hard to manage. I've been trying to find some options for making this work better and I've come up with the following: log4net & Chainsaw (ah, if it works). Logging via log4net or another framework into a central database & rolling our own management tool. Logging to the Windows event log and using MOM or System Center Operations Manager to aggregate and manage each of these servers & their apps. A hand-rolled solution to suck all the log files into one point and work some magic across them. Essentially what we are after is something which can pull log entries all together and allow for some analytics to be run across them, plus use a kind of event based system to, for example, send out a warning email when there have been 30+ warning level logs for an application in the last x minutes. So is there anything I've missed, or something someone else can suggest?

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  • Is there a PHP benchmark that meets these specific criteria? [closed]

    - by Alex R
    I'm working on a tool which converts PHP code to Scala. As one of the finishing touches, I'm in need of a really good (er, somewhat biased) benchmark. By dumb luck my first benchmark attempt was with some code which uses bcmath extensively, which unfortunately is 1000x slower in Java, making the Scala code 22x slower overall than the original PHP. So I'm looking for some meaningful PHP benchmark with the following characteristics: The PHP source needs to be in a single file. It should solve a real-world problem. No silly looping over empty methods etc. I need it to be simple to setup - no databases, hard-to-find input files, etc. Simple text input and output preferred. It should not use features that are slow in Java (BigInteger, trigonometric functions, etc). It should not use exoteric or dynamic PHP functions (e.g. no "eval" or "variable vars"). It should not over-rely on built-in libraries, e.g. MD5, crypt, etc. It should not be I/O bound. A CPU-bound memory-hungry algorithm is preferred. Basically, intensive OO operations, integer and string manipulation, recursion, etc would be great. Thanks

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  • IE performance issues with offsetHeight and offsetWidth

    - by Paul
    I have a site that grabs the response text from an AJAX call and does 'innerHTML' on a div that is going to contain it. After I do the 'innerHTML' I process the DIV by traversing the whole hierarchy of nodes and grabbing their [offsetWidth/offsetHeight] to do some operations with it. Why not css style width/height? because sometimes those values are not available since I don't control what is coming from the AJAX response, plus I want the real box dimensions including borders/scrolls/padding. On large injections (let's say 7,000 new DOM elements) IE takes way longer time than FF/Safari just to get this [offsetWidth/offsetHeight], actually if I wasn't doing injection but just render the contents of the HTML in the browser and processing it, it would be much faster. But that is not an option since I have to inject it on a div that will contain it. Anybody has deal with this kind of issue before? is there an alternative to innerHTML, I have try using documentFragment to inject and process and the move it to the div and still I don't see much gain. How can I get the values that are available with [offsetWidth/offsetHeight]? Thanks a bunch for any suggestions. Paul

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  • Complex derived attributes in Django models

    - by rabidpebble
    What I want to do is implement submission scoring for a site with users voting on the content, much like in e.g. reddit (see the 'hot' function in http://code.reddit.com/browser/sql/functions.sql). My submission model currently keeps track of up and down vote totals. Currently, when a user votes I create and save a related Vote object and then use F() expressions to update the Submission object's voting totals. The problem is that I want to update the score for the submission at the same time, but F() expressions are limited to only simple operations (it's missing support for log(), date_part(), sign() etc.) From my limited experience with Django I can see 4 options here: extend F() somehow (haven't looked at the code yet) to support the missing SQL functions; this is my preferred option and seems to fit within the Django framework the best define a scoring function (much like reddit's 'hot' function) in my database, and have Django use the value of that function for the value of the score field; as far as I can tell, #2 is not possible wrap my two step voting process in a suitably isolated transaction so that I can calculate the voting totals in Python and then update the Submission's voting totals without fear that another vote against the submission could be added/changed in the meantime; I'm hesitant to take this route because it seems overly complex - what is a "suitably isolated transaction" in this case anyway? use raw SQL; I would prefer to avoid this entirely -- what's the point of an ORM if I have to revert to SQL for such a common use case as this! (Note that this coming from somebody who loves sprocs, but is using Django for ease of development.) Before I embark on this mission to extend F() (which I'm not sure is even possible), am I about to reinvent the wheel? Is there a more standard way to do this? It seems like such a common use case and yet in an hour of searching I have yet to find a common solution...

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  • Game of life in F# with accelerator

    - by jpalmer
    I'm trying to write life in F# using accelerator v2, but for some odd reason my output isn't square despite all my arrays being square - It appears that everything but a rectangular area in the top left of the matrix is being set to false. I've got no idea how this could be happening as all my operations should treat the entire array equally. Any ideas? open Microsoft.ParallelArrays open System.Windows.Forms open System.Drawing type IPA = IntParallelArray type BPA = BoolParallelArray type PAops = ParallelArrays let RNG = new System.Random() let size = 1024 let arrinit i = Array2D.init size size (fun x y -> i) let target = new DX9Target() let threearr = new IPA(arrinit 3) let twoarr = new IPA(arrinit 2) let onearr = new IPA(arrinit 1) let zeroarr = new IPA(arrinit 0) let shifts = [|-1;-1|]::[|-1;0|]::[|-1;1|]::[|0;-1|]::[|0;1|]::[|1;-1|]::[|1;0|]::[|1;1|]::[] let progress (arr:BPA) = let sums = shifts //adds up whether a neighbor is on or not |> List.fold (fun (state:IPA) t ->PAops.Add(PAops.Cond(PAops.Rotate(arr,t),onearr,zeroarr),state)) zeroarr PAops.Or(PAops.CompareEqual(sums,threearr),PAops.And(PAops.CompareEqual(sums,twoarr),arr)) //rule for life let initrandom () = Array2D.init size size (fun x y -> if RNG.NextDouble() > 0.5 then true else false) type meform () as self= inherit Form() let mutable array = new BoolParallelArray(initrandom()) let timer = new System.Timers.Timer(1.0) //redrawing timer do base.DoubleBuffered <- true do base.Size <- Size(size,size) do timer.Elapsed.Add(fun _ -> self.Invalidate()) do timer.Start() let draw (t:Graphics) = array <- array |> progress let bmap = new System.Drawing.Bitmap(size,size) target.ToArray2D array |> Array2D.iteri (fun x y t -> if not t then bmap.SetPixel(x,y,Color.Black)) t.DrawImageUnscaled(bmap,0,0) do self.Paint.Add(fun t -> draw t.Graphics) do Application.Run(new meform())

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  • Pass a data.frame column name to a function

    - by Kevin Middleton
    I'm trying to write a function to accept a data.frame (x) and a column from it. The function performs some calculations on x and later returns another data.frame. I'm stuck on the best-practices method to pass the column name to the function. The two minimal examples fun1 and fun2 below produce the desired result, being able to perform operations on x$column, using max() as an example. However, both rely on the seemingly (at least to me) inelegant (1) call to substitute() and possibly eval() and (2) the need to pass the column name as a character vector. fun1 <- function(x, column){ do.call("max", list(substitute(x[a], list(a = column)))) } fun2 <- function(x, column){ max(eval((substitute(x[a], list(a = column))))) } df <- data.frame(A = 1:20, B = rnorm(10)) fun1(df, "B") fun2(df, "B") I would like to be able to call the function as fun(df, B), for example. Other options I have considered but have not tried: Pass column as an integer of the column number. I think this would avoid substitute(). Ideally, the function could accept either. with(x, get(column)), but, even if it works, I think this would still require substitute Make use of formula() and match.call(), neither of which I have much experience with. Subquestion: Is do.call() preferred over eval()? Thanks, Kevin

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  • Parsing basic math equations for children's educational software?

    - by Simucal
    Inspired by a recent TED talk, I want to write a small piece of educational software. The researcher created little miniature computers in the shape of blocks called "Siftables". [David Merril, inventor - with Siftables in the background.] There were many applications he used the blocks in but my favorite was when each block was a number or basic operation symbol. You could then re-arrange the blocks of numbers or operation symbols in a line, and it would display an answer on another siftable block. So, I've decided I wanted to implemented a software version of "Math Siftables" on a limited scale as my final project for a CS course I'm taking. What is the generally accepted way for parsing and interpreting a string of math expressions, and if they are valid, perform the operation? Is this a case where I should implement a full parser/lexer? I would imagine interpreting basic math expressions would be a semi-common problem in computer science so I'm looking for the right way to approach this. For example, if my Math Siftable blocks where arranged like: [1] [+] [2] This would be a valid sequence and I would perform the necessary operation to arrive at "3". However, if the child were to drag several operation blocks together such as: [2] [\] [\] [5] It would obviously be invalid. Ultimately, I want to be able to parse and interpret any number of chains of operations with the blocks that the user can drag together. Can anyone explain to me or point me to resources for parsing basic math expressions? I'd prefer as much of a language agnostic answer as possible.

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  • How do I test database-related code with NUnit?

    - by Michael Haren
    I want to write unit tests with NUnit that hit the database. I'd like to have the database in a consistent state for each test. I thought transactions would allow me to "undo" each test so I searched around and found several articles from 2004-05 on the topic: http://weblogs.asp.net/rosherove/archive/2004/07/12/180189.aspx http://weblogs.asp.net/rosherove/archive/2004/10/05/238201.aspx http://davidhayden.com/blog/dave/archive/2004/07/12/365.aspx http://haacked.com/archive/2005/12/28/11377.aspx These seem to resolve around implementing a custom attribute for NUnit which builds in the ability to rollback DB operations after each test executes. That's great but... Does this functionality exists somewhere in NUnit natively? Has this technique been improved upon in the last 4 years? Is this still the best way to test database-related code? Edit: it's not that I want to test my DAL specifically, it's more that I want to test pieces of my code that interact with the database. For these tests to be "no-touch" and repeatable, it'd be awesome if I could reset the database after each one. Further, I want to ease this into an existing project that has no testing place at the moment. For that reason, I can't practically script up a database and data from scratch for each test.

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  • Fastest way to generate delimited string from 1d numpy array

    - by Abiel
    I have a program which needs to turn many large one-dimensional numpy arrays of floats into delimited strings. I am finding this operation quite slow relative to the mathematical operations in my program and am wondering if there is a way to speed it up. For example, consider the following loop, which takes 100,000 random numbers in a numpy array and joins each array into a comma-delimited string. import numpy as np x = np.random.randn(100000) for i in range(100): ",".join(map(str, x)) This loop takes about 20 seconds to complete (total, not each cycle). In contrast, consider that 100 cycles of something like elementwise multiplication (x*x) would take than one 1/10 of a second to complete. Clearly the string join operation creates a large performance bottleneck; in my actual application it will dominate total runtime. This makes me wonder, is there a faster way than ",".join(map(str, x))? Since map() is where almost all the processing time occurs, this comes down to the question of whether there a faster to way convert a very large number of numbers to strings.

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  • OpenGL bitmap text fails after drawing polygon

    - by kaykun
    Hi, I'm using Win32 and OpenGL to to draw text onto a window. I'm using the bitmap font method, with wglUseFontBitmaps. Here is my main rendering function: glClear(GL_COLOR_BUFFER_BIT); glPushMatrix(); glColor3f(1.0f, 0.0f, 1.0f); glBegin(GL_QUADS); glVertex2f(0.0f, 0.0f); glVertex2f(128.0f, 0.0f); glVertex2f(128.0f, 128.0f); glVertex2f(0.0f, 128.0f); glEnd(); glPopMatrix(); glPushMatrix(); glColor3f(1.0f, 1.0f, 1.0f); glRasterPos2i(200, 200); glListBase(fontList); glCallLists(5, GL_UNSIGNED_BYTE, "Test."); glPopMatrix(); SwapBuffers(hDC); As you can see it's very simple and the only thing that it's supposed to do is draw a quadrilateral and draw the text "Test.". But the problem is that drawing a polygon seems to mess up any text operations I try to do after it. If I place the text drawing functions before the polygon, both the text and the polygon draw fine. Is there something I'm missing here? Any help is appreciated.

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  • Is a red-black tree my ideal data structure?

    - by Hugo van der Sanden
    I have a collection of items (big rationals) that I'll be processing. In each case, processing will consist of removing the smallest item in the collection, doing some work, and then adding 0-2 new items (which will always be larger than the removed item). The collection will be initialised with one item, and work will continue until it is empty. I'm not sure what size the collection is likely to reach, but I'd expect in the range 1M-100M items. I will not need to locate any item other than the smallest. I'm currently planning to use a red-black tree, possibly tweaked to keep a pointer to the smallest item. However I've never used one before, and I'm unsure whether my pattern of use fits its characteristics well. 1) Is there a danger the pattern of deletion from the left + random insertion will affect performance, eg by requiring a significantly higher number of rotations than random deletion would? Or will delete and insert operations still be O(log n) with this pattern of use? 2) Would some other data structure give me better performance, either because of the deletion pattern or taking advantage of the fact I only ever need to find the smallest item? Update: glad I asked, the binary heap is clearly a better solution for this case, and as promised turned out to be very easy to implement. Hugo

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  • Templates, and C++ operator for logic: B contained by set A

    - by James Morris
    In C++, I'm looking to implement an operator for selecting items in a list (of type B) based upon B being contained entirely within A. In the book "the logical design of digital computers" by Montgomery Phister jr (published 1958), p54, it says: F11 = A + ~B has two interesting and useful associations, neither of them having much to do with computer design. The first is the logical notation of implication... The second is notation of inclusion... This may be expressed by a familiar looking relation, B < A; or by the statement "B is included in A"; or by the boolean equation F11= A + ~B = 1. My initial implementation was in C. Callbacks were given to the list to use for such operations. An example being a list of ints, and a struct containting two ints, min and max, for selection purposes. There, selection would be based upon B = A-min && B <= A-max. Using C++ and templates, how would you approach this after having implemented a generic list in C using void pointers and callbacks? Is using < as an over-ridden operator for such purposes... <ugh> evil? </ugh> (or by using a class B for the selection criteria, implementing the comparison by overloading ?)

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  • POSTing JSON data to WCF REST

    - by Randall Sexton
    I'm trying to send data from a client application using jQuery to a REST WCF service based on the WCF REST starter kit. Here's what I have so far. Service Definition: [WebHelp(Comment = "Save PropertyValues to the database")] [WebInvoke(Method = "POST", UriTemplate = "PropertyValues_Save", BodyStyle = WebMessageBodyStyle.WrappedRequest, RequestFormat = WebMessageFormat.Json, ResponseFormat = WebMessageFormat.Json)] [OperationContract] public bool PropertyValues_Save(Guid assetId, Dictionary<Guid, string> newValues) { ... } Call from the client: $.ajax({ url:SVC_PROPERTYVALUES_SAVE, type: "POST", contentType: "application/json; charset=utf-8", data: jsonData, dataType: "json", error: function(XMLHttpRequest, textStatus, errorThrown) { alert(textStatus + ' ' + errorThrown); }, success: function(data) { if (data) { alert('Values saved'); $("#confirmSubmit").dialog('close'); } else { alert('Values failed to save'); $("#confirmSubmit").dialog('close'); } } }); Example of the JSON being passed: { "assetId": "d70714c3-e403-4cc5-b8a9-9713d05b2ee0", "newValues": [ { "key": "bd01aa88-b48d-47c7-8d3f-eadf47a46680", "value": "0e9fdf34-2d12-4639-8d70-19b88e753ab1" }, { "key": "06e8eda2-a004-450e-90ab-64df357013cf", "value": "1d490aec-f40e-47d5-865c-07fe9624f955" } ] } I'm using Windows Authentication on the virtual directory. When I call operations that are GETs, everything is fine. This code is prompting the browser to log in. When I enter my credentials, I simply get an alert in my browser which says "error undefined". Even if you can't help my specific error, do you see anything that looks wrong from glancing? I've been beating my head on this nearly all day. Thanks in advance.

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  • An unusual type signature

    - by Travis Brown
    In Monads for natural language semantics, Chung-Chieh Shan shows how monads can be used to give a nicely uniform restatement of the standard accounts of some different kinds of natural language phenomena (interrogatives, focus, intensionality, and quantification). He defines two composition operations, A_M and A'_M, that are useful for this purpose. The first is simply ap. In the powerset monad ap is non-deterministic function application, which is useful for handling the semantics of interrogatives; in the reader monad it corresponds to the usual analysis of extensional composition; etc. This makes sense. The secondary composition operation, however, has a type signature that just looks bizarre to me: (<?>) :: (Monad m) => m (m a -> b) -> m a -> m b (Shan calls it A'_M, but I'll call it <?> here.) The definition is what you'd expect from the types; it corresponds pretty closely to ap: g <?> x = g >>= \h -> return $ h x I think I can understand how this does what it's supposed to in the context of the paper (handle question-taking verbs for interrogatives, serve as intensional composition, etc.). What it does isn't terribly complicated, but it's a bit odd to see it play such a central role here, since it's not an idiom I've seen in Haskell before. Nothing useful comes up on Hoogle for either m (m a -> b) -> m a -> m b or m (a -> b) -> a -> m b. Does this look familiar to anyone from other contexts? Have you ever written this function?

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  • Strange EListError occurance (when accessing variable-defined index)

    - by michal
    Hi, I have a TList which stores some objects. Now I have a function which does some operations on that list: function SomeFunct(const AIndex: integer): IInterface begin if (AIndex > -1) and (AIndex < fMgr.Windows.Count ) then begin if (fMgr.Windows[AIndex] <> nil) then begin if not Supports(TForm(fMgr.Windows[AIndex]), IMyFormInterface, result) then result:= nil; end; end else result:= nil; end; now, what is really strange is that accessing fMgr.Windows with any proper index causes EListError... However if i hard-code it (in example, replace AIndex with value 0 or 1) it works fine. I tried debugging it, the function gets called twice, with arguments 0 and 1 (as supposed). while AIndex = 0, evaluating fMgr.Windows[AIndex] results in EListError at $someAddress, while evaluating fMgr.Windws[0] instead - returns proper results ... what is even more strange, even though there is an EListError, the function returns proper data ... and doesn't show anything. Just info on two EListError memory leaks on shutdown (using FastMM) any ideas what could be wrong?! Thanks in advance michal

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  • A linked list with multiple heads in Java

    - by Emile
    Hi, I have a list in which I'd like to keep several head pointers. I've tried to create multiple ListIterators on the same list but this forbid me to add new elements in my list... (see Concurrent Modification exception). I could create my own class but I'd rather use a built-in implementation ;) To be more specific, here is an inefficient implementation of two basic operations and the one wich doesn't work : class MyList <E { private int[] _heads; private List<E _l; public MyList ( int nbHeads ) { _heads = new int[nbHeads]; _l = new LinkedList<E(); } public void add ( E e ) { _l.add(e); } public E next ( int head ) { return _l.get(_heads[head++]); // ugly } } class MyList <E { private Vector<ListIterator<E _iters; private List<E _l; public MyList ( int nbHeads ) { _iters = new Vector<ListIterator<E(nbHeads); _l = new LinkedList<E(); for( ListIterator<E iter : _iters ) iter = _l.listIterator(); } public void add ( E e ) { _l.add(e); } public E next ( int head ) { // ConcurrentModificationException because of the add() return _iters.get(head).next(); } } Emile

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