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• How to add a user to Wheel group?

  - by Natasha Thapa

  I am trying to add a use to wheel group using in a Ubuntu server. sudo usermod -aG wheel john I get: usermod: group 'wheel' does not exist On my /etc/sudoers I have this: > cat /etc/sudoers > # sudoers file. > # > # This file MUST be edited with the 'visudo' command as root. > # > # See the sudoers man page for the details on how to write a sudoers file. > # > > # Host alias specification > > # User alias specification > > # Cmnd alias specification > > # Defaults specification > > # User privilege specification root ALL=(ALL) ALL %root ALL=(ALL) NOPASSWD: ALL > > %wheel ALL=(ALL) NOPASSWD: ALL Do I have to do groupadd of wheel?

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• How to invert scroll wheel in certain applications using AutoHotkey?

  - by endolith

  I want to be able to modify the scrolling/middle click behavior for individual apps on Windows 7, so that the scroll to zoom direction is always consistent across apps. This script makes the middle button act as a hand tool in Adobe Acrobat, for instance: ; Hand tool with middle button in Adobe Reader #IfWinActive ahk_class AdobeAcrobat Mbutton:: #IfWinActive ahk_class AcrobatSDIWindow Mbutton:: Send {Space down}{LButton down} ; Hold down the left mouse button. KeyWait Mbutton ; Wait for the user to release the middle button. Send {LButton up}{Space up} ; Release the left mouse button. return #IfWinActive (It would be great if this could be adapted to allow "throwing" the document, too, like in Android or iPhone interfaces, but I don't know if it's possible to control scrolling that precisely) How do I invert the scroll wheel--zoom direction?

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• My Thoughts on Reinventing the Wheel

  - by Matt Christian

  For awhile now I've known that XNA Game Studio contains built-in scene management however I still built my own for each engine.  Obviously it was redundant and probably inefficient due to the amount of searching and such I was required to do.  And even though I knew this, why did I continue to do it? I've always been very detail oriented, probably part of my mild OCD.  But when it comes to technology I believe in both reinventing the wheel and not reinventing it all at the same time.  Here's what I imagine most programmers doing.  When they pick up XNA, they're typically focused on 'I want to make a game with as little code as possible'.  This is great and XNA GS is a great tool, but what will it do for programmers that want to make games with XNA?  If they don't have any prior experience with other tools they will probably not ever learn scene management. So is it better to leverage code and risk not learning valuable techniques, or write it all yourself and fight through the headaches and hours of time you may spend on something already built?

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• SDL mouse wheel not picking up

  - by Chris

  Running Ubuntu 11.04, SDL 1.2 trying to pickup mouse wheel up/down movement with this (stripped down) code: int main( int argc, char **argv ) { SDL_MouseButtonEvent *mousebutton = NULL; while ( !done ) { if(mousebutton != NULL && mousebutton->button == SDL_BUTTON_LEFT) yrot += 0.75f; else if(mousebutton != NULL && mousebutton->button == SDL_BUTTON_RIGHT) yrot -= 0.75f; else if(mousebutton != NULL && mousebutton->button == SDL_BUTTON_WHEELUP){ xrot += 0.75f; }else if(mousebutton != NULL && mousebutton->button == SDL_BUTTON_WHEELDOWN){ xrot -= 0.75f; } while ( SDL_PollEvent( &event ) ) { switch( event.type ) { case SDL_MOUSEBUTTONDOWN: mousebutton = &event.button; break; case SDL_MOUSEBUTTONUP: mousebutton = NULL; break; default: break; } } } return 0; } strange thing is, scrolling with the mouse button does nothing, but if I hold down a mouse button or two and then move the mouse it hits the SDL_BUTTON_WHEEL code occasionally. This honestly reeks of a pointer issue, which would make sense since I've been spoiled with C# for the past couple years, but I am just not seeing it. How do i correctly find mouse scroll events in SDL?

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• Virtual terminal with at least 16bit color?

  - by trusktr

  It's 2013 and there should be terminals with more than 256 colors by now (you'd think). Are there any terminals with more than 8bit colors (usually from 8 bit we jump to 16bit) to use with linux? Ideally, I'd like to have a linux terminal with 32bit colors for the foreground and background of each character. So, the functionality would be the same, with escape sequences, but just more of them (or something like that?).

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• Setting background color in gvim

  - by petersohn

  I use a terminal with white text on black background (I just like it better), so I wrote the following line in my .vimrc file: set background=dark However, gvim has black on white text. How do I do either of the following: Set the background of gvim to black Check in .vimrc if I'm using gvim I tried this: I started up gvim, and typed echo &term. The answer was "builtin_gui". So I wrote the following into .vimrc: if &term == "builtin_gui" set background=light else set background=dark endif Somehow, it didn't work.

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• Download and Share Visual Studio Color Schemes

  - by ScottGu

  As developers we often spend a large part of our day staring at code within Visual Studio.  If you are like me, after awhile the default VS text color scheme starts to get a little boring. The good news is that Visual Studio allows you to completely customize the editor background and text colors to whatever you want – allowing you to tweak them to create the experience that is “just right” for your eyes and personality.  You can then optionally export/import your color scheme preferences to an XML file via the Tools->Import and Export Settings menu command. [In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu] New website that makes it easy to download and share VS color schemes Luke Sampson launched the http://studiostyles.info/ site a week ago (built using ASP.NET MVC 2, ASP.NET 4 and VS 2010). Studiostyles.info enables you to easily browse and download Visual Studio color schemes that others have already created.  The color schemes work for both VS 2008 and VS 2010 (all versions – including the free VS express editions): Color schemes are sorted by popularity and voting (you can vote on whether you find each “hot or not”).  You can click any of the schemes to see screen-shots of it in use for common coding scenarios.  You can then download the color settings for either VS 2010 or VS 2008: You can also optionally upload color schemes of your own if you have a good one you want to share with others.  If you haven’t visited it yet – check it out: http://studiostyles.info/  And thank you Luke Sampson for building it! Hope this helps, Scott

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• How to stop Cairo Dock minimizing Conky on Show Desktop?

  - by César

  Every time I use Cairo Dock Show Desktop add-on Conky minimizes: I've read about the own_window_type override option on .conkyrc and it seems to work for some people but it doesn't work for me. Conky won't show up if I use this option (it is currently set to own_window_type normal). Any suggestions? .conkyrc # Conky settings # background no update_interval 1 cpu_avg_samples 2 net_avg_samples 2 override_utf8_locale yes double_buffer yes no_buffers yes text_buffer_size 2048 #imlib_cache_size 0 temperature_unit fahrenheit # Window specifications # own_window yes own_window_type normal own_window_transparent yes own_window_hints undecorate,sticky,skip_taskbar,skip_pager,below border_inner_margin 0 border_outer_margin 0 minimum_size 200 250 maximum_width 200 alignment tr gap_x 35 gap_y 55 # Graphics settings # draw_shades no draw_outline no draw_borders no draw_graph_borders no # Text settings # use_xft yes override_utf8_locale yes xftfont Neuropolitical:size=8 xftalpha 0.8 uppercase no temperature_unit celsius default_color FFFFFF # Lua Load # lua_load ~/.lua/scripts/clock_rings.lua lua_draw_hook_pre clock_rings TEXT ${font Neuropolitical:size=42}${time %e} ${goto 100}${font Neuropolitical:size=18}${color FF3300}${voffset -75}${time %b} ${font Neuropolitical:size=10}${color FF3300}${voffset 15}${time %A}${color FF3300}${hr} ${goto 100}${font Neuropolitical:size=15}${color FFFFFF}${voffset -35}${time %Y} ${font Neuropolitical:size=30}${voffset 40}${alignc}${time %H}:${time %M} ${goto 175}${voffset -30}${font Neuropolitical:size=10}${time %S} ${voffset 10}${font Neuropolitical:size=11}${color FF3300}${alignr}HOME${font} ${font Neuropolitical:size=13}${color FFFFFF}${alignr}temp: ${weather http://weather.noaa.gov/pub/data/observations/metar/stations/ LQBK temperature temperature 30} °C${font} ${hr} ${image ~/.conky/logo.png -p 165,10 -s 35x35} ${color FFFFFF}${font Neuropolitical:size=8}Uptime: ${uptime_short} ${color FFFFFF}${font Neuropolitical:size=8}Processes: ${processes} ${color FFFFFF}${font Neuropolitical:size=8}Running: ${running_processes} ${color FF3300}${goto 125}${voffset 27}CPU ${color FFFFFF}${goto 125}${cpu cpu0}% ${color FF3300}${goto 125}${voffset 55}RAM ${color FFFFFF}${goto 125}${memperc}% ${color FF3300}${goto 125}${voffset 56}Swap ${color FFFFFF}${goto 125}${swapperc}% ${color FF3300}${goto 125}${voffset 57}Disk ${color FFFFFF}${goto 125}${fs_used_perc /}% ${color FF3300}${goto 130}${voffset 55}Net ${color FFFFFF}${goto 130}${downspeed eth0} ${color FFFFFF}${goto 130}${upspeed eth0} ${color FF3300}${font Neuropolitical:size=8}${alignr}${nodename} ${color FF3300}${font Neuropolitical:size=8}${alignr}${pre_exec cat /etc/issue.net} $machine ${color FF3300}${font Neuropolitical:size=8}${alignr}Kernel: ${kernel} ${hr}

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• Need to modify gnome 3 theme for browser

  - by Mario De Schaepmeester

  I have recently begun using the DarkGreen theme for Gnome 3, however there are some problems on some webpages in FireFox regarding text input fields. This happens in the search field on Google, some fields on Facebook, etc... This theme uses a dark background and light color text for input fields by defaut. I have managed to modify the foreground color of input text succesfully for those fields that were never affected (from near white to gray), but it doesn't help for the "broken" fields. I also want to change the background color for all input fields to white, but I get no luck with that either. In the theme folder there is a gtk folder with a css file. Here are the relevant contents: @define-color theme_base_color #202020; @define-color theme_text_color #25DC00; /* #ffffff */ @define-color theme_bg_color #121212; @define-color theme_fg_color @theme_text_color; @define-color selected_bg_color #3E8753; @define-color selected_fg_color #ffffff; @define-color theme_selected_bg_color @selected_bg_color; @define-color menu_bg_color #555555; @define-color menu_fg_color @theme_text_color; @define-color menu_combobox_border @theme_selected_bg_color; @define-color menu_separator mix (@theme_bg_color, @menu_bg_color, 0.90); @define-color insensitive_bg_color alpha(#0b0b0d, 0.0); @define-color insensitive_fg_color alpha(#717171, 0.50); @define-color insensitive_border_color alpha(#717171, 0.50); @define-color entry_text_color /* #fafafa */ #707070; @define-color entry_background_a #ffffff; @define-color entry_background_b #ffffff; @define-color entry_background_c #ffffff; @define-color entry_background_d #ffffff; /* 121212 */ @define-color frame_color #707070; Is this CSS file the only thing I would need to change?

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• What is the best method for implementing mouse wheel activity in Delphi VCL forms?

  - by Brian Frost

  As a long time user of Delphi 7, I've rolled my own mouse wheel handling in a few controls but lately I've noticed that some recent applications only need the mouse cursor to be placed over a control (e.g a list box or tree view) for the mouse wheel activity to cause that control to scroll. This feels nice (as opposed to having to click focus a control before it responds to the wheel. Now I've moved to Delphi 2010 I'm wondering what is the 'correct' behavior? And what can I use in Delphi that avoids me having to bodge this with my own solutions now? Thanks.

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• background-color hex to js variable (jquery)

  - by Ezdaroth

  I'm kinda new to javascript and jquery and now I'm facing a problem: I need to post some data to php and one bit of the data needs to be the background color hex of div X. Jquery has css("background-color") function and with it I can get rgb value of the background into a javascript variable. The css function seems to return a string like this rgb(0, 70, 255). I couldn't find any way to get hex of the background-color (even tho it's set as hex in css). So it seems like I need to convert it. I found a function for converting rgb to hex, but it needs to be called with three different variables, r, g and b. So I would need to parse the string rgb(x,xx,xxx) into var r=x; var g=xx; var b=xxx; somehow. I tried to google parsing strings with javascript, but didn't really understand the regular expressions thing. Could someone tell me if there's a way to get background-color of div as hex, or explain how to convert the string into 3 different variables.

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• What is the best method for implementing mouse wheel activity in Delph1 VCL forms?

  - by Brian Frost

  As a long time user of Delphi 7, I've rolled my own mouse wheel handling in a few controls but lately I've noticed that some recent applications only need the mouse cursor to be placed over a control (e.g a list box or tree view) for the mouse wheel activity to cause that control to scroll. This feels nice (as opposed to having to click focus a control before it responds to the wheel. Now I've moved to Delphi 2010 I'm wondering what is the 'correct' behaviour? And what can I use in Delphi that avoids me having to bodge this with my own solutions now? Thanks.

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• ActionScript 3.0 Color Output Error?

  - by TheDarkIn1978

  I'm employing color in a current AS3 project, and have come across what appears to be an error in the Flash Player (version 10). it might also be an error with Apple's DigitalColor Meter (version 3.7.2), which is what i'm using to sample the displayed colors on Mac OS X Snow Leopard (version 10.6.3). //Primary, secondary, and tertiary colors of the RGB color wheel var red:Number = 0xFF0000; var orange:Number = 0xFF7D00; var yellow:Number = 0xFFFF00; var chartreuse:Number = 0x7DFF00; var green:Number = 0x00FF00; var spring:Number = 0x00FF7D; var cyan:Number = 0x00FFFF; var azure:Number = 0x007DFF; //reads 0x0077FF var blue:Number = 0x0000FF; var violet:Number = 0x7D00FF; var magenta:Number = 0xFF00FF; //reads 0xFF00F8 var rose:Number = 0xFF007D; //reads 0xFF0077 all of these colors display normally except for 3: Azure, Magenta and Rose. they are coded with the appropriate number, but when i use the color meter to sample the displayed colors, those 3 return inaccurate results. anyone have any insight about this issue? what is causing the error, the Flash runtime or the color sampler? if it's the Flash player, could this problem be much deeper? *sampling this image will return inaccurate results due to .jpg compression. it's simply for illustration

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• Stable random color algorithm

  - by Olmo

  Here we have an interesting real-world algorithm requirement involving colors. 1) Nice random colors: In ordeeing to draw a beautifull chart (i.e: pie chart) we need to pick a random set of Colors that: a) are different enought b) Play nicely Doesnt Look hard. For example u fix bright and saturation and divide hue in steps of 360/Num_sectors 2) Stable: given Pie1 with sectors with labes ('A','B','C') and Pie2 with sector with labels ('B','C','D'), will be nice if color('B',pie1)= color('B',pie2) and the same for 'C' and so on, so people don't get crazy when seeing similar updated charts, even if some sectors appear some dissapeared or the number of sectors changed. The label is the only stable thing. 3) hard-coded colors: the algorithm allows hardcoded label-color relationships as an input but stills doing a good work (1 & 2) for the rest of free labels. I think this algorithm, even if it looks quite ad-hoc, will be usefull in more then one situation. Any ideas?

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• Setting glutBitmapCharacter color?

  - by colordot

  Just wondering if someone can help me track down my issue with the following code where the text color is not being set correctly (its just rendering whatever color is in the background) void RenderText(int x, int y, const char *string) { int i, len; glUseProgram(0); glLoadIdentity(); glColor3f(1.0f, 1.0f, 1.0f); glTranslatef(0.0f, 0.0f, -5.0f); glRasterPos2i(x, y); glDisable(GL_TEXTURE_2D); for (i = 0, len = strlen(string); i < len; i++) { glutBitmapCharacter(GLUT_BITMAP_8_BY_13, (int)string[i]); } glEnable(GL_TEXTURE_2D); } I've checked all the usual things (I think), disabling texturing, setting color before rasterPos'ing, etc Ive disabled shaders but Im still having issues

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• OpenGL Color Interpolation across vertices

  - by gutsblow

  Right now, I have more than 25 vertices that form a model. I want to interpolate color linearly between the first and last vertex. The Problem is when I write the following code glColor3f(1.0,0.0,0.0); vertex3f(1.0,1.0,1.0); vertex3f(0.9,1.0,1.0); . .`<more vertices>; glColor3f(0.0,0.0,1.0); vertex3f(0.0,0.0,0.0); All the vertices except that last one are red. Now I am wondering if there is a way to interpolate color across these vertices without me having to manually interpolate color natively (like how opengl does it automatically) at each vertex since, I will be having a lot more number of colors at various vertices. Any help would be extremely appreciated. Thank you!

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• jQuery - color cycle animation with hsv colorspace?

  - by Sgt. Floyd Pepper

  Hi there, I am working on a project, which I need a special body-background for. The background-color should cycle through the color spectrum like a mood light. So I found this: http://buildinternet.com/2009/09/its-a-rainbow-color-changing-text-and-backgrounds/ "But" this snippet is working with the RGB colorspace which has some very light and dark colors in it. Getting just bright colors will only work with the HSV colorspace (e.g. having S and V static at 100 and letting H cycle). I don’t know how to convert and in fact how to pimp this snippet for my needs. Does anyone has an idea?? Thanks in advance. Best, Floyd

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• creating a color coded time chart using colorbar and colormaps in python

  - by Rusty

  I'm trying to make a time tracking chart based on a daily time tracking file that I used. I wrote code that crawls through my files and generates a few lists. endTimes is a list of times that a particular activity ends in minutes going from 0 at midnight the first day of the month to however many minutes are in a month. labels is a list of labels for the times listed in endTimes. It is one shorter than endtimes since the trackers don't have any data about before 0 minute. Most labels are repeats. categories contains every unique value of labels in order of how well I regard that time. I want to create a colorbar or a stack of colorbars (1 for eachday) that will depict how I spend my time for a month and put a color associated with each label. Each value in categories will have a color associated. More blue for more good. More red for more bad. It is already in order for the jet colormap to be right, but I need to get desecrate color values evenly spaced out for each value in categories. Then I figure the next step would be to convert that to a listed colormap to use for the colorbar based on how the labels associated with the categories. I think this is the right way to do it, but I am not sure. I am not sure how to associate the labels with color values. Here is the last part of my code so far. I found one function to make a discrete colormaps. It does, but it isn't what I am looking for and I am not sure what is happening. Thanks for the help! # now I need to develop the graph import numpy as np from matplotlib import pyplot,mpl import matplotlib from scipy import interpolate from scipy import * def contains(thelist,name): # checks if the current list of categories contains the one just read for val in thelist: if val == name: return True return False def getCategories(lastFile): ''' must determine the colors to use I would like to make a gradient so that the better the task, the closer to blue bad labels will recieve colors closer to blue read the last file given for the information on how I feel the order should be then just keep them in the order of how good they are in the tracker use a color range and develop discrete values for each category by evenly spacing them out any time not found should assume to be sleep sleep should be white ''' tracker = open(lastFile+'.txt') # open the last file # find all the categories categories = [] for line in tracker: pos = line.find(':') # does it have a : or a ? if pos==-1: pos=line.find('?') if pos != -1: # ignore if no : or ? name = line[0:pos].strip() # split at the : or ? if contains(categories,name)==False: # if the category is new categories.append(name) # make a new one return categories # find good values in order of last day newlabels=[] for val in getCategories(lastDay): if contains(labels,val): newlabels.append(val) categories=newlabels # convert discrete colormap to listed colormap python for ii,val in enumerate(labels): if contains(categories,val)==False: labels[ii]='sleep' # create a figure fig = pyplot.figure() axes = [] for x in range(endTimes[-1]%(24*60)): ax = fig.add_axes([0.05, 0.65, 0.9, 0.15]) axes.append(ax) # figure out the colors to use # stole this function to make a discrete colormap # http://www.scipy.org/Cookbook/Matplotlib/ColormapTransformations def cmap_discretize(cmap, N): """Return a discrete colormap from the continuous colormap cmap. cmap: colormap instance, eg. cm.jet. N: Number of colors. Example x = resize(arange(100), (5,100)) djet = cmap_discretize(cm.jet, 5) imshow(x, cmap=djet) """ cdict = cmap._segmentdata.copy() # N colors colors_i = np.linspace(0,1.,N) # N+1 indices indices = np.linspace(0,1.,N+1) for key in ('red','green','blue'): # Find the N colors D = np.array(cdict[key]) I = interpolate.interp1d(D[:,0], D[:,1]) colors = I(colors_i) # Place these colors at the correct indices. A = zeros((N+1,3), float) A[:,0] = indices A[1:,1] = colors A[:-1,2] = colors # Create a tuple for the dictionary. L = [] for l in A: L.append(tuple(l)) cdict[key] = tuple(L) # Return colormap object. return matplotlib.colors.LinearSegmentedColormap('colormap',cdict,1024) # jet colormap goes from blue to red (good to bad) cmap = cmap_discretize(mpl.cm.jet, len(categories)) cmap.set_over('0.25') cmap.set_under('0.75') #norm = mpl.colors.Normalize(endTimes,cmap.N) print endTimes print labels # make a color list by matching labels to a picture #norm = mpl.colors.ListedColormap(colorList) cb1 = mpl.colorbar.ColorbarBase(axes[0],cmap=cmap ,orientation='horizontal' ,boundaries=endTimes ,ticks=endTimes ,spacing='proportional') pyplot.show()

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• converting rgb values to System.Drawing

  - by Chris

  Hi, I've looked around, but don't see this question - maybe its too easy, but I don't have it. If I have file containing color values like: 255, 65535, 65280 ( I think this is green) is there a way to either: convert these to a System.Drawing.Color type or....better yet.. have .NET accept them as is to represent the color? thanks,

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• How do I invert a colour?

  - by ThePower

  I know that this won't directly invert a colour, it will just 'oppose' it. I was wondering if anyone knew a simple way (a few lines of code) to invert a colour from any given colour? At the moment I have this (which isn't exactly the definition of an invert): const int RGBMAX = 255; Color InvertMeAColour(Color ColourToInvert) { return Color.FromArgb(RGBMAX - ColourToInvert.R, RGBMAX - ColourToInvert.G, RGBMAX - ColourToInvert.B); }

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• Liskov Substitution Principle and the Oft Forgot Third Wheel

  - by Stacy Vicknair

  Liskov Substitution Principle (LSP) is a principle of object oriented programming that many might be familiar with from the SOLID principles mnemonic from Uncle Bob Martin. The principle highlights the relationship between a type and its subtypes, and, according to Wikipedia, is defined by Barbara Liskov and Jeanette Wing as the following principle:   Let be a property provable about objects of type . Then should be provable for objects of type where is a subtype of .   Rectangles gonna rectangulate The iconic example of this principle is illustrated with the relationship between a rectangle and a square. Let’s say we have a class named Rectangle that had a property to set width and a property to set its height. 1: Public Class Rectangle 2: Overridable Property Width As Integer 3: Overridable Property Height As Integer 4: End Class   We all at some point here that inheritance mocks an “IS A” relationship, and by gosh we all know square IS A rectangle. So let’s make a square class that inherits from rectangle. However, squares do maintain the same length on every side, so let’s override and add that behavior. 1: Public Class Square 2: Inherits Rectangle 3:  4: Private _sideLength As Integer 5:  6: Public Overrides Property Width As Integer 7: Get 8: Return _sideLength 9: End Get 10: Set(value As Integer) 11: _sideLength = value 12: End Set 13: End Property 14:  15: Public Overrides Property Height As Integer 16: Get 17: Return _sideLength 18: End Get 19: Set(value As Integer) 20: _sideLength = value 21: End Set 22: End Property 23: End Class   Now, say we had the following test: 1: Public Sub SetHeight_DoesNotAffectWidth(rectangle As Rectangle) 2: 'arrange 3: Dim expectedWidth = 4 4: rectangle.Width = 4 5:  6: 'act 7: rectangle.Height = 7 8:  9: 'assert 10: Assert.AreEqual(expectedWidth, rectangle.Width) 11: End Sub   If we pass in a rectangle, this test passes just fine. What if we pass in a square?   This is where we see the violation of Liskov’s Principle! A square might "IS A” to a rectangle, but we have differing expectations on how a rectangle should function than how a square should! Great expectations Here’s where we pat ourselves on the back and take a victory lap around the office and tell everyone about how we understand LSP like a boss. And all is good… until we start trying to apply it to our work. If I can’t even change functionality on a simple setter without breaking the expectations on a parent class, what can I do with subtyping? Did Liskov just tell me to never touch subtyping again? The short answer: NO, SHE DIDN’T. When I first learned LSP, and from those I’ve talked with as well, I overlooked a very important but not appropriately stressed quality of the principle: our expectations. Our inclination is to want a logical catch-all, where we can easily apply this principle and wipe our hands, drop the mic and exit stage left. That’s not the case because in every different programming scenario, our expectations of the parent class or type will be different. We have to set reasonable expectations on the behaviors that we expect out of the parent, then make sure that those expectations are met by the child. Any expectations not explicitly expected of the parent aren’t expected of the child either, and don’t register as a violation of LSP that prevents implementation. You can see the flexibility mentioned in the Wikipedia article itself: A typical example that violates LSP is a Square class that derives from a Rectangle class, assuming getter and setter methods exist for both width and height. The Square class always assumes that the width is equal with the height. If a Square object is used in a context where a Rectangle is expected, unexpected behavior may occur because the dimensions of a Square cannot (or rather should not) be modified independently. This problem cannot be easily fixed: if we can modify the setter methods in the Square class so that they preserve the Square invariant (i.e., keep the dimensions equal), then these methods will weaken (violate) the postconditions for the Rectangle setters, which state that dimensions can be modified independently. Violations of LSP, like this one, may or may not be a problem in practice, depending on the postconditions or invariants that are actually expected by the code that uses classes violating LSP. Mutability is a key issue here. If Square and Rectangle had only getter methods (i.e., they were immutable objects), then no violation of LSP could occur. What this means is that the above situation with a rectangle and a square can be acceptable if we do not have the expectation for width to leave height unaffected, or vice-versa, in our application. Conclusion – the oft forgot third wheel Liskov Substitution Principle is meant to act as a guidance and warn us against unexpected behaviors. Objects can be stateful and as a result we can end up with unexpected situations if we don’t code carefully. Specifically when subclassing, make sure that the subclass meets the expectations held to its parent. Don’t let LSP think you cannot deviate from the behaviors of the parent, but understand that LSP is meant to highlight the importance of not only the parent and the child class, but also of the expectations WE set for the parent class and the necessity of meeting those expectations in order to help prevent sticky situations.   Code examples, in both VB and C# Technorati Tags: LSV,Liskov Substitution Principle,Uncle Bob,Robert Martin,Barbara Liskov,Liskov

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• Changing color of HighlighBrushKey in XAML

  - by phil

  Hi, I have the following problem. The background color in a ListView is set LightGreen or White, whether a boolflag is true or false. Example Screen Window1.xaml: <Window.Resources> <Style TargetType="{x:Type ListViewItem}"> <Style.Triggers> <DataTrigger Binding="{Binding Path=BoolFlag}" Value="True"> <Setter Property="Background" Value="LightGreen" /> </DataTrigger> </Style.Triggers> </Style> </Window.Resources> <StackPanel> <ListView ItemsSource="{Binding Path=Personen}" SelectionMode="Single" SelectionChanged="ListViewSelectionChanged"> <ListView.View> <GridView> <GridViewColumn DisplayMemberBinding="{Binding Path=Vorname}" Header="Vorname" /> <GridViewColumn DisplayMemberBinding="{Binding Path=Nachname}" Header="Nachname" /> <GridViewColumn DisplayMemberBinding="{Binding Path=Alter}" Header="Alter" /> <GridViewColumn DisplayMemberBinding="{Binding Path=BoolFlag}" Header="BoolFlag" /> </GridView> </ListView.View> </ListView> </StackPanel> Window1.xaml.cs: public partial class Window1 : Window { private IList<Person> _personen = new List<Person>(); public Window1() { _personen.Add(new Person { Vorname = "Max", Nachname = "Mustermann", Alter = 18, BoolFlag = false, }); _personen.Add(new Person { Vorname = "Karl", Nachname = "Mayer", Alter = 27, BoolFlag = true, }); _personen.Add(new Person { Vorname = "Josef", Nachname = "Huber", Alter = 38, BoolFlag = false, }); DataContext = this; InitializeComponent(); } public IList<Person> Personen { get { return _personen; } } private void ListViewSelectionChanged(object sender, SelectionChangedEventArgs e) { Person person = e.AddedItems[0] as Person; if (person != null) { if (person.BoolFlag) { this.Resources[SystemColors.HighlightBrushKey] = Brushes.Green; } else { this.Resources[SystemColors.HighlightBrushKey] = Brushes.RoyalBlue; } } } } Person.cs: public class Person { public string Vorname { get; set; } public string Nachname { get; set; } public int Alter { get; set; } public bool BoolFlag { get; set; } } Now I want to set the highlight color of the selected item, depending on the boolflag. In Code-Behind I do this with: private void ListViewSelectionChanged(object sender, SelectionChangedEventArgs e) { Person person = e.AddedItems[0] as Person; if (person != null) { if (person.BoolFlag) { this.Resources[SystemColors.HighlightBrushKey] = Brushes.Green; } else { this.Resources[SystemColors.HighlightBrushKey] = Brushes.RoyalBlue; } } } } This works fine, but now I want to define the code above in the XAML-file. With <SolidColorBrush x:Key="{x:Static SystemColors.HighlightBrushKey}" Color="Green" /> I can overwrite the default-value. However, it works, but the color is set to Green for all selected items. I have tried different ways to switch the color of HighlightBrushKey between Green and Blue in XAML, depending on the boolflag, but I didn't succeed. May you can help me and give me some examples?

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• [Windows 8] Update TextBox’s binding on TextChanged

  - by Benjamin Roux

  Since UpdateSourceTrigger is not available in WinRT we cannot update the text’s binding of a TextBox at will (or at least not easily) especially when using MVVM (I surely don’t want to write behind-code to do that in each of my apps !). Since this kind of demand is frequent (for example to disable of button if the TextBox is empty) I decided to create some attached properties to to simulate this missing behavior. namespace Indeed.Controls { public static class TextBoxEx { public static string GetRealTimeText(TextBox obj) { return (string)obj.GetValue(RealTimeTextProperty); } public static void SetRealTimeText(TextBox obj, string value) { obj.SetValue(RealTimeTextProperty, value); } public static readonly DependencyProperty RealTimeTextProperty = DependencyProperty.RegisterAttached("RealTimeText", typeof(string), typeof(TextBoxEx), null); public static bool GetIsAutoUpdate(TextBox obj) { return (bool)obj.GetValue(IsAutoUpdateProperty); } public static void SetIsAutoUpdate(TextBox obj, bool value) { obj.SetValue(IsAutoUpdateProperty, value); } public static readonly DependencyProperty IsAutoUpdateProperty = DependencyProperty.RegisterAttached("IsAutoUpdate", typeof(bool), typeof(TextBoxEx), new PropertyMetadata(false, OnIsAutoUpdateChanged)); private static void OnIsAutoUpdateChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e) { var value = (bool)e.NewValue; var textbox = (TextBox)sender; if (value) { Observable.FromEventPattern<TextChangedEventHandler, TextChangedEventArgs>( o => textbox.TextChanged += o, o => textbox.TextChanged -= o) .Do(_ => textbox.SetValue(TextBoxEx.RealTimeTextProperty, textbox.Text)) .Subscribe(); } } } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } The code is composed of two attached properties. The first one “RealTimeText” reflects the text in real time (updated after each TextChanged event). The second one is only used to enable the functionality. To subscribe to the TextChanged event I used Reactive Extensions (Rx-Metro package in Nuget). If you’re not familiar with this framework just replace the code with a simple: textbox.TextChanged += textbox.SetValue(TextBoxEx.RealTimeTextProperty, textbox.Text); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } To use these attached properties, it’s fairly simple <TextBox Text="{Binding Path=MyProperty, Mode=TwoWay}" ic:TextBoxEx.IsAutoUpdate="True" ic:TextBoxEx.RealTimeText="{Binding Path=MyProperty, Mode=TwoWay}" /> .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Just make sure to create a binding (in TwoWay) for both Text and RealTimeText. Hope this helps !

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• How can I change mouse keymapping

  - by zuberuber

  I have Razer DeathAdder(left handed edition) and A4Tech wireless mouse. My problem is I don't know how to change wireless mouse keymapping(swaping left/right click). Can somebody guide me how to do such thing? List of my devices: ? Virtual core pointer id=2 [master pointer (3)] ? ? Virtual core XTEST pointer id=4 [slave pointer (2)] ? ? Logitech Unifying Device. Wireless PID:4004 id=8 [slave pointer (2)] ? ? Razer Razer DeathAdder id=11 [slave pointer (2)] ? ? A4TECH USB Device id=12 [slave pointer (2)] ? ? A4TECH USB Device id=13 [slave pointer (2)] ? Virtual core keyboard id=3 [master keyboard (2)] ? Virtual core XTEST keyboard id=5 [slave keyboard (3)] ? Power Button id=6 [slave keyboard (3)] ? Power Button id=7 [slave keyboard (3)] ? Logitech USB Keyboard id=9 [slave keyboard (3)] ? Logitech USB Keyboard id=10 [slave keyboard (3)] This is my Razer xinput: Device 'Razer Razer DeathAdder': Device Enabled (121): 1 Coordinate Transformation Matrix (123): 1.000000, 0.000000, 0.000000, 0.000000, 1.000000, 0.000000, 0.000000, 0.000000, 1.000000 Device Accel Profile (246): 0 Device Accel Constant Deceleration (247): 5.000000 Device Accel Adaptive Deceleration (248): 1.000000 Device Accel Velocity Scaling (249): 10.000000 Device Product ID (240): 5426, 22 Device Node (241): "/dev/input/event4" Evdev Axis Inversion (250): 0, 0 Evdev Axes Swap (252): 0 Axis Labels (253): "Rel X" (131), "Rel Y" (132), "Rel Vert Wheel" (274) Button Labels (254): "Button Left" (124), "Button Middle" (125), "Button Right" (126), "Button Wheel Up" (127), "Button Wheel Down" (128), "Button Horiz Wheel Left" (129), "Button Horiz Wheel Right" (130), "Button Side" (269), "Button Extra" (270), "Button Forward" (271), "Button Back" (272), "Button Task" (273), "Button Unknown" (243), "Button Unknown" (243), "Button Unknown" (243), "Button Unknown" (243) Evdev Middle Button Emulation (255): 0 Evdev Middle Button Timeout (256): 50 Evdev Third Button Emulation (257): 0 Evdev Third Button Emulation Timeout (258): 1000 Evdev Third Button Emulation Button (259): 3 Evdev Third Button Emulation Threshold (260): 20 Evdev Wheel Emulation (261): 0 Evdev Wheel Emulation Axes (262): 0, 0, 4, 5 Evdev Wheel Emulation Inertia (263): 10 Evdev Wheel Emulation Timeout (264): 200 Evdev Wheel Emulation Button (265): 4 Evdev Drag Lock Buttons (266): 0 And this is my wireless mouse xinput: Device 'A4TECH USB Device': Device Enabled (121): 1 Coordinate Transformation Matrix (123): 1.000000, 0.000000, 0.000000, 0.000000, 1.000000, 0.000000, 0.000000, 0.000000, 1.000000 Device Accel Profile (246): 0 Device Accel Constant Deceleration (247): 1.000000 Device Accel Adaptive Deceleration (248): 1.000000 Device Accel Velocity Scaling (249): 10.000000 Device Product ID (240): 2522, 1359 Device Node (241): "/dev/input/event16" Evdev Axis Inversion (250): 0, 0 Evdev Axes Swap (252): 0 Axis Labels (253): "Rel X" (131), "Rel Y" (132), "Rel Horiz Wheel" (245), "Rel Vert Wheel" (274) Button Labels (254): "Button Left" (124), "Button Middle" (125), "Button Right" (126), "Button Wheel Up" (127), "Button Wheel Down" (128), "Button Horiz Wheel Left" (129), "Button Horiz Wheel Right" (130), "Button Side" (269), "Button Extra" (270), "Button Forward" (271), "Button Back" (272), "Button Task" (273), "Button Unknown" (243), "Button Unknown" (243), "Button Unknown" (243), "Button Unknown" (243), "Button Unknown" (243), "Button Unknown" (243), "Button Unknown" (243), "Button Unknown" (243), "Button Unknown" (243), "Button Unknown" (243), "Button Unknown" (243), "Button Unknown" (243) Evdev Middle Button Emulation (255): 0 Evdev Middle Button Timeout (256): 50 Evdev Third Button Emulation (257): 0 Evdev Third Button Emulation Timeout (258): 1000 Evdev Third Button Emulation Button (259): 3 Evdev Third Button Emulation Threshold (260): 20 Evdev Wheel Emulation (261): 0 Evdev Wheel Emulation Axes (262): 0, 0, 4, 5 Evdev Wheel Emulation Inertia (263): 10 Evdev Wheel Emulation Timeout (264): 200 Evdev Wheel Emulation Button (265): 4 Evdev Drag Lock Buttons (266): 0

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• [Windows 8] Application bar popup button

  - by Benjamin Roux

  Here is a small control to create an application bar button which will display a content in a popup when the button is clicked. Visually it gives this So how to create this? First you have to use the AppBarPopupButton control below.   namespace Indeed.Controls { public class AppBarPopupButton : Button { public FrameworkElement PopupContent { get { return (FrameworkElement)GetValue(PopupContentProperty); } set { SetValue(PopupContentProperty, value); } } public static readonly DependencyProperty PopupContentProperty = DependencyProperty.Register("PopupContent", typeof(FrameworkElement), typeof(AppBarPopupButton), new PropertyMetadata(null, (o, e) => (o as AppBarPopupButton).CreatePopup())); private Popup popup; private SerialDisposable sizeChanged = new SerialDisposable(); protected override void OnTapped(Windows.UI.Xaml.Input.TappedRoutedEventArgs e) { base.OnTapped(e); if (popup != null) { var transform = this.TransformToVisual(Window.Current.Content); var offset = transform.TransformPoint(default(Point)); sizeChanged.Disposable = PopupContent.ObserveSizeChanged().Do(_ => popup.VerticalOffset = offset.Y - (PopupContent.ActualHeight + 20)).Subscribe(); popup.HorizontalOffset = offset.X + 24; popup.DataContext = this.DataContext; popup.IsOpen = true; } } private void CreatePopup() { popup = new Popup { IsLightDismissEnabled = true }; popup.Closed += (o, e) => this.GetParentOfType<AppBar>().IsOpen = false; popup.ChildTransitions = new Windows.UI.Xaml.Media.Animation.TransitionCollection(); popup.ChildTransitions.Add(new Windows.UI.Xaml.Media.Animation.PopupThemeTransition()); var container = new Grid(); container.Children.Add(PopupContent); popup.Child = container; } } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } The ObserveSizeChanged method is just an extension method which observe the SizeChanged event (using Reactive Extensions - Rx-Metro package in Nuget). If you’re not familiar with Rx, you can replace this line (and the SerialDisposable stuff) by a simple subscription to the SizeChanged event (using +=) but don’t forget to unsubscribe to it ! public static IObservable<Unit> ObserveSizeChanged(this FrameworkElement element) { return Observable.FromEventPattern<SizeChangedEventHandler, SizeChangedEventArgs>( o => element.SizeChanged += o, o => element.SizeChanged -= o) .Select(_ => Unit.Default); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } The GetParentOfType extension method just retrieve the first parent of type (it’s a common extension method that every Windows 8 developer should have created !). You can of course tweak to control (for example if you want to center the content to the button or anything else) to fit your needs. How to use this control? It’s very simple, in an AppBar control just add it and define the PopupContent property. <ic:AppBarPopupButton Style="{StaticResource RefreshAppBarButtonStyle}" HorizontalAlignment="Left"> <ic:AppBarPopupButton.PopupContent> <Grid> [...] </Grid> </ic:AppBarPopupButton.PopupContent> </ic:AppBarPopupButton> .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } When the button is clicked the popup is displayed. When the popup is closed, the app bar is closed too. I hope this will help you !

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