/usr/share/psychtoolbox-3/PsychDemos/DrawManuallyAntiAliasedTextDemo.m is in psychtoolbox-3-common 3.0.11.20131230.dfsg1-1build1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 | function DrawManuallyAntiAliasedTextDemo(ts)
% DrawManuallyAntiAliasedTextDemo([textSize=96]) - Manually anti-alias text for special purpose applications.
%
% This demo shows how to draw somewhat anti-aliased text efficiently if you
% can't use the operating systems built-in text anti-aliasing for some
% reason.
%
% It draws the text oversized, without anti-aliasing, into an offscreen
% window. Then it draws the offscreen window into the onscreen window,
% applying alpha-blending and bilinear texture filtering, shrinking to 50%
% size. A GLSL shader based gaussian blur operator is applied during
% drawing to reduce aliasing caused high-frequency edges in the texts
% contour.
%
% This needs a modern graphics card to work and is not as efficient as the
% operating systems anti-aliasing, but still reasonably fast if done right.
%
% see also: PsychDemos
% 3/8/04 awi Wrote it.
% 7/13/04 awi Added comments section.
% 9/8/04 awi Added Try/Catch, cosmetic changes to documentation.
% 1/21/05 awi Replaced call to GetChar with call to KbWait.
% 10/6/05 awi Note here cosmetic changes by dgp between 1/21/05 and 10/6/05 .
% 08/24/09 mk Derived from DrawSomeTextDemo.
AssertOpenGL;
% Define default textsize for oversized text:
if nargin < 1
ts = 96;
end
try
% Disable automatic text anti-aliasing by operating system:
oldSetting = Screen('Preference', 'TextAntiAliasing', 0);
% Choosing the display with the highest display number is
% a best guess about where you want the stimulus displayed.
screens=Screen('Screens');
screenNumber=max(screens);
% Open double-buffered onscreen window with gray (128) background
% color. We also use the imaging pipeline to enable support for fast
% offscreen windows. This would also work with a regular
% Screen('OpenWindow',...) call, but would be slower:
PsychImaging('PrepareConfiguration');
PsychImaging('AddTask', 'General', 'UseFastOffscreenWindows');
w=PsychImaging('OpenWindow', screenNumber, 128);
% Need alpha-blending:
Screen('Blendfunction', w, GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
% Create a convolution shader for a gaussian blur of width 5 and
% stddev. 1.5. Needs image processing toolbox for fspecial() function, or
% alternatively compute your own 5 x 5 kernel matrix with a gaussian
% convolution kernel inside:
kernel = fspecial('gaussian', 5, 1.5);
shader = EXPCreateStatic2DConvolutionShader(kernel, 4, 4, 0, 2);
Screen('TextFont',w, 'Courier New');
Screen('TextSize',w, ts);
Screen('TextStyle', w, 1+2);
% Compute bounding box of textstring:
bbox = ceil(Screen('TextBounds', w, 'Hello World!'));
% Create offscreen window of sufficient size, with a background color
% that matches the wanted background color, and a alpha value of zero:
woff = Screen('OpenOffscreenwindow', w, [128 128 128 0], bbox);
% Set same text properties for woff as for w:
Screen('TextFont',woff, 'Courier New');
Screen('TextSize',woff, ts);
Screen('TextStyle', woff, 1+2);
% Draw text to offscreenw window:
Screen('DrawText', woff, 'Hello World!', 0, 0, 255); %[0, 0, 255, 255]);
% Draw offscreen window with text, reduced to 50% in size, with
% bilinear texture filtering and alpha-blending enabled. Use the
% gaussian blur shader to remove high frequencies during drawing to
% reduce aliasing artifacts:
Screen('DrawTexture', w, woff, [], OffsetRect(ScaleRect(bbox, 0.5, 0.5), 100, 100), [], [], [], [], shader);
% Same without gaussian blur, just for comparison:
Screen('DrawTexture', w, woff, [], OffsetRect(ScaleRect(bbox, 0.5, 0.5), 100, 220), [], [], [], [], 0);
% Show it:
Screen('Flip',w);
KbStrokeWait;
% Done.
Screen('CloseAll');
% Restore anti-aliasing setting:
Screen('Preference', 'TextAntiAliasing', oldSetting);
catch %#ok<CTCH>
% This "catch" section executes in case of an error in the "try" section
% above. Importantly, it closes the onscreen window if it's open.
Screen('CloseAll');
% Restore anti-aliasing setting:
Screen('Preference', 'TextAntiAliasing', oldSetting);
psychrethrow(psychlasterror);
end
|