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
110
111
112
113
|
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
if IsOctave
pkg load image;
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.
sca;
% 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.
sca;
% Restore anti-aliasing setting:
Screen('Preference', 'TextAntiAliasing', oldSetting);
psychrethrow(psychlasterror);
end
|
