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
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
|
//
// "$Id$"
//
// WIN32 image reading routines for the Fast Light Tool Kit (FLTK).
//
// Copyright 1998-2010 by Bill Spitzak and others.
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Library General Public
// License as published by the Free Software Foundation; either
// version 2 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Library General Public License for more details.
//
// You should have received a copy of the GNU Library General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
// USA.
//
// Please report all bugs and problems on the following page:
//
// http://www.fltk.org/str.php
//
//
// 'fl_read_image()' - Read an image from the current window.
//
uchar * // O - Pixel buffer or NULL if failed
fl_read_image(uchar *p, // I - Pixel buffer or NULL to allocate
int X, // I - Left position
int Y, // I - Top position
int w, // I - Width of area to read
int h, // I - Height of area to read
int alpha) { // I - Alpha value for image (0 for none)
int d; // Depth of image
// Allocate the image data array as needed...
d = alpha ? 4 : 3;
if (!p) p = new uchar[w * h * d];
// Initialize the default colors/alpha in the whole image...
memset(p, alpha, w * h * d);
// Grab all of the pixels in the image...
// Assure that we are not trying to read non-existing data. If it is so, the
// function should still work, but the out-of-bounds part of the image is
// untouched (initialized with the alpha value or 0 (black), resp.).
int ww = w; // We need the original width for output data line size
int shift_x = 0; // X target shift if X modified
int shift_y = 0; // Y target shift if X modified
if (X < 0) {
shift_x = -X;
w += X;
X = 0;
}
if (Y < 0) {
shift_y = -Y;
h += Y;
Y = 0;
}
if (h < 1 || w < 1) return p; // nothing to copy
int line_size = ((3*w+3)/4) * 4; // each line is aligned on a DWORD (4 bytes)
uchar *dib = new uchar[line_size*h]; // create temporary buffer to read DIB
// fill in bitmap info for GetDIBits
BITMAPINFO bi;
bi.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
bi.bmiHeader.biWidth = w;
bi.bmiHeader.biHeight = -h; // negative => top-down DIB
bi.bmiHeader.biPlanes = 1;
bi.bmiHeader.biBitCount = 24; // 24 bits RGB
bi.bmiHeader.biCompression = BI_RGB;
bi.bmiHeader.biSizeImage = 0;
bi.bmiHeader.biXPelsPerMeter = 0;
bi.bmiHeader.biYPelsPerMeter = 0;
bi.bmiHeader.biClrUsed = 0;
bi.bmiHeader.biClrImportant = 0;
// copy bitmap from original DC (Window, Fl_Offscreen, ...)
HDC hdc = CreateCompatibleDC(fl_gc);
HBITMAP hbm = CreateCompatibleBitmap(fl_gc,w,h);
int save_dc = SaveDC(hdc); // save context for cleanup
SelectObject(hdc,hbm); // select bitmap
BitBlt(hdc,0,0,w,h,fl_gc,X,Y,SRCCOPY); // copy image section to DDB
// copy RGB image data to the allocated DIB
GetDIBits(hdc, hbm, 0, h, dib, (BITMAPINFO *)&bi, DIB_RGB_COLORS);
// finally copy the image data to the user buffer
for (int j = 0; j<h; j++) {
const uchar *src = dib + j * line_size; // source line
uchar *tg = p + (j + shift_y) * d * ww + shift_x * d; // target line
for (int i = 0; i<w; i++) {
uchar b = *src++;
uchar g = *src++;
*tg++ = *src++; // R
*tg++ = g; // G
*tg++ = b; // B
if (alpha)
*tg++ = alpha; // alpha
}
}
// free used GDI and other structures
RestoreDC(hdc,save_dc); // reset DC
DeleteDC(hdc);
DeleteObject(hbm);
delete[] dib; // delete DIB temporary buffer
return p;
}
//
// End of "$Id$".
//
|
