120 lines
3.3 KiB
C++
120 lines
3.3 KiB
C++
//
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// "$Id$"
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//
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// WIN32 image reading routines for the Fast Light Tool Kit (FLTK).
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//
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// Copyright 1998-2014 by Bill Spitzak and others.
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//
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// This library is free software. Distribution and use rights are outlined in
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// the file "COPYING" which should have been included with this file. If this
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// file is missing or damaged, see the license at:
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//
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// http://www.fltk.org/COPYING.php
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//
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// Please report all bugs and problems on the following page:
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//
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// http://www.fltk.org/str.php
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//
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static uchar * // O - Pixel buffer or NULL if failed
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read_win_rectangle(uchar *p, // I - Pixel buffer or NULL to allocate
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int X, // I - Left position
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int Y, // I - Top position
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int w, // I - Width of area to read
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int h, // I - Height of area to read
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int alpha) { // I - Alpha value for image (0 for none)
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int d; // Depth of image
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// Allocate the image data array as needed...
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d = alpha ? 4 : 3;
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if (!p) p = new uchar[w * h * d];
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// Initialize the default colors/alpha in the whole image...
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memset(p, alpha, w * h * d);
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// Grab all of the pixels in the image...
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// Assure that we are not trying to read non-existing data. If it is so, the
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// function should still work, but the out-of-bounds part of the image is
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// untouched (initialized with the alpha value or 0 (black), resp.).
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int ww = w; // We need the original width for output data line size
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int shift_x = 0; // X target shift if X modified
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int shift_y = 0; // Y target shift if X modified
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if (X < 0) {
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shift_x = -X;
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w += X;
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X = 0;
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}
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if (Y < 0) {
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shift_y = -Y;
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h += Y;
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Y = 0;
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}
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if (h < 1 || w < 1) return p; // nothing to copy
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int line_size = ((3*w+3)/4) * 4; // each line is aligned on a DWORD (4 bytes)
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uchar *dib = new uchar[line_size*h]; // create temporary buffer to read DIB
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// fill in bitmap info for GetDIBits
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BITMAPINFO bi;
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bi.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
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bi.bmiHeader.biWidth = w;
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bi.bmiHeader.biHeight = -h; // negative => top-down DIB
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bi.bmiHeader.biPlanes = 1;
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bi.bmiHeader.biBitCount = 24; // 24 bits RGB
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bi.bmiHeader.biCompression = BI_RGB;
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bi.bmiHeader.biSizeImage = 0;
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bi.bmiHeader.biXPelsPerMeter = 0;
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bi.bmiHeader.biYPelsPerMeter = 0;
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bi.bmiHeader.biClrUsed = 0;
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bi.bmiHeader.biClrImportant = 0;
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// copy bitmap from original DC (Window, Fl_Offscreen, ...)
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HDC hdc = CreateCompatibleDC(fl_gc);
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HBITMAP hbm = CreateCompatibleBitmap(fl_gc,w,h);
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int save_dc = SaveDC(hdc); // save context for cleanup
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SelectObject(hdc,hbm); // select bitmap
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BitBlt(hdc,0,0,w,h,fl_gc,X,Y,SRCCOPY); // copy image section to DDB
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// copy RGB image data to the allocated DIB
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GetDIBits(hdc, hbm, 0, h, dib, (BITMAPINFO *)&bi, DIB_RGB_COLORS);
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// finally copy the image data to the user buffer
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for (int j = 0; j<h; j++) {
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const uchar *src = dib + j * line_size; // source line
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uchar *tg = p + (j + shift_y) * d * ww + shift_x * d; // target line
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for (int i = 0; i<w; i++) {
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uchar b = *src++;
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uchar g = *src++;
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*tg++ = *src++; // R
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*tg++ = g; // G
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*tg++ = b; // B
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if (alpha)
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*tg++ = alpha; // alpha
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}
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}
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// free used GDI and other structures
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RestoreDC(hdc,save_dc); // reset DC
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DeleteDC(hdc);
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DeleteObject(hbm);
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delete[] dib; // delete DIB temporary buffer
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return p;
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}
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//
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// End of "$Id$".
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//
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