141 lines
3.8 KiB
C
141 lines
3.8 KiB
C
/*
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* Dithering functions
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*
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* Copyright 1994 Alexandre Julliard
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*/
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static char Copyright[] = "Copyright Alexandre Julliard, 1994";
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#include <stdlib.h>
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#include <X11/Xlib.h>
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#include <X11/Xutil.h>
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#include "gdi.h"
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#include "bitmap.h"
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/* Levels of each primary */
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#define PRIMARY_LEVELS 3
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#define TOTAL_LEVELS (PRIMARY_LEVELS*PRIMARY_LEVELS*PRIMARY_LEVELS)
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/* Dithering matrix size */
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#define MATRIX_SIZE 8
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#define MATRIX_SIZE_2 (MATRIX_SIZE*MATRIX_SIZE)
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/* Total number of possible levels for a dithered primary color */
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#define DITHER_LEVELS (MATRIX_SIZE_2 * (PRIMARY_LEVELS-1) + 1)
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/* Dithering matrix */
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static const int dither_matrix[MATRIX_SIZE_2] =
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{
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0, 32, 8, 40, 2, 34, 10, 42,
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48, 16, 56, 24, 50, 18, 58, 26,
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12, 44, 4, 36, 14, 46, 6, 38,
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60, 28, 52, 20, 62, 30, 54, 22,
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3, 35, 11, 43, 1, 33, 9, 41,
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51, 19, 59, 27, 49, 17, 57, 25,
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15, 47, 7, 39, 13, 45, 5, 37,
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63, 31, 55, 23, 61, 29, 53, 21
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};
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/* Mapping between (R,G,B) triples and EGA colors */
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static const int EGAmapping[TOTAL_LEVELS] =
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{
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0, /* 000000 -> 000000 */
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4, /* 00007f -> 000080 */
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12, /* 0000ff -> 0000ff */
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2, /* 007f00 -> 008000 */
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6, /* 007f7f -> 008080 */
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6, /* 007fff -> 008080 */
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10, /* 00ff00 -> 00ff00 */
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6, /* 00ff7f -> 008080 */
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14, /* 00ffff -> 00ffff */
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1, /* 7f0000 -> 800000 */
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5, /* 7f007f -> 800080 */
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5, /* 7f00ff -> 800080 */
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3, /* 7f7f00 -> 808000 */
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8, /* 7f7f7f -> 808080 */
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7, /* 7f7fff -> c0c0c0 */
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3, /* 7fff00 -> 808000 */
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7, /* 7fff7f -> c0c0c0 */
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7, /* 7fffff -> c0c0c0 */
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9, /* ff0000 -> ff0000 */
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5, /* ff007f -> 800080 */
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13, /* ff00ff -> ff00ff */
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3, /* ff7f00 -> 808000 */
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7, /* ff7f7f -> c0c0c0 */
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7, /* ff7fff -> c0c0c0 */
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11, /* ffff00 -> ffff00 */
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7, /* ffff7f -> c0c0c0 */
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15 /* ffffff -> ffffff */
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};
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/* Map an EGA index (0..15) to a pixel value */
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extern int COLOR_mapEGAPixel[16]; /* in color.c */
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#define PIXEL_VALUE(r,g,b) \
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COLOR_mapEGAPixel[EGAmapping[((r)*PRIMARY_LEVELS+(g))*PRIMARY_LEVELS+(b)]]
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/* X image for building dithered pixmap */
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static XImage *ditherImage = NULL;
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static char *imageData = NULL;
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/***********************************************************************
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* DITHER_Init
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*
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* Create the X image used for dithering.
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*/
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BOOL DITHER_Init()
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{
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int bytes_per_line = (screenDepth * MATRIX_SIZE + 7) / 8;
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if (!(imageData = (char *) malloc( bytes_per_line * MATRIX_SIZE )))
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return FALSE;
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ditherImage = XCreateImage( display, DefaultVisualOfScreen(screen),
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screenDepth, ZPixmap, 0, imageData,
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MATRIX_SIZE, MATRIX_SIZE, 8, bytes_per_line );
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return (ditherImage != NULL);
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}
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/***********************************************************************
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* DITHER_DitherColor
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*/
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Pixmap DITHER_DitherColor( DC *dc, COLORREF color )
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{
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static COLORREF prevColor = 0xffffffff;
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unsigned int x, y;
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Pixmap pixmap;
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/* printf( "Dither: %x\n", color ); */
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if (color != prevColor)
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{
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int r = GetRValue( color ) * DITHER_LEVELS;
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int g = GetGValue( color ) * DITHER_LEVELS;
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int b = GetBValue( color ) * DITHER_LEVELS;
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const int *pmatrix = dither_matrix;
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WORD *mapping = (WORD *) GDI_HEAP_ADDR( dc->u.x.pal.hMapping );
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for (y = 0; y < MATRIX_SIZE; y++)
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{
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for (x = 0; x < MATRIX_SIZE; x++)
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{
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int d = *pmatrix++ * 256;
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int dr = ((r + d) / MATRIX_SIZE_2) / 256;
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int dg = ((g + d) / MATRIX_SIZE_2) / 256;
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int db = ((b + d) / MATRIX_SIZE_2) / 256;
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XPutPixel( ditherImage, x, y, PIXEL_VALUE(dr,dg,db) );
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}
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}
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prevColor = color;
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}
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pixmap = XCreatePixmap( display, rootWindow,
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MATRIX_SIZE, MATRIX_SIZE, screenDepth );
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XPutImage( display, pixmap, BITMAP_colorGC, ditherImage, 0, 0,
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0, 0, MATRIX_SIZE, MATRIX_SIZE );
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return pixmap;
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}
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