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freebsd-ports/graphics/xv/files/patch-ae
Eric L. Hernes afbc09ff62 add a patch for Guido Vollbeding's FixPix dithering. 
This is a big win for 15/16 bit displays.
Obtained from: Guido Vollbeding <guivol@esc.de>
1996-10-16 15:42:04 +00:00

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--- xvimage.c~ Fri Jan 13 18:11:36 1995
+++ xvimage.c Tue Oct 15 16:41:47 1996
@@ -46,6 +46,274 @@
static int ReadImageFile1 PARM((char *, PICINFO *));
+/* The following array represents the pixel values for each shade of
+ * the primary color components.
+ * If 'p' is a pointer to a source image rgb-byte-triplet, we can
+ * construct the output pixel value simply by 'oring' together
+ * the corresponding components:
+ *
+ * unsigned char *p;
+ * unsigned long pixval;
+ *
+ * pixval = screen_rgb[0][*p++];
+ * pixval |= screen_rgb[1][*p++];
+ * pixval |= screen_rgb[2][*p++];
+ *
+ * This is both efficient and generic, since the only assumption
+ * is that the primary color components have separate bits.
+ * The order and distribution of bits does not matter, and we
+ * don't need additional vaiables and shifting/masking code.
+ * The array size is 3 KBytes total and thus very reasonable.
+ */
+
+static unsigned long screen_rgb[3][256];
+
+/* The following array holds the exact color representations
+ * reported by the system.
+ * This is useful for less than 24 bit deep displays as a base
+ * for additional dithering to get smoother output.
+ */
+
+static byte screen_set[3][256];
+
+/* The following routine initializes the screen_rgb and screen_set
+ * arrays.
+ * Since it is executed only once per program run, it does not need
+ * to be super-efficient.
+ *
+ * The method is to draw points in a pixmap with the specified shades
+ * of primary colors and then get the corresponding XImage pixel
+ * representation.
+ * Thus we can get away with any Bit-order/Byte-Order dependencies.
+ *
+ * The routine uses some global X variables: theDisp, theScreen,
+ * and dispDEEP. Adapt these to your application as necessary.
+ * I've not passed them in as parameters, since for other platforms
+ * than X these may be different (see vfixpix.c), and so the
+ * screen_init() interface is unique.
+ *
+ * BUG: I've read in the "Xlib Programming Manual" from O'Reilly &
+ * Associates, that the DefaultColormap in TrueColor might not
+ * provide the full shade representation in XAllocColor.
+ * In this case one had to provide a 'best' colormap instead.
+ * However, my tests with Xaccel on a Linux-Box with a Mach64
+ * card were fully successful, so I leave that potential problem
+ * to you at the moment and would appreciate any suggestions...
+ */
+
+static void screen_init()
+{
+ static int init_flag; /* assume auto-init as 0 */
+ Pixmap check_map;
+ GC check_gc;
+ XColor check_col;
+ XImage *check_image;
+ int ci, i;
+
+ if (init_flag) return;
+ init_flag = 1;
+
+ check_map = XCreatePixmap(theDisp, RootWindow(theDisp,theScreen),
+ 1, 1, dispDEEP);
+ check_gc = XCreateGC(theDisp, RootWindow(theDisp,theScreen), 0, NULL);
+ for (ci = 0; ci < 3; ci++) {
+ for (i = 0; i < 256; i++) {
+ check_col.flags = DoRed | DoGreen | DoBlue;
+ check_col.red = 0;
+ check_col.green = 0;
+ check_col.blue = 0;
+ /* Do proper upscaling from unsigned 8 bit (image data values)
+ to unsigned 16 bit (X color representation). */
+ ((unsigned short *)&check_col.red)[ci] = (unsigned short)((i << 8) | i);
+ if (!XAllocColor(theDisp, DefaultColormap(theDisp,theScreen), &check_col))
+ FatalError("XAllocColor in screen_init() failed"); /* shouldn't happen */
+ screen_set[ci][i] =
+ (((unsigned short *)&check_col.red)[ci] >> 8) & 0xff;
+ XSetForeground(theDisp, check_gc, check_col.pixel);
+ XDrawPoint(theDisp, check_map, check_gc, 0, 0);
+ check_image = XGetImage(theDisp, check_map, 0, 0, 1, 1,
+ AllPlanes, ZPixmap);
+ if (!check_image) FatalError("XGetImage in screen_init() failed");
+ switch (check_image->bits_per_pixel) {
+ case 8:
+ screen_rgb[ci][i] = *(CARD8 *)check_image->data;
+ break;
+ case 16:
+ screen_rgb[ci][i] = *(CARD16 *)check_image->data;
+ break;
+ case 24:
+ screen_rgb[ci][i] =
+ ((unsigned long)*(CARD8 *)check_image->data << 16) |
+ ((unsigned long)*(CARD8 *)(check_image->data + 1) << 8) |
+ (unsigned long)*(CARD8 *)(check_image->data + 2);
+ break;
+ case 32:
+ screen_rgb[ci][i] = *(CARD32 *)check_image->data;
+ break;
+ }
+ XDestroyImage(check_image);
+ }
+ }
+ XFreeGC(theDisp, check_gc);
+ XFreePixmap(theDisp, check_map);
+}
+
+
+/* The following switch should better be provided at runtime for
+ * comparison purposes.
+ * At the moment it's only compile time, unfortunately.
+ * Who can make adaptions for use as a runtime switch by a menu option?
+ */
+
+#define DO_FIXPIX_SMOOTH
+
+#ifdef DO_FIXPIX_SMOOTH
+
+/* The following code is based in part on:
+ *
+ * jquant1.c
+ *
+ * Copyright (C) 1991-1996, Thomas G. Lane.
+ * This file is part of the Independent JPEG Group's software.
+ * For conditions of distribution and use, see the accompanying README file.
+ *
+ * This file contains 1-pass color quantization (color mapping) routines.
+ * These routines provide mapping to a fixed color map using equally spaced
+ * color values. Optional Floyd-Steinberg or ordered dithering is available.
+ */
+
+/* Declarations for Floyd-Steinberg dithering.
+ *
+ * Errors are accumulated into the array fserrors[], at a resolution of
+ * 1/16th of a pixel count. The error at a given pixel is propagated
+ * to its not-yet-processed neighbors using the standard F-S fractions,
+ * ... (here) 7/16
+ * 3/16 5/16 1/16
+ * We work left-to-right on even rows, right-to-left on odd rows.
+ *
+ * We can get away with a single array (holding one row's worth of errors)
+ * by using it to store the current row's errors at pixel columns not yet
+ * processed, but the next row's errors at columns already processed. We
+ * need only a few extra variables to hold the errors immediately around the
+ * current column. (If we are lucky, those variables are in registers, but
+ * even if not, they're probably cheaper to access than array elements are.)
+ *
+ * The fserrors[] array is indexed [component#][position].
+ * We provide (#columns + 2) entries per component; the extra entry at each
+ * end saves us from special-casing the first and last pixels.
+ */
+
+typedef INT16 FSERROR; /* 16 bits should be enough */
+typedef int LOCFSERROR; /* use 'int' for calculation temps */
+
+typedef struct { byte *colorset;
+ FSERROR *fserrors;
+ } FSBUF;
+
+/* Floyd-Steinberg initialization function.
+ *
+ * It is called 'fs2_init' since it's specialized for our purpose and
+ * could be embedded in a more general FS-package.
+ *
+ * Returns a malloced FSBUF pointer which has to be passed as first
+ * parameter to subsequent 'fs2_dither' calls.
+ * The FSBUF structure does not need to be referenced by the calling
+ * application, it can be treated from the app like a void pointer.
+ *
+ * The current implementation does only require to free() this returned
+ * pointer after processing.
+ *
+ * Returns NULL if malloc fails.
+ *
+ * NOTE: The FSBUF structure is designed to allow the 'fs2_dither'
+ * function to work with an *arbitrary* number of color components
+ * at runtime! This is an enhancement over the IJG code base :-).
+ * Only fs2_init() specifies the (maximum) number of components.
+ */
+
+static FSBUF *fs2_init(width)
+int width;
+{
+ FSBUF *fs;
+ FSERROR *p;
+
+ fs = (FSBUF *)
+ malloc(sizeof(FSBUF) * 3 + ((size_t)width + 2) * sizeof(FSERROR) * 3);
+ if (fs == 0) return fs;
+
+ fs[0].colorset = screen_set[0];
+ fs[1].colorset = screen_set[1];
+ fs[2].colorset = screen_set[2];
+
+ p = (FSERROR *)(fs + 3);
+ memset(p, 0, ((size_t)width + 2) * sizeof(FSERROR) * 3);
+
+ fs[0].fserrors = p;
+ fs[1].fserrors = p + 1;
+ fs[2].fserrors = p + 2;
+
+ return fs;
+}
+
+/* Floyd-Steinberg dithering function.
+ *
+ * NOTE:
+ * (1) The image data referenced by 'ptr' is *overwritten* (input *and*
+ * output) to allow more efficient implementation.
+ * (2) Alternate FS dithering is provided by the sign of 'nc'. Pass in
+ * a negative value for right-to-left processing. The return value
+ * provides the right-signed value for subsequent calls!
+ * (3) This particular implementation assumes *no* padding between lines!
+ * Adapt this if necessary.
+ */
+
+static int fs2_dither(fs, ptr, nc, num_rows, num_cols)
+FSBUF *fs;
+byte *ptr;
+int nc, num_rows, num_cols;
+{
+ int abs_nc, ci, row, col;
+ LOCFSERROR delta, cur, belowerr, bpreverr;
+ byte *dataptr, *colsetptr;
+ FSERROR *errorptr;
+
+ if ((abs_nc = nc) < 0) abs_nc = -abs_nc;
+ for (row = 0; row < num_rows; row++) {
+ for (ci = 0; ci < abs_nc; ci++, ptr++) {
+ dataptr = ptr;
+ colsetptr = fs[ci].colorset;
+ errorptr = fs[ci].fserrors;
+ if (nc < 0) {
+ dataptr += (num_cols - 1) * abs_nc;
+ errorptr += (num_cols + 1) * abs_nc;
+ }
+ cur = belowerr = bpreverr = 0;
+ for (col = 0; col < num_cols; col++) {
+ cur += errorptr[nc];
+ cur += 8; cur >>= 4;
+ if ((cur += *dataptr) < 0) cur = 0;
+ else if (cur > 255) cur = 255;
+ *dataptr = cur & 0xff;
+ cur -= colsetptr[cur];
+ delta = cur << 1; cur += delta;
+ bpreverr += cur; cur += delta;
+ belowerr += cur; cur += delta;
+ errorptr[0] = (FSERROR)bpreverr;
+ bpreverr = belowerr;
+ belowerr = delta >> 1;
+ dataptr += nc;
+ errorptr += nc;
+ }
+ errorptr[0] = (FSERROR)bpreverr;
+ }
+ ptr += (num_cols - 1) * abs_nc;
+ nc = -nc;
+ }
+ return nc;
+}
+
+#endif /* DO_FIXPIX_SMOOTH */
+
#define DO_CROP 0
#define DO_ZOOM 1
@@ -1883,33 +2151,17 @@
/* Non-ColorMapped Visuals: TrueColor, DirectColor */
/************************************************************************/
- unsigned long r, g, b, rmask, gmask, bmask, xcol;
- int rshift, gshift, bshift, bperpix, bperline, border, cshift;
- int maplen;
+ unsigned long xcol;
+ int bperpix, bperline;
byte *imagedata, *lip, *ip, *pp;
- /* compute various shifting constants that we'll need... */
-
- rmask = theVisual->red_mask;
- gmask = theVisual->green_mask;
- bmask = theVisual->blue_mask;
-
- rshift = 7 - highbit(rmask);
- gshift = 7 - highbit(gmask);
- bshift = 7 - highbit(bmask);
-
- maplen = theVisual->map_entries;
- if (maplen>256) maplen=256;
- cshift = 7 - highbit((u_long) (maplen-1));
-
xim = XCreateImage(theDisp, theVisual, dispDEEP, ZPixmap, 0, NULL,
wide, high, 32, 0);
if (!xim) FatalError("couldn't create X image!");
bperline = xim->bytes_per_line;
bperpix = xim->bits_per_pixel;
- border = xim->byte_order;
imagedata = (byte *) malloc((size_t) (high * bperline));
if (!imagedata) FatalError("couldn't malloc imagedata");
@@ -1923,82 +2175,87 @@
FatalError(buf);
}
+ screen_init();
- lip = imagedata; pp = pic24;
- for (i=0; i<high; i++, lip+=bperline) {
- for (j=0, ip=lip; j<wide; j++) {
- r = *pp++; g = *pp++; b = *pp++;
-
- /* shift r,g,b so that high bit of 8-bit color specification is
- * aligned with high bit of r,g,b-mask in visual,
- * AND each component with its mask,
- * and OR the three components together
- */
-
- if (theVisual->class == DirectColor) {
- r = (u_long) directConv[(r>>cshift) & 0xff] << cshift;
- g = (u_long) directConv[(g>>cshift) & 0xff] << cshift;
- b = (u_long) directConv[(b>>cshift) & 0xff] << cshift;
- }
-
-
- /* shift the bits around */
- if (rshift<0) r = r << (-rshift);
- else r = r >> rshift;
-
- if (gshift<0) g = g << (-gshift);
- else g = g >> gshift;
-
- if (bshift<0) b = b << (-bshift);
- else b = b >> bshift;
-
- r = r & rmask;
- g = g & gmask;
- b = b & bmask;
-
- xcol = r | g | b;
-
- if (bperpix == 32) {
- if (border == MSBFirst) {
- *ip++ = (xcol>>24) & 0xff;
- *ip++ = (xcol>>16) & 0xff;
- *ip++ = (xcol>>8) & 0xff;
- *ip++ = xcol & 0xff;
- }
- else { /* LSBFirst */
- *ip++ = xcol & 0xff;
- *ip++ = (xcol>>8) & 0xff;
- *ip++ = (xcol>>16) & 0xff;
- *ip++ = (xcol>>24) & 0xff;
- }
- }
-
- else if (bperpix == 24) {
- if (border == MSBFirst) {
- *ip++ = (xcol>>16) & 0xff;
- *ip++ = (xcol>>8) & 0xff;
- *ip++ = xcol & 0xff;
- }
- else { /* LSBFirst */
- *ip++ = xcol & 0xff;
- *ip++ = (xcol>>8) & 0xff;
- *ip++ = (xcol>>16) & 0xff;
+#ifdef DO_FIXPIX_SMOOTH
+#if 0
+ /* If we wouldn't have to save the original pic24 image data,
+ * the following code would do the dither job by overwriting
+ * the image data, and the normal render code would then work
+ * without any change on that data.
+ * Unfortunately, this approach would hurt the xv assumptions...
+ */
+ if (bperpix < 24) {
+ FSBUF *fs = fs2_init(wide);
+ if (fs) {
+ fs2_dither(fs, pic24, 3, high, wide);
+ free(fs);
+ }
+ }
+#else
+ /* ...so we have to take a different approach with linewise
+ * dithering/rendering in a loop using a temporary line buffer.
+ */
+ if (bperpix < 24) {
+ int alldone = 0;
+ FSBUF *fs = fs2_init(wide);
+ if (fs) {
+ byte *row_buf = malloc((size_t)wide * 3);
+ if (row_buf) {
+ int nc = 3;
+ byte *picp = pic24; lip = imagedata;
+ for (i=0; i<high; i++, lip+=bperline, picp+=(size_t)wide*3) {
+ memcpy(row_buf, picp, (size_t)wide * 3);
+ nc = fs2_dither(fs, row_buf, nc, 1, wide);
+ for (j=0, ip=lip, pp=row_buf; j<wide; j++) {
+
+ xcol = screen_rgb[0][*pp++];
+ xcol |= screen_rgb[1][*pp++];
+ xcol |= screen_rgb[2][*pp++];
+
+ switch (bperpix) {
+ case 8:
+ *ip++ = xcol & 0xff;
+ break;
+ case 16:
+ *((CARD16 *)ip)++ = (CARD16)xcol;
+ break;
+ }
+ }
}
+ alldone = 1;
+ free(row_buf);
}
+ free(fs);
+ }
+ if (alldone) return xim;
+ }
+#endif
+#endif
- else if (bperpix == 16) {
- if (border == MSBFirst) {
- *ip++ = (xcol>>8) & 0xff;
- *ip++ = xcol & 0xff;
- }
- else { /* LSBFirst */
- *ip++ = xcol & 0xff;
- *ip++ = (xcol>>8) & 0xff;
- }
- }
+ lip = imagedata; pp = pic24;
+ for (i=0; i<high; i++, lip+=bperline) {
+ for (j=0, ip=lip; j<wide; j++) {
- else if (bperpix == 8) {
- *ip++ = xcol & 0xff;
+ xcol = screen_rgb[0][*pp++];
+ xcol |= screen_rgb[1][*pp++];
+ xcol |= screen_rgb[2][*pp++];
+
+ switch (bperpix) {
+ case 8:
+ *ip++ = xcol & 0xff;
+ break;
+ case 16:
+ *((CARD16 *)ip)++ = (CARD16)xcol;
+ break;
+ case 24:
+ *ip++ = (xcol >> 16) & 0xff;
+ *ip++ = (xcol >> 8) & 0xff;
+ *ip++ = xcol & 0xff;
+ break;
+ case 32:
+ *((CARD32 *)ip)++ = (CARD32)xcol;
+ break;
}
}
}
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