$OpenBSD: patch-xvimage_c,v 1.1 2004/09/21 18:46:04 sturm Exp $
--- xvimage.c.orig	Tue Sep 21 06:49:19 2004
+++ xvimage.c	Tue Sep 21 06:50:28 2004
@@ -46,7 +46,275 @@ static int  doPadPaste        PARM((byte
 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
 
@@ -1885,33 +2153,17 @@ XImage *Pic24ToXImage(pic24, wide, high)
     /* 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");
@@ -1925,82 +2177,87 @@ XImage *Pic24ToXImage(pic24, wide, high)
       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++;
+#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++) {
 
-	/* 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
-	 */
+	      xcol  = screen_rgb[0][*pp++];
+	      xcol |= screen_rgb[1][*pp++];
+	      xcol |= screen_rgb[2][*pp++];
 
-	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;
+	      switch (bperpix) {
+	      case 8:
+		*ip++ = xcol & 0xff;
+		break;
+	      case 16:
+		*((CARD16 *)ip)++ = (CARD16)xcol;
+		break;
+	      }
+	    }
 	  }
-	  else {  /* LSBFirst */
-	    *ip++ =  xcol      & 0xff;
-	    *ip++ = (xcol>>8)  & 0xff;
-	    *ip++ = (xcol>>16) & 0xff;
-	    *ip++ = (xcol>>24) & 0xff;
-	  }
+	  alldone = 1;
+	  free(row_buf);
 	}
+	free(fs);
+      }
+      if (alldone) return xim;
+    }
+#endif
+#endif
 
-	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;
-	  }
-	}
+    lip = imagedata;  pp = pic24;
+    for (i=0; i<high; i++, lip+=bperline) {
+      for (j=0, ip=lip; j<wide; j++) {
 
-	else if (bperpix == 16) {
-	  if (border == MSBFirst) {
-	    *ip++ = (xcol>>8)  & 0xff;
-	    *ip++ =  xcol      & 0xff;
-	  }
-	  else {  /* LSBFirst */
-	    *ip++ =  xcol      & 0xff;
-	    *ip++ = (xcol>>8)  & 0xff;
-	  }
-	}
+	xcol  = screen_rgb[0][*pp++];
+	xcol |= screen_rgb[1][*pp++];
+	xcol |= screen_rgb[2][*pp++];
 
-	else if (bperpix == 8) {
-	  *ip++ =  xcol      & 0xff;
+	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;
 	}
       }
     }
@@ -2699,7 +2956,7 @@ static int doPadBggen(str, wide, high, o
 #else
   strcpy(fname, "Sys$Disk:[]xvuXXXXXX");
 #endif
-  mktemp(fname);
+  close(mkstemp(fname));
 
   /* run bggen to generate the background */
   sprintf(syscmd, "bggen -g %dx%d %s > %s", wide, high, str, fname);
