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-rw-r--r--ChangeLog9
-rw-r--r--generic/tkImgPhoto.c178
2 files changed, 119 insertions, 68 deletions
diff --git a/ChangeLog b/ChangeLog
index ceb9641..25a53b8 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2004-08-04 Donal K. Fellows <donal.k.fellows@man.ac.uk>
+
+ * generic/tkImgPhoto.c (ImgPhotoBlendComplexAlpha): Clean the code
+ up a bit and add a few more comments.
+ (Tk_PhotoPutBlock, Tk_PhotoPutZoomedBlock): Clarified the code,
+ corrected the compositing rule now that I have looked up what the
+ right thing to do is, and factorized out the compositing rule code
+ into a few simpler macros.
+
2004-07-30 Daniel Steffen <das@users.sourceforge.net>
* unix/configure:
diff --git a/generic/tkImgPhoto.c b/generic/tkImgPhoto.c
index 83a7f8b..e6b7846 100644
--- a/generic/tkImgPhoto.c
+++ b/generic/tkImgPhoto.c
@@ -17,7 +17,7 @@
* Department of Computer Science,
* Australian National University.
*
- * RCS: @(#) $Id: tkImgPhoto.c,v 1.36.2.9 2004/06/25 08:46:20 dkf Exp $
+ * RCS: @(#) $Id: tkImgPhoto.c,v 1.36.2.10 2004/08/05 08:57:50 dkf Exp $
*/
#include "tkInt.h"
@@ -375,6 +375,15 @@ static int imgPhotoColorHashInitialized;
#define N_COLOR_HASH (sizeof(ColorTableId) / sizeof(int))
/*
+ * Implementation of the Porter-Duff Source-Over compositing rule.
+ */
+
+#define PD_SRC_OVER(srcColor,srcAlpha,dstColor,dstAlpha) \
+ (srcColor*srcAlpha/255) + dstAlpha*(255-srcAlpha)/255*dstColor/255
+#define PD_SRC_OVER_ALPHA(srcAlpha,dstAlpha) \
+ (srcAlpha + (255-srcAlpha)*dstAlpha/255)
+
+/*
* Forward declarations
*/
@@ -2541,26 +2550,30 @@ ToggleComplexAlphaIfNeeded(PhotoMaster *mPtr)
*
*----------------------------------------------------------------------
*/
+
/*
* This should work on all platforms that set mask and shift data properly
* from the visualInfo.
* RGB is really only a 24+ bpp version whereas RGB15 is the correct version
* and works for 15bpp+, but it slower, so it's only used for 15bpp+.
+ *
+ * Note that Win32 pre-defines those operations that we really need.
*/
+
#ifndef __WIN32__
#define GetRValue(rgb) (UCHAR((rgb & red_mask) >> red_shift))
#define GetGValue(rgb) (UCHAR((rgb & green_mask) >> green_shift))
#define GetBValue(rgb) (UCHAR((rgb & blue_mask) >> blue_shift))
#define RGB(r,g,b) ((unsigned)((UCHAR(r)<<red_shift)|(UCHAR(g)<<green_shift)|(UCHAR(b)<<blue_shift)))
#define RGB15(r,g,b) ((unsigned)(((r*red_mask/255)&red_mask)|((g*green_mask/255)&green_mask)|((b*blue_mask/255)&blue_mask)))
-#endif
+#endif /* !__WIN32__ */
-static void ImgPhotoBlendComplexAlpha (
- XImage *bgImg, /* background image to draw on */
- PhotoInstance *iPtr, /* image instance to draw */
- int xOffset, int yOffset, /* X & Y offset into image instance to draw */
- int width, int height /* width & height of image to draw */
- )
+static void
+ImgPhotoBlendComplexAlpha(bgImg, iPtr, xOffset, yOffset, width, height)
+ XImage *bgImg; /* background image to draw on */
+ PhotoInstance *iPtr; /* image instance to draw */
+ int xOffset, yOffset; /* X & Y offset into image instance to draw */
+ int width, height; /* width & height of image to draw */
{
int x, y, line;
unsigned long pixel;
@@ -2568,46 +2581,62 @@ static void ImgPhotoBlendComplexAlpha (
unsigned char *alphaAr = iPtr->masterPtr->pix32;
unsigned char *masterPtr;
-#ifndef __WIN32__
/*
- * We have to get the mask and shift info from the visual.
- * This might be cached for better performance.
+ * This blending is an integer version of the Source-Over
+ * compositing rule (see Porter&Duff, "Compositing Digital
+ * Images", proceedings of SIGGRAPH 1984) that has been hard-coded
+ * (for speed) to work with targetting a solid surface.
+ */
+
+#define ALPHA_BLEND(bgPix, imgPix, alpha, unalpha) \
+ ((bgPix * unalpha + imgPix * alpha) / 255)
+
+ /*
+ * We have to get the mask and shift info from the visual on
+ * non-Win32 so that the macros Get*Value(), RGB() and RGB15()
+ * work correctly. This might be cached for better performance.
*/
+
+#ifndef __WIN32__
unsigned long red_mask, green_mask, blue_mask;
unsigned long red_shift, green_shift, blue_shift;
Visual *visual = iPtr->visualInfo.visual;
- red_mask = visual->red_mask;
- green_mask = visual->green_mask;
- blue_mask = visual->blue_mask;
- red_shift = 0;
+ red_mask = visual->red_mask;
+ green_mask = visual->green_mask;
+ blue_mask = visual->blue_mask;
+ red_shift = 0;
green_shift = 0;
- blue_shift = 0;
- while ((0x0001 & (red_mask >> red_shift)) == 0) red_shift++;
- while ((0x0001 & (green_mask >> green_shift)) == 0) green_shift++;
- while ((0x0001 & (blue_mask >> blue_shift)) == 0) blue_shift++;
-#endif
-
-#define ALPHA_BLEND(bgPix, imgPix, alpha, unalpha) \
- ((bgPix * unalpha + imgPix * alpha) / 255)
+ blue_shift = 0;
+ while ((0x0001 & (red_mask >> red_shift)) == 0) {
+ red_shift++;
+ }
+ while ((0x0001 & (green_mask >> green_shift)) == 0) {
+ green_shift++;
+ }
+ while ((0x0001 & (blue_mask >> blue_shift)) == 0) {
+ blue_shift++;
+ }
+#endif /* !__WIN32__ */
-#if !(defined(__WIN32__) || defined(MAC_OSX_TK))
/*
* Only unix requires the special case for <24bpp. It varies with
* 3 extra shifts and uses RGB15. The 24+bpp version could also
* then be further optimized.
*/
+
+#if !(defined(__WIN32__) || defined(MAC_OSX_TK))
if (bgImg->depth < 24) {
unsigned char red_mlen, green_mlen, blue_mlen;
- red_mlen = 8 - CountBits(red_mask >> red_shift);
+ red_mlen = 8 - CountBits(red_mask >> red_shift);
green_mlen = 8 - CountBits(green_mask >> green_shift);
- blue_mlen = 8 - CountBits(blue_mask >> blue_shift);
+ blue_mlen = 8 - CountBits(blue_mask >> blue_shift);
for (y = 0; y < height; y++) {
line = (y + yOffset) * iPtr->masterPtr->width;
for (x = 0; x < width; x++) {
masterPtr = alphaAr + ((line + x + xOffset) * 4);
- alpha = masterPtr[3];
+ alpha = masterPtr[3];
/*
* Ignore pixels that are fully transparent
*/
@@ -2638,43 +2667,46 @@ static void ImgPhotoBlendComplexAlpha (
}
}
}
- } else
-#endif
- for (y = 0; y < height; y++) {
- line = (y + yOffset) * iPtr->masterPtr->width;
- for (x = 0; x < width; x++) {
- masterPtr = alphaAr + ((line + x + xOffset) * 4);
- alpha = masterPtr[3];
+ return;
+ }
+#endif /* !__WIN32__ && !MAC_OSX_TK */
+
+ for (y = 0; y < height; y++) {
+ line = (y + yOffset) * iPtr->masterPtr->width;
+ for (x = 0; x < width; x++) {
+ masterPtr = alphaAr + ((line + x + xOffset) * 4);
+ alpha = masterPtr[3];
+ /*
+ * Ignore pixels that are fully transparent
+ */
+ if (alpha) {
/*
- * Ignore pixels that are fully transparent
+ * We could perhaps be more efficient than XGetPixel for
+ * 24 and 32 bit displays, but this seems "fast enough".
*/
- if (alpha) {
+ r = masterPtr[0];
+ g = masterPtr[1];
+ b = masterPtr[2];
+ if (alpha != 255) {
/*
- * We could perhaps be more efficient than XGetPixel for
- * 24 and 32 bit displays, but this seems "fast enough".
+ * Only blend pixels that have some transparency
*/
- r = masterPtr[0];
- g = masterPtr[1];
- b = masterPtr[2];
- if (alpha != 255) {
- /*
- * Only blend pixels that have some transparency
- */
- unsigned char ra, ga, ba;
-
- pixel = XGetPixel(bgImg, x, y);
- ra = GetRValue(pixel);
- ga = GetGValue(pixel);
- ba = GetBValue(pixel);
- unalpha = 255 - alpha;
- r = ALPHA_BLEND(ra, r, alpha, unalpha);
- g = ALPHA_BLEND(ga, g, alpha, unalpha);
- b = ALPHA_BLEND(ba, b, alpha, unalpha);
- }
- XPutPixel(bgImg, x, y, RGB(r, g, b));
+ unsigned char ra, ga, ba;
+
+ pixel = XGetPixel(bgImg, x, y);
+ ra = GetRValue(pixel);
+ ga = GetGValue(pixel);
+ ba = GetBValue(pixel);
+ unalpha = 255 - alpha;
+ r = ALPHA_BLEND(ra, r, alpha, unalpha);
+ g = ALPHA_BLEND(ga, g, alpha, unalpha);
+ b = ALPHA_BLEND(ba, b, alpha, unalpha);
}
+ XPutPixel(bgImg, x, y, RGB(r, g, b));
}
}
+ }
+
#undef ALPHA_BLEND
}
@@ -4395,6 +4427,7 @@ Tk_PhotoPutBlock(handle, blockPtr, x, y, width, height, compRule)
srcPtr = srcLinePtr;
for (; wCopy > 0; --wCopy) {
alpha = srcPtr[alphaOffset];
+
/*
* In the easy case, we can just copy.
*/
@@ -4429,10 +4462,17 @@ Tk_PhotoPutBlock(handle, blockPtr, x, y, width, height, compRule)
}
if (alpha) {
- destPtr[0] += (srcPtr[0] - destPtr[0]) * alpha / 255;
- destPtr[1] += (srcPtr[greenOffset] - destPtr[1]) * alpha / 255;
- destPtr[2] += (srcPtr[blueOffset] - destPtr[2]) * alpha / 255;
- destPtr[3] += (255 - destPtr[3]) * alpha / 255;
+ int Alpha = destPtr[3];
+
+ /*
+ * This implements the Porter-Duff
+ * Source-Over compositing rule.
+ */
+
+ destPtr[0] = PD_SRC_OVER(srcPtr[0],alpha,destPtr[0],Alpha);
+ destPtr[1] = PD_SRC_OVER(srcPtr[greenOffset],alpha,destPtr[1],Alpha);
+ destPtr[2] = PD_SRC_OVER(srcPtr[blueOffset],alpha,destPtr[2],Alpha);
+ destPtr[3] = PD_SRC_OVER_ALPHA(alpha,Alpha);
}
/*
* else should be empty space
@@ -4706,10 +4746,11 @@ Tk_PhotoPutZoomedBlock(handle, blockPtr, x, y, width, height, zoomX, zoomY,
srcPtr = srcLinePtr;
for (; wCopy > 0; wCopy -= zoomX) {
for (xRepeat = MIN(wCopy, zoomX); xRepeat > 0; xRepeat--) {
+ int alpha = srcPtr[alphaOffset];
/*
* Common case (solid pixels) first
*/
- if (!alphaOffset || (srcPtr[alphaOffset] == 255)) {
+ if (!alphaOffset || (alpha == 255)) {
*destPtr++ = srcPtr[0];
*destPtr++ = srcPtr[greenOffset];
*destPtr++ = srcPtr[blueOffset];
@@ -4722,7 +4763,7 @@ Tk_PhotoPutZoomedBlock(handle, blockPtr, x, y, width, height, zoomX, zoomY,
*destPtr++ = srcPtr[0];
*destPtr++ = srcPtr[greenOffset];
*destPtr++ = srcPtr[blueOffset];
- *destPtr++ = srcPtr[alphaOffset];
+ *destPtr++ = alpha;
break;
case TK_PHOTO_COMPOSITE_OVERLAY:
if (!destPtr[3]) {
@@ -4732,11 +4773,12 @@ Tk_PhotoPutZoomedBlock(handle, blockPtr, x, y, width, height, zoomX, zoomY,
*/
destPtr[0] = destPtr[1] = destPtr[2] = 0xd9;
}
- if (srcPtr[alphaOffset]) {
- destPtr[0] += (srcPtr[0] - destPtr[0]) * srcPtr[alphaOffset] / 255;
- destPtr[1] += (srcPtr[greenOffset] - destPtr[1]) * srcPtr[alphaOffset] / 255;
- destPtr[2] += (srcPtr[blueOffset] - destPtr[2]) * srcPtr[alphaOffset] / 255;
- destPtr[3] += (255 - destPtr[3]) * srcPtr[alphaOffset] / 255;
+ if (alpha) {
+ int Alpha = destPtr[3];
+ destPtr[0] = PD_SRC_OVER(srcPtr[0],alpha,destPtr[0],Alpha);
+ destPtr[1] = PD_SRC_OVER(srcPtr[greenOffset],alpha,destPtr[1],Alpha);
+ destPtr[2] = PD_SRC_OVER(srcPtr[blueOffset],alpha,destPtr[2],Alpha);
+ destPtr[3] = PD_SRC_OVER_ALPHA(alpha,Alpha);
}
destPtr += 4;
break;
generated by cgit v0.12 at 2024-11-07 20:27:23 (GMT)