Add an option on SkImageDecoder to skip writing 0s.

src/images/SkImageDecoder_libpng.cpp

 
 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #include "SkImageDecoder.h"
@@ skipping 73 matching lines @@
 
 private:
     SkPNGImageIndex* fImageIndex;
 
     bool onDecodeInit(SkStream* stream, png_structp *png_ptrp, png_infop *info_ptrp);
     bool decodePalette(png_structp png_ptr, png_infop info_ptr,
                        bool * SK_RESTRICT hasAlphap, bool *reallyHasAlphap,
                        SkColorTable **colorTablep);
     bool getBitmapConfig(png_structp png_ptr, png_infop info_ptr,
                          SkBitmap::Config *config, bool *hasAlpha,
-                         bool *doDither, SkPMColor *theTranspColor);
+                         SkPMColor *theTranspColor);
 
     typedef SkImageDecoder INHERITED;
 };
 
 #ifndef png_jmpbuf
 #  define png_jmpbuf(png_ptr) ((png_ptr)->jmpbuf)
 #endif
 
 #define PNG_BYTES_TO_CHECK 4
 
@@ skipping 182 matching lines @@
 
     PNGAutoClean autoClean(png_ptr, info_ptr);
 
     png_uint_32 origWidth, origHeight;
     int bitDepth, colorType, interlaceType;
     png_get_IHDR(png_ptr, info_ptr, &origWidth, &origHeight, &bitDepth,
                  &colorType, &interlaceType, int_p_NULL, int_p_NULL);
 
     SkBitmap::Config    config;
     bool                hasAlpha = false;
-    bool                doDither = this->getDitherImage();
     SkPMColor           theTranspColor = 0; // 0 tells us not to try to match
 
-    if (!getBitmapConfig(png_ptr, info_ptr, &config, &hasAlpha, &doDither, &theTranspColor)) {
+    if (!this->getBitmapConfig(png_ptr, info_ptr, &config, &hasAlpha, &theTranspColor)) {
         return false;
     }
 
     const int sampleSize = this->getSampleSize();
     SkScaledBitmapSampler sampler(origWidth, origHeight, sampleSize);
     decodedBitmap->setConfig(config, sampler.scaledWidth(), sampler.scaledHeight());
 
     if (SkImageDecoder::kDecodeBounds_Mode == mode) {
         return true;
     }
@@ skipping 59 matching lines @@
             sc = SkScaledBitmapSampler::kRGBA;
         } else {
             sc = SkScaledBitmapSampler::kRGBX;
         }
 
         /*  We have to pass the colortable explicitly, since we may have one
             even if our decodedBitmap doesn't, due to the request that we
             upscale png's palette to a direct model
          */
         SkAutoLockColors ctLock(colorTable);
-        if (!sampler.begin(decodedBitmap, sc, doDither, ctLock.colors(),
-                           this->getRequireUnpremultipliedColors())) {
+        if (!sampler.begin(decodedBitmap, sc, *this, ctLock.colors())) {
             return false;
         }
         const int height = decodedBitmap->height();
 
         if (number_passes > 1) {
             SkAutoMalloc storage(origWidth * origHeight * srcBytesPerPixel);
             uint8_t* base = (uint8_t*)storage.get();
             size_t rowBytes = origWidth * srcBytesPerPixel;
 
             for (int i = 0; i < number_passes; i++) {
@@ skipping 47 matching lines @@
     }
     decodedBitmap->setIsOpaque(!reallyHasAlpha);
     return true;
 }
 
 
 
 bool SkPNGImageDecoder::getBitmapConfig(png_structp png_ptr, png_infop info_ptr,
                                         SkBitmap::Config* SK_RESTRICT configp,
                                         bool* SK_RESTRICT hasAlphap,
-                                        bool* SK_RESTRICT doDitherp,
                                         SkPMColor* SK_RESTRICT theTranspColorp) {
     png_uint_32 origWidth, origHeight;
     int bitDepth, colorType;
     png_get_IHDR(png_ptr, info_ptr, &origWidth, &origHeight, &bitDepth,
                  &colorType, int_p_NULL, int_p_NULL, int_p_NULL);
 
     // check for sBIT chunk data, in case we should disable dithering because
     // our data is not truely 8bits per component
     png_color_8p sig_bit;
-    if (*doDitherp && png_get_sBIT(png_ptr, info_ptr, &sig_bit)) {
+    if (this->getDitherImage() && png_get_sBIT(png_ptr, info_ptr, &sig_bit)) {
 #if 0
         SkDebugf("----- sBIT %d %d %d %d\n", sig_bit->red, sig_bit->green,
                  sig_bit->blue, sig_bit->alpha);
 #endif
         // 0 seems to indicate no information available
         if (pos_le(sig_bit->red, SK_R16_BITS) &&
             pos_le(sig_bit->green, SK_G16_BITS) &&
             pos_le(sig_bit->blue, SK_B16_BITS)) {
-            *doDitherp = false;
+            this->setDitherImage(false);
         }
     }
 
     if (colorType == PNG_COLOR_TYPE_PALETTE) {
         bool paletteHasAlpha = hasTransparencyInPalette(png_ptr, info_ptr);
         *configp = this->getPrefConfig(kIndex_SrcDepth, paletteHasAlpha);
         // now see if we can upscale to their requested config
         if (!canUpscalePaletteToConfig(*configp, paletteHasAlpha)) {
             *configp = SkBitmap::kIndex8_Config;
         }
@@ skipping 238 matching lines @@
     SkIRect rect = SkIRect::MakeWH(origWidth, origHeight);
 
     if (!rect.intersect(region)) {
         // If the requested region is entirely outside the image, just
         // returns false
         return false;
     }
 
     SkBitmap::Config    config;
     bool                hasAlpha = false;
-    bool                doDither = this->getDitherImage();
     SkPMColor           theTranspColor = 0; // 0 tells us not to try to match
 
-    if (!getBitmapConfig(png_ptr, info_ptr, &config, &hasAlpha, &doDither, &theTranspColor)) {
+    if (!this->getBitmapConfig(png_ptr, info_ptr, &config, &hasAlpha, &theTranspColor)) {
         return false;
     }
 
     const int sampleSize = this->getSampleSize();
     SkScaledBitmapSampler sampler(origWidth, rect.height(), sampleSize);
 
     SkBitmap decodedBitmap;
     decodedBitmap.setConfig(config, sampler.scaledWidth(), sampler.scaledHeight());
 
     // from here down we are concerned with colortables and pixels
@@ skipping 86 matching lines @@
             sc = SkScaledBitmapSampler::kRGBA;
         } else {
             sc = SkScaledBitmapSampler::kRGBX;
         }
 
         /*  We have to pass the colortable explicitly, since we may have one
             even if our decodedBitmap doesn't, due to the request that we
             upscale png's palette to a direct model
          */
         SkAutoLockColors ctLock(colorTable);
-        if (!sampler.begin(&decodedBitmap, sc, doDither, ctLock.colors(),
-                           this->getRequireUnpremultipliedColors())) {
+        if (!sampler.begin(&decodedBitmap, sc, *this, ctLock.colors())) {
             return false;
         }
         const int height = decodedBitmap.height();
 
         if (number_passes > 1) {
             SkAutoMalloc storage(origWidth * origHeight * srcBytesPerPixel);
             uint8_t* base = (uint8_t*)storage.get();
             size_t rb = origWidth * srcBytesPerPixel;
 
             for (int i = 0; i < number_passes; i++) {
@@ skipping 348 matching lines @@
     return SkImageDecoder::kUnknown_Format;
 }
 
 SkImageEncoder* sk_libpng_efactory(SkImageEncoder::Type t) {
     return (SkImageEncoder::kPNG_Type == t) ? SkNEW(SkPNGImageEncoder) : NULL;
 }
 
 static SkImageDecoder_DecodeReg gDReg(sk_libpng_dfactory);
 static SkImageDecoder_FormatReg gFormatReg(get_format_png);
 static SkImageEncoder_EncodeReg gEReg(sk_libpng_efactory);