Fill incomplete images in SkCodec parent class

src/codec/SkJpegCodec.cpp

Index: src/codec/SkJpegCodec.cpp
diff --git a/src/codec/SkJpegCodec.cpp b/src/codec/SkJpegCodec.cpp
index 30c1a39f06f5f647755d2b2b4404c11b21703a79..c0c503863a5033759a62a412823497c6ee477855 100644
--- a/src/codec/SkJpegCodec.cpp
+++ b/src/codec/SkJpegCodec.cpp
@@ -325,7 +325,8 @@ bool SkJpegCodec::onDimensionsSupported(const SkISize& size) {
  */
 SkCodec::Result SkJpegCodec::onGetPixels(const SkImageInfo& dstInfo,
                                          void* dst, size_t dstRowBytes,
-                                         const Options& options, SkPMColor*, int*) {
+                                         const Options& options, SkPMColor*, int*,
+                                         int* rowsDecoded) {
     if (options.fSubset) {
         // Subsets are not supported.
         return kUnimplemented;
@@ -343,6 +344,7 @@ SkCodec::Result SkJpegCodec::onGetPixels(const SkImageInfo& dstInfo,
     if (!this->setOutputColorSpace(dstInfo)) {
         return fDecoderMgr->returnFailure("conversion_possible", kInvalidConversion);
     }
+    fDstInfo = dstInfo;
 
     // Now, given valid output dimensions, we can start the decompress
     if (!jpeg_start_decompress(dinfo)) {
@@ -358,20 +360,11 @@ SkCodec::Result SkJpegCodec::onGetPixels(const SkImageInfo& dstInfo,
     JSAMPLE* dstRow = (JSAMPLE*) dst;
     for (uint32_t y = 0; y < dstHeight; y++) {
         // Read rows of the image
-        uint32_t rowsDecoded = jpeg_read_scanlines(dinfo, &dstRow, 1);
+        uint32_t lines = jpeg_read_scanlines(dinfo, &dstRow, 1);
 
         // If we cannot read enough rows, assume the input is incomplete
-        if (rowsDecoded != 1) {
-            // Fill the remainder of the image with black. This error handling
-            // behavior is unspecified but SkCodec consistently uses black as
-            // the fill color for opaque images.  If the destination is kGray,
-            // the low 8 bits of SK_ColorBLACK will be used.  Conveniently,
-            // these are zeros, which is the representation for black in kGray.
-            // If the destination is kRGB_565, the low 16 bits of SK_ColorBLACK
-            // will be used.  Conveniently, these are zeros, which is the
-            // representation for black in kRGB_565.
-            SkSwizzler::Fill(dstRow, dstInfo, dstRowBytes, dstHeight - y,
-                    SK_ColorBLACK, nullptr, options.fZeroInitialized);
+        if (lines != 1) {
+            *rowsDecoded = y;
 
             return fDecoderMgr->returnFailure("Incomplete image data", kIncompleteInput);
         }
@@ -394,9 +387,8 @@ SkSampler* SkJpegCodec::getSampler() {
         return fSwizzler;
     }
 
-    const SkImageInfo& info = this->dstInfo();
     SkSwizzler::SrcConfig srcConfig;
-    switch (info.colorType()) {
+    switch (fDstInfo.colorType()) {
         case kGray_8_SkColorType:
             srcConfig = SkSwizzler::kGray;
             break;
@@ -414,7 +406,7 @@ SkSampler* SkJpegCodec::getSampler() {
             SkASSERT(false);
     }
 
-    fSwizzler.reset(SkSwizzler::CreateSwizzler(srcConfig, nullptr, info,
+    fSwizzler.reset(SkSwizzler::CreateSwizzler(srcConfig, nullptr, fDstInfo,

[scroggo, 2015/10/07 16:04:24]

After SkScaledCodec calls this, it will modify the swizzler (that's the only
reason we call it, right?), so fDstInfo will no longer apply to the output,
right?

[msarett, 2015/10/07 17:40:41]

That's correct.

The point of fDstInfo was to ensure that we always created a swizzler with a
valid width, even when calling onGetPixels().

Patch Set 11 uses a better approach though.

                                                this->options().fZeroInitialized));
     if (!fSwizzler) {
         return nullptr;
@@ -442,6 +434,7 @@ SkCodec::Result SkJpegCodec::onStartScanlineDecode(const SkImageInfo& dstInfo,
     fSwizzler.reset(nullptr);
     fSrcRow = nullptr;
     fStorage.free();
+    fDstInfo = dstInfo;
 
     // Now, given valid output dimensions, we can start the decompress
     if (!jpeg_start_decompress(fDecoderMgr->dinfo())) {
@@ -452,7 +445,7 @@ SkCodec::Result SkJpegCodec::onStartScanlineDecode(const SkImageInfo& dstInfo,
     return kSuccess;
 }
 
-SkCodec::Result SkJpegCodec::onGetScanlines(void* dst, int count, size_t rowBytes) {
+int SkJpegCodec::onGetScanlines(void* dst, int count, size_t rowBytes) {
     // Set the jump location for libjpeg errors
     if (setjmp(fDecoderMgr->getJmpBuf())) {
         return fDecoderMgr->returnFailure("setjmp", kInvalidInput);
@@ -471,10 +464,8 @@ SkCodec::Result SkJpegCodec::onGetScanlines(void* dst, int count, size_t rowByte
         // Read row of the image
         uint32_t rowsDecoded = jpeg_read_scanlines(fDecoderMgr->dinfo(), &dstRow, 1);
         if (rowsDecoded != 1) {
-            SkSwizzler::Fill(dstRow, this->dstInfo(), rowBytes, count - y,
-                        SK_ColorBLACK, nullptr, this->options().fZeroInitialized);
             fDecoderMgr->dinfo()->output_scanline = this->dstInfo().height();
-            return kIncompleteInput;
+            return y;
         }
 
         // Convert to RGBA if necessary
@@ -490,7 +481,7 @@ SkCodec::Result SkJpegCodec::onGetScanlines(void* dst, int count, size_t rowByte
             dstRow = SkTAddOffset<JSAMPLE>(dstRow, rowBytes);
         }
     }
-    return kSuccess;
+    return count;
 }
 
 #ifndef TURBO_HAS_SKIP
@@ -504,14 +495,11 @@ SkCodec::Result SkJpegCodec::onGetScanlines(void* dst, int count, size_t rowByte
     }
 #endif
 
-SkCodec::Result SkJpegCodec::onSkipScanlines(int count) {
+bool SkJpegCodec::onSkipScanlines(int count) {
     // Set the jump location for libjpeg errors
     if (setjmp(fDecoderMgr->getJmpBuf())) {
         return fDecoderMgr->returnFailure("setjmp", kInvalidInput);
     }
 
-    jpeg_skip_scanlines(fDecoderMgr->dinfo(), count);
-
-    return kSuccess;
+    return count == jpeg_skip_scanlines(fDecoderMgr->dinfo(), count);
 }
-