Support decoding opaque to *premul

If a client requests unpremul or premul from an opaque SkCodec,
support it. The opaque image can be treated as any of them, though
it will be less efficient to draw than if the client had used
opaque.

Change the filling code (i.e. for incomplete images) to base its color on
the source alpha type. Prior to adding the support to decode opaque to
any, it was fine to use either source or dest (which would have yielded
the same result). If the client requests non-opaque, we do not want this
to switch the fill value from black to transparent. This also allows
simplifying the signatures for getFillValue and onGetFillValue.

In CodexTest, expect the same result when decoding opaque to *premul,
and compare to the opaque version.

BUG=skia:4616
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1641273003

Review URL: https://codereview.chromium.org/1641273003

3 files changed, 66 insertions, 30 deletions

diff --git a/dm/DM.cpp b/dm/DM.cpp
index eb40113a9b..e5a6e4d196 100644
--- a/dm/DM.cpp
+++ b/dm/DM.cpp
@@ -225,7 +225,7 @@ static void push_src(ImplicitString tag, ImplicitString options, Src* s) {
 }
 
 static void push_codec_src(Path path, CodecSrc::Mode mode, CodecSrc::DstColorType dstColorType,
-        float scale) {
+        SkAlphaType dstAlphaType, float scale) {
     SkString folder;
     switch (mode) {
         case CodecSrc::kCodec_Mode:
@@ -259,16 +259,30 @@ static void push_codec_src(Path path, CodecSrc::Mode mode, CodecSrc::DstColorTyp
             break;
     }
 
+    switch (dstAlphaType) {
+        case kOpaque_SkAlphaType:
+            folder.append("_opaque");
+            break;
+        case kPremul_SkAlphaType:
+            folder.append("_premul");
+            break;
+        case kUnpremul_SkAlphaType:
+            folder.append("_unpremul");
+            break;
+        default:
+            break;
+    }
+
     if (1.0f != scale) {
         folder.appendf("_%.3f", scale);
     }
 
-    CodecSrc* src = new CodecSrc(path, mode, dstColorType, scale);
+    CodecSrc* src = new CodecSrc(path, mode, dstColorType, dstAlphaType, scale);
     push_src("image", folder, src);
 }
 
 static void push_android_codec_src(Path path, AndroidCodecSrc::Mode mode,
-        CodecSrc::DstColorType dstColorType, int sampleSize) {
+        CodecSrc::DstColorType dstColorType, SkAlphaType dstAlphaType, int sampleSize) {
     SkString folder;
     switch (mode) {
         case AndroidCodecSrc::kFullImage_Mode:
@@ -290,11 +304,22 @@ static void push_android_codec_src(Path path, AndroidCodecSrc::Mode mode,
             break;
     }
 
+    switch (dstAlphaType) {
+        case kOpaque_SkAlphaType:
+            folder.append("_opaque");
+            break;
+        case kPremul_SkAlphaType:
+            folder.append("_premul");
+            break;
+        default:
+            break;
+    }
+
     if (1 != sampleSize) {
         folder.appendf("_%.3f", 1.0f / (float) sampleSize);
     }
 
-    AndroidCodecSrc* src = new AndroidCodecSrc(path, mode, dstColorType, sampleSize);
+    AndroidCodecSrc* src = new AndroidCodecSrc(path, mode, dstColorType, dstAlphaType, sampleSize);
     push_src("image", folder, src);
 }
 
@@ -344,6 +369,13 @@ static void push_codec_srcs(Path path) {
             break;
     }
 
+    SkTArray<SkAlphaType> alphaModes;
+    alphaModes.push_back(kPremul_SkAlphaType);
+    // FIXME: Currently we cannot draw unpremultiplied sources. skbug.com/3338 and skbug.com/3339
+    // alphaModes.push_back(kUnpremul_SkAlphaType);
+    if (codec->getInfo().alphaType() == kOpaque_SkAlphaType) {
+        alphaModes.push_back(kOpaque_SkAlphaType);
+    }
 
     for (CodecSrc::Mode mode : nativeModes) {
         // SkCodecImageGenerator only runs for the default colorType
@@ -353,14 +385,17 @@ static void push_codec_srcs(Path path) {
         if (CodecSrc::kGen_Mode == mode) {
             // FIXME: The gpu backend does not draw kGray sources correctly. (skbug.com/4822)
             if (kGray_8_SkColorType != codec->getInfo().colorType()) {
-                push_codec_src(path, mode, CodecSrc::kGetFromCanvas_DstColorType, 1.0f);
+                push_codec_src(path, mode, CodecSrc::kGetFromCanvas_DstColorType,
+                               codec->getInfo().alphaType(), 1.0f);
             }
             continue;
         }
 
         for (float scale : nativeScales) {
             for (uint32_t i = 0; i < numColorTypes; i++) {
-                push_codec_src(path, mode, colorTypes[i], scale);
+                for (SkAlphaType alphaType : alphaModes) {
+                    push_codec_src(path, mode, colorTypes[i], alphaType, scale);
+                }
             }
         }
     }
@@ -384,11 +419,13 @@ static void push_codec_srcs(Path path) {
 
     for (int sampleSize : sampleSizes) {
         for (uint32_t i = 0; i < numColorTypes; i++) {
-            push_android_codec_src(path, AndroidCodecSrc::kFullImage_Mode, colorTypes[i],
-                    sampleSize);
-            if (subset) {
-                push_android_codec_src(path, AndroidCodecSrc::kDivisor_Mode, colorTypes[i],
-                        sampleSize);
+            for (SkAlphaType alphaType : alphaModes) {
+                push_android_codec_src(path, AndroidCodecSrc::kFullImage_Mode, colorTypes[i],
+                        alphaType, sampleSize);
+                if (subset) {
+                    push_android_codec_src(path, AndroidCodecSrc::kDivisor_Mode, colorTypes[i],
+                            alphaType, sampleSize);
+                }
             }
         }
     }
diff --git a/dm/DMSrcSink.cpp b/dm/DMSrcSink.cpp
index 29886807a7..9712fd73a0 100644
--- a/dm/DMSrcSink.cpp
+++ b/dm/DMSrcSink.cpp
@@ -233,10 +233,12 @@ Name BRDSrc::name() const {
 
 /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
 
-CodecSrc::CodecSrc(Path path, Mode mode, DstColorType dstColorType, float scale)
+CodecSrc::CodecSrc(Path path, Mode mode, DstColorType dstColorType, SkAlphaType dstAlphaType,
+                   float scale)
     : fPath(path)
     , fMode(mode)
     , fDstColorType(dstColorType)
+    , fDstAlphaType(dstAlphaType)
     , fScale(scale)
 {}
 
@@ -251,30 +253,26 @@ bool CodecSrc::veto(SinkFlags flags) const {
     return flags.type != SinkFlags::kRaster || flags.approach != SinkFlags::kDirect;
 }
 
-bool get_decode_info(SkImageInfo* decodeInfo, const SkImageInfo& defaultInfo,
-        SkColorType canvasColorType, CodecSrc::DstColorType dstColorType) {
+bool get_decode_info(SkImageInfo* decodeInfo, SkColorType canvasColorType,
+                     CodecSrc::DstColorType dstColorType) {
     switch (dstColorType) {
         case CodecSrc::kIndex8_Always_DstColorType:
             if (kRGB_565_SkColorType == canvasColorType) {
                 return false;
             }
-            *decodeInfo = defaultInfo.makeColorType(kIndex_8_SkColorType);
+            *decodeInfo = decodeInfo->makeColorType(kIndex_8_SkColorType);
             break;
         case CodecSrc::kGrayscale_Always_DstColorType:
             if (kRGB_565_SkColorType == canvasColorType) {
                 return false;
             }
-            *decodeInfo = defaultInfo.makeColorType(kGray_8_SkColorType);
+            *decodeInfo = decodeInfo->makeColorType(kGray_8_SkColorType);
             break;
         default:
-            *decodeInfo = defaultInfo.makeColorType(canvasColorType);
+            *decodeInfo = decodeInfo->makeColorType(canvasColorType);
             break;
     }
 
-    // FIXME: Currently we cannot draw unpremultiplied sources.
-    if (decodeInfo->alphaType() == kUnpremul_SkAlphaType) {
-        *decodeInfo = decodeInfo->makeAlphaType(kPremul_SkAlphaType);
-    }
     return true;
 }
 
@@ -319,9 +317,8 @@ Error CodecSrc::draw(SkCanvas* canvas) const {
         return SkStringPrintf("Couldn't create codec for %s.", fPath.c_str());
     }
 
-    SkImageInfo decodeInfo;
-    if (!get_decode_info(&decodeInfo, codec->getInfo(), canvas->imageInfo().colorType(),
-            fDstColorType)) {
+    SkImageInfo decodeInfo = codec->getInfo().makeAlphaType(fDstAlphaType);
+    if (!get_decode_info(&decodeInfo, canvas->imageInfo().colorType(), fDstColorType)) {
         return Error::Nonfatal("Testing non-565 to 565 is uninteresting.");
     }
 
@@ -570,10 +567,11 @@ Name CodecSrc::name() const {
 /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
 
 AndroidCodecSrc::AndroidCodecSrc(Path path, Mode mode, CodecSrc::DstColorType dstColorType,
-        int sampleSize)
+        SkAlphaType dstAlphaType, int sampleSize)
     : fPath(path)
     , fMode(mode)
     , fDstColorType(dstColorType)
+    , fDstAlphaType(dstAlphaType)
     , fSampleSize(sampleSize)
 {}
 
@@ -593,9 +591,8 @@ Error AndroidCodecSrc::draw(SkCanvas* canvas) const {
         return SkStringPrintf("Couldn't create android codec for %s.", fPath.c_str());
     }
 
-    SkImageInfo decodeInfo;
-    if (!get_decode_info(&decodeInfo, codec->getInfo(), canvas->imageInfo().colorType(),
-            fDstColorType)) {
+    SkImageInfo decodeInfo = codec->getInfo().makeAlphaType(fDstAlphaType);
+    if (!get_decode_info(&decodeInfo, canvas->imageInfo().colorType(), fDstColorType)) {
         return Error::Nonfatal("Testing non-565 to 565 is uninteresting.");
     }
 
diff --git a/dm/DMSrcSink.h b/dm/DMSrcSink.h
index d02eeaf101..a719bd154a 100644
--- a/dm/DMSrcSink.h
+++ b/dm/DMSrcSink.h
@@ -118,7 +118,7 @@ public:
         kIndex8_Always_DstColorType,
         kGrayscale_Always_DstColorType,
     };
-    CodecSrc(Path, Mode, DstColorType, float);
+    CodecSrc(Path, Mode, DstColorType, SkAlphaType, float);
 
     Error draw(SkCanvas*) const override;
     SkISize size() const override;
@@ -128,6 +128,7 @@ private:
     Path                    fPath;
     Mode                    fMode;
     DstColorType            fDstColorType;
+    SkAlphaType             fDstAlphaType;
     float                   fScale;
 };
 
@@ -140,7 +141,7 @@ public:
         kDivisor_Mode,
     };
 
-    AndroidCodecSrc(Path, Mode, CodecSrc::DstColorType, int sampleSize);
+    AndroidCodecSrc(Path, Mode, CodecSrc::DstColorType, SkAlphaType, int sampleSize);
 
     Error draw(SkCanvas*) const override;
     SkISize size() const override;
@@ -150,6 +151,7 @@ private:
     Path                    fPath;
     Mode                    fMode;
     CodecSrc::DstColorType  fDstColorType;
+    SkAlphaType             fDstAlphaType;
     int                     fSampleSize;
 };