Have DM manually encode its .png outputs.

dm/DM.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "CrashHandler.h"
 #include "DMJsonWriter.h"
 #include "DMSrcSink.h"
@@ skipping 10 matching lines @@
 #include "SkMD5.h"
 #include "SkMutex.h"
 #include "SkOSFile.h"
 #include "SkTHash.h"
 #include "SkTaskGroup.h"
 #include "SkThreadUtils.h"
 #include "Test.h"
 #include "Timer.h"
 #include "sk_tool_utils.h"
 
+#ifdef SKIA_PNG_PREFIXED
+    // this must proceed png.h
+    #include "pngprefix.h"
+#endif
+#include "png.h"
+
 DEFINE_string(src, "tests gm skp image", "Source types to test.");
 DEFINE_bool(nameByHash, false,
             "If true, write to FLAGS_writePath[0]/<hash>.png instead of "
             "to FLAGS_writePath[0]/<config>/<sourceType>/<sourceOptions>/<name>.png");
 DEFINE_bool2(pathOpsExtended, x, false, "Run extended pathOps tests.");
 DEFINE_string(matrix, "1 0 0 1",
               "2x2 scale+skew matrix to apply or upright when using "
               "'matrix' or 'upright' in config.");
 DEFINE_bool(gpu_threading, false, "Allow GPU work to run on multiple threads?");
 
@@ skipping 418 matching lines @@
                 break;
             }
             sink = next;
         }
         if (sink) {
             push_sink(config, sink);
         }
     }
 }
 
+static bool dump_png(SkBitmap bitmap, const char* path, const char* md5) {
+    const int w = bitmap.width(),
+              h = bitmap.height();
+
+    // First get the bitmap into N32 color format.  The next step will work only there.
+    if (bitmap.colorType() != kN32_SkColorType) {
+        SkBitmap n32;
+        if (!bitmap.copyTo(&n32, kN32_SkColorType)) {
+            return false;
+        }
+        bitmap = n32;
+    }
+
+    // Convert our N32 bitmap into unpremul RGBA for libpng.
+    SkAutoTMalloc<uint32_t> rgba(w*h);
+    if (!bitmap.readPixels(SkImageInfo::Make(w,h, kRGBA_8888_SkColorType, kUnpremul_SkAlphaType),
+                           rgba, 4*w, 0,0)) {
+        return false;
+    }
+
+    // We don't need bitmap anymore.  Might as well drop our ref.
+    bitmap = SkBitmap();

[hal.canary, 2015/08/24 20:35:06]

bitmap.reset();

+
+    FILE* f = fopen(path, "w");
+    if (!f) { return false; }
+
+    png_structp png = png_create_write_struct(PNG_LIBPNG_VER_STRING, nullptr, nullptr, nullptr);
+    if (!png) {
+        fclose(f);
+        return false;
+    }
+
+    png_infop info = png_create_info_struct(png);
+    if (!info) {
+        png_destroy_write_struct(&png, &info);
+        fclose(f);
+        return false;
+    }
+
+    png_text text[2];
+    text[0].key = (png_charp)"Author";
+    text[0].text = (png_charp)"DM dump_png()";
+    text[0].compression = PNG_TEXT_COMPRESSION_NONE;
+    text[1].key = (png_charp)"Description";
+    text[1].text = (png_charp)md5;
+    text[1].compression = PNG_TEXT_COMPRESSION_NONE;
+    png_set_text(png, info, text, 2);
+
+    png_init_io(png, f);
+    png_set_IHDR(png, info, (png_uint_32)w, (png_uint_32)h, 8,
+                 PNG_COLOR_TYPE_RGB_ALPHA, PNG_INTERLACE_NONE,
+                 PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
+    png_write_info(png, info);
+    for (int j = 0; j < h; j++) {
+        png_bytep row = (png_bytep)(rgba.get() + w*j);
+        png_write_rows(png, &row, 1);
+    }
+    png_write_end(png, info);
+
+    png_destroy_write_struct(&png, &info);
+    fclose(f);
+    return true;
+}
+
 static bool match(const char* needle, const char* haystack) {
     return 0 == strcmp("_", needle) || NULL != strstr(haystack, needle);
 }
 
 static ImplicitString is_blacklisted(const char* sink, const char* src,
                                      const char* srcOptions, const char* name) {
     for (int i = 0; i < FLAGS_blacklist.count() - 3; i += 4) {
         if (match(FLAGS_blacklist[i+0], sink) &&
             match(FLAGS_blacklist[i+1], src) &&
             match(FLAGS_blacklist[i+2], srcOptions) &&
@@ skipping 149 matching lines @@
             sk_mkdir(path.c_str());
             if (strcmp(task.src.options, "") != 0) {
               path = SkOSPath::Join(path.c_str(), task.src.options);
               sk_mkdir(path.c_str());
             }
             path = SkOSPath::Join(path.c_str(), task.src->name().c_str());
             path.append(".");
             path.append(ext);
         }
 
-        SkFILEWStream file(path.c_str());
-        if (!file.isValid()) {
-            fail(SkStringPrintf("Can't open %s for writing.\n", path.c_str()));
-            return;
-        }
-
         if (bitmap) {
-            // We can't encode A8 bitmaps as PNGs.  Convert them to 8888 first.
-            SkBitmap converted;
-            if (bitmap->info().colorType() == kAlpha_8_SkColorType) {
-                if (!bitmap->copyTo(&converted, kN32_SkColorType)) {
-                    fail("Can't convert A8 to 8888.\n");
-                    return;
-                }
-                bitmap = &converted;
-            }
-            if (!SkImageEncoder::EncodeStream(&file, *bitmap, SkImageEncoder::kPNG_Type, 100)) {
+            if (!dump_png(*bitmap, path.c_str(), result.md5.c_str())) {
                 fail(SkStringPrintf("Can't encode PNG to %s.\n", path.c_str()));
                 return;
             }
         } else {
+            SkFILEWStream file(path.c_str());
+            if (!file.isValid()) {
+                fail(SkStringPrintf("Can't open %s for writing.\n", path.c_str()));
+                return;
+            }
             if (!file.writeStream(data, len)) {
                 fail(SkStringPrintf("Can't write to %s.\n", path.c_str()));
                 return;
             }
         }
     }
 };
 
 // Run all tasks in the same enclave serially on the same thread.
 // They can't possibly run concurrently with each other.
@@ skipping 179 matching lines @@
     }
     return 0;
 }
 
 #if !defined(SK_BUILD_FOR_IOS)
 int main(int argc, char** argv) {
     SkCommandLineFlags::Parse(argc, argv);
     return dm_main();
 }
 #endif