Fix SkImage::asLegacyBitmap() rowBytes assert

tests/SurfaceTest.cpp

Index: tests/SurfaceTest.cpp
diff --git a/tests/SurfaceTest.cpp b/tests/SurfaceTest.cpp
index e8ff63cca0d3e4be30b851888b5d9e64bf7e4aa6..57ad5e0ca8340462ac2ddb9f80ca40ee97b66370 100644
--- a/tests/SurfaceTest.cpp
+++ b/tests/SurfaceTest.cpp
@@ -390,6 +390,25 @@ static void test_image_readpixels(skiatest::Reporter* reporter, SkImage* image,
     REPORTER_ASSERT(reporter, has_pixels(&pixels[1], w*h - 1, notExpected));
 }
 
+static void check_legacy_bitmap(skiatest::Reporter* reporter, const SkImage* image,
+                                const SkBitmap& bitmap, SkImage::LegacyBitmapMode mode) {
+    REPORTER_ASSERT(reporter, image->width() == bitmap.width());
+    REPORTER_ASSERT(reporter, image->height() == bitmap.height());
+    REPORTER_ASSERT(reporter, image->isOpaque() == bitmap.isOpaque());
+
+    if (SkImage::kRO_LegacyBitmapMode == mode) {
+        REPORTER_ASSERT(reporter, bitmap.isImmutable());
+    }
+
+    SkAutoLockPixels alp(bitmap);
+    REPORTER_ASSERT(reporter, bitmap.getPixels());
+
+    const SkImageInfo info = SkImageInfo::MakeN32(1, 1, bitmap.alphaType());
+    SkPMColor imageColor;
+    REPORTER_ASSERT(reporter, image->readPixels(info, &imageColor, sizeof(SkPMColor), 0, 0));
+    REPORTER_ASSERT(reporter, imageColor == *bitmap.getAddr32(0, 0));
+}
+
 static void test_legacy_bitmap(skiatest::Reporter* reporter, const SkImage* image) {
     const SkImage::LegacyBitmapMode modes[] = {
         SkImage::kRO_LegacyBitmapMode,
@@ -398,22 +417,18 @@ static void test_legacy_bitmap(skiatest::Reporter* reporter, const SkImage* imag
     for (size_t i = 0; i < SK_ARRAY_COUNT(modes); ++i) {
         SkBitmap bitmap;
         REPORTER_ASSERT(reporter, image->asLegacyBitmap(&bitmap, modes[i]));
-
-        REPORTER_ASSERT(reporter, image->width() == bitmap.width());
-        REPORTER_ASSERT(reporter, image->height() == bitmap.height());
-        REPORTER_ASSERT(reporter, image->isOpaque() == bitmap.isOpaque());
-
-        bitmap.lockPixels();
-        REPORTER_ASSERT(reporter, bitmap.getPixels());
-
-        const SkImageInfo info = SkImageInfo::MakeN32(1, 1, bitmap.alphaType());
-        SkPMColor imageColor;
-        REPORTER_ASSERT(reporter, image->readPixels(info, &imageColor, sizeof(SkPMColor), 0, 0));
-        REPORTER_ASSERT(reporter, imageColor == *bitmap.getAddr32(0, 0));
-
-        if (SkImage::kRO_LegacyBitmapMode == modes[i]) {
-            REPORTER_ASSERT(reporter, bitmap.isImmutable());
-        }
+        check_legacy_bitmap(reporter, image, bitmap, modes[i]);
+
+        // Test subsetting to exercise the rowBytes logic.
+        SkBitmap tmp;
+        REPORTER_ASSERT(reporter, bitmap.extractSubset(&tmp, SkIRect::MakeWH(image->width() / 2,
+                                                                             image->height() / 2)));
+        SkAutoTUnref<SkImage> subsetImage(SkImage::NewFromBitmap(tmp));
+        REPORTER_ASSERT(reporter, subsetImage);
+
+        SkBitmap subsetBitmap;
+        REPORTER_ASSERT(reporter, subsetImage->asLegacyBitmap(&subsetBitmap, modes[i]));
+        check_legacy_bitmap(reporter, subsetImage, subsetBitmap, modes[i]);
     }
 }