Skia upscaling uses filters that are too small. This CL fixes that.

BUG=


Review URL: https://chromiumcodereview.appspot.com/12573012

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@191515 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 86 insertions, 0 deletions

diff --git a/skia/ext/image_operations_unittest.cc b/skia/ext/image_operations_unittest.cc
index a0897ad..fead994 100644
--- a/skia/ext/image_operations_unittest.cc
+++ b/skia/ext/image_operations_unittest.cc
@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 #include <algorithm>
+#include <cmath>
 #include <iomanip>
 #include <vector>
 
@@ -632,3 +633,88 @@ TEST(ImageOperations, CompareLanczosMethods) {
 #endif  // #if DEBUG_BITMAP_GENERATION
   }
 }
+
+#ifndef M_PI
+// No M_PI in math.h on windows? No problem.
+#define M_PI 3.14159265358979323846
+#endif
+
+static double sinc(double x) {
+  if (x == 0.0) return 1.0;
+  x *= M_PI;
+  return sin(x) / x;
+}
+
+static double lanczos3(double offset) {
+  if (fabs(offset) >= 3) return 0.0;
+  return sinc(offset) * sinc(offset / 3.0);
+}
+
+TEST(ImageOperations, ScaleUp) {
+  const int src_w = 3;
+  const int src_h = 3;
+  const int dst_w = 9;
+  const int dst_h = 9;
+  SkBitmap src;
+  src.setConfig(SkBitmap::kARGB_8888_Config, src_w, src_h);
+  src.allocPixels();
+
+  for (int src_y = 0; src_y < src_h; ++src_y) {
+    for (int src_x = 0; src_x < src_w; ++src_x) {
+      *src.getAddr32(src_x, src_y) = SkColorSetARGBInline(255,
+                                                          10 + src_x * 100,
+                                                          10 + src_y * 100,
+                                                          0);
+    }
+  }
+
+  SkBitmap dst = skia::ImageOperations::Resize(
+      src,
+      skia::ImageOperations::RESIZE_LANCZOS3,
+      dst_w, dst_h);
+  SkAutoLockPixels dst_lock(dst);
+  for (int dst_y = 0; dst_y < dst_h; ++dst_y) {
+    for (int dst_x = 0; dst_x < dst_w; ++dst_x) {
+      float dst_x_in_src = (dst_x + 0.5) * src_w / dst_w;
+      float dst_y_in_src = (dst_y + 0.5) * src_h / dst_h;
+      float a = 0.0f;
+      float r = 0.0f;
+      float g = 0.0f;
+      float b = 0.0f;
+      float sum = 0.0f;
+      for (int src_y = 0; src_y < src_h; ++src_y) {
+        for (int src_x = 0; src_x < src_w; ++src_x) {
+          double coeff =
+              lanczos3(src_x + 0.5 - dst_x_in_src) *
+              lanczos3(src_y + 0.5 - dst_y_in_src);
+          sum += coeff;
+          SkColor tmp = *src.getAddr32(src_x, src_y);
+          a += coeff * SkColorGetA(tmp);
+          r += coeff * SkColorGetR(tmp);
+          g += coeff * SkColorGetG(tmp);
+          b += coeff * SkColorGetB(tmp);
+        }
+      }
+      a /= sum;
+      r /= sum;
+      g /= sum;
+      b /= sum;
+      if (a < 0.0f) a = 0.0f;
+      if (r < 0.0f) r = 0.0f;
+      if (g < 0.0f) g = 0.0f;
+      if (b < 0.0f) b = 0.0f;
+      if (a > 255.0f) a = 255.0f;
+      if (r > 255.0f) r = 255.0f;
+      if (g > 255.0f) g = 255.0f;
+      if (b > 255.0f) b = 255.0f;
+      SkColor dst_color = *dst.getAddr32(dst_x, dst_y);
+      EXPECT_LE(fabs(SkColorGetA(dst_color) - a), 1.5f);
+      EXPECT_LE(fabs(SkColorGetR(dst_color) - r), 1.5f);
+      EXPECT_LE(fabs(SkColorGetG(dst_color) - g), 1.5f);
+      EXPECT_LE(fabs(SkColorGetB(dst_color) - b), 1.5f);
+      if (HasFailure()) {
+        return;
+      }
+    }
+  }
+}