Refactor scaling.

webrtc/common_video/i420_video_frame_unittest.cc

Index: webrtc/common_video/i420_video_frame_unittest.cc
diff --git a/webrtc/common_video/i420_video_frame_unittest.cc b/webrtc/common_video/i420_video_frame_unittest.cc
index 5144c2715f3f488f9b8e07fa50770180f24ed38a..c2037c1b632d10603fe0dc52e1be829534b2563e 100644
--- a/webrtc/common_video/i420_video_frame_unittest.cc
+++ b/webrtc/common_video/i420_video_frame_unittest.cc
@@ -19,7 +19,70 @@
 
 namespace webrtc {
 
-int ExpectedSize(int plane_stride, int image_height, PlaneType type);
+namespace {
+
+int ExpectedSize(int plane_stride, int image_height, PlaneType type) {
+  if (type == kYPlane)
+    return plane_stride * image_height;
+  return plane_stride * ((image_height + 1) / 2);
+}
+
+rtc::scoped_refptr<I420Buffer> CreateGradient(int width, int height) {
+  rtc::scoped_refptr<I420Buffer> buffer(
+      new rtc::RefCountedObject<I420Buffer>(width, height));
+  // Initialize with gradient, Y = 128(x/w + y/h), U = 256 x/w, V = 256 y/h
+  for (int x = 0; x < width; x++) {
+    for (int y = 0; y < height; y++) {
+      buffer->MutableDataY()[x + y * width] =
+          128 * (x * height + y * width) / (width * height);
+    }
+  }
+  int chroma_width = (width + 1) / 2;
+  int chroma_height = (height + 1) / 2;
+  for (int x = 0; x < chroma_width; x++) {
+    for (int y = 0; y < chroma_height; y++) {
+      buffer->MutableDataU()[x + y * chroma_width] =
+          255 * x / (chroma_width - 1);
+      buffer->MutableDataV()[x + y * chroma_width] =
+          255 * y / (chroma_height - 1);
+    }
+  }
+  return buffer;
+}
+
+// The offsets and sizes describe the rectangle extracted from the
+// original (gradient) frame, in relative coordinates where the
+// original frame correspond to the unit square, 0.0 <= x, y < 1.0.
+void CheckCrop(webrtc::VideoFrameBuffer* frame,
+               double offset_x,
+               double offset_y,
+               double rel_width,
+               double rel_height) {
+  int width = frame->width();
+  int height = frame->height();
+  // Check that pixel values in the corners match the gradient used
+  // for initialization.
+  for (int i = 0; i < 2; i++) {
+    for (int j = 0; j < 2; j++) {
+      // Pixel coordinates of the corner.
+      int x = i * (width - 1);
+      int y = j * (height - 1);
+      // Relative coordinates, range 0.0 - 1.0 correspond to the
+      // size of the uncropped input frame.
+      double orig_x = offset_x + i * rel_width;
+      double orig_y = offset_y + j * rel_height;
+
+      EXPECT_NEAR(frame->DataY()[x + y * frame->StrideY()] / 256.0,
+                  (orig_x + orig_y) / 2, 0.02);
+      EXPECT_NEAR(frame->DataU()[x / 2 + (y / 2) * frame->StrideU()] / 256.0,
+                  orig_x, 0.02);
+      EXPECT_NEAR(frame->DataV()[x / 2 + (y / 2) * frame->StrideV()] / 256.0,
+                  orig_y, 0.02);
+    }
+  }
+}
+
+}  // namespace
 
 TEST(TestVideoFrame, InitialValues) {
   VideoFrame frame;
@@ -241,4 +304,70 @@ TEST(TestI420FrameBuffer, Copy) {
   EXPECT_TRUE(test::FrameBufsEqual(buf1, buf2));
 }
 
+TEST(TestI420FrameBuffer, Scale) {
+  rtc::scoped_refptr<I420Buffer> buf = CreateGradient(200, 100);
+
+  // Pure scaling, no cropping.
+  rtc::scoped_refptr<I420Buffer> scaled_buffer(
+      new rtc::RefCountedObject<I420Buffer>(150, 75));
+
+  scaled_buffer->ScaleFrom(buf);
+  CheckCrop(scaled_buffer, 0.0, 0.0, 1.0, 1.0);
+}
+
+TEST(TestI420FrameBuffer, CropXCenter) {
+  rtc::scoped_refptr<I420Buffer> buf = CreateGradient(200, 100);
+
+  // Pure center cropping, no scaling.
+  rtc::scoped_refptr<I420Buffer> scaled_buffer(
+      new rtc::RefCountedObject<I420Buffer>(100, 100));
+
+  scaled_buffer->CropAndScaleFrom(buf, 50, 0, 100, 100);
+  CheckCrop(scaled_buffer, 0.25, 0.0, 0.5, 1.0);
+}
+
+TEST(TestI420FrameBuffer, CropXNotCenter) {
+  rtc::scoped_refptr<I420Buffer> buf = CreateGradient(200, 100);
+
+  // Non-center cropping, no scaling.
+  rtc::scoped_refptr<I420Buffer> scaled_buffer(
+      new rtc::RefCountedObject<I420Buffer>(100, 100));
+
+  scaled_buffer->CropAndScaleFrom(buf, 25, 0, 100, 100);
+  CheckCrop(scaled_buffer, 0.125, 0.0, 0.5, 1.0);
+}
+
+TEST(TestI420FrameBuffer, CropYCenter) {
+  rtc::scoped_refptr<I420Buffer> buf = CreateGradient(100, 200);
+
+  // Pure center cropping, no scaling.
+  rtc::scoped_refptr<I420Buffer> scaled_buffer(
+      new rtc::RefCountedObject<I420Buffer>(100, 100));
+
+  scaled_buffer->CropAndScaleFrom(buf, 0, 50, 100, 100);
+  CheckCrop(scaled_buffer, 0.0, 0.25, 1.0, 0.5);
+}
+
+TEST(TestI420FrameBuffer, CropYNotCenter) {
+  rtc::scoped_refptr<I420Buffer> buf = CreateGradient(100, 200);
+
+  // Non-center cropping, no scaling.
+  rtc::scoped_refptr<I420Buffer> scaled_buffer(
+      new rtc::RefCountedObject<I420Buffer>(100, 100));
+
+  scaled_buffer->CropAndScaleFrom(buf, 0, 25, 100, 100);
+  CheckCrop(scaled_buffer, 0.0, 0.125, 1.0, 0.5);
+}
+
+TEST(TestI420FrameBuffer, CropAndScale16x9) {
+  rtc::scoped_refptr<I420Buffer> buf = CreateGradient(640, 480);
+
+  // Center crop to 640 x 360 (16/9 aspect), then scale down by 2.
+  rtc::scoped_refptr<I420Buffer> scaled_buffer(
+      new rtc::RefCountedObject<I420Buffer>(320, 180));
+
+  scaled_buffer->CropAndScaleFrom(buf);
+  CheckCrop(scaled_buffer, 0.0, 0.125, 1.0, 0.75);
+}
+
 }  // namespace webrtc