Introducing a helper wrapper for YUV-to-RGB convertion and/or scaling.

remoting/base/util.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "remoting/base/util.h"
 
 #include <math.h>
 
 #include "base/logging.h"
 #include "base/stringprintf.h"
@@ skipping 37 matching lines @@
 }
 
 static int CalculateYOffset(int x, int y, int stride) {
   return stride * y + x;
 }
 
 static int CalculateUVOffset(int x, int y, int stride) {
   return stride * y / 2 + x / 2;
 }
 
-void ConvertYUVToRGB32WithRect(const uint8* y_plane,
-                               const uint8* u_plane,
-                               const uint8* v_plane,
-                               uint8* rgb_plane,
-                               const SkIRect& rect,
-                               int y_stride,
-                               int uv_stride,
-                               int rgb_stride) {
-  DCHECK((rect.x() & 1) == 0 && (rect.y() & 1) == 0);
-  int rgb_offset = CalculateRGBOffset(rect.left(), rect.top(), rgb_stride);
-  int y_offset = CalculateYOffset(rect.left(), rect.top(), y_stride);
-  int uv_offset = CalculateUVOffset(rect.left(), rect.top(), uv_stride);
-
-  media::ConvertYUVToRGB32(y_plane + y_offset,
-                           u_plane + uv_offset,
-                           v_plane + uv_offset,
-                           rgb_plane + rgb_offset,
-                           rect.width(),
-                           rect.height(),
-                           y_stride,
-                           uv_stride,
-                           rgb_stride,
-                           media::YV12);
-}
-
 void ConvertRGB32ToYUVWithRect(const uint8* rgb_plane,
                                uint8* y_plane,
                                uint8* u_plane,
                                uint8* v_plane,
                                int x,
                                int y,
                                int width,
                                int height,
                                int rgb_stride,
                                int y_stride,
                                int uv_stride) {
   int rgb_offset = CalculateRGBOffset(x, y, rgb_stride);
   int y_offset = CalculateYOffset(x, y, y_stride);
   int uv_offset = CalculateUVOffset(x, y, uv_stride);;
 
   media::ConvertRGB32ToYUV(rgb_plane + rgb_offset,
                            y_plane + y_offset,
                            u_plane + uv_offset,
                            v_plane + uv_offset,
                            width,
                            height,
                            rgb_stride,
                            y_stride,
                            uv_stride);
 }
 
+void ConvertAndScaleYUVToRGB32Rect(const uint8* source_yplane,
+                                   const uint8* source_uplane,
+                                   const uint8* source_vplane,
+                                   int source_ystride,
+                                   int source_uvstride,
+                                   const SkISize& source_size,
+                                   const SkIRect& source_clip,
+                                   uint8* dest_buffer,
+                                   int dest_stride,
+                                   const SkISize& dest_size,
+                                   const SkIRect& dest_clip,
+                                   const SkIRect& dest_rect) {
+  // N.B. It is caller's responsibility to check if strides are large enough. We
+  // cannot do it here anyway.
+  DCHECK(SkIRect::MakeSize(source_size).contains(source_clip));
+  DCHECK(SkIRect::MakeSize(dest_size).contains(dest_clip));
+  DCHECK(dest_clip.contains(dest_rect));
+  DCHECK(source_clip.contains(ScaleRect(dest_rect, dest_size, source_size)));
+
+  // If the source and/or destination buffers don't start at (0, 0)
+  // offset the pointers to pretend we have complete buffers.
+  int y_offset = - CalculateYOffset(source_clip.x(), source_clip.y(),
+                                    source_ystride);
+  int uv_offset = - CalculateUVOffset(source_clip.x(), source_clip.y(),
+                                      source_uvstride);
+  int rgb_offset = - CalculateRGBOffset(dest_clip.x(), dest_clip.y(),
+                                        dest_stride);
+
+  // See if scaling is needed.
+  if (source_size == dest_size) {
+    DCHECK((dest_rect.x() & 1) == 0 && (dest_rect.y() & 1) == 0);

[Wez, 2012/02/02 01:35:29]

Since the API specifies that you should always provide even X & Y coords,
DCHECK() on function entry, rather than just on this path.

[alexeypa (please no reviews), 2012/02/02 21:33:03]

I made the function more tolerant to unaligned rectangles.

+
+    y_offset += CalculateYOffset(dest_rect.left(), dest_rect.top(),
+                                 source_ystride);
+    uv_offset += CalculateUVOffset(dest_rect.left(), dest_rect.top(),
+                                   source_uvstride);
+    rgb_offset += CalculateRGBOffset(dest_rect.left(), dest_rect.top(),
+                                     dest_stride);
+
+    media::ConvertYUVToRGB32(source_yplane + y_offset,
+                             source_uplane + uv_offset,
+                             source_vplane + uv_offset,
+                             dest_buffer + rgb_offset,
+                             dest_rect.width(),
+                             dest_rect.height(),
+                             source_ystride,
+                             source_uvstride,
+                             dest_stride,
+                             media::YV12);
+  } else {
+    media::ScaleYUVToRGB32WithRect(source_yplane + y_offset,
+                                   source_uplane + uv_offset,
+                                   source_vplane + uv_offset,
+                                   dest_buffer + rgb_offset,
+                                   source_size.width(),
+                                   source_size.height(),
+                                   dest_size.width(),
+                                   dest_size.height(),
+                                   dest_rect.left(),
+                                   dest_rect.top(),
+                                   dest_rect.right(),
+                                   dest_rect.bottom(),
+                                   source_ystride,
+                                   source_uvstride,
+                                   dest_stride);
+  }
+}
+
 int RoundToTwosMultiple(int x) {
   return x & (~1);
 }
 
 SkIRect AlignRect(const SkIRect& rect) {
   int x = RoundToTwosMultiple(rect.left());
   int y = RoundToTwosMultiple(rect.top());
   int right = RoundToTwosMultiple(rect.right() + 1);
   int bottom = RoundToTwosMultiple(rect.bottom() + 1);
   return SkIRect::MakeLTRB(x, y, right, bottom);
 }
 
 SkIRect ScaleRect(const SkIRect& rect,
                   const SkISize& in_size,
                   const SkISize& out_size) {
-  int left = (rect.left() * out_size.width()) / in_size.width();
-  int top = (rect.top() * out_size.height()) / in_size.height();
-  int right = (rect.right() * out_size.width() + out_size.width() - 1) /
-      in_size.width();
-  int bottom = (rect.bottom() * out_size.height() + out_size.height() - 1) /
-      in_size.height();
+  SkScalar scale_x = SkScalarDiv(out_size.width(), in_size.width());
+  SkScalar scale_y = SkScalarDiv(out_size.height(), in_size.height());
+
+  int left = SkScalarFloorToInt(scale_x * rect.left());
+  int top = SkScalarFloorToInt(scale_y * rect.top());
+  int right = SkScalarCeilToInt(scale_x * rect.right());
+  int bottom = SkScalarCeilToInt(scale_y * rect.bottom());

[Wez, 2012/02/02 01:35:29]

Why are you changing from pure integer arithmetic to SkScalar (which might be
float, depending on build settings)?

[alexeypa (please no reviews), 2012/02/02 21:33:03]

That was needed to support up-scaling at some point and my new code used this.
But then I realized that the scaling routines that we have do not support
upscaling anyway so it is a moot point now. I reverted this function to the
original form.

[Wez, 2012/02/03 22:40:35]

I think the full-frame scaling routines support up-scaling, so we could probably
fall back to use those.  We didn't bother getting up-scaling working for the
sub-rect scaler because the client doesn't never scales up the host (unless you
use full page zoom...)

[alexeypa (please no reviews), 2012/02/03 23:29:35]

I guess we could do this if we decide to support up-scaling in the future. Right
now there is no code that would use this functionality.

On 2012/02/03 22:40:35, Wez wrote:

   return SkIRect::MakeLTRB(left, top, right, bottom);
 }
 
 void CopyRect(const uint8* src_plane,
               int src_plane_stride,
               uint8* dest_plane,
               int dest_plane_stride,
               int bytes_per_pixel,
               const SkIRect& rect) {
   // Get the address of the starting point.
   const int src_y_offset = src_plane_stride * rect.top();
   const int dest_y_offset = dest_plane_stride * rect.top();
   const int x_offset = bytes_per_pixel * rect.left();
   src_plane += src_y_offset + x_offset;
   dest_plane += dest_y_offset + x_offset;
 
   // Copy pixels in the rectangle line by line.
   const int bytes_per_line = bytes_per_pixel * rect.width();
   const int height = rect.height();
   for (int i = 0 ; i < height; ++i) {
     memcpy(dest_plane, src_plane, bytes_per_line);
     src_plane += src_plane_stride;
     dest_plane += dest_plane_stride;
   }
 }
 
+void CopyRGB32Rect(const uint8* source_buffer,
+                   int source_stride,
+                   const SkIRect& source_clip,
+                   uint8* dest_buffer,
+                   int dest_stride,
+                   const SkIRect& dest_clip,
+                   const SkIRect& dest_rect) {
+  DCHECK(dest_clip.contains(dest_rect));
+  DCHECK(source_clip.contains(dest_rect));
+
+  // Get the address of the starting point.
+  int source_offset = CalculateRGBOffset(dest_rect.x() - source_clip.x(),
+                                         dest_rect.y() - source_clip.y(),
+                                         source_stride);
+  int dest_offset = CalculateRGBOffset(dest_rect.x() - dest_clip.x(),
+                                         dest_rect.y() - dest_clip.y(),
+                                         source_stride);
+
+  // Copy bits.
+  CopyRect(source_buffer + source_offset,
+           source_stride,
+           dest_buffer + dest_offset,
+           dest_stride,
+           GetBytesPerPixel(media::VideoFrame::RGB32),
+           SkIRect::MakeWH(dest_rect.width(), dest_rect.height()));
+}
+
 }  // namespace remoting