Add DesktopFrame rotation functions

webrtc/modules/desktop_capture/desktop_frame_rotator.cc

+/*
+ *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "webrtc/modules/desktop_capture/desktop_frame_rotator.h"
+
+#include <string.h>
+
+#include "webrtc/base/checks.h"
+
+#include "third_party/libyuv/include/libyuv/rotate_argb.h"
+
+namespace webrtc {
+
+namespace {
+
+// Returns a rotated DesktopRect of |rect|. The |size| represents the size of
+// the DesktopFrame which |rect| belongs in.
+DesktopRect Rotate(DesktopRect rect, DesktopSize size, Rotation rotation) {

[Sergey Ulanov, 2016/11/15 20:50:22]

Maybe call it RotateRect()?

[Hzj_jie, 2016/11/16 01:18:33]

Done.

+  switch (rotation) {
+    case Rotation::CLOCK_WISE_0:
+      return rect;
+    case Rotation::CLOCK_WISE_90:
+      return DesktopRect::MakeLTRB(size.height() - rect.bottom(), rect.left(),
+                                   size.height() - rect.top(), rect.right());
+    case Rotation::CLOCK_WISE_180:
+      return DesktopRect::MakeLTRB(

[Sergey Ulanov, 2016/11/15 20:50:22]

nit: this would be slightly simpler with MakeXYWH() - it would make it clear
that rect size doesn't change and the math for the last two parameters would be
simpler.

[Hzj_jie, 2016/11/16 01:18:33]

Done.

+          size.width() - rect.right(), size.height() - rect.bottom(),
+          size.width() - rect.left(), size.height() - rect.top());
+    case Rotation::CLOCK_WISE_270:
+      return DesktopRect::MakeLTRB(rect.top(), size.width() - rect.right(),
+                                   rect.bottom(), size.width() - rect.left());
+    default:

[Sergey Ulanov, 2016/11/15 20:50:22]

Don't need default case. Maybe add NOTREACHED after switch.

[Hzj_jie, 2016/11/16 01:18:33]

Done.

+      RTC_NOTREACHED();
+      return DesktopRect();
+  }
+}
+
+// Returns a reverse-rotated Rotation of |rotation|.
+Rotation Reverse(Rotation rotation) {
+  switch (rotation) {
+    case Rotation::CLOCK_WISE_0:
+      return rotation;
+    case Rotation::CLOCK_WISE_90:
+      return Rotation::CLOCK_WISE_270;
+    case Rotation::CLOCK_WISE_180:
+      return Rotation::CLOCK_WISE_180;
+    case Rotation::CLOCK_WISE_270:
+      return Rotation::CLOCK_WISE_90;
+    default:

[Sergey Ulanov, 2016/11/15 20:50:22]

don't need default case.

[Hzj_jie, 2016/11/16 01:18:33]

Done.

+      RTC_NOTREACHED();
+      return Rotation::CLOCK_WISE_0;
+  }
+}
+
+// Returns a reverse-rotated DesktopRect of |rect|. The |size| represents the
+// size of the DesktopFrame which |rect| belongs in.
+DesktopRect Derotate(DesktopRect rect, DesktopSize size, Rotation rotation) {

[Sergey Ulanov, 2016/11/15 20:50:22]

I don't think you need this function, given that it's simple and is used in only
one place.

[Hzj_jie, 2016/11/16 01:18:33]

Done.

+  return Rotate(rect, size, Reverse(rotation));
+}
+
+// Returns a reverse-rotated DesktopSize of |size|.
+DesktopSize Derotate(DesktopSize size, Rotation rotation) {

[Sergey Ulanov, 2016/11/15 20:50:22]

GetRotatedSize()?

[Hzj_jie, 2016/11/16 01:18:33]

Done.

+  switch (rotation) {
+    case Rotation::CLOCK_WISE_0:
+    case Rotation::CLOCK_WISE_180:
+      return size;
+    case Rotation::CLOCK_WISE_90:
+    case Rotation::CLOCK_WISE_270:
+      return DesktopSize(size.height(), size.width());
+    default:
+      RTC_NOTREACHED();
+      return DesktopSize();
+  }
+}
+
+libyuv::RotationMode ToYuvRotationMode(Rotation rotation) {

[Sergey Ulanov, 2016/11/15 20:50:22]

ToLibyuvRotationMode

[Hzj_jie, 2016/11/16 01:18:33]

Done.

+  switch (rotation) {
+    case Rotation::CLOCK_WISE_0:
+      return libyuv::kRotate0;
+    case Rotation::CLOCK_WISE_90:
+      return libyuv::kRotate90;
+    case Rotation::CLOCK_WISE_180:
+      return libyuv::kRotate180;
+    case Rotation::CLOCK_WISE_270:
+      return libyuv::kRotate270;
+    default:
+      RTC_NOTREACHED();
+      return libyuv::kRotate0;
+  }
+}
+
+}  // namespace
+
+bool CopyRotatedRectTo(const DesktopFrame& src,
+                       DesktopRect rect,
+                       Rotation rotation,
+                       DesktopFrame* target) {
+  if (!target) {

[Sergey Ulanov, 2016/11/15 20:50:22]

Do you really need this? Maybe replace with a DCHECK?

[Hzj_jie, 2016/11/16 01:18:33]

Done.

+    return false;
+  }
+  if (!DesktopRect::MakeSize(target->size()).ContainsRect(rect)) {
+    return false;
+  }
+  if (rect.is_empty()) {

[Sergey Ulanov, 2016/11/15 20:50:22]

Do we need this special case? I think CopyPixelsFrom() and libyuv::ARGBRotate()
should handle zero size rect correctly.

[Hzj_jie, 2016/11/16 01:18:33]

When the input rectangle is empty, ARGBRotate will return -1 (error), which is a
little bit different than our expectation.

+    return true;
+  }
+
+  target->mutable_updated_region()->AddRect(rect);
+  if (rotation == Rotation::CLOCK_WISE_0) {
+    // A shortcut: if |rotation| is 0, this function uses
+    // DesktopFrame::CopyPixelsFrom() for a better performance.

[Sergey Ulanov, 2016/11/15 20:50:22]

Does it actually perform better? I would guess libyuv::ARGBRotate() should
already have optimizations for this case, so this special case isn't necessary.

[Hzj_jie, 2016/11/16 01:18:33]

Done.
No, it's for old version, and should be removed.

+    target->CopyPixelsFrom(src, rect.top_left(), rect);
+    return true;
+  }
+
+  // The rectangle in |src|.
+  const DesktopRect src_rect =
+      Derotate(rect, Derotate(src.size(), rotation), rotation);
+  return libyuv::ARGBRotate(
+             src.GetFrameDataAtPos(src_rect.top_left()), src.stride(),
+             target->GetFrameDataAtPos(rect.top_left()), target->stride(),
+             src_rect.width(), src_rect.height(),
+             ToYuvRotationMode(rotation)) == 0;
+}
+
+bool CopyUnrotatedRectTo(const DesktopFrame& src,
+                         DesktopRect rect,
+                         Rotation rotation,
+                         DesktopFrame* target) {
+  return CopyRotatedRectTo(src, Rotate(rect, src.size(), rotation), rotation,
+                           target);
+}
+
+}  // namespace webrtc