Add DesktopFrame rotation functions

webrtc/modules/desktop_capture/desktop_frame_rotation.h

+/*
+ *  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.
+ */
+
+#ifndef WEBRTC_MODULES_DESKTOP_CAPTURE_DESKTOP_FRAME_ROTATION_H_
+#define WEBRTC_MODULES_DESKTOP_CAPTURE_DESKTOP_FRAME_ROTATION_H_
+
+#include "webrtc/modules/desktop_capture/desktop_frame.h"
+#include "webrtc/modules/desktop_capture/desktop_geometry.h"
+
+namespace webrtc {
+
+// Represents the rotation of a DesktopFrame.
+enum class Rotation {
+  CLOCK_WISE_0,
+  CLOCK_WISE_90,
+  CLOCK_WISE_180,
+  CLOCK_WISE_270,
+};
+
+// Rotates input DesktopFrame |source|, copies pixel in an unrotated rectangle
+// |source_rect| into the target rectangle of another DesktopFrame |target|, and
+// adds target rectangle into |target|->mutable_updated_region().
+// Target rectangle here is the rotated |source_rect| plus |target_offset|.
+// |rotation| specifies |source| to |target| rotation. |source_rect| is in
+// |source| coordinate. |target_offset| is in |target| coordinate.
+// This function triggers check failure if |source| does not cover the
+// |source_rect|, or |target| does not cover the rotated |rect|.
+void RotateDesktopFrame(const DesktopFrame& source,
+                        const DesktopRect& source_rect,
+                        const Rotation& rotation,
+                        const DesktopVector& target_offset,
+                        DesktopFrame* target);
+
+// Returns a reverse rotation of |rotation|.
+Rotation ReverseRotation(Rotation rotation);
+
+// Returns a rotated DesktopSize of |size|.
+DesktopSize RotateSize(DesktopSize size, Rotation rotation);
+
+// Returns a rotated DesktopRect of |rect|. The |size| represents the size of
+// the DesktopFrame which |rect| belongs in.
+DesktopRect RotateRect(DesktopRect rect, DesktopSize size, Rotation rotation);
+
+}  // namespace webrtc
+
+#endif  // WEBRTC_MODULES_DESKTOP_CAPTURE_DESKTOP_FRAME_ROTATION_H_