[WebRTC] A real ScreenCapturer test

webrtc/modules/desktop_capture/color.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_COLOR_H_
+#define WEBRTC_MODULES_DESKTOP_CAPTURE_COLOR_H_
+
+#include <stdint.h>
+
+#include "webrtc/modules/desktop_capture/desktop_frame.h"
+
+namespace webrtc {
+
+// A four bytes strcture to store a color in BGRA format, which can be converted

[Jamie, 2016/08/26 22:29:09]

s/four bytes/four-byte/
s/strcture/structure/

[Hzj_jie, 2016/08/29 21:57:27]

Done.

+// from and to uint32_t format. This structure also provides functions to
+// compare with uint8_t array, say, DesktopFrame::data(). When converting from
+// or to uint32_t format, it's big-ending and little-ending safe, but it always

[Jamie, 2016/08/26 22:29:09]

s/ending/endian/

[Hzj_jie, 2016/08/29 21:57:27]

Done.

+// uses BGRA order for internal storage to match DesktopFrame::data().
+//
+// This struct is for testing purpose only, and should not be used in production
+// logic.
+struct Color final {
+  // Creates a color from a BGRA ordered uint.
+  static Color FromBGRA(uint32_t bgra);
+
+  // Creates an opaque color from a BGR ordered uint, only low 24 bits of
+  // |bgr| are used.
+  static Color FromBGR(uint32_t bgr);
+
+  // Creates a color with BGRA channels.
+  static Color FromBGRA(uint8_t blue,
+                        uint8_t green,
+                        uint8_t red,
+                        uint8_t alpha);

[Jamie, 2016/08/26 22:29:09]

I think it would be better to include only this ctor. You're only using the
uint32 version to set black, for which I think (0,0,0) is just as readable. The
only place you're using FromBRGA is with a random number which I don't think
makes for a very robust test.

Optionally, also consider making this a ctor (which is permitted if you don't
need to overload it). FromBGRA has the advantage of making the endianness
explicit, but it's not particularly idiomatic C++.

[Hzj_jie, 2016/08/29 21:57:27]

Done.

+
+  // Creates a color with BGR channels, and set alpha channel to 255 (opaque).
+  static Color FromBGR(uint8_t blue, uint8_t green, uint8_t red);
+
+  // Returns true if |bgra| four bytes in BGRA order represents a same color
+  // as |this|.
+  bool operator==(const uint8_t* const bgra) const;
+
+  // Returns true if |bgra| four bytes in BGRA order represents a different
+  // color as |this|.
+  bool operator!=(const uint8_t* const bgra) const;
+
+  // Returns true if |this| and |right| is the same color.
+  bool operator==(const Color& right) const;
+
+  // Returns true if |this| and |right| are different colors.
+  bool operator!=(const Color& right) const;
+
+  // Converts current Color into its uint format in BGRA order for a quick
+  // assignment or compare.
+  uint32_t ToUInt32() const;
+
+  uint8_t blue() const;
+
+  uint8_t green() const;
+
+  uint8_t red() const;
+
+  uint8_t alpha() const;
+
+  uint8_t bgra[DesktopFrame::kBytesPerPixel];
+};
+static_assert(
+    DesktopFrame::kBytesPerPixel == sizeof(uint32_t),
+    "A pixel in DesktopFrame should be safe to represent by a uint32_t");
+
+}  // namespace webrtc
+
+#endif  // WEBRTC_MODULES_DESKTOP_CAPTURE_COLOR_H_