[aura-mus] Add ui::CursorData, with mojo serialization.

ui/base/cursor/cursor_data.h

+// Copyright 2017 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.
+
+#ifndef UI_BASE_CURSOR_CURSOR_DATA_H_
+#define UI_BASE_CURSOR_CURSOR_DATA_H_
+
+#include <vector>
+
+#include "build/build_config.h"
+#include "ui/base/ui_base_export.h"
+#include "ui/gfx/geometry/point.h"
+
+class SkBitmap;
+
+namespace ui {
+
+// The new Cursor class. (aka, Cursor2)
+//
+// Contains all data for a cursor. Its type, along with any custom bitmap
+// images, hotspot data, scaling factors, etc.
+//
+// Why a new class? ui::Cursor currently wraps a PlatformCursor, which is a
+// platform specific representation, which is generated in //content/. This
+// previously was OK, as a WebCursor was sent over chrome IPC from the renderer
+// to the browser process, and then the data in WebCursor was turned into the
+// an opaque platform specific structure, stuffed inside ui::Cursor, and then
+// read by win32 or x11. Now, the windowing server can be in a separate
+// process, so this doesn't work.
+//
+// Using a raw mojo struct is not convenient; we want to have copyable classes
+// which are internally copy-on-write for large data, like the internally used
+// SkBitmap, as we cache this data at multiple layers.
+//
+// TODO(erg): Rename this to ui::Cursor once we've mojoified the entire chain
+// from the renderer to the window server.
+class UI_BASE_EXPORT CursorData {
+ public:
+  CursorData();
+  CursorData(int type);
+  CursorData(const gfx::Point& hostpot_point,
+             const std::vector<SkBitmap>& cursor_frames,
+             int frame_delay_ms);
+  CursorData(const CursorData& cursor);
+  ~CursorData();
+
+  CursorData& operator=(const CursorData& cursor);
+
+  int native_type() const { return native_type_; }
+  uint32_t frame_delay_ms() const { return frame_delay_ms_; }
+  gfx::Point hotspot() const { return hotspot_; }
+  const std::vector<SkBitmap>& cursor_frames() const { return cursor_frames_; }
+
+  // Returns true if this CursorData instance is of |native_type|.
+  bool IsType(int native_type) const;
+
+  // Checks if the data in |rhs| was created from the same input data.
+  //
+  // This is subtly different from operator==, as we need this to be a
+  // lightweight operation instead of performing pixel equality checks on
+  // arbitrary sized SkBitmaps. So we check the internal SkBitmap generation
+  // IDs, which are per-process, monotonically increasing ids which get changed
+  // whenever there's a modification to the pixel data. This means that this
+  // method can have false negatives: two SkBitmap instances made with the same
+  // input data (but which weren't copied from each other) can have equal pixel
+  // data, but different generation ids.
+  bool IsSameAs(const CursorData& rhs) const;
+
+ private:
+  // A native type constant from cursor.h.
+  int native_type_;
+
+  // The delay between cursor frames in milliseconds.
+  uint32_t frame_delay_ms_;
+
+  // The hotspot in cursor frames.
+  gfx::Point hotspot_;
+
+  // The frames of a cursor.
+  std::vector<SkBitmap> cursor_frames_;
+
+  // Generator IDs. The size of |generator_ids_| must be equal to the size of
+  // cursor_frames_, and is generated when we set the bitmaps. We produce these
+  // unique IDs so we can do quick equality checks.
+  std::vector<uint32_t> generator_ids_;
+};
+
+}  // namespace ui
+
+#endif  // UI_BASE_CURSOR_CURSOR_DATA_H_