exo: Fix multi-display hardware cursor

components/exo/pointer.h

 // Copyright 2015 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 COMPONENTS_EXO_POINTER_H_
 #define COMPONENTS_EXO_POINTER_H_
 
 #include <memory>
 
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "base/unguessable_token.h"
 #include "components/exo/surface_delegate.h"
 #include "components/exo/surface_observer.h"
 #include "components/exo/wm_helper.h"
+#include "third_party/skia/include/core/SkBitmap.h"
 #include "ui/base/cursor/cursor.h"
+#include "ui/display/display.h"
 #include "ui/events/event_constants.h"
 #include "ui/events/event_handler.h"
 #include "ui/gfx/geometry/point.h"
 #include "ui/gfx/geometry/point_f.h"
 #include "ui/gfx/native_widget_types.h"
 
 namespace cc {
 class CopyOutputResult;
 }
 
@@ skipping 25 matching lines @@
 
   // Returns the current cursor for the pointer.
   gfx::NativeCursor GetCursor();
 
   // Overridden from ui::EventHandler:
   void OnMouseEvent(ui::MouseEvent* event) override;
   void OnScrollEvent(ui::ScrollEvent* event) override;
 
   // Overridden from WMHelper::CursorObserver:
   void OnCursorSetChanged(ui::CursorSetType cursor_set) override;
+  void OnCursorDisplayChanging(const display::Display& display) override;
 
   // Overridden from SurfaceDelegate:
   void OnSurfaceCommit() override;
   bool IsSurfaceSynchronized() const override;
 
   // Overridden from SurfaceObserver:
   void OnSurfaceDestroying(Surface* surface) override;
 
  private:
   // Returns the effective target for |event|.
   Surface* GetEffectiveTargetForEvent(ui::Event* event) const;
 
-  // Recompute cursor scale and update cursor if scale changed.
-  void UpdateCursorScale();
-
   // Asynchronously update the cursor by capturing a snapshot of |surface_|.
-  void CaptureCursor();
+  void CaptureCursor(const gfx::Point& hotspot);

[reveman, 2017/05/25 10:52:55]

why do we need to pass hotspot as an argument to this now?

[Dominik Laskowski, 2017/05/31 02:06:27]

As discussed offline, the bitmap and hotspot are updated together.

 
   // Called when cursor snapshot has been captured.
   void OnCursorCaptured(const gfx::Point& hotspot,
                         std::unique_ptr<cc::CopyOutputResult> result);
 
-  // Update cursor to reflect the current value of |cursor_|.
+  // Synchronously update the cursor to the latest snapshot.
   void UpdateCursor();
 
+  void SetCursor(gfx::NativeCursor cursor);

[reveman, 2017/05/25 10:52:55]

Please a comment for this function and I think we should remove the argument and
have it use |cursor_| instead.

[Dominik Laskowski, 2017/05/31 02:06:27]

Done.

+
   // The delegate instance that all events are dispatched to.
   PointerDelegate* const delegate_;
 
   // The current pointer surface.
   Surface* surface_ = nullptr;
 
   // The current focus surface for the pointer.
   Surface* focus_ = nullptr;
 
   // The location of the pointer in the current focus surface.
   gfx::PointF location_;
 
-  // The scale applied to the cursor to compensate for the UI scale.
+  // The display-independent scale applied to the cursor.
   float cursor_scale_ = 1.0f;

[reveman, 2017/05/25 10:52:55]

Please keep this the scale of |cursor_| as before.

[Dominik Laskowski, 2017/05/31 02:06:26]

Removed per offline chat.

 
+  // Device scale factor of the display where the cursor sprite is located.
+  float cursor_device_scale_factor_ = 1.0f;

[reveman, 2017/05/25 10:52:55]

Actually, I don't think we need this as all it should do is affect
cursor_scale_. cursor_scale_ is set to the scale that is currently used by
|cursor_|. 

[Dominik Laskowski, 2017/05/31 02:06:27]

Removed per offline chat.

+
+  // Rotation of the display where the cursor sprite is located.
+  display::Display::Rotation cursor_rotation_ = display::Display::ROTATE_0;
+
   // The position of the pointer surface relative to the pointer location.
   gfx::Point hotspot_;
 
-  // The current cursor.
-  ui::Cursor cursor_;

[reveman, 2017/05/25 10:52:55]

Please keep cursor in addition to bitmap as it's hard to see if GetCursor always
return the right thing otherwise and what the lifetime of this is otherwise.

[Dominik Laskowski, 2017/05/31 02:06:27]

Done.

+  // Latest cursor snapshot.
+  SkBitmap cursor_bitmap_;
 
   // Source used for cursor capture copy output requests.
   const base::UnguessableToken cursor_capture_source_id_;
 
   // Last received event type.
   ui::EventType last_event_type_ = ui::ET_UNKNOWN;
 
   // Weak pointer factory used for cursor capture callbacks.
   base::WeakPtrFactory<Pointer> cursor_capture_weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(Pointer);
 };
 
 }  // namespace exo
 
 #endif  // COMPONENTS_EXO_POINTER_H_