Improved Pinch-Zoom for PDF.

pdf/paint_manager.h

Index: pdf/paint_manager.h
diff --git a/pdf/paint_manager.h b/pdf/paint_manager.h
index dd99f9d2a61f4203be6d884667a268783a3f6ad7..16dcb773782ff6d4ed26593ad534cfd4d6c46616 100644
--- a/pdf/paint_manager.h
+++ b/pdf/paint_manager.h
@@ -146,6 +146,18 @@ class PaintManager {
   pp::Size GetEffectiveSize() const;
   float GetEffectiveDeviceScale() const;
 
+  // Set the transform for the graphics layer.
+  // If |schedule_flush| is true, it ensures a flush will be scheduled for
+  // this change. If |schedule_flush| is false, then the change will not take
+  // effect until another change causes a flush.
+  void SetTransform(float scale,
+                    const pp::Point& origin,
+                    const pp::Point& translate,
+                    bool schedule_flush);
+  // Resets any transform for the graphics layer.
+  // This does not schedule a flush.
+  void ClearTransform();
+
  private:
   // Disallow copy and assign (these are unimplemented).
   PaintManager(const PaintManager&);
@@ -160,6 +172,9 @@ class PaintManager {
   // Does the client paint and executes a Flush if necessary.
   void DoPaint();
 
+  // Executes a Flush.
+  void Flush();
+
   // Callback for asynchronous completion of Flush.
   void OnFlushComplete(int32_t);
 
@@ -185,6 +200,7 @@ class PaintManager {
   // See comment for EnsureCallbackPending for more on how these work.
   bool manual_callback_pending_;
   bool flush_pending_;

[Lei Zhang, 2016/10/31 22:49:04]

Are all four possible state combinations of |flush_pending_| and
|flush_requested_| valid? If not and there's only 3 possible states, replace
both with an enum?

[Kevin McNee - google account, 2016/11/07 23:08:27]

Yes, all are valid:
When |flush_requested_| is false, the behaviour of |flush_pending_| is the same
as before. When |flush_requested_| is true and |flush_pending_| is true, we have
an ongoing flush and the request for an additional flush after completion. When
|flush_requested_| is true and |flush_pending_| is false, then a flush has
completed and there have been no flushes scheduled by paints before we carry out
the flush request. 

+  bool flush_requested_;
 
   // When we get a resize, we don't bind right away (see SetSize). The
   // has_pending_resize_ tells us that we need to do a resize for the next