Scale to DIPs in ppb_graphics2d_impl for proper invalidation

webkit/plugins/ppapi/ppb_graphics_2d_impl.cc

 // Copyright (c) 2012 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.
 
 #include "webkit/plugins/ppapi/ppb_graphics_2d_impl.h"
 
 #include <iterator>
 
 #include "base/bind.h"
 #include "base/debug/trace_event.h"
@@ skipping 54 matching lines @@
         static_cast<int64>(rect->size.height) >
         static_cast<int64>(image_height))
       return false;
 
     *dest = gfx::Rect(rect->point.x, rect->point.y,
                       rect->size.width, rect->size.height);
   }
   return true;
 }
 
+// Scale the rectangle, taking care to round coordinates outward so a
+// rectangle scaled down then scaled back up by the inverse scale would
+// fully contain the entire area affected by the original rectangle.
+gfx::Rect ScaleRectBounds(const gfx::Rect& rect, float scale) {
+  int left = static_cast<int>(floorf(rect.x() * scale));
+  int top = static_cast<int>(floorf(rect.y() * scale));
+  int right = static_cast<int>(ceilf((rect.x() + rect.width()) * scale));
+  int bottom = static_cast<int>(ceilf((rect.y() + rect.height()) * scale));
+  return gfx::Rect(left, top, right - left, bottom - top);
+}
+
 // Converts BGRA <-> RGBA.
 void ConvertBetweenBGRAandRGBA(const uint32_t* input,
                                int pixel_length,
                                uint32_t* output) {
   for (int i = 0; i < pixel_length; i++) {
     const unsigned char* pixel_in =
         reinterpret_cast<const unsigned char*>(&input[i]);
     unsigned char* pixel_out = reinterpret_cast<unsigned char*>(&output[i]);
     pixel_out[0] = pixel_in[2];
     pixel_out[1] = pixel_in[1];
@@ skipping 258 matching lines @@
         break;
     }
 
     // For correctness with accelerated compositing, we must issue an invalidate
     // on the full op_rect even if it is partially or completely off-screen.
     // However, if we issue an invalidate for a clipped-out region, WebKit will
     // do nothing and we won't get any ViewWillInitiatePaint/ViewFlushedPaint
     // calls, leaving our callback stranded. So we still need to check whether
     // the repainted area is visible to determine how to deal with the callback.
     if (bound_instance_ && !op_rect.IsEmpty()) {
+      gfx::Point scroll_delta(operation.scroll_dx, operation.scroll_dy);
+      if (!ConvertToLogicalPixels(scale_,
+                                  &op_rect,
+                                  operation.type == QueuedOperation::SCROLL ?
+                                      &scroll_delta : NULL)) {
+        // Conversion requires falling back to InvalidateRect.
+        operation.type = QueuedOperation::PAINT;
+      }
 
       // Set |nothing_visible| to false if the change overlaps the visible area.
       gfx::Rect visible_changed_rect =
           PP_ToGfxRect(bound_instance_->view_data().clip_rect).
           Intersect(op_rect);
       if (!visible_changed_rect.IsEmpty())
         nothing_visible = false;
 
       // Notify the plugin of the entire change (op_rect), even if it is
       // partially or completely off-screen.
       if (operation.type == QueuedOperation::SCROLL) {
-        bound_instance_->ScrollRect(operation.scroll_dx, operation.scroll_dy,
+        bound_instance_->ScrollRect(scroll_delta.x(), scroll_delta.y(),
                                     op_rect);
       } else {
         bound_instance_->InvalidateRect(op_rect);
       }
     }
   }
   queued_operations_.clear();
 
   if (nothing_visible) {
     // There's nothing visible to invalidate so just schedule the callback to
@@ skipping 142 matching lines @@
 
   CGRect bounds;
   bounds.origin.x = plugin_rect.origin().x();
   bounds.origin.y = window_height - plugin_rect.origin().y() -
       plugin_rect.height();
   bounds.size.width = plugin_rect.width();
   bounds.size.height = plugin_rect.height();
 
   CGContextClipToRect(canvas, bounds);
 
+  // TODO(jhorwich) Figure out if this code is even active anymore, and if so
+  // how to properly handle scaling.
+  DCHECK_EQ(1.0f, scale_);
+
   // TODO(brettw) bug 56673: do a direct memcpy instead of going through CG
   // if the is_always_opaque_ flag is set. Must ensure bitmap is still clipped.
 
   CGContextDrawImage(canvas, bitmap_rect, image);
   CGContextRestoreGState(canvas);
 #else
   SkRect sk_plugin_rect = SkRect::MakeXYWH(
       SkIntToScalar(plugin_rect.origin().x()),
       SkIntToScalar(plugin_rect.origin().y()),
       SkIntToScalar(plugin_rect.width()),
@@ skipping 66 matching lines @@
 }
 
 void PPB_Graphics2D_Impl::ViewFlushedPaint() {
   TRACE_EVENT0("pepper", "PPB_Graphics2D_Impl::ViewFlushedPaint");
   // Notify any "painted" callback. See |unpainted_flush_callback_| in the
   // header for more.
   if (!painted_flush_callback_.is_null())
     painted_flush_callback_.Execute(PP_OK);
 }
 
+// static
+bool PPB_Graphics2D_Impl::ConvertToLogicalPixels(float scale,
+                                                 gfx::Rect* op_rect,
+                                                 gfx::Point* delta) {
+  if (scale == 1.0f || scale <= 0.0f)
+    return true;
+
+  gfx::Rect original_rect = *op_rect;
+  *op_rect = ScaleRectBounds(*op_rect, scale);
+  if (delta) {
+    gfx::Point original_delta = *delta;
+    float inverse_scale = 1.0f / scale;
+    *delta = delta->Scale(scale);
+    if (original_rect != ScaleRectBounds(*op_rect, inverse_scale) ||
+        original_delta != delta->Scale(inverse_scale)) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
 void PPB_Graphics2D_Impl::ExecutePaintImageData(PPB_ImageData_Impl* image,
                                                 int x, int y,
                                                 const gfx::Rect& src_rect,
                                                 gfx::Rect* invalidated_rect) {
   // Ensure the source image is mapped to read from it.
   ImageDataAutoMapper auto_mapper(image);
   if (!auto_mapper.is_valid())
     return;
 
   // Portion within the source image to cut out.
@@ skipping 77 matching lines @@
 }
 
 bool PPB_Graphics2D_Impl::HasPendingFlush() const {
   return !unpainted_flush_callback_.is_null() ||
          !painted_flush_callback_.is_null() ||
          offscreen_flush_pending_;
 }
 
 }  // namespace ppapi
 }  // namespace webkit