Add non-member non-mutating methods for common gfx::Rect operations.

This adds non-member methods that return a new Rect (or RectF) object
as their result instead of mutating an existing rect. We add:

Rect gfx::IntersectRects(Rect, Rect)
RectF gfx::IntersectRects(RectF, RectF)
Rect gfx::UnionRects(Rect, Rect)
RectF gfx::UnionRects(RectF, RectF)
Rect gfx::SubtractRects(Rect, Rect)
RectF gfx::SubtractRects(RectF, RectF)
RectF gfx::ScaleRect(RectF, scale)
RectF gfx::ScaleRect(RectF, x_scale, y_scale)

In CL https://codereview.chromium.org/11110004/ we made all
member methods of Rect (and RectF) mutate the existing
object, so these methods are added for cases where we want
the result to create a new object instead.

BUG=147395
R=sky

Review URL: https://codereview.chromium.org/11270042

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@164760 0039d316-1c4b-4281-b951-d872f2087c98

4 files changed, 16 insertions, 22 deletions

diff --git a/webkit/plugins/npapi/webplugin_delegate_impl_gtk.cc b/webkit/plugins/npapi/webplugin_delegate_impl_gtk.cc
index 869ea9f..382a975 100644
--- a/webkit/plugins/npapi/webplugin_delegate_impl_gtk.cc
+++ b/webkit/plugins/npapi/webplugin_delegate_impl_gtk.cc
@@ -355,8 +355,7 @@ void WebPluginDelegateImpl::WindowlessPaint(cairo_t* context,
   // "real" means as seen by Chrome
   // "apparent" means as seen by the plugin.
 
-  gfx::Rect draw_rect = window_rect_;
-  draw_rect.Intersect(damage_rect);
+  gfx::Rect draw_rect = gfx::IntersectRects(window_rect_, damage_rect);
 
   // clip_rect_ is relative to the plugin
   gfx::Rect clip_rect_window = clip_rect_;
diff --git a/webkit/plugins/ppapi/ppapi_plugin_instance.cc b/webkit/plugins/ppapi/ppapi_plugin_instance.cc
index 0b858c6..c0c6c78 100644
--- a/webkit/plugins/ppapi/ppapi_plugin_instance.cc
+++ b/webkit/plugins/ppapi/ppapi_plugin_instance.cc
@@ -1174,14 +1174,12 @@ bool PluginInstance::GetBitmapForOptimizedPluginPaint(
   gfx::Rect pixel_plugin_backing_store_rect(
       0, 0, image_data->width(), image_data->height());
   float scale = GetBoundGraphics2D()->GetScale();
-  gfx::RectF scaled_backing_store_rect = pixel_plugin_backing_store_rect;
-  scaled_backing_store_rect.Scale(scale);
-  gfx::Rect plugin_backing_store_rect =
-    gfx::ToEnclosedRect(scaled_backing_store_rect);
+  gfx::Rect plugin_backing_store_rect = gfx::ToEnclosedRect(
+      gfx::ScaleRect(pixel_plugin_backing_store_rect, scale));
 
   gfx::Rect clip_page = PP_ToGfxRect(view_data_.clip_rect);
-  gfx::Rect plugin_paint_rect = plugin_backing_store_rect;
-  plugin_paint_rect.Intersect(clip_page);
+  gfx::Rect plugin_paint_rect =
+      gfx::IntersectRects(plugin_backing_store_rect, clip_page);
   if (!plugin_paint_rect.Contains(relative_paint_bounds))
     return false;
 
diff --git a/webkit/plugins/ppapi/ppb_graphics_2d_impl.cc b/webkit/plugins/ppapi/ppb_graphics_2d_impl.cc
index 923b88d..aaad035 100644
--- a/webkit/plugins/ppapi/ppb_graphics_2d_impl.cc
+++ b/webkit/plugins/ppapi/ppb_graphics_2d_impl.cc
@@ -376,8 +376,7 @@ int32_t PPB_Graphics2D_Impl::Flush(scoped_refptr<TrackedCallback> callback,
 
       // Set |no_update_visible| to false if the change overlaps the visible
       // area.
-      gfx::Rect visible_changed_rect = clip;
-      visible_changed_rect.Intersect(op_rect);
+      gfx::Rect visible_changed_rect = gfx::IntersectRects(clip, op_rect);
       if (!visible_changed_rect.IsEmpty())
         no_update_visible = false;
 
@@ -561,8 +560,7 @@ void PPB_Graphics2D_Impl::Paint(WebKit::WebCanvas* canvas,
 
   CGContextDrawImage(canvas, bitmap_rect, image);
 #else
-  gfx::Rect invalidate_rect = plugin_rect;
-  invalidate_rect.Intersect(paint_rect);
+  gfx::Rect invalidate_rect = gfx::IntersectRects(plugin_rect, paint_rect);
   SkRect sk_invalidate_rect = gfx::RectToSkRect(invalidate_rect);
   SkAutoCanvasRestore auto_restore(canvas, true);
   canvas->clipRect(sk_invalidate_rect);
@@ -649,20 +647,20 @@ bool PPB_Graphics2D_Impl::ConvertToLogicalPixels(float scale,
   // Take the enclosing rectangle after scaling 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::RectF scaled_rect = *op_rect;
-  scaled_rect.Scale(scale);
-  *op_rect = gfx::ToEnclosingRect(scaled_rect);
+  *op_rect = gfx::ToEnclosingRect(gfx::ScaleRect(*op_rect, scale));
   if (delta) {
     gfx::Point original_delta = *delta;
     float inverse_scale = 1.0f / scale;
     *delta = gfx::ToFlooredPoint(delta->Scale(scale));
 
-    gfx::RectF inverse_scaled_rect = *op_rect;
-    inverse_scaled_rect.Scale(inverse_scale);
-    if (original_rect != gfx::ToEnclosingRect(inverse_scaled_rect) ||
-        original_delta != gfx::ToFlooredPoint(delta->Scale(inverse_scale))) {
+    gfx::Rect inverse_scaled_rect =
+        gfx::ToEnclosingRect(gfx::ScaleRect(*op_rect, inverse_scale));
+    if (original_rect != inverse_scaled_rect)
+      return false;
+    gfx::Point inverse_scaled_point =
+        gfx::ToFlooredPoint(delta->Scale(inverse_scale));
+    if (original_delta != inverse_scaled_point)
       return false;
-    }
   }
 
   return true;
diff --git a/webkit/plugins/webview_plugin.cc b/webkit/plugins/webview_plugin.cc
index 9888b73..4e5c8c4 100644
--- a/webkit/plugins/webview_plugin.cc
+++ b/webkit/plugins/webview_plugin.cc
@@ -120,8 +120,7 @@ bool WebViewPlugin::getFormValue(WebString& value) {
 }
 
 void WebViewPlugin::paint(WebCanvas* canvas, const WebRect& rect) {
-  gfx::Rect paintRect = rect_;
-  paintRect.Intersect(rect);
+  gfx::Rect paintRect = gfx::IntersectRects(rect_, rect);
   if (paintRect.IsEmpty())
     return;