Clipping textured quads explicitly without scissoring

cc/texture_draw_quad.cc

Index: cc/texture_draw_quad.cc
diff --git a/cc/texture_draw_quad.cc b/cc/texture_draw_quad.cc
index d552c3991c21a2d3a1f89aa3f03dee46dbdd1109..ca2c62b9e72247fef8c34ff85601826d18f48304 100644
--- a/cc/texture_draw_quad.cc
+++ b/cc/texture_draw_quad.cc
@@ -58,4 +58,50 @@ const TextureDrawQuad* TextureDrawQuad::MaterialCast(
   return static_cast<const TextureDrawQuad*>(quad);
 }
 
+bool const TextureDrawQuad::PerformClipping()
+{

[jamesr, 2012/12/05 23:19:45]

{ goes on the previous line

+  // This only occurs if the rect is only scaled and translated (and thus still axis alinged).

[jamesr, 2012/12/05 23:19:45]

typo "alinged" -> "aligned"

+  if (quadTransform().IsScaleOrTranslation())

[jamesr, 2012/12/05 23:19:45]

you'd have slightly less indentation if this was phrased as an early return,
i.e.:

if (!quadTransform().IsScaleOrTranslation())
  return;

// rest of function body

+  {

[jamesr, 2012/12/05 23:19:45]

{ goes on the previous line

+    // Grab our scale and offset.
+    float x_scale = quadTransform().matrix().getDouble(0,0);
+    float y_scale = quadTransform().matrix().getDouble(1,1);
+    gfx::Vector2dF offset(
+      quadTransform().matrix().getDouble(0,3),

[jamesr, 2012/12/05 23:19:45]

continuations should have 4-space indents

+      quadTransform().matrix().getDouble(1,3));
+
+    // Transform the rect by the scale and offset.
+    gfx::RectF rectF = rect;
+    rectF.Scale(x_scale, y_scale);
+    rectF += offset;
+
+    // Perform clipping and check to see if the result is empty.
+    gfx::RectF clippedRect = IntersectRects(rectF, clipRect());
+    if (clippedRect.IsEmpty())
+    {

[jamesr, 2012/12/05 23:19:45]

{ on previous line

+      rect = gfx::Rect();
+      uv_rect = gfx::RectF();
+      return true;
+    }
+
+    // Create a new uv-rect by clipping the old one to the new bounds.
+    uv_rect = gfx::RectF(
+      uv_rect.x() + uv_rect.width () / rectF.width () * (clippedRect.x() - rectF.x()),

[jamesr, 2012/12/05 23:19:45]

continuations should be indented 4 spaces from previous line, and please wrap
this to 80col since this is a chromium-style file

+      uv_rect.y() + uv_rect.height() / rectF.height() * (clippedRect.y() - rectF.y()),
+      uv_rect.width () / rectF.width () * clippedRect.width (),
+      uv_rect.height() / rectF.height() * clippedRect.height());
+
+    // Move the clipped rectangle back into its space.
+    clippedRect -= offset;
+    clippedRect.Scale(1.0f / x_scale, 1.0f / y_scale);
+    rect = gfx::Rect(
+      static_cast<int>(clippedRect.x() + 0.5f),

[jamesr, 2012/12/05 23:19:45]

4 space indent

+      static_cast<int>(clippedRect.y() + 0.5f),
+      static_cast<int>(clippedRect.width() + 0.5f),
+      static_cast<int>(clippedRect.height() + 0.5f));
+    return true;
+  }
+  return false;
+}
+
 }  // namespace cc