cc: fix pixel-moving filter effects on a rotated layer.

cc/output/gl_renderer.cc

 // Copyright 2010 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 "cc/output/gl_renderer.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 992 matching lines @@
         // in the compositor.
         use_color_matrix = true;
       } else {
         gfx::Vector2dF scale = quad->filters_scale;
         SkMatrix scale_matrix;
         scale_matrix.setScale(scale.x(), scale.y());
         SkIRect result_rect =
             filter->filterBounds(gfx::RectToSkIRect(quad->rect), scale_matrix,
                                  SkImageFilter::kForward_MapDirection);
         gfx::RectF dst_rect = gfx::SkRectToRectF(SkRect::Make(result_rect));
+        // If the destination rect is not the same as the source rect, the edges
+        // computed for AA will be wrong. So disable antialiasing, and use

[enne (OOO), 2016/05/03 18:25:39]

It might be worth saying the correct aa edges *could* be computed, and this just
is a simplification?

[Stephen White, 2016/05/03 18:44:15]

Done.

+        // a 1-pixel transparent border to achieve a similar effect.
+        if (use_aa && dst_rect != rect) {
+          dst_rect.Inset(-1.0f, -1.0f);
+          use_aa = false;
+        }
         gfx::Rect clip_rect = quad->shared_quad_state->clip_rect;
         if (clip_rect.IsEmpty()) {
           clip_rect = current_draw_rect_;
         }
         gfx::Transform transform =
             quad->shared_quad_state->quad_to_target_transform;
         gfx::QuadF clip_quad = gfx::QuadF(gfx::RectF(clip_rect));
         gfx::QuadF local_clip = MapQuadToLocalSpace(transform, clip_quad);
         dst_rect.Intersect(local_clip.BoundingBox());
         // If we've been fully clipped out (by crop rect or clipping), there's
@@ skipping 22 matching lines @@
     mask_resource_lock.reset(new ResourceProvider::ScopedSamplerGL(
         resource_provider_, quad->mask_resource_id(), GL_TEXTURE1, GL_LINEAR));
     mask_texture_id = mask_resource_lock->texture_id();
     mask_sampler = SamplerTypeFromTextureTarget(mask_resource_lock->target());
   }
 
   std::unique_ptr<ResourceProvider::ScopedSamplerGL> contents_resource_lock;
   if (filter_image_id) {
     DCHECK_EQ(GL_TEXTURE0, GetActiveTextureUnit(gl_));
     gl_->BindTexture(GL_TEXTURE_2D, filter_image_id);
+    gl_->TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+    gl_->TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
   } else {
     contents_resource_lock =
         base::WrapUnique(new ResourceProvider::ScopedSamplerGL(
             resource_provider_, contents_texture->id(), GL_LINEAR));
     DCHECK_EQ(static_cast<GLenum>(GL_TEXTURE_2D),
               contents_resource_lock->target());
   }
 
   if (!use_shaders_for_blending) {
     if (!use_blend_equation_advanced_coherent_ && use_blend_equation_advanced_)
@@ skipping 2573 matching lines @@
       texture_id = pending_overlay_resources_.back()->texture_id();
     }
 
     context_support_->ScheduleOverlayPlane(
         overlay.plane_z_order, overlay.transform, texture_id,
         ToNearestRect(overlay.display_rect), overlay.uv_rect);
   }
 }
 
 }  // namespace cc