Draw omnibox shadow with a ninebox layer.

chrome/browser/ui/views/omnibox/omnibox_popup_contents_view.cc

Index: chrome/browser/ui/views/omnibox/omnibox_popup_contents_view.cc
diff --git a/chrome/browser/ui/views/omnibox/omnibox_popup_contents_view.cc b/chrome/browser/ui/views/omnibox/omnibox_popup_contents_view.cc
index 04bb74bcb783ba4cd6281b2a1d5d38b63aed88aa..57e080010e84f0130efe12cfae389386eb034609 100644
--- a/chrome/browser/ui/views/omnibox/omnibox_popup_contents_view.cc
+++ b/chrome/browser/ui/views/omnibox/omnibox_popup_contents_view.cc
@@ -22,6 +22,7 @@
 #include "ui/compositor/paint_recorder.h"
 #include "ui/gfx/canvas.h"
 #include "ui/gfx/geometry/safe_integer_conversions.h"
+#include "ui/gfx/image/canvas_image_source.h"
 #include "ui/gfx/image/image.h"
 #include "ui/gfx/image/image_skia_operations.h"
 #include "ui/gfx/path.h"
@@ -33,10 +34,38 @@
 
 namespace {
 
-// Cache the shadow images so that potentially expensive shadow drawing isn't
+// This source takes two images and draws one above the other.
+class StackedImagesImageSource : public gfx::CanvasImageSource {
+ public:
+  StackedImagesImageSource(const gfx::ImageSkia& top,
+                           const gfx::ImageSkia& bottom)
+      : CanvasImageSource(
+            gfx::Size(top.width(), top.height() + bottom.height()),
+            false),
+        top_(top),
+        bottom_(bottom) {
+    DCHECK_EQ(top.width(), bottom.width());
+  }
+  ~StackedImagesImageSource() override {}
+
+  // CanvasImageSource overrides:
+  void Draw(gfx::Canvas* canvas) override {
+    canvas->DrawImageInt(top_, 0, 0);
+    canvas->DrawImageInt(bottom_, 0, top_.height());
+  }
+
+ private:
+  const gfx::ImageSkia top_;
+  const gfx::ImageSkia bottom_;
+
+  DISALLOW_COPY_AND_ASSIGN(StackedImagesImageSource);
+};
+
+// Cache the shadow image so that potentially expensive shadow drawing isn't
 // repeated.
-base::LazyInstance<gfx::ImageSkia> g_top_shadow = LAZY_INSTANCE_INITIALIZER;
-base::LazyInstance<gfx::ImageSkia> g_bottom_shadow = LAZY_INSTANCE_INITIALIZER;
+static int g_top_shadow_height = 0;
+static int g_bottom_shadow_height = 0;
+base::LazyInstance<gfx::ImageSkia> g_shadow_ninebox = LAZY_INSTANCE_INITIALIZER;
 
 }  // namespace
 
@@ -83,30 +112,42 @@ OmniboxPopupContentsView::OmniboxPopupContentsView(
   // The contents is owned by the LocationBarView.
   set_owned_by_client();
 
-  if (g_top_shadow.Get().isNull()) {
-    std::vector<gfx::ShadowValue> shadows;
+  if (g_shadow_ninebox.Get().isNull()) {
+    std::vector<gfx::ShadowValue> top_shadows;
     // Blur by 1dp. See comment below about blur accounting.
-    shadows.emplace_back(gfx::Vector2d(), 2, SK_ColorBLACK);
-    g_top_shadow.Get() =
-        gfx::ImageSkiaOperations::CreateHorizontalShadow(shadows, false);
-  }
-  if (g_bottom_shadow.Get().isNull()) {
+    top_shadows.emplace_back(gfx::Vector2d(), 2, SK_ColorBLACK);
+    gfx::ImageSkia top_shadow_image =
+        gfx::ImageSkiaOperations::CreateHorizontalShadow(top_shadows, false);
+    g_top_shadow_height = top_shadow_image.height();
+
+    // Values for the bottom shadow.
     const int kSmallShadowBlur = 3;
     const int kLargeShadowBlur = 8;
     const int kLargeShadowYOffset = 3;
 
-    std::vector<gfx::ShadowValue> shadows;
+    std::vector<gfx::ShadowValue> bottom_shadows;
     // gfx::ShadowValue counts blur pixels both inside and outside the shape,
     // whereas these blur values only describe the outside portion, hence they
     // must be doubled.
-    shadows.emplace_back(gfx::Vector2d(), 2 * kSmallShadowBlur,
-                         SK_ColorBLACK);
-    shadows.emplace_back(gfx::Vector2d(0, kLargeShadowYOffset),
-                         2 * kLargeShadowBlur, SK_ColorBLACK);
-
-    g_bottom_shadow.Get() =
-        gfx::ImageSkiaOperations::CreateHorizontalShadow(shadows, true);
+    bottom_shadows.emplace_back(gfx::Vector2d(), 2 * kSmallShadowBlur,
+                                SK_ColorBLACK);
+    bottom_shadows.emplace_back(gfx::Vector2d(0, kLargeShadowYOffset),
+                                2 * kLargeShadowBlur, SK_ColorBLACK);
+
+    gfx::ImageSkia bottom_shadow_image =
+        gfx::ImageSkiaOperations::CreateHorizontalShadow(bottom_shadows, true);
+    g_bottom_shadow_height = bottom_shadow_image.height();
+    auto source =
+        new StackedImagesImageSource(top_shadow_image, bottom_shadow_image);
+    g_shadow_ninebox.Get() = gfx::ImageSkia(source, source->size());
   }
+  shadow_layer_.reset(new ui::Layer(ui::LAYER_NINE_PATCH));
+  shadow_layer_->SetFillsBoundsOpaquely(false);
+  shadow_layer_->UpdateNinePatchLayerImage(g_shadow_ninebox.Get());
+  shadow_layer_->UpdateNinePatchLayerAperture(
+      gfx::Rect(0, g_top_shadow_height, 1, 0));
+  shadow_layer_->UpdateNinePatchLayerBorder(gfx::Rect(
+      0, g_top_shadow_height, 0, g_top_shadow_height + g_bottom_shadow_height));
 
   SetEventTargeter(
       std::unique_ptr<views::ViewTargeter>(new views::ViewTargeter(this)));
@@ -148,8 +189,7 @@ gfx::Rect OmniboxPopupContentsView::GetPopupBounds() const {
 void OmniboxPopupContentsView::LayoutChildren() {
   gfx::Rect contents_rect = GetContentsBounds();
   contents_rect.Inset(GetLayoutInsets(OMNIBOX_DROPDOWN));
-  contents_rect.Inset(start_margin_, g_top_shadow.Get().height(), end_margin_,
-                      0);
+  contents_rect.Inset(start_margin_, g_top_shadow_height, end_margin_, 0);
 
   int top = contents_rect.y();
   for (size_t i = 0; i < AutocompleteResult::kMaxMatches; ++i) {
@@ -226,8 +266,8 @@ void OmniboxPopupContentsView::UpdatePopupAppearance() {
   // We want the popup to appear to overlay the bottom of the toolbar. So we
   // shift the popup to completely cover the client edge, and then draw an
   // additional semitransparent shadow above that.
-  int top_edge_overlap = views::NonClientFrameView::kClientEdgeThickness +
-                         g_top_shadow.Get().height();
+  int top_edge_overlap =
+      views::NonClientFrameView::kClientEdgeThickness + g_top_shadow_height;
 
   gfx::Point top_left_screen_coord;
   int width;
@@ -246,6 +286,13 @@ void OmniboxPopupContentsView::UpdatePopupAppearance() {
   target_bounds_ = new_target_bounds;
 
   if (!popup_) {
+    // Create a new layer even if one already exists to make sure it's correctly
+    // parented.

[Evan Stade, 2016/12/01 02:39:02]

I'm not entirely sure why this is necessary --- it took me a while to figure out
the layer wasn't being properly reparented and I didn't track down why.

[sadrul, 2016/12/06 20:05:22]

Yeah ... this seems weird.

+    SetPaintToLayer(false);
+    SetPaintToLayer(true);
+    layer()->SetFillsBoundsOpaquely(false);
+    layer()->Add(shadow_layer_.get());
+
     views::Widget* popup_parent = location_bar_view_->GetWidget();
 
     // If the popup is currently closed, we need to create it.
@@ -357,6 +404,15 @@ views::View* OmniboxPopupContentsView::GetTooltipHandlerForPoint(
   return nullptr;
 }
 
+void OmniboxPopupContentsView::OnBoundsChanged(
+    const gfx::Rect& previous_bounds) {
+  gfx::Rect shadow_bounds = GetLocalBounds();
+  shadow_layer_->SetBounds(shadow_bounds);
+  shadow_bounds.Inset(
+      gfx::Insets(g_top_shadow_height, 0, g_bottom_shadow_height, 0));
+  shadow_layer_->UpdateNinePatchOcclusion(shadow_bounds);

[sadrul, 2016/12/06 20:05:22]

ui::Shadow seems to update layer-border/aperture as well. Should this do that
too?

+}
+
 bool OmniboxPopupContentsView::OnMousePressed(
     const ui::MouseEvent& event) {
   ignore_mouse_drag_ = false;  // See comment on |ignore_mouse_drag_| in header.
@@ -435,7 +491,7 @@ int OmniboxPopupContentsView::CalculatePopupHeight() {
   // amount of space between the text and the popup border as there is in the
   // interior between each row of text.
   return popup_height + GetLayoutInsets(OMNIBOX_DROPDOWN).height() +
-         g_top_shadow.Get().height() + g_bottom_shadow.Get().height();
+         g_top_shadow_height + g_bottom_shadow_height;
 }
 
 OmniboxResultView* OmniboxPopupContentsView::CreateResultView(
@@ -451,18 +507,10 @@ const char* OmniboxPopupContentsView::GetClassName() const {
   return "OmniboxPopupContentsView";
 }
 
-void OmniboxPopupContentsView::OnPaint(gfx::Canvas* canvas) {
-  canvas->TileImageInt(g_top_shadow.Get(), 0, 0, width(),
-                       g_top_shadow.Get().height());
-  canvas->TileImageInt(g_bottom_shadow.Get(), 0,
-                       height() - g_bottom_shadow.Get().height(), width(),
-                       g_bottom_shadow.Get().height());
-}
-
 void OmniboxPopupContentsView::PaintChildren(const ui::PaintContext& context) {
   gfx::Rect contents_bounds = GetContentsBounds();
-  contents_bounds.Inset(0, g_top_shadow.Get().height(), 0,
-                        g_bottom_shadow.Get().height());
+  contents_bounds.Inset(
+      gfx::Insets(g_top_shadow_height, 0, g_bottom_shadow_height, 0));
 
   ui::ClipRecorder clip_recorder(context);
   clip_recorder.ClipRect(contents_bounds);