Add shadow/corner radius to notifications (toasts and in-center).

ui/gfx/shadow_util.cc

+// Copyright 2017 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 "ui/gfx/shadow_util.h"
+
+#include <map>
+#include <vector>
+
+#include "base/lazy_instance.h"
+#include "third_party/skia/include/core/SkDrawLooper.h"
+#include "third_party/skia/include/core/SkRRect.h"
+#include "ui/gfx/canvas.h"
+#include "ui/gfx/geometry/insets.h"
+#include "ui/gfx/image/canvas_image_source.h"
+#include "ui/gfx/shadow_value.h"
+#include "ui/gfx/skia_util.h"
+
+namespace gfx {
+namespace {
+
+// Creates an image with the given shadows painted around a round rect with
+// the given corner radius. The image will be just large enough to paint the
+// shadows appropriately with a 1px square region reserved for "content".
+class ShadowNineboxSource : public CanvasImageSource {
+ public:
+  ShadowNineboxSource(const std::vector<ShadowValue>& shadows,
+                      float corner_radius)
+      : CanvasImageSource(CalculateSize(shadows, corner_radius), false),
+        shadows_(shadows),
+        corner_radius_(corner_radius) {
+    DCHECK(!shadows.empty());
+  }
+  ~ShadowNineboxSource() override {}
+
+  // CanvasImageSource overrides:
+  void Draw(Canvas* canvas) override {
+    SkPaint paint;
+    paint.setLooper(CreateShadowDrawLooperCorrectBlur(shadows_));
+    Insets insets = -ShadowValue::GetMargin(shadows_);
+    gfx::Rect bounds(size());
+    bounds.Inset(insets);
+    SkRRect r_rect = SkRRect::MakeRectXY(gfx::RectToSkRect(bounds),
+                                         corner_radius_, corner_radius_);
+
+    // Clip out the center so it's not painted with the shadow.
+    canvas->sk_canvas()->clipRRect(r_rect, SkClipOp::kDifference, true);
+    // Clipping alone is not enough --- due to anti aliasing there will still be
+    // some of the fill color in the rounded corners. We must make the fill
+    // color transparent.
+    paint.setColor(SK_ColorTRANSPARENT);
+    canvas->sk_canvas()->drawRRect(r_rect, paint);
+  }
+
+ private:
+  static Size CalculateSize(const std::vector<ShadowValue>& shadows,
+                            float corner_radius) {
+    // The "content" area (the middle tile in the 3x3 grid) is a single pixel.
+    gfx::Rect bounds(0, 0, 1, 1);
+    // We need enough space to render the full range of blur.
+    bounds.Inset(-ShadowValue::GetBlurRegion(shadows));
+    // We also need space for the full roundrect corner rounding.
+    bounds.Inset(-gfx::Insets(corner_radius));
+    return bounds.size();
+  }
+
+  const std::vector<ShadowValue> shadows_;
+
+  const float corner_radius_;
+
+  DISALLOW_COPY_AND_ASSIGN(ShadowNineboxSource);
+};
+
+// Map from elevation/corner radius pair to a cached shadow.
+using ShadowDetailsMap = std::map<std::pair<int, int>, ShadowDetails>;
+base::LazyInstance<ShadowDetailsMap> g_shadow_cache = LAZY_INSTANCE_INITIALIZER;
+
+}  // namespace
+
+ShadowDetails::ShadowDetails() {}
+ShadowDetails::ShadowDetails(const ShadowDetails& other) {

[sky, 2017/01/05 00:39:17]

Does = default; work here?

[Evan Stade, 2017/01/05 00:51:15]

ah, that's nifty. Seems to work.

+  values = other.values;
+  ninebox_image = other.ninebox_image;
+}
+ShadowDetails::~ShadowDetails() {}
+
+const ShadowDetails& ShadowDetails::Get(int elevation, int corner_radius) {
+  auto iter =
+      g_shadow_cache.Get().find(std::make_pair(elevation, corner_radius));
+  if (iter != g_shadow_cache.Get().end())
+    return iter->second;
+
+  auto insertion = g_shadow_cache.Get().insert(std::make_pair(
+      std::make_pair(elevation, corner_radius), ShadowDetails()));
+  DCHECK(insertion.second);
+  ShadowDetails* shadow = &insertion.first->second;
+  // To match the CSS notion of blur (spread outside the bounding box) to the
+  // Skia notion of blur (spread outside and inside the bounding box), we have
+  // to double the designer-provided blur values.
+  const int kBlurCorrection = 2;
+  // "Key shadow": y offset is elevation and blur is twice the elevation.
+  shadow->values.emplace_back(gfx::Vector2d(0, elevation),
+                              kBlurCorrection * elevation * 2,
+                              SkColorSetA(SK_ColorBLACK, 0x3d));
+  // "Ambient shadow": no offset and blur matches the elevation.
+  shadow->values.emplace_back(gfx::Vector2d(), kBlurCorrection * elevation,
+                              SkColorSetA(SK_ColorBLACK, 0x1f));
+  // To see what this looks like for elevation 24, try this CSS:
+  //   box-shadow: 0 24px 48px rgba(0, 0, 0, .24),
+  //               0 0 24px rgba(0, 0, 0, .12);
+  auto source = new ShadowNineboxSource(shadow->values, corner_radius);
+  shadow->ninebox_image = ImageSkia(source, source->size());
+  return *shadow;
+}
+
+}  // namespace gfx