[Aura] Implement views-based applist.

ui/aura_shell/app_list/drop_shadow_label.cc

+// Copyright (c) 2011 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/aura_shell/app_list/drop_shadow_label.h"
+
+#include "base/utf_string_conversions.h"
+#include "third_party/skia/include/effects/SkGradientShader.h"
+#include "ui/gfx/canvas_skia.h"
+#include "ui/gfx/color_utils.h"
+#include "ui/gfx/skbitmap_operations.h"
+
+using views::Label;
+
+namespace aura_shell {
+
+static const int kDefaultDropShadowSize = 2;
+
+DropShadowLabel::DropShadowLabel() : drop_shadow_size_(kDefaultDropShadowSize) {
+}
+
+void DropShadowLabel::SetDropShadowSize(int drop_shadow_size) {
+  if (drop_shadow_size != drop_shadow_size_) {
+    drop_shadow_size_ = drop_shadow_size;
+    invalidate_text_size();
+    SchedulePaint();
+  }
+}
+
+void DropShadowLabel::PaintText(gfx::Canvas* canvas,
+                                const string16& text,
+                                const gfx::Rect& text_bounds,
+                                int flags) {
+  SkColor text_color = enabled() ? enabled_color() : disabled_color();
+  if (drop_shadow_size_ > 0) {
+    // To properly render shadow with elliding fade effect, text and shadow
+    // is rendered to this canvas first with elliding disable so that underlying
+    // code would not mix shadow color into text area because of elliding fade.
+    // When that is done and if we need elliding fade, an alpha mask is applied
+    // when transfering contents on this canvas to target canvas.
+    gfx::Size canvas_size(text_bounds.width() + drop_shadow_size_,
+                          text_bounds.height() + drop_shadow_size_);
+    gfx::CanvasSkia text_canvas(canvas_size, false);
+
+    const double kShadowOpacity = 0.2;
+    const SkColor shadow_color =
+        SkColorSetA(SK_ColorBLACK, kShadowOpacity * SkColorGetA(text_color));
+    gfx::Size text_size = GetTextSize();
+    for (int i = 0; i < drop_shadow_size_; i++) {
+      text_canvas.DrawStringInt(text, font(), shadow_color, i, 0,
+                                text_size.width(), text_size.height(),
+                                flags | gfx::Canvas::NO_ELLIPSIS);
+      text_canvas.DrawStringInt(text, font(), shadow_color, i, i,
+                                text_size.width(), text_size.height(),
+                                flags | gfx::Canvas::NO_ELLIPSIS);
+      text_canvas.DrawStringInt(text, font(), shadow_color, 0, i,
+                                text_size.width(), text_size.height(),
+                                flags | gfx::Canvas::NO_ELLIPSIS);
+    }
+    text_canvas.DrawStringInt(text, font(), text_color, 0, 0,
+                              text_size.width(), text_size.height(),
+                              flags | gfx::Canvas::NO_ELLIPSIS);
+
+    const SkBitmap& text_bitmap = const_cast<SkBitmap&>(
+        skia::GetTopDevice(*text_canvas.sk_canvas())->accessBitmap(false));
+
+    if (text_size.width() > text_bounds.width() &&
+        !(flags & gfx::Canvas::NO_ELLIPSIS)) {
+      // Apply an gradient alpha mask for elliding fade effect.
+      const double kFadeWidthFactor = 1.5;
+      int fade_width = std::min(text_size.width() / 2,
+          static_cast<int>(text_size.height() * kFadeWidthFactor));
+
+      const SkColor kColors[] = { SK_ColorWHITE, 0 };
+      const SkScalar kPoints[] = { SkIntToScalar(0), SkIntToScalar(1) };
+      SkPoint p[2];
+      p[0].set(SkIntToScalar(text_bounds.width() - fade_width),
+               SkIntToScalar(0));
+      p[1].set(SkIntToScalar(text_bounds.width()),
+               SkIntToScalar(0));
+      SkShader* s = SkGradientShader::CreateLinear(
+          p, kColors, kPoints, 2, SkShader::kClamp_TileMode, NULL);
+
+      SkPaint paint;
+      paint.setShader(s)->unref();
+
+      gfx::CanvasSkia alpha_canvas(canvas_size, false);
+      alpha_canvas.DrawRect(gfx::Rect(canvas_size), paint);
+
+      const SkBitmap& alpha_bitmap = const_cast<SkBitmap&>(
+          skia::GetTopDevice(*alpha_canvas.sk_canvas())->accessBitmap(false));
+      SkBitmap blended = SkBitmapOperations::CreateMaskedBitmap(text_bitmap,
+          alpha_bitmap);
+      canvas->DrawBitmapInt(blended, text_bounds.x(), text_bounds.y());
+    } else {
+      canvas->DrawBitmapInt(text_bitmap, text_bounds.x(), text_bounds.y());
+    }
+  } else {
+    canvas->DrawStringInt(text, font(), text_color, text_bounds.x(),
+        text_bounds.y(), text_bounds.width(), text_bounds.height(), flags);
+  }
+
+  if (HasFocus() || paint_as_focused()) {
+    gfx::Rect focus_bounds = text_bounds;
+    focus_bounds.Inset(-Label::kFocusBorderPadding,
+                       -Label::kFocusBorderPadding);
+    canvas->DrawFocusRect(focus_bounds);
+  }
+}
+
+gfx::Size DropShadowLabel::GetTextSize() const {
+  gfx::Size text_size = Label::GetTextSize();
+  text_size.SetSize(text_size.width() + drop_shadow_size_,
+                    text_size.height() + drop_shadow_size_);
+  return text_size;
+}
+
+}  // namespace aura_shell