Gradient overlay for constrained window

chrome/renderer/webview_animating_overlay.cc

+// Copyright (c) 2012 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 "chrome/renderer/webview_animating_overlay.h"
+
+#include "base/logging.h"
+#include "content/public/renderer/render_view.h"
+#include "third_party/skia/include/core/SkCanvas.h"
+#include "third_party/skia/include/core/SkPaint.h"
+#include "third_party/skia/include/core/SkRect.h"
+#include "third_party/skia/include/effects/SkGradientShader.h"
+#include "third_party/WebKit/Source/WebKit/chromium/public/WebView.h"
+#include "ui/gfx/size.h"
+#include "ui/gfx/skia_util.h"
+
+const int kAnimationDurationMiliseconds = 500;
+const int kAnimationFrameRate = 60;
+const int kTargetAlpha = 191;
+
+WebViewAnimatingOverlay::WebViewAnimatingOverlay(
+    content::RenderView* render_view)
+    : render_view_(render_view),
+      state_(HIDDEN),
+      animation_(kAnimationDurationMiliseconds, kAnimationFrameRate, this) {
+}
+
+WebViewAnimatingOverlay::~WebViewAnimatingOverlay() {
+  if (render_view_->GetWebView())
+    render_view_->GetWebView()->removePageOverlay(this);
+}
+
+void WebViewAnimatingOverlay::Show() {
+  if (state_ == ANIMATING_IN || state_ == VISIBLE)
+    return;
+
+  if (state_ == ANIMATING_OUT) {
+    animation_.SetCurrentValue(1.0 - animation_.GetCurrentValue());
+  } else {
+    DCHECK_EQ(HIDDEN, state_);
+    if (render_view_->GetWebView())
+      render_view_->GetWebView()->addPageOverlay(this, 0);
+  }
+
+  state_ = ANIMATING_IN;
+  animation_.Start();
+}
+
+void WebViewAnimatingOverlay::Hide() {
+  if (state_ == ANIMATING_OUT || state_ == HIDDEN)
+    return;
+
+  if (state_ == ANIMATING_IN)
+    animation_.SetCurrentValue(1.0 - animation_.GetCurrentValue());
+
+  state_ = ANIMATING_OUT;
+  animation_.Start();
+}
+
+void WebViewAnimatingOverlay::paintPageOverlay(WebKit::WebCanvas* canvas) {
+  SkRect rect = gfx::RectToSkRect(gfx::Rect(render_view_->GetSize()));
+
+  // The center of the radial gradient should be near the top middle.
+  SkPoint center_point;
+  center_point.iset(rect.width() * 0.5, rect.height() * 0.05);
+  int radius = static_cast<int>(rect.width());
+
+  // Animate in or out using the alpha.
+  int alpha = GetCurrentAlpha();
+  SkColor colors[] = {
+    SkColorSetARGB(alpha, 255, 255, 255),
+    SkColorSetARGB(alpha, 127, 127, 127)
+  };
+
+  SkAutoTUnref<SkShader> shader(SkGradientShader::CreateRadial(center_point,
+      SkIntToScalar(radius), colors, NULL, arraysize(colors),
+      SkShader::kClamp_TileMode));
+  SkPaint paint;
+  paint.setShader(shader);
+  paint.setDither(true);
+
+  canvas->drawRect(rect, paint);
+}
+
+void WebViewAnimatingOverlay::AnimationEnded(const ui::Animation* animation) {
+  if (state_ == ANIMATING_IN) {
+    state_ = VISIBLE;
+  } else {
+    DCHECK_EQ(ANIMATING_OUT, state_);
+    state_ = HIDDEN;
+    if (render_view_->GetWebView())
+      render_view_->GetWebView()->removePageOverlay(this);
+  }
+}
+
+void WebViewAnimatingOverlay::AnimationProgressed(
+    const ui::Animation* animation) {
+  render_view_->Repaint(render_view_->GetSize());
+}
+
+int WebViewAnimatingOverlay::GetCurrentAlpha() {
+  switch (state_) {
+    case ANIMATING_IN:
+      return animation_.CurrentValueBetween(0, kTargetAlpha);
+    case ANIMATING_OUT:
+      return animation_.CurrentValueBetween(kTargetAlpha, 0);
+    case VISIBLE:
+    case HIDDEN:
+      return kTargetAlpha;
+  }
+  NOTREACHED();
+  return 1.0;
+}