Panels: Adding 3-step animation on minimize on Linux

chrome/browser/ui/panels/panel_slide_animation.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 "chrome/browser/ui/panels/panel_slide_animation.h"
+
+#include "chrome/browser/ui/panels/panel.h"
+
+namespace {
+
+// These values are experimental and subjective.
+const int kSetBoundsAnimationMs = 180;
+const int kSetBoundsAnimationBigMinimizeMs = 1500;
+
+}
+
+PanelSlideAnimation::PanelSlideAnimation(ui::AnimationDelegate* target,
+                                         Panel* panel,
+                                         const gfx::Rect& initial_bounds,
+                                         const gfx::Rect& final_bounds)
+    : ui::SlideAnimation(target),
+      panel_(panel),
+      for_big_minimize_(false),
+      animation_stop_to_show_titlebar_(0) {
+  // Detect animation that happens when expansion state is set to MINIMIZED
+  // and there is relatively big portion of the panel to hide from view.
+  // Initialize animation differently in this case, using fast-pause-slow
+  // method, see below for more details.
+  int duration = kSetBoundsAnimationMs;
+  if (panel_->expansion_state() == Panel::MINIMIZED) {
+    double hidden_title_height =
+        panel_->TitleOnlyHeight() - final_bounds.height();
+    double distance_y = initial_bounds.height() - final_bounds.height();
+    animation_stop_to_show_titlebar_ = 1.0 - hidden_title_height / distance_y;
+    if (animation_stop_to_show_titlebar_ > 0.7) {  // Relatively big movement.
+      for_big_minimize_ = true;
+      duration = kSetBoundsAnimationBigMinimizeMs;
+    }
+  }
+  SetSlideDuration(duration);
+}
+
+PanelSlideAnimation::~PanelSlideAnimation() {
+}
+
+double PanelSlideAnimation::GetCurrentValue() const {
+  double progress = ui::SlideAnimation::GetCurrentValue();
+  return ComputeAnimationValue(progress,
+                               for_big_minimize_,
+                               animation_stop_to_show_titlebar_);
+}
+
+double PanelSlideAnimation::ComputeAnimationValue(double progress,
+    bool for_big_minimize, double animation_stop_to_show_titlebar) {
+  if (!for_big_minimize) {
+    // Cubic easing out.
+    double value = 1.0 - progress;
+    return 1.0 - value * value * value;
+  }
+
+  // Minimize animation is done in 3 steps:
+  // 1. Quickly (0 -> 0.15) make only titlebar visible.
+  // 2. Freeze for a little bit (0.15->0.6), just showing titlebar.
+  // 3. Slowly minimize to thin strip (0.6->1.0)
+  const double kProgressAtFreezeStart = 0.15;
+  const double kProgressAtFreezeEnd = 0.6;
+  double value;
+  if (progress <= kProgressAtFreezeStart) {
+    value = animation_stop_to_show_titlebar *
+        (progress / kProgressAtFreezeStart);
+  } else if (progress <= kProgressAtFreezeEnd) {
+    value = animation_stop_to_show_titlebar;
+  } else {
+    value = animation_stop_to_show_titlebar +
+        (1.0 - animation_stop_to_show_titlebar) *
+        ((progress - kProgressAtFreezeEnd) / (1.0 - kProgressAtFreezeEnd));
+  }
+  return value;
+}
+