MacViews: Overlay Scrollbars with Show/Hide Animations

ui/views/controls/scrollbar/native_cocoa_scroll_bar.mm

+// Copyright 2016 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/views/controls/scrollbar/native_cocoa_scroll_bar.h"
+
+#include "ui/compositor/layer.h"
+#include "ui/compositor/layer_animator.h"
+#include "ui/gfx/animation/tween.h"
+#include "ui/views/controls/button/custom_button.h"
+#include "ui/views/controls/scrollbar/native_scroll_bar_wrapper.h"
+
+namespace views {
+
+namespace {
+
+// How long we should wait before hiding the scrollbar.
+const int kScrollbarHideTimeoutMs = 300;
+
+// How long animations should take by default.
+const int kFadeDurationMs = 120;
+}
+
+////////////////////////////////
+// NativeCocoaScrollBar
+////////////////////////////////
+
+NativeCocoaScrollBar::NativeCocoaScrollBar(bool horizontal)
+    : NativeScrollBar(horizontal) {}
+
+NativeCocoaScrollBar::~NativeCocoaScrollBar() {}
+
+NativeScrollBarWrapper* NativeCocoaScrollBar::CreateWrapper() {
+  return new NativeCocoaScrollBarViews(this);
+}
+
+////////////////////////////////
+// NativeCocoaScrollBarViews
+////////////////////////////////
+
+NativeCocoaScrollBarViews::NativeCocoaScrollBarViews(
+    NativeScrollBar* native_scroll_bar)
+    : NativeScrollBarViews(native_scroll_bar) {
+  bridge_.reset([[ViewsScrollbarBridge alloc] init]);
+  [bridge_ setDelegate:this];
+
+  scroller_style_ = [bridge_ getPreferredScrollerStyle];
+
+  SetPaintToLayer(true);
+  layer()->SetOpacity(scroller_style_ == NSScrollerStyleOverlay ? 0.0 : 1.0);
+  layer()->SetAnimator(new ui::LayerAnimator(
+      base::TimeDelta::FromMilliseconds(kFadeDurationMs)));
+}
+
+NativeCocoaScrollBarViews::~NativeCocoaScrollBarViews() {}

[tapted, 2016/02/09 23:51:48]

[bridge_ setDelegate:nullptr];

[spqchan, 2016/02/10 00:35:16]

Done.

+
+void NativeCocoaScrollBarViews::OnScrollerStyleChanged() {
+  NSScrollerStyle scroller_style = [bridge_ getPreferredScrollerStyle];
+  if (scroller_style_ == scroller_style)
+    return;
+
+  scroller_style_ = scroller_style;
+  if (scroller_style_)
+    HideScrollbar();
+  else
+    ShowScrollbar();
+}
+
+bool NativeCocoaScrollBarViews::OnScroll(float dx, float dy) {
+  bool didScroll = BaseScrollBar::OnScroll(dx, dy);
+
+  // If we're using the overlay style, then we should fire the timer.
+  if (didScroll && scroller_style_ == NSScrollerStyleOverlay) {
+    ShowScrollbar();
+    if (hide_scrollbar_timer_.IsRunning()) {
+      hide_scrollbar_timer_.Reset();
+    } else {
+      hide_scrollbar_timer_.Start(
+          FROM_HERE, base::TimeDelta::FromMilliseconds(kScrollbarHideTimeoutMs),
+          this, &NativeCocoaScrollBarViews::HideScrollbar);
+    }
+  }
+  return didScroll;
+}
+
+void NativeCocoaScrollBarViews::HideScrollbar() {
+  layer()->GetAnimator()->SetOpacity(0.0);
+}
+
+void NativeCocoaScrollBarViews::ShowScrollbar() {
+  layer()->SetOpacity(1.0);
+}
+
+}  // end of views namespace

[tapted, 2016/02/09 23:51:48]

-> // namespace views

[spqchan, 2016/02/10 00:35:16]

Done.