mac: Makeshift UI for scroll feedback.

chrome/browser/ui/cocoa/history_overlay_controller.mm

+// 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.
+
+#import "chrome/browser/ui/cocoa/history_overlay_controller.h"
+
+#import <QuartzCore/QuartzCore.h>
+
+#include <cmath>
+
+// OverlayFrameView ////////////////////////////////////////////////////////////
+
+// The content view of the window that draws a custom frame.
+@interface OverlayFrameView : NSView {
+ @private
+  NSTextField* message_;  // Weak, owned by the view hierarchy.
+}
+- (void)setMessageText:(NSString*)text;
+@end
+
+// The content view of the window that draws a custom frame.
+@implementation OverlayFrameView
+
+- (id)initWithFrame:(NSRect)frameRect {
+  if ((self = [super initWithFrame:frameRect])) {
+    scoped_nsobject<NSTextField> message(
+        // The frame will be fixed up when |-setMessageText:| is called.
+        [[NSTextField alloc] initWithFrame:NSZeroRect]);
+    message_ = message.get();
+    [message_ setEditable:NO];
+    [message_ setSelectable:NO];
+    [message_ setBezeled:NO];
+    [message_ setDrawsBackground:NO];
+    [message_ setFont:[NSFont boldSystemFontOfSize:72]];
+    [message_ setTextColor:[NSColor whiteColor]];
+    [self addSubview:message_];
+  }
+  return self;
+}
+
+- (void)drawRect:(NSRect)dirtyRect {
+  const CGFloat kCornerRadius = 5.0;
+  NSBezierPath* path = [NSBezierPath bezierPathWithRoundedRect:[self bounds]
+                                                       xRadius:kCornerRadius
+                                                       yRadius:kCornerRadius];
+
+  NSColor* fillColor = [NSColor colorWithCalibratedWhite:0.2 alpha:0.85];
+  [fillColor set];
+  [path fill];
+}
+
+- (void)setMessageText:(NSString*)text {
+  const CGFloat kHorizontalPadding = 30;  // In view coordinates.
+
+  // Style the string.
+  scoped_nsobject<NSMutableAttributedString> attrString(
+      [[NSMutableAttributedString alloc] initWithString:text]);
+  scoped_nsobject<NSShadow> textShadow([[NSShadow alloc] init]);
+  [textShadow.get() setShadowColor:[NSColor colorWithCalibratedWhite:0
+                                                               alpha:0.6]];
+  [textShadow.get() setShadowOffset:NSMakeSize(0, -1)];
+  [textShadow setShadowBlurRadius:1.0];
+  [attrString addAttribute:NSShadowAttributeName
+                     value:textShadow
+                     range:NSMakeRange(0, [text length])];
+  [message_ setAttributedStringValue:attrString];
+
+  // Fix up the frame of the string.
+  [message_ sizeToFit];
+  NSRect messageFrame = [message_ frame];
+  NSRect frameInViewSpace =
+      [message_ convertRect:[[self window] frame] fromView:nil];
+
+  if (NSWidth(messageFrame) > NSWidth(frameInViewSpace))
+    frameInViewSpace.size.width = NSWidth(messageFrame) + kHorizontalPadding;
+
+  messageFrame.origin.x =
+      (NSWidth(frameInViewSpace) - NSWidth(messageFrame)) / 2;
+  messageFrame.origin.y =
+      (NSHeight(frameInViewSpace) - NSHeight(messageFrame)) / 2;
+
+  [[self window] setFrame:[message_ convertRect:frameInViewSpace toView:nil]
+                  display:YES];
+  [message_ setFrame:messageFrame];
+}
+
+@end
+
+// HistoryOverlayController ////////////////////////////////////////////////////
+
+@implementation HistoryOverlayController
+
+- (id)initForMode:(HistoryOverlayMode)mode {
+  const NSRect kWindowFrame = NSMakeRect(0, 0, 120, 70);
+  scoped_nsobject<NSWindow> window(
+      [[NSWindow alloc] initWithContentRect:kWindowFrame
+                                  styleMask:NSBorderlessWindowMask
+                                    backing:NSBackingStoreBuffered
+                                      defer:NO]);
+  if ((self = [super initWithWindow:window])) {
+    mode_ = mode;
+
+    [window setDelegate:self];
+    [window setBackgroundColor:[NSColor clearColor]];
+    [window setOpaque:NO];
+    [window setHasShadow:NO];
+
+    // Create the content view. Take the frame from the existing content view.
+    NSRect frame = [[window contentView] frame];
+    scoped_nsobject<OverlayFrameView> frameView(
+        [[OverlayFrameView alloc] initWithFrame:frame]);
+    contentView_ = frameView.get();
+    [window setContentView:contentView_];
+
+    const unichar kBackArrowCharacter = 0x2190;
+    const unichar kForwardArrowCharacter = 0x2192;
+
+    unichar commandChar = mode_ == kHistoryOverlayModeForward ?
+        kForwardArrowCharacter : kBackArrowCharacter;
+    NSString* text =
+        [NSString stringWithCharacters:&commandChar length:1];
+    [contentView_ setMessageText:text];
+  }
+  return self;
+}
+
+- (void)setProgress:(CGFloat)gestureAmount {
+  const CGFloat kVerticalPositionRatio = 0.65;
+  NSRect windowFrame = [parent_ frame];
+  CGFloat minX = NSMinX(windowFrame);
+  CGFloat maxX = NSMaxX(windowFrame) - NSWidth([[self window] frame]);
+  CGFloat x = 0;
+  if (mode_ == kHistoryOverlayModeForward)
+    x = maxX + gestureAmount * (maxX - minX);
+  else if (mode_ == kHistoryOverlayModeBack)
+    x = minX + gestureAmount * (maxX - minX);
+  NSPoint p = [parent_ frame].origin;
+  p.x = x;
+  p.y += (NSHeight(windowFrame) - NSHeight([[self window] frame])) *
+         kVerticalPositionRatio;
+  [[self window] setFrameOrigin:p];
+
+  CGFloat alpha =
+      -(std::abs(gestureAmount) - 1) * (std::abs(gestureAmount) - 1) + 1;
+  [[self window] setAlphaValue:alpha];
+}
+
+- (void)dismiss {
+  const CGFloat kFadeOutDurationSeconds = 0.2;
+
+  NSWindow* overlayWindow = [self window];
+
+  scoped_nsobject<CAAnimation> animation(
+      [[overlayWindow animationForKey:@"alphaValue"] copy]);
+  [animation setDelegate:self];
+  [animation setDuration:kFadeOutDurationSeconds];
+  NSMutableDictionary* dictionary =
+      [NSMutableDictionary dictionaryWithCapacity:1];
+  [dictionary setObject:animation forKey:@"alphaValue"];
+  [overlayWindow setAnimations:dictionary];
+  [[overlayWindow animator] setAlphaValue:0.0];
+}
+
+- (void)windowWillClose:(NSNotification*)notification {
+  // Release all animations because CAAnimation retains its delegate (self),
+  // which will cause a retain cycle. Break it!
+  [[self window] setAnimations:[NSDictionary dictionary]];
+}
+
+- (void)showPanelForWindow:(NSWindow*)window {
+  parent_.reset([window retain]);
+  [self setProgress:0];  // Set initial window position.
+  [self showWindow:self];
+}
+
+- (void)animationDidStop:(CAAnimation*)theAnimation finished:(BOOL)finished {
+  [self close];
+}
+
+@end