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;

[Alexei Svitkine (slow), 2011/08/16 14:10:04]

Can you DCHECK() the mode to be one of the expected ones?

[Mark Mentovai, 2011/08/16 14:17:24]

asvitkine_ wrote:
Such a check is likely to be optimized away. enums aren’t ints, so compilers
take some tricky liberties.

[Alexei Svitkine (slow), 2011/08/16 14:21:26]

Good point - I take that back, the compiler would already validate the call
sites.

+
+    [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 {
+  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);

[Alexei Svitkine (slow), 2011/08/16 14:10:04]

Maybe just initialize x to "gestureAmount * (maxX - minX)" and then just add
maxX or minX based on the mode? Also, if mode can only be one of those two
values, you can change the else if to an else.

[Nico, 2011/08/16 16:07:53]

That's shorter, but harder to understand imho.

+  NSPoint p = [parent_ frame].origin;
+  p.x = x;
+  p.y += (NSHeight(windowFrame) - NSHeight([[self window] frame])) * 0.65;

[Alexei Svitkine (slow), 2011/08/16 14:10:04]

Can you make move 0.65 to a constant? Something like kVerticalPositionRatio.

[Nico, 2011/08/16 16:07:53]

Done.

+  [[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