chrome/browser/ui/cocoa/tabs/tab_strip_view.mm

// 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.

#import "chrome/browser/ui/cocoa/tabs/tab_strip_view.h"

#include <cmath>  // floor

#include "base/logging.h"
#include "base/mac/mac_util.h"
#include "chrome/browser/themes/theme_service.h"
#import "chrome/browser/ui/cocoa/browser_window_controller.h"
#import "chrome/browser/ui/cocoa/new_tab_button.h"
#import "chrome/browser/ui/cocoa/nsview_additions.h"
#import "chrome/browser/ui/cocoa/tabs/tab_strip_controller.h"
#import "chrome/browser/ui/cocoa/tabs/tab_view.h"
#import "chrome/browser/ui/cocoa/view_id_util.h"
#include "grit/generated_resources.h"
#include "grit/theme_resources.h"
#import "ui/base/cocoa/nsgraphics_context_additions.h"
#include "ui/base/l10n/l10n_util_mac.h"
#include "ui/gfx/scoped_ns_graphics_context_save_gstate_mac.h"

@implementation TabStripView

@synthesize dropArrowShown = dropArrowShown_;
@synthesize dropArrowPosition = dropArrowPosition_;

- (id)initWithFrame:(NSRect)frame {
  self = [super initWithFrame:frame];
  if (self) {
    newTabButton_.reset([[NewTabButton alloc] initWithFrame:
        NSMakeRect(295, 0, 40, 27)]);
    [newTabButton_ setToolTip:l10n_util::GetNSString(IDS_TOOLTIP_NEW_TAB)];

    // Set lastMouseUp_ = -1000.0 so that timestamp-lastMouseUp_ is big unless
    // lastMouseUp_ has been reset.
    lastMouseUp_ = -1000.0;

    // Register to be an URL drop target.
    dropHandler_.reset([[URLDropTargetHandler alloc] initWithView:self]);
  }
  return self;
}

// Draw bottom border bitmap. Each tab is responsible for mimicking this bottom
// border, unless it's the selected tab.
- (void)drawBorder:(NSRect)dirtyRect {
  ThemeService* themeProvider =
      static_cast<ThemeService*>([[self window] themeProvider]);
  if (!themeProvider)
    return;

  // First draw the toolbar bitmap, so that theme colors can shine through.
  CGFloat backgroundHeight = 2 * [self cr_lineWidth];
  if (NSMinY(dirtyRect) < backgroundHeight) {
    gfx::ScopedNSGraphicsContextSaveGState scopedGState;
    NSGraphicsContext *context = [NSGraphicsContext currentContext];
    NSPoint position = [[self window] themeImagePositionForAlignment:
        THEME_IMAGE_ALIGN_WITH_TAB_STRIP];
    [context cr_setPatternPhase:position forView:self];

    // Themes don't have an inactive image so only look for one if there's no
    // theme.
    bool active = [[self window] isKeyWindow] || [[self window] isMainWindow] ||
                  !themeProvider->UsingDefaultTheme();
    int resource_id = active ? IDR_THEME_TOOLBAR : IDR_THEME_TOOLBAR_INACTIVE;
    [themeProvider->GetNSImageColorNamed(resource_id) set];
    NSRectFill(
        NSMakeRect(NSMinX(dirtyRect), 0, NSWidth(dirtyRect), backgroundHeight));
  }

  // Draw the border bitmap, which is partially transparent.
  NSImage* image = themeProvider->GetNSImageNamed(IDR_TOOLBAR_SHADE_TOP);
  if (NSMinY(dirtyRect) >= [image size].height)
    return;

  NSRect borderRect = dirtyRect;
  borderRect.size.height = [image size].height;
  borderRect.origin.y = 0;

  BOOL focused = [[self window] isKeyWindow] || [[self window] isMainWindow];
  NSDrawThreePartImage(borderRect, nil, image, nil, /*vertical=*/ NO,
                       NSCompositeSourceOver,
                       focused ?  1.0 : tabs::kImageNoFocusAlpha,
                       /*flipped=*/ NO);
}

- (void)drawRect:(NSRect)rect {
  NSRect boundsRect = [self bounds];

  [self drawBorder:boundsRect];

  // Draw drop-indicator arrow (if appropriate).
  // TODO(viettrungluu): this is all a stop-gap measure.
  if ([self dropArrowShown]) {
    // Programmer art: an arrow parametrized by many knobs. Note that the arrow
    // points downwards (so understand "width" and "height" accordingly).

    // How many (pixels) to inset on the top/bottom.
    const CGFloat kArrowTopInset = 1.5;
    const CGFloat kArrowBottomInset = 1;

    // What proportion of the vertical space is dedicated to the arrow tip,
    // i.e., (arrow tip height)/(amount of vertical space).
    const CGFloat kArrowTipProportion = 0.55;

    // This is a slope, i.e., (arrow tip height)/(0.5 * arrow tip width).
    const CGFloat kArrowTipSlope = 1.2;

    // What proportion of the arrow tip width is the stem, i.e., (stem
    // width)/(arrow tip width).
    const CGFloat kArrowStemProportion = 0.33;

    NSPoint arrowTipPos = [self dropArrowPosition];
    arrowTipPos.x = std::floor(arrowTipPos.x);  // Draw on the pixel.
    arrowTipPos.y += kArrowBottomInset;  // Inset on the bottom.

    // Height we have to work with (insetting on the top).
    CGFloat availableHeight =
        NSMaxY(boundsRect) - arrowTipPos.y - kArrowTopInset;
    DCHECK(availableHeight >= 5);

    // Based on the knobs above, calculate actual dimensions which we'll need
    // for drawing.
    CGFloat arrowTipHeight = kArrowTipProportion * availableHeight;
    CGFloat arrowTipWidth = 2 * arrowTipHeight / kArrowTipSlope;
    CGFloat arrowStemHeight = availableHeight - arrowTipHeight;
    CGFloat arrowStemWidth = kArrowStemProportion * arrowTipWidth;
    CGFloat arrowStemInset = (arrowTipWidth - arrowStemWidth) / 2;

    // The line width is arbitrary, but our path really should be mitered.
    NSBezierPath* arrow = [NSBezierPath bezierPath];
    [arrow setLineJoinStyle:NSMiterLineJoinStyle];
    [arrow setLineWidth:1];

    // Define the arrow's shape! We start from the tip and go clockwise.
    [arrow moveToPoint:arrowTipPos];
    [arrow relativeLineToPoint:NSMakePoint(-arrowTipWidth / 2, arrowTipHeight)];
    [arrow relativeLineToPoint:NSMakePoint(arrowStemInset, 0)];
    [arrow relativeLineToPoint:NSMakePoint(0, arrowStemHeight)];
    [arrow relativeLineToPoint:NSMakePoint(arrowStemWidth, 0)];
    [arrow relativeLineToPoint:NSMakePoint(0, -arrowStemHeight)];
    [arrow relativeLineToPoint:NSMakePoint(arrowStemInset, 0)];
    [arrow closePath];

    // Draw and fill the arrow.
    [[NSColor colorWithCalibratedWhite:0 alpha:0.67] set];
    [arrow stroke];
    [[NSColor colorWithCalibratedWhite:1 alpha:0.67] setFill];
    [arrow fill];
  }
}

// YES if a double-click in the background of the tab strip minimizes the
// window.
- (BOOL)doubleClickMinimizesWindow {
  return YES;
}

// We accept first mouse so clicks onto close/zoom/miniaturize buttons and
// title bar double-clicks are properly detected even when the window is in the
// background.
- (BOOL)acceptsFirstMouse:(NSEvent*)event {
  return YES;
}

// Trap double-clicks and make them miniaturize the browser window.
- (void)mouseUp:(NSEvent*)event {
  // Bail early if double-clicks are disabled.
  if (![self doubleClickMinimizesWindow]) {
    [super mouseUp:event];
    return;
  }

  NSInteger clickCount = [event clickCount];
  NSTimeInterval timestamp = [event timestamp];

  // Double-clicks on Zoom/Close/Mininiaturize buttons shouldn't cause
  // miniaturization. For those, we miss the first click but get the second
  // (with clickCount == 2!). We thus check that we got a first click shortly
  // before (measured up-to-up) a double-click. Cocoa doesn't have a documented
  // way of getting the proper interval (= (double-click-threshold) +
  // (drag-threshold); the former is Carbon GetDblTime()/60.0 or
  // com.apple.mouse.doubleClickThreshold [undocumented]). So we hard-code
  // "short" as 0.8 seconds. (Measuring up-to-up isn't enough to properly
  // detect double-clicks, but we're actually using Cocoa for that.)
  if (clickCount == 2 && (timestamp - lastMouseUp_) < 0.8) {
    if (base::mac::ShouldWindowsMiniaturizeOnDoubleClick())
      [[self window] performMiniaturize:self];
  } else {
    [super mouseUp:event];
  }

  // If clickCount is 0, the drag threshold was passed.
  lastMouseUp_ = (clickCount == 1) ? timestamp : -1000.0;
}

// (URLDropTarget protocol)
- (id<URLDropTargetController>)urlDropController {
  return controller_;
}

// (URLDropTarget protocol)
- (NSDragOperation)draggingEntered:(id<NSDraggingInfo>)sender {
  return [dropHandler_ draggingEntered:sender];
}

// (URLDropTarget protocol)
- (NSDragOperation)draggingUpdated:(id<NSDraggingInfo>)sender {
  return [dropHandler_ draggingUpdated:sender];
}

// (URLDropTarget protocol)
- (void)draggingExited:(id<NSDraggingInfo>)sender {
  return [dropHandler_ draggingExited:sender];
}

// (URLDropTarget protocol)
- (BOOL)performDragOperation:(id<NSDraggingInfo>)sender {
  return [dropHandler_ performDragOperation:sender];
}

- (BOOL)accessibilityIsIgnored {
  return NO;
}

- (id)accessibilityAttributeValue:(NSString*)attribute {
  if ([attribute isEqual:NSAccessibilityRoleAttribute])
    return NSAccessibilityTabGroupRole;
  if ([attribute isEqual:NSAccessibilityTabsAttribute]) {
    NSMutableArray* tabs = [[[NSMutableArray alloc] init] autorelease];
    NSArray* children =
        [self accessibilityAttributeValue:NSAccessibilityChildrenAttribute];
    for (id child in children) {
      if ([[child accessibilityAttributeValue:NSAccessibilityRoleAttribute]
          isEqual:NSAccessibilityRadioButtonRole]) {
        [tabs addObject:child];
      }
    }
    return tabs;
  }
  if ([attribute isEqual:NSAccessibilityContentsAttribute])
    return [self accessibilityAttributeValue:NSAccessibilityChildrenAttribute];
  if ([attribute isEqual:NSAccessibilityValueAttribute])
    return [controller_ activeTabView];

  return [super accessibilityAttributeValue:attribute];
}

- (NSArray*)accessibilityAttributeNames {
  NSMutableArray* attributes =
      [[super accessibilityAttributeNames] mutableCopy];
  [attributes addObject:NSAccessibilityTabsAttribute];
  [attributes addObject:NSAccessibilityContentsAttribute];
  [attributes addObject:NSAccessibilityValueAttribute];

  return [attributes autorelease];
}

- (ViewID)viewID {
  return VIEW_ID_TAB_STRIP;
}

- (NewTabButton*)getNewTabButton {
  return newTabButton_;
}

- (void)setNewTabButton:(NewTabButton*)button {
  newTabButton_.reset([button retain]);
}

- (void)setController:(TabStripController*)controller {
  controller_ = controller;
}

@end