OmniboxPopupViewMac refactoring Part 3 (truncation)

chrome/browser/ui/cocoa/omnibox/omnibox_popup_cell.mm

 // Copyright 2013 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/omnibox/omnibox_popup_cell.h"
 
+#include <algorithm>
 #include <cmath>
 
+#include "ui/gfx/scoped_ns_graphics_context_save_gstate_mac.h"
+
 namespace {
 
 // How far to offset image column from the left.
 const CGFloat kImageXOffset = 5.0;
 
 // How far to offset the text column from the left.
 const CGFloat kTextXOffset = 28.0;
 
+// Maximum fraction of the popup width that can be used to display match
+// contents.
+const CGFloat kMinDescriptionFraction = 0.7;
+
 // Rounding radius of selection and hover background on popup items.
 const CGFloat kCellRoundingRadius = 2.0;
 
-NSColor* SelectedBackgroundColor() {
-  return [NSColor selectedControlColor];
-}
-NSColor* HoveredBackgroundColor() {
-  return [NSColor controlHighlightColor];
+void DrawFadeTruncatingTitle(NSAttributedString* title,
+                             NSRect titleRect,
+                             NSColor* backgroundColor) {
+  gfx::ScopedNSGraphicsContextSaveGState scopedGState;
+  NSRectClip(titleRect);
+
+  // Draw the entire text.
+  NSSize textSize = [title size];
+  NSPoint textOrigin = titleRect.origin;
+  textOrigin.y += roundf((NSHeight(titleRect) - textSize.height) / 2.0) - 1.0;
+  [title drawAtPoint:textOrigin];
+
+  // Empirically, Cocoa will draw an extra 2 pixels past NSWidth(titleRect)
+  // before it clips the text.
+  const CGFloat kOverflowBeforeClip = 2.0;
+  BOOL clipping =
+      std::floor(textSize.width) > NSWidth(titleRect) + kOverflowBeforeClip;
+  if (!clipping)

[Scott Hess - ex-Googler, 2013/07/08 20:53:11]

You don't use |clipping| again, but the initialization of |clipping| isn't super
clean to parse.  What about:
  CGFloat clipped_width = NSWidth(titleRect) + kOverflowBeforeClip;
  if (std::floor(textSize.width) <= clipped_width)
    return;

Though ... why the floor()?  Clipped is clipped, even if it's the anti-aliased
bit being clipped.

[sail, 2013/08/12 17:39:30]

Done.
Removed the floor.

+    return;
+
+  // Gradient is about twice our line height long.
+  CGFloat gradientWidth = std::min(textSize.height * 2, NSWidth(titleRect) / 4);
+
+  // Draw the gradient part.
+  NSColor *alphaColor = [backgroundColor colorWithAlphaComponent:0.0];
+  base::scoped_nsobject<NSGradient> mask(
+      [[NSGradient alloc] initWithStartingColor:alphaColor
+                                    endingColor:backgroundColor]);
+  [mask drawFromPoint:NSMakePoint(NSMaxX(titleRect) - gradientWidth,
+                                  NSMinY(titleRect))
+              toPoint:NSMakePoint(NSMaxX(titleRect),
+                                  NSMinY(titleRect))
+              options:NSGradientDrawsBeforeStartingLocation];
 }
 
 }  // namespace
 
 @implementation OmniboxPopupCell
 
 - (id)init {
-  self = [super init];
-  if (self) {
+  if ((self = [super init])) {
     [self setImagePosition:NSImageLeft];
     [self setBordered:NO];
     [self setButtonType:NSRadioButton];
 
     // Without this highlighting messes up white areas of images.
     [self setHighlightsBy:NSNoCellMask];
   }
   return self;
 }
 
-// The default NSButtonCell drawing leaves the image flush left and
-// the title next to the image.  This spaces things out to line up
-// with the star button and autocomplete field.
+- (void)setContentText:(NSAttributedString*)contentText {
+  contentText_.reset([contentText retain]);
+}
+
+- (void)setDescriptionText:(NSAttributedString*)descriptionText {
+  base::scoped_nsobject<NSMutableAttributedString> dashDescriptionText(
+      [[NSMutableAttributedString alloc]
+          initWithAttributedString:descriptionText]);
+  NSString* raw_en_dash = @" \u2013 ";

[Scott Hess - ex-Googler, 2013/07/08 20:53:11]

Should this be rawEnDash now that this isn't embedded in a C++ implementation
file?

[sail, 2013/08/12 17:39:30]

Done.

+  [dashDescriptionText replaceCharactersInRange:NSMakeRange(0, 0)
+                                     withString:raw_en_dash];
+  descriptionText_.reset(dashDescriptionText.release());
+}
+
 - (void)drawInteriorWithFrame:(NSRect)cellFrame inView:(NSView *)controlView {
+  NSColor* backgroundColor = [NSColor controlBackgroundColor];
   if ([self state] == NSOnState || [self isHighlighted]) {
     if ([self state] == NSOnState)
-      [SelectedBackgroundColor() set];
+      backgroundColor = [NSColor selectedControlColor];
     else
-      [HoveredBackgroundColor() set];
+      backgroundColor = [NSColor controlHighlightColor];
+    [backgroundColor set];
     NSBezierPath* path =
         [NSBezierPath bezierPathWithRoundedRect:cellFrame
                                         xRadius:kCellRoundingRadius
                                         yRadius:kCellRoundingRadius];
     [path fill];
   }
 
   // Put the image centered vertically but in a fixed column.
   NSImage* image = [self image];
   if (image) {
     NSRect imageRect = cellFrame;
     imageRect.size = [image size];
     imageRect.origin.y +=
         std::floor((NSHeight(cellFrame) - NSHeight(imageRect)) / 2.0);
     imageRect.origin.x += kImageXOffset;
     [image drawInRect:imageRect
              fromRect:NSZeroRect  // Entire image
             operation:NSCompositeSourceOver
              fraction:1.0
        respectFlipped:YES
                 hints:nil];
   }
 
   // Adjust the title position to be lined up under the field's text.
-  NSAttributedString* title = [self attributedTitle];
-  if (title && [title length]) {
-    NSRect titleRect = cellFrame;
-    titleRect.size.width -= kTextXOffset;
-    titleRect.origin.x += kTextXOffset;
-    [self drawTitle:title withFrame:titleRect inView:controlView];
+  if ([contentText_ length]) {
+    NSRect availRect = cellFrame;
+    availRect.size.width = NSWidth(cellFrame) - kTextXOffset;
+    availRect.origin.x += kTextXOffset;
+    CGFloat availWidth = NSWidth(availRect);
+    CGFloat contentWidth = [contentText_ size].width;
+    CGFloat descWidth =
+        [descriptionText_ length] ? [descriptionText_ size].width : 0;
+
+    CGFloat tempDescWidth =
+        std::min(descWidth, kMinDescriptionFraction * availWidth);
+    contentWidth = std::min(contentWidth, availWidth - tempDescWidth);
+
+    NSRect contentRect;
+    NSRect descRect;
+    NSDivideRect(
+        availRect, &contentRect, &descRect, contentWidth, NSMinXEdge);
+
+    DrawFadeTruncatingTitle(contentText_, contentRect, backgroundColor);
+    if ([descriptionText_ length])
+      DrawFadeTruncatingTitle(descriptionText_, descRect, backgroundColor);
   }
 }
 
 @end