Mac: Make image dragging 162.4% more awesome.

chrome/browser/cocoa/web_drag_source.mm

 // Copyright (c) 2009 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/cocoa/web_drag_source.h"
 
 #include "base/file_path.h"
 #include "base/nsimage_cache_mac.h"
 #include "base/string_util.h"
 #include "base/sys_string_conversions.h"
@@ skipping 17 matching lines @@
 using base::SysUTF16ToNSString;
 using net::FileStream;
 
 
 namespace {
 
 // An unofficial standard pasteboard title type to be provided alongside the
 // |NSURLPboardType|.
 NSString* const kNSURLTitlePboardType = @"public.url-name";
 
-// Make a drag image from the drop data.
-// TODO(viettrungluu): Move this somewhere more sensible.
-NSImage* MakeDragImage(const WebDropData* drop_data) {
-  // TODO(viettrungluu): Just a stub for now. Make it do something (see, e.g.,
-  // WebKit/WebKit/mac/Misc/WebNSViewExtras.m: |-_web_DragImageForElement:...|).
-
-  // Default to returning a generic image.
-  return nsimage_cache::ImageNamed(@"nav.pdf");
-}
-
 // Returns a filename appropriate for the drop data
 // TODO(viettrungluu): Refactor to make it common across platforms,
 // and move it somewhere sensible.
 FilePath GetFileNameFromDragData(const WebDropData& drop_data) {
   // Images without ALT text will only have a file extension so we need to
   // synthesize one from the provided extension and URL.
   FilePath file_name([SysUTF16ToNSString(drop_data.file_description_filename)
           fileSystemRepresentation]);
   file_name = file_name.BaseName().RemoveExtension();
 
@@ skipping 57 matching lines @@
 - (void)fillPasteboard;
 - (NSImage*)dragImage;
 
 @end  // @interface WebDragSource(Private)
 
 
 @implementation WebDragSource
 
 - (id)initWithContentsView:(TabContentsViewCocoa*)contentsView
                   dropData:(const WebDropData*)dropData
+                     image:(NSImage*)image
+                    offset:(NSPoint)offset
                 pasteboard:(NSPasteboard*)pboard
          dragOperationMask:(NSDragOperation)dragOperationMask {
   if ((self = [super init])) {
     contentsView_ = contentsView;
     DCHECK(contentsView_);
 
     dropData_.reset(new WebDropData(*dropData));
     DCHECK(dropData_.get());
 
+    dragImage_.reset([image retain]);
+    imageOffset_ = offset;
+
     pasteboard_.reset([pboard retain]);
     DCHECK(pasteboard_.get());
 
     dragOperationMask_ = dragOperationMask;
 
     [self fillPasteboard];
   }
 
   return self;
 }
@@ skipping 74 matching lines @@
   NSEvent* dragEvent = [NSEvent mouseEventWithType:NSLeftMouseDragged
                                           location:position
                                      modifierFlags:NSLeftMouseDraggedMask
                                          timestamp:eventTime
                                       windowNumber:[window windowNumber]
                                            context:nil
                                        eventNumber:0
                                         clickCount:1
                                           pressure:1.0];
 
+  if (dragImage_) {
+    position.x -= imageOffset_.x;
+    // Deal with Cocoa's flipped coordinate system.
+    position.y -= [dragImage_.get() size].height - imageOffset_.y;
+  }
+  // Per kwebster, offset arg is ignored, see -_web_DragImageForElement: in
+  // third_party/WebKit/WebKit/mac/Misc/WebNSViewExtras.m.
   [window dragImage:[self dragImage]
                  at:position
              offset:NSZeroSize
               event:dragEvent
          pasteboard:pasteboard_
              source:contentsView_
           slideBack:YES];
 }
 
 - (void)endDragAt:(NSPoint)screenPoint
@@ skipping 141 matching lines @@
     }
   }
 
   // Plain text.
   if (!dropData_->plain_text.empty())
     [pasteboard_ addTypes:[NSArray arrayWithObject:NSStringPboardType]
                     owner:contentsView_];
 }
 
 - (NSImage*)dragImage {
-  return MakeDragImage(dropData_.get());
+  if (dragImage_)
+    return dragImage_;
+
+  // Default to returning a generic image.
+  return nsimage_cache::ImageNamed(@"nav.pdf");
 }
 
 @end  // @implementation WebDragSource (Private)