[blink/mac] Support getting baseline point for showing dictionary lookup bubble.

Source/web/mac/WebSubstringUtil.mm

 /*
  * Copyright (C) 2005, 2007, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 92 matching lines @@
             [[[NSString alloc] initWithCharacters:characters.data()
                                            length:characters.size()] autorelease];
         [string replaceCharactersInRange:NSMakeRange(position, 0)
                               withString:substring];
         [string setAttributes:attrs range:NSMakeRange(position, numCharacters)];
         position += numCharacters;
     }
     return [string autorelease];
 }
 
+WebPoint getBaselinePoint(FrameView* frameView, const EphemeralRange& range, const NSAttributedString* string)
+{
+    // Compute bottom left corner and convert to AppKit coordinates.
+    // TODO(yosin) We shold avoid to create |Range| object.

[eae, 2015/09/09 16:56:04]

Could you please file a bug about this and add a link here?

[Shu Chen, 2015/09/10 01:14:07]

Done.

+    IntRect stringRect = enclosingIntRect(createRange(range)->boundingRect());
+    IntPoint stringPoint = stringRect.minXMaxYCorner();
+    stringPoint.setY(frameView->height() - stringPoint.y());

[eae, 2015/09/09 16:56:04]

You take the bottom left corner of the bounding rect for the range and then
adjust it by the height of the frame view. What type of coordinate does that
give you? I know this code was just moved but an explanation here would help.

[Shu Chen, 2015/09/10 01:14:07]

Actually, I don't understand why adjust y() by the height of the frame view.
The y() will be adjusted back when using it at here:
https://code.google.com/p/chromium/codesearch#chromium/src/content/browser/re....

The point type is changed as IntPoint -> WebPoint -> gfx::Point -> CGPoint ->
NSPoint.
I suspect the computation on certain point type requires that strange adjust.

Do you have any ideas?

+
+    // Adjust for the font's descender. AppKit wants the baseline point.
+    if ([string length]) {
+        NSDictionary* attributes = [string attributesAtIndex:0 effectiveRange:NULL];
+        NSFont* font = [attributes objectForKey:NSFontAttributeName];
+        if (font)
+            stringPoint.move(0, ceil(-[font descender]));
+    }
+    return stringPoint;
+}
+
 namespace blink {
 
 NSAttributedString* WebSubstringUtil::attributedWordAtPoint(WebView* view, WebPoint point, WebPoint& baselinePoint)
 {
     HitTestResult result = static_cast<WebViewImpl*>(view)->coreHitTestResultAt(point);
     if (!result.innerNode())
       return nil;
     LocalFrame* frame = result.innerNode()->document().frame();
-    FrameView* frameView = frame->view();
-
     EphemeralRange range = frame->rangeForPoint(result.roundedPointInInnerNodeFrame());
     if (range.isNull())
         return nil;
 
     // Expand to word under point.
     VisibleSelection selection(range);
     selection.expandUsingGranularity(WordGranularity);
     const EphemeralRange wordRange = selection.toNormalizedEphemeralRange();
 
     // Convert to NSAttributedString.
     NSAttributedString* string = attributedSubstringFromRange(wordRange);
-
-    // Compute bottom left corner and convert to AppKit coordinates.
-    // TODO(yosin) We shold avoid to create |Range| object.
-    IntRect stringRect = enclosingIntRect(createRange(wordRange)->boundingRect());
-    IntPoint stringPoint = stringRect.minXMaxYCorner();
-    stringPoint.setY(frameView->height() - stringPoint.y());
-
-    // Adjust for the font's descender. AppKit wants the baseline point.
-    if ([string length]) {
-        NSDictionary* attributes = [string attributesAtIndex:0 effectiveRange:NULL];
-        NSFont* font = [attributes objectForKey:NSFontAttributeName];
-        if (font)
-            stringPoint.move(0, ceil(-[font descender]));
-    }
-
-    baselinePoint = stringPoint;
+    baselinePoint = getBaselinePoint(frame->view(), wordRange, string);
     return string;
 }
 
 NSAttributedString* WebSubstringUtil::attributedSubstringInRange(WebLocalFrame* webFrame, size_t location, size_t length)
 {
+    return WebSubstringUtil::attributedSubstringInRange(webFrame, location, length, nil);
+}
+
+NSAttributedString* WebSubstringUtil::attributedSubstringInRange(WebLocalFrame* webFrame, size_t location, size_t length, WebPoint* baselinePoint)
+{
     LocalFrame* frame = toWebLocalFrameImpl(webFrame)->frame();
     if (frame->view()->needsLayout())
         frame->view()->layout();
 
     Element* editable = frame->selection().rootEditableElementOrDocumentElement();
     if (!editable)
         return nil;
     const EphemeralRange ephemeralRange(PlainTextRange(location, location + length).createRange(*editable));
     if (ephemeralRange.isNull())
         return nil;
 
-    return attributedSubstringFromRange(ephemeralRange);
+    NSAttributedString* ret = attributedSubstringFromRange(ephemeralRange);
+    if (baselinePoint)
+        *baselinePoint = getBaselinePoint(frame->view(), ephemeralRange, ret);
+    return ret;
 }
 
 } // namespace blink