MacViews: Implement Force Touch/Mac dictionary lookup for Textfields.

ui/gfx/render_text_harfbuzz_mac.mm

Index: ui/gfx/render_text_harfbuzz_mac.mm
diff --git a/ui/gfx/render_text_harfbuzz_mac.mm b/ui/gfx/render_text_harfbuzz_mac.mm
new file mode 100644
index 0000000000000000000000000000000000000000..50f440101f58c45673528cb90d06a8e77cecc78f
--- /dev/null
+++ b/ui/gfx/render_text_harfbuzz_mac.mm
@@ -0,0 +1,94 @@
+// Copyright 2016 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 <Cocoa/Cocoa.h>
+
+#include "base/mac/foundation_util.h"
+#include "base/strings/sys_string_conversions.h"
+#include "third_party/skia/include/ports/SkTypeface_mac.h"
+#include "ui/gfx/font.h"
+#include "ui/gfx/render_text_harfbuzz.h"
+
+namespace gfx {
+
+namespace internal {
+
+sk_sp<SkTypeface> CreateSkiaTypeface(const Font& font,
+                                     bool italic,
+                                     Font::Weight weight) {
+  const Font::FontStyle style = italic ? Font::ITALIC : Font::NORMAL;
+  Font font_with_style = font.Derive(0, style, weight);
+  if (!font_with_style.GetNativeFont())
+    return nullptr;
+
+  return sk_sp<SkTypeface>(SkCreateTypefaceFromCTFont(
+      base::mac::NSToCFCast(font_with_style.GetNativeFont())));
+}
+
+}  // namespace internal
+
+bool RenderTextHarfBuzz::GetStyledStringForRange(
+    const Range& range,
+    NSMutableAttributedString* str) const {

[tapted, 2016/09/21 04:06:56]

I'm not sure I like the idea of plumbing through an NSMutableAttributedString
:/. WDYT about borrowing some ideas from
content/common/mac/attributed_string_coder.h

E.g. rather than taking an NSMutableAttributedString*, take a
std:vector<DecoratedText>*

struct DecoratedText {
  struct RangedAttribute {
    gfx::Range range;
    gfx::Font font;
    // is there more? Seems it's just [DIAGONAL_]STRIKE that's missing, which
probably isn't important for this.

   // Disallow default construction of gfx::Font, since that's slow.
   RangedAttribute() = delete;
   /* add constructor that works */
  };
  base::string16 string;
  std::vector<RangedAttribute> attributes;
};


Then this stuff should be able to be implemented somewhere more generic, like
render_text.cc

[karandeepb, 2016/09/22 08:17:39]

Yeah the typedef looked ugly. Encapsulating all the styling info. in a struct
looks better.
But don't think that this can be moved to render_text.cc. We need to still
gather the info. from the individual runs.

+  if (obscured())
+    return false;
+
+  NSMutableDictionary* attrs = [NSMutableDictionary dictionary];
+
+  [str beginEditing];
+  [[str mutableString]
+      setString:base::SysUTF16ToNSString(GetTextFromRange(range))];
+
+  const internal::TextRunList* run_list = GetRunList();
+  for (size_t i = 0; i < run_list->size(); i++) {
+    const internal::TextRunHarfBuzz& run = *run_list->runs()[i];
+
+    const Range& intersection = range.Intersect(run.range);
+    DCHECK(!intersection.is_reversed());
+
+    if (!intersection.is_empty()) {
+      // Get range relative to |str|.
+      NSRange strRange = NSMakeRange(intersection.start() - range.GetMin(),
+                                     intersection.length());
+
+      // Font.
+      if (run.font.GetNativeFont())
+        [attrs setObject:run.font.GetNativeFont() forKey:NSFontAttributeName];
+      else
+        [attrs removeObjectForKey:NSFontAttributeName];
+
+      // Underline.
+      if (run.underline) {
+        [attrs setObject:@(NSUnderlineStyleSingle | NSUnderlinePatternSolid)
+                  forKey:NSUnderlineStyleAttributeName];
+      } else {
+        [attrs removeObjectForKey:NSUnderlineStyleAttributeName];
+      }
+
+      // Strikethrough.
+      if (run.strike) {
+        [attrs setObject:@(NSUnderlineStyleSingle | NSUnderlinePatternSolid)
+                  forKey:NSStrikethroughStyleAttributeName];
+      } else {
+        [attrs removeObjectForKey:NSStrikethroughStyleAttributeName];
+      }
+
+      // Apply attributes.
+      [str setAttributes:attrs range:strRange];
+
+      // Bold.
+      if (run.weight >= Font::Weight::BOLD)
+        [str applyFontTraits:NSBoldFontMask range:strRange];
+
+      // Italics.
+      if (run.italic)
+        [str applyFontTraits:NSItalicFontMask range:strRange];

[tapted, 2016/09/21 04:06:55]

does this work for bold+italic (i.e. should the traits be OR'd together?)

[karandeepb, 2016/09/22 08:17:39]

Thanks for the catch. Done.

+    }
+  }
+
+  [str endEditing];
+  return true;
+}
+
+}  // namespace gfx