Re-land: RenderTextHarfBuzz: Set font render parameters in font data functions

Originally landed at: https://codereview.chromium.org/480533002/

- Properly pass font render settings to Skia font data functions. Otherwise Skia always returns rounded values.

- If subpixel positioning is off, round the glyph positions to match Pango's rounding logic.

BUG=402715,402374,402347
TEST=On Linux, character positions in UI text (address bar, infobars, tab titles) should be identical with --enable-harfbuzz-rendertext and --disable-harfbuzz-rendertext.

Review URL: https://codereview.chromium.org/484883003

Cr-Commit-Position: refs/heads/master@{#291767}

1 files changed, 38 insertions, 0 deletions

diff --git a/ui/gfx/font_render_params_mac.cc b/ui/gfx/font_render_params_mac.cc
new file mode 100644
index 0000000..0062f3b1
--- /dev/null
+++ b/ui/gfx/font_render_params_mac.cc
@@ -0,0 +1,38 @@
+// Copyright 2014 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.
+
+#include "ui/gfx/font_render_params.h"
+
+#include "base/logging.h"
+#include "base/macros.h"
+
+namespace gfx {
+
+namespace {
+
+// Returns params that match SkiaTextRenderer's default render settings.
+FontRenderParams LoadDefaults() {
+  FontRenderParams params;
+  params.antialiasing = true;
+  params.autohinter = false;
+  params.use_bitmaps = true;
+  params.subpixel_rendering = FontRenderParams::SUBPIXEL_RENDERING_RGB;
+  params.subpixel_positioning = true;
+  params.hinting = FontRenderParams::HINTING_MEDIUM;
+
+  return params;
+}
+
+}  // namespace
+
+FontRenderParams GetFontRenderParams(const FontRenderParamsQuery& query,
+                                     std::string* family_out) {
+  // TODO: Query the OS for font render settings instead of returning defaults.
+  if (!query.is_empty() || family_out)
+    NOTIMPLEMENTED();
+  CR_DEFINE_STATIC_LOCAL(const gfx::FontRenderParams, params, (LoadDefaults()));
+  return params;
+}
+
+}  // namespace gfx