"Bootstrap" a toolkit-views Typography spec.

ui/views/style/typography_provider.h

+// Copyright 2017 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.
+
+#ifndef UI_VIEWS_STYLE_TYPOGRAPHY_PROVIDER_H_
+#define UI_VIEWS_STYLE_TYPOGRAPHY_PROVIDER_H_
+
+#include <memory>
+
+#include "base/macros.h"
+#include "third_party/skia/include/core/SkColor.h"
+#include "ui/gfx/font.h"
+#include "ui/views/views_export.h"
+
+namespace gfx {
+class FontList;
+}
+
+namespace views {
+
+class TextContext;
+class TextStyle;
+
+// Provides fonts to use in toolkit-views UI.
+class VIEWS_EXPORT TypographyProvider {
+ public:
+  // Gets the FontList for the given |context| and |style|.
+  virtual const gfx::FontList& GetFont(TextContext context,
+                                       TextStyle style) const = 0;
+
+  // Gets the color for the given |context| and |style|. This may consult
+  // ui::NativeTheme.
+  virtual SkColor GetColor(TextContext context, TextStyle style) const = 0;
+
+  // Gets the line spacing, or 0 if it should be provided by gfx::FontList.
+  virtual int GetLineSpacing(TextContext context, TextStyle style) const = 0;

[tapted, 2017/03/15 11:04:07]

(note to self: rename to GetLineHeight to match views::Label?)

[tapted, 2017/03/16 11:13:39]

Done.

+
+  virtual ~TypographyProvider() = default;
+
+  static void Set(std::unique_ptr<TypographyProvider> provider);
+  static const TypographyProvider& Get();
+
+ protected:
+  TypographyProvider() = default;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(TypographyProvider);
+};
+
+// The default provider aims to provide values to match pre-Harmony constants
+// for the given contexts so that old UI does not change.
+class VIEWS_EXPORT DefaultTypographyProvider : public TypographyProvider {
+ public:
+  DefaultTypographyProvider() = default;
+
+  const gfx::FontList& GetFont(TextContext context,
+                               TextStyle style) const override;
+  SkColor GetColor(TextContext context, TextStyle style) const override;
+  int GetLineSpacing(TextContext context, TextStyle style) const override;
+
+  // Describes the font that the default GetFont() implementation uses. Always
+  // writes a value, even for styles it doesn't know about.
+  void GetDefaultFont(TextContext context,
+                      TextStyle style,
+                      int* size_delta,
+                      gfx::Font::Weight* font_weight) const;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(DefaultTypographyProvider);
+};
+
+}  // namespace views
+
+#endif  // UI_VIEWS_STYLE_TYPOGRAPHY_PROVIDER_H_