1// Copyright 2014 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef UI_GFX_FONT_RENDER_PARAMS_H_
6#define UI_GFX_FONT_RENDER_PARAMS_H_
7
8#include <string>
9#include <vector>
10
11#include "ui/gfx/gfx_export.h"
12
13namespace gfx {
14
15// A collection of parameters describing how text should be rendered on Linux.
16struct GFX_EXPORT FontRenderParams {
17  FontRenderParams();
18  ~FontRenderParams();
19
20  // Level of hinting to be applied.
21  enum Hinting {
22    HINTING_NONE = 0,
23    HINTING_SLIGHT,
24    HINTING_MEDIUM,
25    HINTING_FULL,
26  };
27
28  // Different subpixel orders to be used for subpixel rendering.
29  enum SubpixelRendering {
30    SUBPIXEL_RENDERING_NONE = 0,
31    SUBPIXEL_RENDERING_RGB,
32    SUBPIXEL_RENDERING_BGR,
33    SUBPIXEL_RENDERING_VRGB,
34    SUBPIXEL_RENDERING_VBGR,
35  };
36
37  // Antialiasing (grayscale if |subpixel_rendering| is SUBPIXEL_RENDERING_NONE
38  // and RGBA otherwise).
39  bool antialiasing;
40
41  // Should subpixel positioning (i.e. fractional X positions for glyphs) be
42  // used?
43  // TODO(derat): Remove this; we don't set it in the browser and mostly ignore
44  // it in Blink: http://crbug.com/396659
45  bool subpixel_positioning;
46
47  // Should FreeType's autohinter be used (as opposed to Freetype's bytecode
48  // interpreter, which uses fonts' own hinting instructions)?
49  bool autohinter;
50
51  // Should embedded bitmaps in fonts should be used?
52  bool use_bitmaps;
53
54  // Hinting level.
55  Hinting hinting;
56
57  // Whether subpixel rendering should be used or not, and if so, the display's
58  // subpixel order.
59  SubpixelRendering subpixel_rendering;
60};
61
62// A query used to determine the appropriate FontRenderParams.
63struct GFX_EXPORT FontRenderParamsQuery {
64  explicit FontRenderParamsQuery(bool for_web_contents);
65  ~FontRenderParamsQuery();
66
67  bool is_empty() const {
68    return families.empty() && pixel_size <= 0 && point_size <= 0 && style < 0;
69  }
70
71  // True if rendering text for the web.
72  // TODO(derat): Remove this once FontRenderParams::subpixel_positioning is
73  // gone: http://crbug.com/396659
74  bool for_web_contents;
75
76  // Requested font families, or empty if unset.
77  std::vector<std::string> families;
78
79  // Font size in pixels or points, or 0 if unset.
80  int pixel_size;
81  int point_size;
82
83  // gfx::Font::FontStyle bit field, or -1 if unset.
84  int style;
85};
86
87// Returns the appropriate parameters for rendering the font described by
88// |query|. If |family_out| is non-NULL, it will be updated to contain the
89// recommended font family from |query.families|.
90GFX_EXPORT FontRenderParams GetFontRenderParams(
91    const FontRenderParamsQuery& query,
92    std::string* family_out);
93
94// Clears GetFontRenderParams()'s cache. Intended to be called by tests that are
95// changing Fontconfig's configuration.
96// TODO(derat): This is only defined for Linux, but OS_LINUX doesn't seem to be
97// set when font_render_params_linux_unittest.cc includes this header. Figure
98// out what's going on here.
99GFX_EXPORT void ClearFontRenderParamsCacheForTest();
100
101#if defined(OS_CHROMEOS)
102// Sets the device scale factor for FontRenderParams to decide
103// if it should enable subpixel positioning.
104GFX_EXPORT void SetFontRenderParamsDeviceScaleFactor(
105    float device_scale_factor);
106#endif
107
108}  // namespace gfx
109
110#endif  // UI_GFX_FONT_RENDER_PARAMS_H_
111