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// Copyright 2014 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef UI_GFX_FONT_RENDER_PARAMS_H_
#define UI_GFX_FONT_RENDER_PARAMS_H_
#include <string>
#include <vector>
#include "base/component_export.h"
#include "build/build_config.h"
#include "device/vr/buildflags/buildflags.h"
#include "third_party/skia/include/core/SkSurfaceProps.h"
#include "ui/gfx/font.h"
namespace gfx {
// A collection of parameters describing how text should be rendered on Linux.
struct COMPONENT_EXPORT(GFX) FontRenderParams {
bool operator==(const FontRenderParams& other) const {
return antialiasing == other.antialiasing &&
text_contrast == other.text_contrast &&
text_gamma == other.text_gamma &&
subpixel_positioning == other.subpixel_positioning &&
autohinter == other.autohinter && use_bitmaps == other.use_bitmaps &&
hinting == other.hinting &&
subpixel_rendering == other.subpixel_rendering;
}
// Level of hinting to be applied.
enum Hinting {
HINTING_NONE = 0,
HINTING_SLIGHT,
HINTING_MEDIUM,
HINTING_FULL,
HINTING_MAX = HINTING_FULL,
};
// Different subpixel orders to be used for subpixel rendering.
enum SubpixelRendering {
SUBPIXEL_RENDERING_NONE = 0,
SUBPIXEL_RENDERING_RGB,
SUBPIXEL_RENDERING_BGR,
SUBPIXEL_RENDERING_VRGB,
SUBPIXEL_RENDERING_VBGR,
SUBPIXEL_RENDERING_MAX = SUBPIXEL_RENDERING_VBGR,
};
// Antialiasing (grayscale if |subpixel_rendering| is SUBPIXEL_RENDERING_NONE
// and RGBA otherwise).
bool antialiasing = true;
// Should subpixel positioning (i.e. fractional X positions for glyphs) be
// used?
// TODO(derat): Remove this; we don't set it in the browser and mostly ignore
// it in Blink: http://crbug.com/396659
bool subpixel_positioning = true;
// Should FreeType's autohinter be used (as opposed to Freetype's bytecode
// interpreter, which uses fonts' own hinting instructions)?
bool autohinter = false;
// Should embedded bitmaps in fonts should be used?
bool use_bitmaps = false;
// Hinting level.
Hinting hinting = HINTING_MEDIUM;
// Whether subpixel rendering should be used or not, and if so, the display's
// subpixel order.
SubpixelRendering subpixel_rendering = SUBPIXEL_RENDERING_NONE;
// Text contrast and gamma settings, defaulted to Skia's fixed values.
float text_contrast = SK_GAMMA_CONTRAST;
float text_gamma = SK_GAMMA_EXPONENT;
static SkPixelGeometry SubpixelRenderingToSkiaPixelGeometry(
SubpixelRendering subpixel_rendering);
};
// A query used to determine the appropriate FontRenderParams.
struct COMPONENT_EXPORT(GFX) FontRenderParamsQuery {
FontRenderParamsQuery();
FontRenderParamsQuery(const FontRenderParamsQuery& other);
~FontRenderParamsQuery();
bool is_empty() const {
return families.empty() && pixel_size <= 0 && point_size <= 0 && style < 0;
}
// Requested font families, or empty if unset.
std::vector<std::string> families;
// Font size in pixels or points, or 0 if unset.
int pixel_size;
int point_size;
// Font::FontStyle bit field, or -1 if unset.
int style;
// Weight of the font. Weight::NORMAL by default.
Font::Weight weight;
// The device scale factor of the display, or 0 if unset.
float device_scale_factor;
};
// Returns the appropriate parameters for rendering the font described by
// |query|. If |family_out| is non-NULL, it will be updated to contain the
// recommended font family from |query.families|.
COMPONENT_EXPORT(GFX)
FontRenderParams GetFontRenderParams(const FontRenderParamsQuery& query,
std::string* family_out);
#if BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_CHROMEOS) || BUILDFLAG(IS_WIN)
// Clears GetFontRenderParams()'s cache. Intended to be called by tests that are
// changing Fontconfig's configuration.
COMPONENT_EXPORT(GFX) void ClearFontRenderParamsCacheForTest();
#endif
// Gets the device scale factor to query the FontRenderParams.
COMPONENT_EXPORT(GFX) float GetFontRenderParamsDeviceScaleFactor();
#if BUILDFLAG(IS_WIN) || BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_CHROMEOS) || \
BUILDFLAG(IS_ANDROID) || BUILDFLAG(IS_FUCHSIA)
// Sets the device scale factor for FontRenderParams to decide
// if it should enable subpixel positioning.
COMPONENT_EXPORT(GFX)
void SetFontRenderParamsDeviceScaleFactor(float device_scale_factor);
#endif
} // namespace gfx
#endif // UI_GFX_FONT_RENDER_PARAMS_H_
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