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/*
* This file is part of LibCSS.
* Licensed under the MIT License,
* http://www.opensource.org/licenses/mit-license.php
* Copyright 2008 John-Mark Bell <jmb@netsurf-browser.org>
*/
#ifndef libcss_unit_h_
#define libcss_unit_h_
#ifdef __cplusplus
extern "C"
{
#endif
#include <libcss/types.h>
/**
* Client callback for font measuring.
*
* \param[in] pw Client data.
* \param[in] style Style to measure font for, or NULL.
* \param[in] unit Either CSS_UNIT_EX, or CSS_UNIT_CH.
* \return length in CSS pixels.
*/
typedef css_fixed (*css_unit_len_measure)(
void *pw,
const css_computed_style *style,
const css_unit unit);
/**
* LibCSS unit conversion context.
*
* The client callback is optional. It is used for measuring "ch"
* (glyph '0' advance) and "ex" (height of the letter 'x') units.
* If a NULL pointer is given, LibCSS will use a fixed scaling of
* the "em" unit.
*/
typedef struct css_unit_ctx {
/**
* Viewport width in CSS pixels.
* Used if unit is vh, vw, vi, vb, vmin, or vmax.
*/
css_fixed viewport_width;
/**
* Viewport height in CSS pixels.
* Used if unit is vh, vw, vi, vb, vmin, or vmax.
*/
css_fixed viewport_height;
/**
* Client default font size in CSS pixels.
*/
css_fixed font_size_default;
/**
* Client minimum font size in CSS pixels. May be zero.
*/
css_fixed font_size_minimum;
/**
* DPI of the device the style is selected for.
*/
css_fixed device_dpi;
/**
* Computed style for the document root element, needed for rem units.
* May be NULL, in which case font_size_default is used instead, as
* would be the case if rem unit is used on the root element.
*/
const css_computed_style *root_style;
/**
* Optional client private word for measure callback.
*/
void *pw;
/**
* Optional client callback for font measuring.
*/
const css_unit_len_measure measure;
} css_unit_ctx;
/**
* Convert css pixels to physical pixels.
*
* \param[in] css_pixels Length in css pixels.
* \param[in] device_dpi Device dots per inch.
* \return Length in device pixels.
*/
static inline css_fixed css_unit_css2device_px(
const css_fixed css_pixels,
const css_fixed device_dpi)
{
return FDIV(FMUL(css_pixels, device_dpi), F_96);
}
/**
* Convert device pixels to css pixels.
*
* \param[in] device_pixels Length in physical pixels.
* \param[in] device_dpi Device dots per inch.
* \return Length in css pixels.
*/
static inline css_fixed css_unit_device2css_px(
const css_fixed device_pixels,
const css_fixed device_dpi)
{
return FDIV(FMUL(device_pixels, F_96), device_dpi);
}
/**
* Convert a length to points (pt).
*
* \param[in] style Style to perform conversion for or NULL.
* \param[in] ctx Length unit conversion context.
* \param[in] length Length to convert.
* \param[in] unit Current unit of length.
* \return A length in points.
*/
css_fixed css_unit_font_size_len2pt(
const css_computed_style *style,
const css_unit_ctx *ctx,
const css_fixed length,
const css_unit unit);
/**
* Convert a length to CSS pixels.
*
* \param[in] style Style to perform conversion for or NULL.
* \param[in] ctx Length unit conversion context.
* \param[in] length Length to convert.
* \param[in] unit Current unit of length.
* \return A length in CSS pixels.
*/
css_fixed css_unit_len2css_px(
const css_computed_style *style,
const css_unit_ctx *ctx,
const css_fixed length,
const css_unit unit);
/**
* Convert a length to device pixels.
*
* \param[in] style Style to perform conversion for or NULL.
* \param[in] ctx Length unit conversion context.
* \param[in] length Length to convert.
* \param[in] unit Current unit of length.
* \return A length in device pixels.
*/
css_fixed css_unit_len2device_px(
const css_computed_style *style,
const css_unit_ctx *ctx,
const css_fixed length,
const css_unit unit);
#ifdef __cplusplus
}
#endif
#endif
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