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/*
* This file is part of LibCSS
* Licensed under the MIT License,
* http://www.opensource.org/licenses/mit-license.php
*
* Copyright 2021 Michael Drake <tlsa@netsurf-browser.org>
*/
#ifndef css_select_unit_h_
#define css_select_unit_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_len_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;
/**
* Reference style. Most of the time, this is the element's style.
* When converting a length for a typographical property, such as
* font-size, then this should be the parent node. If the node has
* no parent then this may be NULL.
*/
const css_computed_style *ref_style;
/**
* Computed style for the document root element.
* May be NULL if unit is not rem.
*/
const css_computed_style *root_style;
/**
* Client private word for measure callback.
*/
void *pw;
/**
* Client callback for font measuring.
*/
const css_unit_len_measure measure;
} css_unit_len_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] 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_unit_len_ctx *ctx,
const css_fixed length,
const css_unit unit);
/**
* Convert a length to CSS pixels.
*
* \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_unit_len_ctx *ctx,
const css_fixed length,
const css_unit unit);
/**
* Convert a length to device pixels.
*
* \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_unit_len_ctx *ctx,
const css_fixed length,
const css_unit unit);
/**
* Convert a length to CSS pixels for a media query context.
*
* \param[in] media Client media specification.
* \param[in] length Length to convert.
* \param[in] unit Current unit of length.
* \return A length in CSS pixels.
*/
css_fixed css_unit_len2px_mq(
const css_media *media,
const css_fixed length,
const css_unit unit);
/**
* Convert relative font size units to absolute units.
*
* \param[in] ctx Length unit conversion context.
* \param[in,out] size The length to convert.
* \return CSS_OK on success, or appropriate error otherwise.
*/
css_error css_unit_compute_absolute_font_size(
const css_unit_len_ctx *ctx,
css_hint *size);
#endif
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