diff options
Diffstat (limited to 'src/select/unit.h')
| -rw-r--r-- | src/select/unit.h | 169 |
1 files changed, 169 insertions, 0 deletions
diff --git a/src/select/unit.h b/src/select/unit.h new file mode 100644 index 0000000..738c181 --- /dev/null +++ b/src/select/unit.h @@ -0,0 +1,169 @@ +/* + * 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 |