Selection: Remove client callback for unit conversion.

Now clients provide a unit conversion context and libcss provides
code to perform unit conversion.

This reduces the amount of common code that clients have to write.

3 files changed, 160 insertions, 7 deletions

diff --git a/include/libcss/computed.h b/include/libcss/computed.h
index f4b3e21..1587d78 100644
--- a/include/libcss/computed.h
+++ b/include/libcss/computed.h
@@ -19,6 +19,7 @@ extern "C"
 #include <libcss/functypes.h>
 #include <libcss/properties.h>
 #include <libcss/types.h>
+#include <libcss/unit.h>
 
 struct css_hint;
 struct css_select_handler;
@@ -81,10 +82,7 @@ css_error css_computed_style_destroy(css_computed_style *style);
 css_error css_computed_style_compose(
 		const css_computed_style *restrict parent,
 		const css_computed_style *restrict child,
-		css_error (*compute_font_size)(void *pw,
-				const struct css_hint *parent,
-				struct css_hint *size),
-		void *pw,
+		const css_unit_len_ctx *unit_len_ctx,
 		css_computed_style **restrict result);
 
 /******************************************************************************
diff --git a/include/libcss/select.h b/include/libcss/select.h
index ca57456..bfaf531 100644
--- a/include/libcss/select.h
+++ b/include/libcss/select.h
@@ -18,6 +18,7 @@ extern "C"
 #include <libcss/hint.h>
 #include <libcss/types.h>
 #include <libcss/computed.h>
+#include <libcss/unit.h>
 
 typedef enum css_pseudo_element {
 	CSS_PSEUDO_ELEMENT_NONE         = 0,
@@ -123,9 +124,6 @@ typedef struct css_select_handler {
 	css_error (*ua_default_for_property)(void *pw, uint32_t property,
 			css_hint *hint);
 
-	css_error (*compute_font_size)(void *pw, const css_hint *parent,
-			css_hint *size);
-
 	/**
 	 * Set libcss_node_data on a DOM node.
 	 *
@@ -221,6 +219,7 @@ css_error css_select_default_style(css_select_ctx *ctx,
 		css_select_handler *handler, void *pw,
 		css_computed_style **style);
 css_error css_select_style(css_select_ctx *ctx, void *node,
+		const css_unit_len_ctx *unit_len_ctx,
 		const css_media *media, const css_stylesheet *inline_style,
 		css_select_handler *handler, void *pw,
 		css_select_results **result);
diff --git a/include/libcss/unit.h b/include/libcss/unit.h
new file mode 100644
index 0000000..a847077
--- /dev/null
+++ b/include/libcss/unit.h
@@ -0,0 +1,156 @@
+/*
+ * 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_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;
+	/**
+	 * 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_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]  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_len_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_len_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_len_ctx *ctx,
+		const css_fixed length,
+		const css_unit unit);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+