sway/common/pango.c

#include <cairo.h>
#include <pango/pangocairo.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "cairo_util.h"
#include "log.h"
#include "stringop.h"

size_t escape_markup_text(const char *src, char *dest) {
	size_t length = 0;
	if (dest) {
		dest[0] = '\0';
	}

	while (src[0]) {
		switch (src[0]) {
		case '&':
			length += 5;
			lenient_strcat(dest, "&amp;");
			break;
		case '<':
			length += 4;
			lenient_strcat(dest, "&lt;");
			break;
		case '>':
			length += 4;
			lenient_strcat(dest, "&gt;");
			break;
		case '\'':
			length += 6;
			lenient_strcat(dest, "&apos;");
			break;
		case '"':
			length += 6;
			lenient_strcat(dest, "&quot;");
			break;
		default:
			if (dest) {
				dest[length] = *src;
				dest[length + 1] = '\0';
			}
			length += 1;
		}
		src++;
	}
	return length;
}

PangoLayout *get_pango_layout(cairo_t *cairo, const PangoFontDescription *desc,
		const char *text, double scale, bool markup) {
	PangoLayout *layout = pango_cairo_create_layout(cairo);
	PangoAttrList *attrs;
	if (markup) {
		char *buf;
		GError *error = NULL;
		if (pango_parse_markup(text, -1, 0, &attrs, &buf, NULL, &error)) {
			pango_layout_set_text(layout, buf, -1);
			free(buf);
		} else {
			sway_log(SWAY_ERROR, "pango_parse_markup '%s' -> error %s", text,
					error->message);
			g_error_free(error);
			markup = false; // fallback to plain text
		}
	}
	if (!markup) {
		attrs = pango_attr_list_new();
		pango_layout_set_text(layout, text, -1);
	}

	pango_attr_list_insert(attrs, pango_attr_scale_new(scale));
	pango_layout_set_font_description(layout, desc);
	pango_layout_set_single_paragraph_mode(layout, 1);
	pango_layout_set_attributes(layout, attrs);
	pango_attr_list_unref(attrs);
	return layout;
}

void get_text_size(cairo_t *cairo, const PangoFontDescription *desc, int *width, int *height,
		int *baseline, double scale, bool markup, const char *fmt, ...) {
	va_list args;
	va_start(args, fmt);
	// Add one since vsnprintf excludes null terminator.
	int length = vsnprintf(NULL, 0, fmt, args) + 1;
	va_end(args);

	char *buf = malloc(length);
	if (buf == NULL) {
		sway_log(SWAY_ERROR, "Failed to allocate memory");
		return;
	}
	va_start(args, fmt);
	vsnprintf(buf, length, fmt, args);
	va_end(args);

	PangoLayout *layout = get_pango_layout(cairo, desc, buf, scale, markup);
	pango_cairo_update_layout(cairo, layout);
	pango_layout_get_pixel_size(layout, width, height);
	if (baseline) {
		*baseline = pango_layout_get_baseline(layout) / PANGO_SCALE;
	}
	g_object_unref(layout);
	free(buf);
}

void get_text_metrics(const PangoFontDescription *description, int *height, int *baseline) {
	cairo_t *cairo = cairo_create(NULL);
	PangoContext *pango = pango_cairo_create_context(cairo);
	// When passing NULL as a language, pango uses the current locale.
	PangoFontMetrics *metrics = pango_context_get_metrics(pango, description, NULL);

	*baseline = pango_font_metrics_get_ascent(metrics) / PANGO_SCALE;
	*height = *baseline + pango_font_metrics_get_descent(metrics) / PANGO_SCALE;

	pango_font_metrics_unref(metrics);
	g_object_unref(pango);
	cairo_destroy(cairo);
}

void render_text(cairo_t *cairo, const PangoFontDescription *desc,
		double scale, bool markup, const char *fmt, ...) {
	va_list args;
	va_start(args, fmt);
	// Add one since vsnprintf excludes null terminator.
	int length = vsnprintf(NULL, 0, fmt, args) + 1;
	va_end(args);

	char *buf = malloc(length);
	if (buf == NULL) {
		sway_log(SWAY_ERROR, "Failed to allocate memory");
		return;
	}
	va_start(args, fmt);
	vsnprintf(buf, length, fmt, args);
	va_end(args);

	PangoLayout *layout = get_pango_layout(cairo, desc, buf, scale, markup);
	cairo_font_options_t *fo = cairo_font_options_create();
	cairo_get_font_options(cairo, fo);
	pango_cairo_context_set_font_options(pango_layout_get_context(layout), fo);
	cairo_font_options_destroy(fo);
	pango_cairo_update_layout(cairo, layout);
	pango_cairo_show_layout(cairo, layout);
	g_object_unref(layout);
	free(buf);
}