1 files changed, 118 insertions, 0 deletions
diff --git a/render.c b/render.c
new file mode 100644
index 0000000..fdc2f0c
--- /dev/null
+++ b/render.c
@@ -0,0 +1,118 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+
+#include <string.h>
+
+static uint8_t
+unpremultiply(double colour, double alpha)
+{
+	if (colour <= 0.04045)
+		colour = colour / 12.92;
+	else
+		colour = pow((colour + 0.055) / 1.055, 2.4);
+
+	colour /= alpha;
+
+	if (colour <= 0.0031308)
+		colour = 12.92 * colour;
+	else
+		colour = fma(1.055, pow(colour, 1.0 / 2.4), -0.055);
+
+	colour = fma(255.0, colour, 0.5);
+	if (colour <= 0.0)
+		return 0u;
+	if (colour >= 255.0)
+		return 255u;
+	return (uint8_t)colour;
+}
+
+GdkPixbuf *
+rasterise(RsvgHandle *vector, int width, int height)
+{
+	RsvgRectangle viewport = {0.0, 0.0, width, height};
+	cairo_surface_t *surface = NULL;
+	cairo_t *cr = NULL;
+	GdkPixbuf *image;
+	int x, y, sstride, dstride;
+	const uint8_t *s, *sy;
+	uint8_t *d, *dy;
+	double a, r, g, b;
+	uint32_t pixel;
+
+	surface = cairo_image_surface_create(CAIRO_FORMAT_ARGB32, width, height);
+	if (cairo_surface_status(surface) != CAIRO_STATUS_SUCCESS)
+		goto fail;
+
+	cr = cairo_create(surface);
+	if (cairo_status(cr) != CAIRO_STATUS_SUCCESS)
+		goto fail;
+
+	cairo_set_operator(cr, CAIRO_OPERATOR_SOURCE);
+	cairo_set_source_rgba(cr, 0.0, 0.0, 0.0, 0.0);
+	cairo_paint(cr);
+	cairo_set_operator(cr, CAIRO_OPERATOR_OVER);
+	if (!rsvg_handle_render_document(vector, cr, &viewport, NULL))
+		goto fail;
+	cairo_destroy(cr);
+	cr = NULL;
+
+	image = gdk_pixbuf_new(GDK_COLORSPACE_RGB, 1, 8, width, height);
+	if (!image)
+		goto fail;
+
+	/* TODO accelerate */
+	cairo_surface_flush(surface);
+	sy = s = cairo_image_surface_get_data(surface);
+	dy = d = gdk_pixbuf_get_pixels(image);
+	sstride = cairo_image_surface_get_stride(surface);
+	dstride = gdk_pixbuf_get_rowstride(image);
+	for (y = 0; y < height; y++, sy = s = &s[sstride], dy = d = &d[dstride]) {
+		for (x = 0; x < width; x++, sy = &sy[4u], dy = &dy[4u]) {
+			memcpy(&pixel, sy, 4u);
+			if ((uint8_t)(pixel >> 24)) {
+				a = (double)(uint8_t)(pixel >> 24) / 255.0;
+				r = (double)(uint8_t)(pixel >> 16) / 255.0;
+				g = (double)(uint8_t)(pixel >> 8) / 255.0;
+				b = (double)(uint8_t)(pixel >> 0) / 255.0;
+				dy[0] = unpremultiply(r, a);
+				dy[1] = unpremultiply(g, a);
+				dy[2] = unpremultiply(b, a);
+				dy[3] = (uint8_t)(pixel >> 24);
+			} else {
+				dy[0] = dy[1] = dy[2] = dy[3] = 0u;
+			}
+		}
+	}
+
+	cairo_surface_destroy(surface);
+	return image;
+
+fail:
+	if (cr)
+		cairo_destroy(cr);
+	if (surface)
+		cairo_surface_destroy(surface);
+	return NULL;
+}
+
+void
+paint_image(cairo_t *cr, struct image *image)
+{
+	RsvgRectangle viewport = {0.0, 0.0, image->width, image->height};
+	int rendered;
+
+	if (image->vector) {
+		cairo_save(cr);
+		if (image->has_transformer)
+			cairo_transform(cr, &image->transformer);
+		rendered = rsvg_handle_render_document(image->vector, cr, &viewport, NULL);
+		cairo_restore(cr);
+		if (rendered)
+			return;
+	}
+
+	if (image->raster) {
+		gdk_cairo_set_source_pixbuf(cr, image->raster, 0.0, 0.0);
+		cairo_paint(cr);
+	}
+}