[cairo] Recording surfaces fail to replay onto SVG surfaces

[Antonio Ospite]

On Thu, 5 Oct 2017 20:54:53 +1030
ajohnson at redneon.com (Adrian Johnson) wrote:

> I've pushed a fix for painting unbounded recordings to the SVG surface.
>

Hi

I too experienced a similar problem recently.

The changes in 5a9dba9929d9 seem to fix the original test case of
replaying to an SVG surface, but only for the first time: I noticed that
replaying a second time still fails, producing an empty SVG.

BTW, these seems to be regressions as 1.14.10 works fine in both cases.

I also noticed that the generated files look a little different when
using the current master: groups and links are used for the replayed
surfaces, while with 1.14.10 the replayed elements are drawn ungrouped,
I don't know if the regression is related to this change.

I can bisect if necessary.

See the following test program, it works as (I think) it should with
1.14.10, but not with the current master (d5b634da6159):

----------------------------------------------------------------------
#include <stdio.h>
#include <cairo/cairo.h>
#include <cairo/cairo-svg.h>

#ifndef M_PI
#define M_PI 3.14159265358979323846
#endif

static void save_as_svg(cairo_surface_t *surface, double width, double height, const char *filename)
{
	cairo_surface_t *output;
	cairo_t *ctx;

	output = cairo_svg_surface_create(filename, width, height);

	ctx = cairo_create(output);

	cairo_set_source_surface(ctx, surface, 0.0, 0.0);
	cairo_paint(ctx);

	cairo_destroy(ctx);
	cairo_surface_destroy(output);
}

static void save_as_png(cairo_surface_t *surface, double width, double height, const char *filename)
{
	cairo_surface_t *output;
	cairo_t *ctx;

	output = cairo_image_surface_create(CAIRO_FORMAT_ARGB32, width, height);
	ctx = cairo_create(output);

	cairo_set_source_surface(ctx, surface, 0.0, 0.0);
	cairo_paint(ctx);
	cairo_surface_write_to_png(output, filename);

	cairo_destroy(ctx);
	cairo_surface_destroy(output);
}

int main(void)
{
	cairo_surface_t *surface;
	cairo_t *ctx;
	double x;
	double y;
	double width;
	double height;

	surface = cairo_recording_surface_create(CAIRO_CONTENT_COLOR_ALPHA, NULL);

	ctx = cairo_create(surface);

	cairo_rectangle(ctx, 0.0, 0.0, 300, 300);
	cairo_set_source_rgb(ctx, 0.3, 0.6, 0.8);
	cairo_fill(ctx);

	cairo_arc(ctx, 150, 150, 100, 0, 2 * M_PI);
	cairo_set_source_rgb(ctx, 1, 1, 1);
	cairo_stroke(ctx);

	cairo_destroy(ctx);

	cairo_recording_surface_ink_extents(surface, &x, &y, &width, &height);
	printf("recording surface ink extents: %f, %f, %f, %f\n", x, y, width, height);

	/* SVG output */
	save_as_svg(surface, width, height, "svg_first_time.svg");
	save_as_svg(surface, width, height, "svg_second_time.svg");

	/* PNG output for comparison */
	save_as_png(surface, width, height, "png_reference_output.png");

	cairo_surface_destroy(surface);
	return 0;
}
----------------------------------------------------------------------

Ciao,
   Antonio

-- 
Antonio Ospite
https://ao2.it
https://twitter.com/ao2it

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