[cairo] Recording surfaces fail to replay onto SVG surfaces

[Adrian Johnson]

Seems to be a bug with unbounded recording surfaces and SVG. As a
workaround if you specify an extents for the recording surface it works.


On 04/10/17 08:39, Antony Lee wrote:
> Hi all,
> 
> I am having an issue with replaying a recording surface onto an SVG
> surface.  A minimal example is included at the end of the email.
> 
> Briefly, the example sets up a recording surface and two 100x100
> surfaces -- one IMAGE and one SVG.  It then draws a 10x10 rectangle on
> each of them at position (10, 10) and saves the results (the IMAGE to a
> PNG).  Both resulting files display the box at the correct position.
> 
> The example then tries to replay the recording surface onto a separate
> 100x100 SVG surface, and also save that surface.  Unfortunately, this
> results in a blank SVG.  Note that if, instead, the recording surface is
> played onto a separate 100x100 IMAGE surface (code not included for
> simplicity), this works perfectly well (the resulting PNG also displays
> the box); so the basic setup of the recording surface seems correct.
> 
> I am using cairo 1.15.8 from Arch Linux.
> 
> Any help would be very welcome.  Thanks!
> 
> Antony Lee
> 
> 
> 
> === Example program; compile and run with:
>     gcc main.c $(pkg-config --cflags --libs cairo) -o main && ./main
> 
> #include <stddef.h>
> #include <cairo/cairo.h>
> #include <cairo/cairo-svg.h>
> 
> int main() {
>   cairo_surface_t* rec_surf =
> cairo_recording_surface_create(CAIRO_CONTENT_COLOR_ALPHA, NULL);
>   cairo_t* rec_ctx = cairo_create(rec_surf);
> 
>   cairo_surface_t* img_surf =
> cairo_image_surface_create(CAIRO_FORMAT_ARGB32, 100, 100);
>   cairo_t* img_ctx = cairo_create(img_surf);
> 
>   cairo_surface_t* svg_surf = cairo_svg_surface_create("/tmp/test.svg",
> 100, 100);
>   cairo_t* svg_ctx = cairo_create(svg_surf);
> 
>   cairo_t* ctxs[3] = {rec_ctx, img_ctx, svg_ctx};
> 
>   for (unsigned i = 0; i < 3; ++i) {
>     cairo_rectangle(ctxs[i], 10, 10, 10, 10);
>     cairo_fill(ctxs[i]);
>   }
> 
>   // Dump image to png.
>   cairo_surface_write_to_png(img_surf, "/tmp/test.png");
> 
>   // Transfer recording surface to SVG.
>   cairo_surface_t* svg1_surf =
> cairo_svg_surface_create("/tmp/test1.svg", 100, 100);
>   cairo_t* svg1_ctx = cairo_create(svg1_surf);
>   cairo_set_source_surface(svg1_ctx, rec_surf, 0, 0);
>   cairo_paint(svg1_ctx);
> 
>   // Done.
>   for (unsigned i = 0; i < 3; ++i) {
>     if (cairo_status(ctxs[i])) {
>       return 1;
>     }
>   }
>   cairo_surface_finish(svg_surf);
>   cairo_surface_finish(svg1_surf);
>   for (unsigned i = 0; i < 3; ++i) {
>     cairo_surface_destroy(cairo_get_target(ctxs[i]));
>     cairo_destroy(ctxs[i]);
>   }
>   cairo_surface_destroy(svg1_surf);
>   cairo_destroy(svg1_ctx);
> }
> 
>