Attachment 39016 Details for Bug 30429 – Example of AA problem when copying PDF to Image

Example of AA problem when copying PDF to Image

simple_copy.c (text/plain), 2.25 KB, created by Ian Britten on 2010-09-28 09:18:17 UTC

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Creator: Ian Britten

Created: 2010-09-28 09:18:17 UTC

Size: 2.25 KB

patch

obsolete

>#include <cairo/cairo.h>
>#include <cairo/cairo-pdf.h>
>
>#include <math.h>
>
>// Draw some data to a PDF surface, then copy it to an image surface for
>// rasterization.  The output should be non-AA'd (But it is...)
>//
>// Build with:
>// gcc -g `pkg-config --cflags --libs cairo` simple_copy.c
>int main(int argc, char *argv[])
>{
>        // Make a PDF surface
>        const char fileName[] = "source.pdf";
>        const int width = 1000;
>        const int height = 1000;
>        cairo_surface_t *pdfSurface = cairo_pdf_surface_create(
>                        fileName, width, height);
>        cairo_t *pdfContext = cairo_create(pdfSurface);
>
>        // Uncomment this to achieve non-AA'd output.  But why?
>        // Why do you have to set this on the PDF surface, *before*
>        // drawing anything?  AA should only be being done during
>        // the copy/rasterization (below).
>/*         cairo_set_antialias(pdfContext, CAIRO_ANTIALIAS_NONE); */
>
>        // Draw some circles
>        {
>                cairo_set_source_rgba(pdfContext, 0.0, 1.0, 0.0, 1);
>                const double ang1 = 0;
>                const double ang2 = 360 * M_PI/180.0;
>                const double cenX = width / 2.0;
>                const double cenY = height / 2.0;
>                int i;
>                for (i=50; i<=700; i+=50)
>                {
>                        cairo_arc(pdfContext, cenX, cenY, i, ang1, ang2);
>                        cairo_stroke(pdfContext);
>                }
>        }
>
>        // Make the image surface
>        cairo_surface_t *imgSurface = cairo_image_surface_create(
>                CAIRO_FORMAT_RGB24, width, height);
>        cairo_t *imgContext = cairo_create(imgSurface);
>
>        // This is where I'd expect to turn off AA, to get non-AA'd output.
>        // However, this seems to have no effect.
>        cairo_set_antialias(imgContext, CAIRO_ANTIALIAS_NONE);
>
>        // Copy the PDF to the image
>        cairo_set_source_surface(imgContext, pdfSurface, 0, 0);
>        cairo_paint(imgContext);
>
>        cairo_surface_write_to_png(imgSurface, "output.png");
>        cairo_destroy(imgContext);
>        cairo_destroy(pdfContext);
>        cairo_surface_destroy(imgSurface);
>        cairo_surface_destroy(pdfSurface);
>
>        cairo_debug_reset_static_data(); // Valgrind
>
>        return 0;
>}

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