On 2007-03-09 17:53-0500 Raul Perez-alejo Neyra wrote:
>
> thanks to allan for forwarding my message to this mailing list, unfortunately
> we still have problems with the plplot mem driver. We want plplot to compose
> a graphic in memory and then pass it to another vector graphic library
> (cairo).
> In our testing it seems that plplot does not write in the defined buffer, the
> problem doesn't seems to be cairo because when we force the values of the
> buffer cairo outputs fine.
> we are using plplot-5.7.2 with xwin and mem drivers only.
>
> here is our test code.
> this example is an hybrid of some code found on sourceforge, and sent to us
> by Hazen.
> any help will be appreciated.
> gratings Raul.
>
>
>
> #include <plplot.h>
> #include <memory.h>
> #include <iostream>
> #include <cairo.h>
>
> using namespace std;
>
>
> int main(int argc, char **argv) {
>
> int width = 200;
> int height = 200;
>
> char *buffer;
> buffer = (char *)malloc(width * height * 3 * sizeof(char));
> for(int ii=0;ii<(width*height*3);ii++) { buffer[ii] = 0; }
>
> plsdev("mem");
> plsmem(width, height, buffer);
> plscolbg (255, 255, 255);
> plinit();
> plenv(0, 10.0, 0, 10.0, 0, 0);
> pljoin(1.0, 2.0, 7.0, 8.0);
> plend();
>
> cairo_surface_t *surface;
> unsigned char *cairo_buffer;
> cairo_buffer = (unsigned char *)malloc(width * height * 4 *
> sizeof(char));
>
> for (int i = 0, j = 0; i < (width * height * 3); i+=3)
> {
> cairo_buffer[j++] = buffer[i+2]; //blue
> cairo_buffer[j++] = buffer[i + 1]; //green
> cairo_buffer[j++] = buffer[i]; //red
> cairo_buffer[j++] = 0;
> }
>
> surface = cairo_image_surface_create_for_data
> (cairo_buffer,
> CAIRO_FORMAT_RGB24,
> width, height, 0);
>
> cairo_surface_write_to_png(surface, "plplot1.png");
> cairo_surface_destroy (surface);
> return 0;
> }
>
Raul, I am not really expert in this area, but I do know that plend closes
_everything_ having to do with plplot. I doubt it would also free the
buffer area, but just to be sure, I would suggest putting the plend call
after the cairo_surface_destroy call.
Alan
__________________________
Alan W. Irwin
Astronomical research affiliation with Department of Physics and Astronomy,
University of Victoria (astrowww.phys.uvic.ca).
Programming affiliations with the FreeEOS equation-of-state implementation
for stellar interiors (freeeos.sf.net); PLplot scientific plotting software
package (plplot.org); the Yorick front-end to PLplot (yplot.sf.net); the
Loads of Linux Links project (loll.sf.net); and the Linux Brochure Project
(lbproject.sf.net).
__________________________
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