[cairo] Regarding saving a image surface as PNG

[Chandra Shekhar Sengupta]

Hi,

i have tried with following code

tsurf = cairo_get_target(cr);
cairo_surface_write_to_png (tsurf, "sticker.png");

but it is saving a zero Byte PNG. Could you tell me where to use
"cairo_get_target" api ?

Thanks in Advance.

Regards,
Chandra Shekhar Sengupta


On Wed, Apr 16, 2008 at 3:34 PM, Gerdus van Zyl <gerdusvanzyl at gmail.com>
wrote:

> Its because you are not working with the surface cr is targeting. You need
> code like
> tsurf = cairo_get_target(cr); to get the temporary surface GTK is giving
> you.
>
> ~Gerdus
>
> On Wed, Apr 16, 2008 at 8:11 AM, Chandra Shekhar Sengupta <
> sayan801 at gmail.com> wrote:
>
> > Hi,
> > I am new to cairo. i am trying to rotate and scale a image . After doing
> > the transformation i am displaying it in the window, it is shown properly .
> > But when i am saving the surface using "cairo_surface_write_to_png" , the
> > original image is saved again , the changes due to transformation is not
> > reflected. And when i was trying to get the width of scaled surface using
> > "cairo_image_surface_get_width", it is giving the original width only.My
> > code segment is given below.
> >
> > /////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
> >
> > static gboolean on_expose_event(GtkWidget *widget,GdkEventExpose *event,
> > gpointer data)
> > {
> >   cairo_t *cr;
> > gint width,height;
> >
> > cr = gdk_cairo_create (widget->window);
> >
> > width = cairo_image_surface_get_width(image);
> > height = cairo_image_surface_get_height(image);
> >
> >
> > cairo_translate(cr,width/2,height/2);
> >
> > cairo_scale(cr,scale_factor,scale_factor);
> >
> > cairo_rotate(cr,rotate_angle*M_PI/180.0);
> >
> >  g_print("rotate_angle %f \n",rotate_angle);
> >
> >
> > gtk_widget_set_size_request (da, width,height);
> >
> >  g_print("width = %d height = %d \n",width,height);
> >
> >  cairo_set_source_surface(cr, image,-width/2,-height/2);
> >
> >  cairo_paint(cr);
> >  cairo_surface_write_to_png (image, "sticker.png");
> >
> >   cairo_destroy(cr);
> >
> >   return FALSE;
> > }
> >
> >
> > int main(int argc, char *argv[])
> > {
> >   /...../
> >
> >   image = cairo_image_surface_create_from_png(argv[1]);
> >   width = cairo_image_surface_get_width(image);
> >   height = cairo_image_surface_get_height(image);
> >  g_print("width = %d height = %d \n",width,height);
> >
> > /...../
> >
> > da = gtk_drawing_area_new ();
> > gtk_widget_set_size_request (da, width,height);
> > gtk_fixed_put(GTK_FIXED(fixed),da,50,50);
> > g_signal_connect(da, "expose-event",G_CALLBACK (on_expose_event), NULL);
> >
> > /...../
> >
> > cairo_surface_destroy(image);
> >
> >   return 0;
> > }
> >
> > /////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
> >
> > Thanks in Advance.
> >
> > Regards,
> > Chandra Shekhar Sengupta
> >
> >
> > _______________________________________________
> > cairo mailing list
> > cairo at cairographics.org
> > http://lists.cairographics.org/mailman/listinfo/cairo
> >
>
>
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