Re: [E-devel] Re: Problem with Imlib2 and Alpha TIFs

[Simon Wistow]

On Wed, Nov 30, 2005 at 09:20:50AM -0600, Nathan Ingersoll said:
> If you draw a white rect on the destination image before copying the source
> image, does it still have the same effect?

No. With this snippet 

      imlib_context_set_image(image);
      // imlib_image_set_has_alpha(0);
      int w = imlib_image_get_width();
      int h = imlib_image_get_height();

      Imlib_Image buffer = imlib_create_image(w, h);
      imlib_context_set_color(255, 255, 255, 255);
      imlib_context_set_image(buffer);
      imlib_image_fill_rectangle(0, 0, w, h);
      imlib_blend_image_onto_image(image, 0, 0, 0, w, h, 0, 0, w, h);
      imlib_context_set_image(image);
      imlib_free_image();
      imlib_context_set_image(buffer);



I get the attached image :/

I'm convinced I'm doing something wrong but for the life of me I can't 
spot it.

I've attached my sample program as well just in case anybody else can 
see what horrendous errors I'm perpetrating. Apologies for the C++-isms.

Simon

<<attachment: alpha_white.jpg>>

/* standard headers */
#include <X11/Xlib.h>
#include <Imlib2.h>
#include <stdio.h>
#include <string.h>

/* main program */
int main(int argc, char **argv)
{
  /* an image handle */
  Imlib_Image image;
  
  /* if we provided < 2 arguments after the command - exit */
  if (argc != 3) {
      fprintf(stderr,"Usage: imlib2convert <input image> <output image>\n");
      exit(1);
  }
  /* load the image */
  image = imlib_load_image(argv[1]);
  /* if the load was successful */
  if (image)
    {
      char *tmp;
      /* set the image we loaded as the current context image to work on */
      imlib_context_set_image(image);
      /* imlib_image_set_has_alpha(0); */
      int w = imlib_image_get_width();
      int h = imlib_image_get_height();

      Imlib_Image buffer = imlib_create_image(w, h);
      imlib_context_set_color(255, 255, 255, 255);
      imlib_context_set_image(buffer);
      imlib_image_fill_rectangle(0, 0, w, h);
      imlib_blend_image_onto_image(image, 0, 0, 0, w, h, 0, 0, w, h);
      imlib_context_set_image(image);
      imlib_free_image();
      imlib_context_set_image(buffer);


      /* Failed attempt at manually setting alpha
      DATA32 * data = imlib_image_get_data();    
      int x, y;
      for (x=0; x<w; x++) {
      for (y=0; y<h; y++) {
          *data |= (255 << 24);
           data++;
          }
      }
      */
      /* set the image format to be the format of the extension of our last */
      /* argument - i.e. .png = png, .tif = tiff etc. */
      tmp = strrchr(argv[2], '.');
      if(tmp)
         imlib_image_set_format(tmp + 1);
      /* save the image */
      imlib_save_image(argv[2]);
      imlib_free_image();
    } else {
        fprintf(stderr,"Couldn't load image %s\n", argv[1]);
    }

    return 0;
}