Subject:
Transparent pixmap
From:
####@####.####
Date:
24 Feb 2008 15:28:37 -0000
Message-Id: <20080224092834.magty7j5usckokgk@localhost>
Hello,
i want to copy the contents of a pixmap on to the screen. The pixmap
contains a gif with a transparent background (=> alpha = 0). When i
copy the pixmap to the screen the transparent background is visible. I
run nano-x for the Linux-X86 platform using the X11 library. When
drawing the gif directly to the screen the transparent background is,
correctly, not visisble. I attach a simple example which demonstrates
the problem. In the example i do not load the gif, instead i have two
pixmaps: one painted with red color (alpha = 0) and the other with
blue (alpha = 255). Still, the red is visible. I also tried the
SRCTRANSCOPY mode as arhument in the GrCopyArea, but i am not sure if
this mode of operation is actually implemented. Any help is greatly
appreciated.
-----------------------------------------------------------------------------
#include <stdio.h>
#include <stdlib.h>
#define MWINCLUDECOLORS
#include "nano-X.h"
int main(int argc, char **argv)
{
GR_WINDOW_ID pid1, pid2;
GR_GC_ID gc;
GR_EVENT event;
int width, height;
char c;
if( GrOpen() < 0 )
{
printf("cannot open graphics\n");
exit(1);
}
width = height = 100;
GrSelectEvents(GR_ROOT_WINDOW_ID, GR_EVENT_MASK_KEY_DOWN);
gc = GrNewGC();
pid1 = GrNewPixmap(width, height, NULL);
GrSetGCForeground(gc, MWARGB(0,255,0,0));
GrFillRect(pid1, gc, 0, 0, width, height);
pid2 = GrNewPixmap(width, height, NULL);
GrSetGCForeground(gc, MWARGB(255,0,0,255));
GrFillRect(pid2, gc, 0, 0, width, height);
GrCopyArea(GR_ROOT_WINDOW_ID, gc, 100, 100, width, height, pid2, 0,
0, MWMODE_COPY);
GrCopyArea(GR_ROOT_WINDOW_ID, gc, 150, 150, width, height, pid1, 0,
0, MWMODE_COPY);
while(1)
{
GrGetNextEvent(&event);
switch (event.type)
{
case GR_EVENT_TYPE_KEY_DOWN:
c = event.keystroke.ch;
if(c == 'q')
{
GrClose();
exit(0);
}
break;
default:
break;
}
}
}
--------------------------------------------------------------------------
Thanks in advance
