On Tue, 2005-11-29 at 15:07 +0000, Michael Noonan wrote:
> Hello,
>
> I'm new to using gtk and would really appreciate it if
> anybody could help me.
>
> I'm trying to display an image on the screen thats
> created from individual pixel information. I create
> the image and then set the indivisual pixels. Then I
> try to display the image but I keep getting errors
> when I try to execute.
>
> Am I going about this the wrong way! I've attached the
> code below.
>
> Thanks in advance.
> Mike
>
> #include <stdio.h>
> #include <gtk/gtk.h>
> #include <gdk/gdktypes.h>
> using namespace std;
this is C++, shouldn't be there
> int main( int argc, char *argv[])
> {
> GtkWidget *window;
> GtkWidget *canvas;
> GdkVisual *visual;
> GdkImage *image;
> GdkGC *gc;
>
> int i, j;
> unsigned char frame_data[128][64];
>
> window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
>
> gtk_widget_set_size_request(GTK_WIDGET(window), 1024,
> 768);
>
> g_signal_connect(G_OBJECT(window), "destroy",
> G_CALLBACK(gtk_main_quit), NULL);
>
> visual = gdk_visual_get_system();
> image = gdk_image_new( GDK_IMAGE_FASTEST, visual, 64,
> 128 );
>
> gc = gdk_gc_new( GTK_WIDGET( window )->window );
You should probably take the drawable (i.e. GdkWindow) from the drawing
area. Furthermore, you cannot create the GC just yet since window (or
canvas) doesn't have a GdkWindow until it is realised. What you need to
do is to create a global variable that contains the resources you need
and then create the GC when the signal "configure-event" is emitted and
store it in the global variable. You can also pass a heap-allocated
structure via the user_data parameter.
> canvas = gtk_drawing_area_new();
> gtk_container_add( GTK_CONTAINER( window ), canvas);
> gtk_widget_show(canvas);
>
> //set the individual pixels
> for( i = 0; i < 128; i++ )
> {
> for( j = 0; j < 64; j++ )
> {
> gdk_image_put_pixel( image, i, j, data[i][j] );
> }
> }
>
> gdk_draw_image( GTK_WIDGET( canvas )->window, gc,
> image, 0,0,0,0, 64, 128);
Same here. You need to connect to the "expose-event" signal (which also
gives you the area that needs to be redrawn). You need to store the data
in the global variable or in a heap-allocated region that you pass via
the user_data pointer.
Hope this helps,
Axel.
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