Hi, When a GdkPixmap is created with gdk_pixmap_new(), its content seems tobe undefined, but GDK's documention [1] says nothing about it. According to Xlib − C Language X Interface [2], in 5.1. Creating andFreeing Pixmaps, "The initial contents of the pixmap are undefined." GDK's documentation should specify this. Now questions: - how to draw a RGBA GdkPixbuf in this GdkPixmap, discarding theprevious content of the GdkPixmap, e.g. gdk_draw_pixbuf() seems tocompose the GdkPixbuf's content with the GdkPixmap's content, creatingsome image corruption. - if not possible, how to clear GdkPixmap's content with a black, fullytransparent content ? - without using cairo, if possible, would be better. Thanks. [1]http://library.gnome.org/devel/gdk/stable/gdk-Bitmaps-and-Pixmaps.html#gdk-pixmap-new[2] http://www.x.org/docs/X11/xlib.pdf Here is a little program which create a pixmap, convert it in GdkPixbufand dump its content to the terminal. --------------8<----------------- #include <gtk/gtk.h>#include <gdk/gdk.h>#include <gdk/gdkx.h> #include <gdk-pixbuf/gdk-pixbuf.h> intmain(int argc, char *argv[]){ GdkColormap *colormap; GdkPixmap *pixmap; GdkPixbuf *pixbuf; unsigned char *p; guint x; guint y; guint n; gtk_init (&argc, &argv); colormap = gdk_screen_get_rgba_colormap(gdk_screen_get_default()); if (colormap == NULL) { g_printerr("no ARGB colormap\n"); return 1; } gtk_widget_set_default_colormap(colormap); pixmap = gdk_pixmap_new(NULL, 16, 16, 32); pixbuf = gdk_pixbuf_get_from_drawable(NULL, pixmap, colormap, 0, 0, 0, 0, 16, 16); n = gdk_pixbuf_get_n_channels(pixbuf); if (n < 3 || n > 4) { g_printerr("Invalid pixbuf format\n"); return 1; } if (gdk_pixbuf_get_bits_per_sample(pixbuf) != 8) { g_printerr("not 8bits per component\n"); return 1; } if (gdk_pixbuf_get_has_alpha(pixbuf) == TRUE) { g_print("pixbuf has alpha !\n"); } p = gdk_pixbuf_get_pixels(pixbuf); for(y = 0; y < gdk_pixbuf_get_height(pixbuf); y ++) { for(x = 0; x < gdk_pixbuf_get_width(pixbuf); x++) { printf("(%d,%d) ", x,y); switch(n) { case 4: g_print("%02x %02x %02x %02x\n", p[x * 4], p[x * 4 + 1], p[x * 4 + 2], p[x * 4 + 3]); break; case 3: g_print("%02x %02x %02x\n", p[x * 3], p[x * 3 + 1], p[x * 3 + 2]); break; } } g_print("\n"); p += gdk_pixbuf_get_rowstride(pixbuf); } return 0;} -- Yann Droneaud <ydroneaud@xxxxxxxxxxxx> _______________________________________________gtk-list mailing listgtk-list@xxxxxxxxxxxxx://mail.gnome.org/mailman/listinfo/gtk-list
