En utilisant GTK / GDK pour obtenir Pango-rendus pixels
Question
Je suis en train d'obtenir un bitmap rendu par Pango avec un caractère donné, dans ce cas, la lettre « T ». Je pensais que cela devrait fonctionner, mais il se contente d'afficher des ordures ..
Dans ce code, gtk_window
est déjà initialisé comme une fenêtre GTK.
int width, height;
PangoLayout *layout = gtk_widget_create_pango_layout(gtk_window, "T");
PangoFontDescription *fontdesc = pango_font_description_from_string("Terminus 12");
pango_layout_set_font_description (layout, fontdesc);
pango_layout_get_pixel_size (layout, &width, &height);
GdkPixmap *temp_pixmap = gdk_pixmap_new(NULL, width, height, 24) ;
GdkGC *gc = gdk_gc_new(temp_pixmap);
gdk_draw_layout( temp_pixmap, gc, 0, 0, layout) ;
GdkColormap *cmap = gdk_colormap_get_system() ;
GdkPixbuf *temp_pixbuf = gdk_pixbuf_get_from_drawable(NULL, temp_pixmap,
cmap, 0, 0, 0, 0, width, height);
int n_channels = gdk_pixbuf_get_n_channels (temp_pixbuf);
int rowstride = gdk_pixbuf_get_rowstride(temp_pixbuf);
guchar *pixels = gdk_pixbuf_get_pixels(temp_pixbuf);
int i,j;
for (j=0; j<height; j++) {
for (i=0; i<(width*n_channels); i++) {
printf("%02x ",
*(pixels + i + j*rowstride));
}
printf("\n");
}
La sortie est différent à chaque fois, mais un exemple:
dd 24 f8 dd 24 f8 8f 28 28 8f 28 28 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 fc 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ef 14 ce 00 00 00 d0 00 20 00 00 00 ef 02 02 d0 00 01 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 fc 00 00 00 00 00 ef 02 02 00 03 40 00 00 b9 00 00 c8
00 00 01 00 00 07 00 00 07 00 00 00 00 00 02 00 00 00 00 00 d0 00 00 c8
00 00 01 00 00 00 00 00 03 00 00 00 00 00 00 00 00 00 00 00 04 00 00 00
00 00 04 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 0e 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 12 ff ff ff 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 7a 4e 00 00 00 01 00 00 00 00 00 00 00 00 00 01 ff ff ff ff ff ff
ff ff ff 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
Ce qui ne ressemble en rien à la lettre "T"!
Toute idée de ce que je fais mal? Merci!
La solution
D'accord, je compris. Je avais besoin de régler correctement les couleurs, et nettoyer la zone avant de tirer à l'aide gdk_draw_rectangle
:
PangoLayout *layout = gtk_widget_create_pango_layout(me->gtk_window, "T");
int width, height;
PangoFontDescription *fontdesc = pango_font_description_from_string("Sans 10");
pango_layout_set_font_description (layout, fontdesc);
pango_layout_get_pixel_size (layout, &width, &height);
GdkPixmap *temp_pixmap = gdk_pixmap_new(NULL, width, height, 24);
GdkGC *gc = gdk_gc_new(temp_pixmap);
GdkColor white = {0,0xFF00,0xFF00,0xFF00};
GdkColor black = {0,0,0,0};
GdkColormap *cmap = gdk_gc_get_colormap(gc);
gdk_gc_set_rgb_fg_color(gc, &black);
gdk_gc_set_rgb_bg_color(gc, &white);
gdk_draw_rectangle(temp_pixmap, gc, TRUE, 0, 0, width, height);
gdk_gc_set_rgb_fg_color(gc, &white);
gdk_gc_set_rgb_bg_color(gc, &black);
gdk_draw_layout(temp_pixmap, gc, 0, 0, layout);
GdkPixbuf *temp_pixbuf = gdk_pixbuf_get_from_drawable(NULL, temp_pixmap,
cmap, 0, 0, 0, 0, width, height);
int n_channels = gdk_pixbuf_get_n_channels (temp_pixbuf);
int rowstride = gdk_pixbuf_get_rowstride(temp_pixbuf);
guchar *pixels = gdk_pixbuf_get_pixels(temp_pixbuf);
int i,j;
for (j=0; j<height; j++) {
for (i=0; i<(width*n_channels); i++) {
printf("%02x ",
*(pixels + i + j*rowstride));
}
printf("\n");
}
me donne:
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
c5 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff e3
25 30 33 33 33 33 33 33 3d 68 ba f6 ff d8 86 4a 35 33 33 33 33 33 31 2a
00 00 00 00 00 00 00 00 0c 41 a7 f1 fe cc 66 1c 03 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 0c 41 a7 f1 fe cc 66 1c 03 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 0c 41 a7 f1 fe cc 66 1c 03 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 0c 41 a7 f1 fe cc 66 1c 03 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 0c 41 a7 f1 fe cc 66 1c 03 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 0c 41 a7 f1 fe cc 66 1c 03 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 0c 41 a7 f1 fe cc 66 1c 03 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 0c 41 a7 f1 fe cc 66 1c 03 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
Autres conseils
Juste quelques conseils de base, ont pas essayé votre code:
- Vous ne mentionnez pas de contrôle d'erreur; vous devriez passer et voir que tous les différents GTK + / GDK appelle succeeed. Ils devraient tous faire NULL vérification sur les entrées et émettent des avertissements, mais quand même.
- Vous imprimez tous les canaux en même temps, qui peut conduire à un disque à interpréter visuellement l'image. J'ai essayé filtrer deux des canaux dans vos données, mais cela n'a pas aidé. Bien sûr, puisque vous dites que la sortie est différent à chaque fois, ce fut un long shot.
- Je ne suis pas sûr de la synchronicité des appels de dessin GDK, s'ils sont garantis pour arriver immédiatement, puis revenir, ou si elles peuvent être reportées à plus tard certains gestionnaire « mettre à jour les zones sales ».
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