/** canvasaffine.c **/
#include <gnome.h>

gint eventDelete(GtkWidget *widget,
        GdkEvent *event,gpointer data);
gint eventDestroy(GtkWidget *widget,
        GdkEvent *event,gpointer data);
GnomeCanvasPoints *makeOriginArrow(gint h,gint v);

#define HORIZ 30
#define VERT 30
#define WIDTH (HORIZ * 6)
#define HEIGHT (VERT * 6)

int main(int argc,char *argv[])
{
    GtkWidget *app;
    GtkWidget *canvas;
    GnomeCanvasGroup *rootGroup;
    GnomeCanvasItem *item;

    double affine[6];

    gnome_init("canvasaffine","1.0",argc,argv);
    app = gnome_app_new("canvasaffine",
            "Canvas Affine");
    gtk_signal_connect(GTK_OBJECT(app),"delete_event",
            GTK_SIGNAL_FUNC(eventDelete),NULL);
    gtk_signal_connect(GTK_OBJECT(app),"destroy",
            GTK_SIGNAL_FUNC(eventDestroy),NULL);

    canvas = gnome_canvas_new();
    gtk_widget_set_usize(canvas,WIDTH,HEIGHT);
    gnome_canvas_set_scroll_region(GNOME_CANVAS(canvas),
            -WIDTH/2,-HEIGHT/2,WIDTH/2,HEIGHT/2);
    rootGroup = gnome_canvas_root(GNOME_CANVAS(canvas));
    gnome_app_set_contents(GNOME_APP(app),canvas);


    item = gnome_canvas_item_new(rootGroup,
                gnome_canvas_polygon_get_type(),
                "points",makeOriginArrow(HORIZ,VERT),
                "fill_color","white",
                "outline_color","black",
                NULL);
    art_affine_scale(affine,1.3,1.3);
    gnome_canvas_item_affine_relative(item,affine);

    item = gnome_canvas_item_new(rootGroup,
                gnome_canvas_polygon_get_type(),
                "points",makeOriginArrow(HORIZ/2,VERT/2),
                "fill_color","black",
                "outline_color","white",
                NULL);
    art_affine_rotate(affine,45.0);
    gnome_canvas_item_affine_relative(item,affine);

    item = gnome_canvas_item_new(rootGroup,
                gnome_canvas_polygon_get_type(),
                "points",makeOriginArrow(HORIZ/2,VERT/2),
                "fill_color","green",
                "outline_color","black",
                NULL);
    art_affine_translate(affine,60,-50);
    gnome_canvas_item_affine_relative(item,affine);

    gtk_widget_show_all(app);
    gtk_main();
    exit(0);
}

GnomeCanvasPoints *makeOriginArrow(gint h,gint v)
{
    int i;
    GnomeCanvasPoints *points;
    static const gint xy[16] = {
        0,-2, -2,0, -1,0, -1,2, 1,2, 1,0, 2,0, 0,-2
    };

    points = gnome_canvas_points_new(8);
    for(i=0; i<16; i += 2) {
        points->coords[i] = (xy[i] * h);
        points->coords[i+1] = (xy[i+1] * v);
    }
    return(points);
}
gint eventDelete(GtkWidget *widget,
        GdkEvent *event,gpointer data) {
    return(FALSE);
}
gint eventDestroy(GtkWidget *widget,
        GdkEvent *event,gpointer data) {
    gtk_main_quit();
    return(0);
}