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

struct stateStruct {
    gboolean havePoints;
    gboolean drawing;
    gint x;
    gint y;
    GdkGC *lineGC;
};

gint eventDelete(GtkWidget *widget,
        GdkEvent *event,gpointer data);
gint eventDestroy(GtkWidget *widget,
        GdkEvent *event,gpointer data);
gboolean canvasEvent(GtkWidget *widget,
        GdkEvent *event,struct stateStruct *state);

#define WIDTH 400
#define HEIGHT 300
#define INTERVAL 30
#define RADIUS 20

int main(int argc,char *argv[])
{
    GtkWidget *app;
    GtkWidget *canvas;
    struct stateStruct state;

    gnome_init("mousefollow","1.0",argc,argv);
    app = gnome_app_new("mousefollow",
            "Following Mouse Events");
    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_app_set_contents(GNOME_APP(app),canvas);
    gtk_signal_connect(GTK_OBJECT(canvas),"event",
            GTK_SIGNAL_FUNC(canvasEvent),&state);

    gtk_widget_show_all(app);
    gtk_main();
    exit(0);
}
gboolean canvasEvent(GtkWidget *widget,
        GdkEvent *event,struct stateStruct *state) {
    GdkColor color;
    GdkEventMotion *eventMotion;
    GdkEventCrossing *eventCrossing;
    GdkEventButton *eventButton;
    GdkEventExpose *eventExpose;

    static gint counter = 1;
    static GdkColormap *colormap;

    switch(event->type) {
    case GDK_MAP:
        g_print("%4d MAP\n",counter++);
        colormap = gdk_colormap_get_system();
        state->lineGC = gdk_gc_new(widget->window);
        state->havePoints = FALSE;
        state->drawing = FALSE;
        break;
    case GDK_ENTER_NOTIFY:
        g_print("%4d ENTER_NOTIFY\n",counter++);
        eventCrossing = (GdkEventCrossing *)event;
        state->x = eventCrossing->x;
        state->y = eventCrossing->y;
        state->havePoints = TRUE;
        break;
    case GDK_LEAVE_NOTIFY:
        g_print("%4d LEAVE_NOTIFY\n",counter++);
        break;
    case GDK_BUTTON_PRESS:
        g_print("%4d BUTTON_PRESS\n",counter++);
        eventButton = (GdkEventButton *)event;
        if(eventButton->button == 1) {
            state->x = eventButton->x;
            state->y = eventButton->y;
            state->havePoints = TRUE;
            state->drawing = TRUE;
        } else if(eventButton->button == 3) {
            color.red=(((double)rand()*0xFFFF)/RAND_MAX);
            color.green=(((double)rand()*0xFFFF)/RAND_MAX);
            color.blue=(((double)rand()*0xFFFF)/RAND_MAX);
            gdk_color_alloc(colormap,&color);
            gdk_gc_set_foreground(state->lineGC,&color);
        }
        break;
    case GDK_BUTTON_RELEASE:
        g_print("%4d BUTTON_RELEASE\n",counter++);
        eventButton = (GdkEventButton *)event;
        if(eventButton->button == 1) {
            state->drawing = FALSE;
            state->havePoints = FALSE;
        }
        break;
    case GDK_2BUTTON_PRESS:
        g_print("%4d 2BUTTON_PRESS\n",counter++);
        eventButton = (GdkEventButton *)event;
        if(eventButton->button == 1) {
            gdk_draw_arc(eventButton->window,state->lineGC,
                    TRUE,
                    eventButton->x - RADIUS,
                    eventButton->y - RADIUS,
                    2 * RADIUS,2 * RADIUS,
                    0,360*64);
        }
        break;
    case GDK_3BUTTON_PRESS:
        g_print("%4d 2BUTTON_PRESS\n",counter++);
        eventButton = (GdkEventButton *)event;
        if(eventButton->button == 2)
            exit(0);
        break;
    case GDK_MOTION_NOTIFY:
        g_print("%4d MOTION_NOTIFY\n",counter++);
        eventMotion = (GdkEventMotion *)event;
        if(state->havePoints && state->drawing) {
            gdk_draw_line(eventMotion->window,
                state->lineGC,
                state->x,state->y,
                (gint)(eventMotion->x),
                (gint)(eventMotion->y));
        }
        state->x = (gint)(eventMotion->x);
        state->y = (gint)(eventMotion->y);
        state->havePoints = TRUE;
        break;
    case GDK_EXPOSE:
        eventExpose = (GdkEventExpose *)event;
        g_print("%4d EXPOSE\n",counter++);
        state->drawing = FALSE;
        state->havePoints = FALSE;
        gdk_window_clear(eventExpose->window);
        break;
    default:
        g_print("%4d Other: %d\n",counter++,event->type);
        break;
    }
    return(TRUE);
}
gint eventDelete(GtkWidget *widget,
        GdkEvent *event,gpointer data) {
    return(FALSE);
}
gint eventDestroy(GtkWidget *widget,
        GdkEvent *event,gpointer data) {
    gtk_main_quit();
    return(0);
}