基本动画不会触发

Question

I'm trying to follow this example to create an animation:

http://seriss.com/people/erco/fltk/#Animate

Except for the fact that instead of changing the image I'm moving it. There's a car image that should move in a down-right direction every half second, for 10 times:

void func(void* data)
{
    static int counter=0;
    counter++;
    Fl_PNG_Image* image= static_cast<Fl_PNG_Image*>(data);
    Fl_Box* box= new Fl_Box(counter*10, counter*10,100,100);
    box->image(image);
    //delete box;
    window->redraw();
    if(counter==10)
    {
        Fl::remove_timeout(func,data);
    }
    else
    {
        Fl::repeat_timeout(.5,func,data);
    }
}

int main(int argc, char **argv)
{
    window = new Fl_Double_Window(width, height);

    Fl_PNG_Image* image= new Fl_PNG_Image("car-down.png");
    Fl_Box* box= new Fl_Box(0,0,100,100);
    box->image(image);
    Fl::add_timeout(.5, func, image);
    //delete box;

    window->end();
    window->show(argc, argv);
    return Fl::run();
}

I have two problems:

1. I can't understand when I should delete the box. I'm using it to draw the image, and if I delete it immediately after having drawn the image, the image disappears.
2. The image doesn't move, and it always stays on the initial position.

Answer 1

Instead of creating new boxes and images, move the box. The box will be deleted when the window is closed

void func(void* data)
{
    static int counter=0;
    counter++;
    //Fl_PNG_Image* image= static_cast<Fl_PNG_Image*>(data);
    Fl_Box* box= static_cast<Fl_Box*) data;
    box->position(counter*10, counter*10);
    window->redraw();
    ...
}

int main(int argc, char **argv)
{
    ...

    Fl::add_timeout(.5, func, box);

    window->end();
    window->show(argc, argv);
    return Fl::run();
}