Verena wrote:
> Hi there,
>
> I need some help with double buffering.
> I made my own fltk class, extending Widget, with a load of drawing code in
> the "draw()" method. The instance of this class gets redrawn many times a
> second, so I get some flickering, which I would like to get rid of.
> I noticed that there is a DoubleBufferWindow class, so that seems like the
> natural thing to use. But just using that as a superclass to my custom widget
> doesn't do the trick.
> What else do I need to do to get rid of the flickering? Is there some "swap
> buffers" method or something that I need to call in draw()?
> Any help greatly appreciated!
>
> VA
Glad someone asked about this, because I'm having a similar problem
with the latest 1.1.x snapshot.
I'm just subclassing Fl_Double_Window and overriding the draw() method.
My subclass is basically just a composite widget. I've been following
the docs but the window just isn't being drawn correctly. Its just
full of garbage, like the buffer hasnt been properly initialized.
Here's the code:
#include <FL/Fl.H>
#include <FL/Fl_Double_Window.H>
#include <FL/fl_draw.H>
class mywin : public Fl_Double_Window {
public:
mywin(int x,int y,int w,int h,const char * label = 0)
: Fl_Double_Window(x,y,w,h,label) {
box(FL_THIN_UP_BOX);
color(fl_rgb_color(190,192,190));
}
~mywin() { }
protected:
void draw();
};
void mywin::draw() {
Fl_Widget * const * a = array();
if(damage() == FL_DAMAGE_CHILD) {
for(int i = children(); i--; a++)
update_child(**a);
}
else if(damage() == FL_DAMAGE_ALL) {
draw_box(box(),color());
for(int i = children(); i--; a++)
draw_child(**a);
}
else if(damage() & (FL_DAMAGE_ALL | 1)) {
// update area 1 ...
}
}
int main(int argc, char ** argv) {
mywin * w = new mywin(200,200,200,200,"mywin");
w->end();
w->show();
return Fl::run();
}
Thanks,
David
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