Albrecht,
Your solution worked perfectly.
I apologize for the delay in my feedback. I have not been able to test it until
today.
Thanks very much,
David
> On 13.04.2012 22:35, David Lopez wrote:
> > Thanks Edzard and Greg for the answers, but I did not explained the issue
> > clearly.
> > I wanted to give a simple example, but indeed the parent (window) may have
> > tens or hundreds of children (boxes). Each of the boxes must be redrawn at
> > a different time independently of the rest (for example to change its fill
> > color according to an asynchronous event).
> > And in some cases, two (or more) of the boxes may be overlapped (the layer
> > order is static).
> >
> > So, a real situation could be:
> > There are 100 boxes in the window (box #1 to box #100).
> > The boxes #90 and #91 are overlapped.
> > The box #91 is above the #90.
> > The box #90 must be redrawn (because must change its color).
> > It redraws OK but overwrites box #91.
> > I would like to get boxes #90 and #91 to be redrawn but not the other 98
> > boxes.
> >
> > I think that there is no way to do this other than add to each widget a
> > list of references to the widgets that need to be redrawn if the current
> > widget is drawn (that is the boxes that are above it).
> > Am I right?
>
> FLTK is not designed to support such overlapping widgets. You
> may experience (re)drawing problems if you create such widget
> layouts. Of course, widgets must overlap their parents, but
> that's it - child widgets shouldn't overlap each other.
>
> That said, drawing always happens in the order of children in a
> group, so that such overlapping widgets seem to work as intended,
> but you're on your own if things like partial occlusion by other
> windows happen, or redrawing as in your description.
>
> So, the more specific answer to your question is: yes, you're on
> your own with this, and if you really need it, you will have to
> manage overlapping hierarchies in your code.
>
> There are ways to use damage() with areas though, but I'm not very
> familiar with this. Maybe this can help: if your box #90 (b90)
> in Fl_Group g changed, try something like this:
>
> g->damage(FL_DAMAGE_ALL, b90->x(), b90->y(), b90->w(), b90->h());
>
> instead of calling redraw(). This *should* have the same effect as
> calling redraw() for the box, but should also redraw all other
> overlapping widgets, if I'm right. You should give it a try and
> report whether it helps (or not).
>
> .... well, I tested it myself, and it seems to work as intended.
> Please see attached demo program. There are still cases where it
> might not work. Look at box 3 (B3). Why does it stay "on top of
> B2" if the damage() button is clicked ? It is as intended, but...
>
> Albrecht
>
> // overlap.cxx - overlapping widget demo.
> // This shows how damage() can be used to redraw overlapping widgets.
> // Use at your own risk. Usage:
> // fltk-config --compile overlap.cxx && ./overlap
> // Use both buttons to see the difference:
> // button1_cb() redraws B1 only,
> // button2_cb() redraws B1 and B2,
> // resizing the window redraws all boxes.
>
> #include <stdio.h>
> #include <FL/Fl.H>
> #include <FL/Fl_Double_Window.H>
> #include <FL/Fl_Widget.H>
> #include <FL/Fl_Group.H>
> #include <FL/Fl_Box.H>
> #include <FL/Fl_Button.H>
>
> Fl_Box *b1, *b2, *b3;
> Fl_Color c = 0;
>
> // This derived class is only to print which box is drawn.
> class MyBox : public Fl_Box {
> public:
> MyBox(int x, int y, int w, int h, const char *L) :
> Fl_Box(x,y,w,h,L) {
> align(FL_ALIGN_INSIDE|FL_ALIGN_LEFT|FL_ALIGN_TOP);
> box(FL_FLAT_BOX);
> }
> void draw() {
> printf("draw() box %s\n",label()); fflush(stdout);
> Fl_Box::draw();
> }
> };
>
> // Button 1 doesn't draw overlapping widgets
> void button1_cb(Fl_Widget *, void *) {
> printf("button 1: redraw()\n");
> if (++c > 7) c = 1;
> b1->color(c);
> b1->redraw();
> }
>
> // Button 2 draws overlapping widgets
> void button2_cb(Fl_Widget *, void *) {
> printf("button 2: damage()\n");
> if (++c > 7) c = 1;
> b1->color(c);
> b1->parent()->damage(FL_DAMAGE_ALL, b1->x(), b1->y(), b1->w(), b1->h());
> }
>
> int main(int argc, char **argv) {
> Fl_Window *window = new Fl_Window(500, 300, "Overlapping widget test");
> Fl_Group *g = new Fl_Group(0,0,300,300);
> b1 = new MyBox(10,10,200,200,"B1");
> b1->color(FL_WHITE);
> b2 = new MyBox(90,90,200,200,"B2");
> b2->color(fl_lighter(fl_lighter(FL_BLUE)));
> b3 = new MyBox(230,30,80,80,"B3");
> b3->color(FL_YELLOW);
> g->end();
> Fl_Button *button1 = new Fl_Button(350, 50,100,50,"redraw()");
> button1->callback(button1_cb);
> Fl_Button *button2 = new Fl_Button(350,150,100,50,"damage()");
> button2->callback(button2_cb);
> window->end();
> window->resizable(window);
> window->show();
> return Fl::run();
> }
>
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