//// "$Id: doublebuffer.cxx,v 1.1.1.1 2003/08/07 21:18:42 jasonk Exp $"//// Double-buffering test program for the Fast Light Tool Kit (FLTK).//// This demo shows how double buffering helps, by drawing the// window in a particularily bad way.//// The single-buffered window will blink as it updates.  The// double buffered one will not.  It will take just as long// (or longer) to update, but often it will appear to be faster.//// This demo should work for both the GL and X versions of Fl,// even though the double buffering mechanism is totally different.//// Copyright 1998-1999 by Bill Spitzak and others.//// This library is free software; you can redistribute it and/or// modify it under the terms of the GNU Library General Public// License as published by the Free Software Foundation; either// version 2 of the License, or (at your option) any later version.//// This library is distributed in the hope that it will be useful,// but WITHOUT ANY WARRANTY; without even the implied warranty of// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU// Library General Public License for more details.//// You should have received a copy of the GNU Library General Public// License along with this library; if not, write to the Free Software// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307// USA.//// Please report all bugs and problems to "fltk-bugs@easysw.com".//#include <FL/Fl.H>#include <FL/Fl_Single_Window.H>#include <FL/Fl_Double_Window.H>#include <FL/Fl_Box.H>#include <FL/fl_draw.H>#include <FL/Fl_Hor_Slider.H>#include <stdlib.h>#include <FL/math.h>#include <stdio.h>// this purposely draws each line 10 times to be slow:void star(int w, int h, int n) {  fl_push_matrix();  fl_translate(w/2, h/2);  fl_scale(w/2, h/2);  for (int i = 0; i < n; i++) {    for (int j = i+1; j < n; j++)/* for (int k=0; k<10; k++)*/ {      fl_begin_line();      fl_vertex(cos(2*M_PI*i/n+.1), sin(2*M_PI*i/n+.1));      fl_vertex(cos(2*M_PI*j/n+.1), sin(2*M_PI*j/n+.1));      fl_end_line();    }  }  fl_pop_matrix();}int sides[2] = {20,20};void slider_cb(Fl_Widget* o, long v) {  sides[v] = int(((Fl_Slider*)o)->value());  o->parent()->redraw();}void bad_draw(int w,int h,int which) {//   for (int i=0; i<10; i++) {//     fl_color(7); fl_rectf(0,0,w,h); fl_color(0); star(w,h);//     fl_color(0); fl_rectf(0,0,w,h); fl_color(7); star(w,h);//   }  fl_color(FL_BLACK); fl_rectf(0,0,w,h);  fl_color(FL_WHITE); star(w,h,sides[which]);  //  for (int x=0; x<sides[which]; x++) for (int y=0; y<sides[which]; y++)  //fl_draw_box(FL_UP_BOX, 10*x, 10*y, 25,25, FL_GRAY);}class single_blink_window : public Fl_Single_Window {  void draw() {bad_draw(w(),h(),0); draw_child(*child(0));}public:  single_blink_window(int x, int y,int w,int h,const char *l)    : Fl_Single_Window(x,y,w,h,l) {resizable(this);}};class double_blink_window : public Fl_Double_Window {  void draw() {bad_draw(w(),h(),1); draw_child(*child(0));}public:  double_blink_window(int x, int y, int w,int h,const char *l)    : Fl_Double_Window(x,y,w,h,l) {resizable(this);}};int main() {  if (!Fl::visual(FL_DOUBLE))    printf("Xdbe not supported, faking double buffer with pixmaps.\n");  Fl_Window w01(420,420,"Fl_Single_Window"); w01.box(FL_FLAT_BOX);  single_blink_window w1(10,10,400,400,"Fl_Single_Window");  w1.box(FL_FLAT_BOX); w1.color(FL_BLACK); //w1.position(100,200);  Fl_Hor_Slider slider0(20,370,360,25);  slider0.range(2,30);  slider0.step(1);  slider0.value(sides[0]);  slider0.callback(slider_cb, 0);  w1.end();  w01.end();  Fl_Window w02(420,420,"Fl_Double_Window"); w02.box(FL_FLAT_BOX);  double_blink_window w2(10,10,400,400,"Fl_Double_Window");  w2.box(FL_FLAT_BOX); w2.color(FL_BLACK); //w2.position(600,200);  Fl_Hor_Slider slider1(20,370,360,25);  slider1.range(2,30);  slider1.step(1);  slider1.value(sides[0]);  slider1.callback(slider_cb, 1);  w2.end();  w02.end();  w01.show();  w1.show();  w02.show();  w2.show();  return Fl::run();}//// End of "$Id: doublebuffer.cxx,v 1.1.1.1 2003/08/07 21:18:42 jasonk Exp $".//