Add a Qt progress bar (modal, no multithread mode)

Polyhedron/demo/Polyhedron/include/Qt_progress_bar_callback.h

@@ -0,0 +1,68 @@
+#ifndef PROGRESS_BAR_CALLBACK_H
+#define PROGRESS_BAR_CALLBACK_H
+
+#include <CGAL/Real_timer.h>
+
+#include <QProgressDialog>
+#include <QApplication>
+
+class Qt_progress_bar_callback
+{
+
+private:
+  
+  CGAL::Real_timer timer;
+  double t_start;
+  mutable double t_latest;
+
+  mutable std::size_t nb;
+  
+  QProgressDialog* dialog;
+
+public:
+
+  Qt_progress_bar_callback()
+  {
+  }
+  
+  Qt_progress_bar_callback(const char* title, QWidget* parent)
+    : dialog (new QProgressDialog (QString(title),
+                                   QString("Cancel"),
+                                   0, 100,
+                                   parent))
+  {
+    dialog->setMinimumDuration(0);
+    dialog->setWindowModality(Qt::WindowModal);
+    timer.start();
+    t_start = timer.time();
+    t_latest = t_start;
+  }
+  ~Qt_progress_bar_callback()
+  {
+  }
+
+  bool operator() (double advancement) const
+  {
+    // Avoid calling time() at every single iteration, which could
+    // impact performances very badly
+    ++ nb;
+    if (advancement != 1 && nb % 1000 != 0)
+      return true;
+
+    // If the limit is reach, interrupt the algorithm
+    double t = timer.time();
+    if (advancement == 1 || (t - t_latest) > 0.25)
+    {
+      dialog->setValue (int (100. * advancement));
+      t_latest = t;
+      
+      if (dialog->wasCanceled())
+        return false;
+    }
+    
+    return true;
+  }
+};
+
+
+#endif // PROGRESS_BAR_CALLBACK_H