Add draggable-group example program.

git-svn-id: file:///fltk/svn/fltk/branches/branch-1.4@12372 ea41ed52-d2ee-0310-a9c1-e6b18d33e121

3 files changed, 264 insertions, 1 deletions

diff --git a/.gitignore b/.gitignore
index bf8c087f7..58f07827a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -68,6 +68,7 @@
 # /examples/
 /examples/*.exe
 /examples/clipboard
+/examples/draggable-group
 /examples/fltk-versions
 /examples/howto-add_fd-and-popen
 /examples/howto-browser-with-icons
@@ -76,6 +77,9 @@
 /examples/howto-text-over-image-button
 /examples/menubar-add
 /examples/nativefilechooser-simple-app
+/examples/nativefilechooser-simple
+/examples/OpenGL3-glut-test
+/examples/OpenGL3test
 /examples/progress-simple
 /examples/shapedwindow
 /examples/table-as-container
diff --git a/examples/Makefile b/examples/Makefile
index a492f7a9a..a7b2d3c01 100644
--- a/examples/Makefile
+++ b/examples/Makefile
@@ -6,6 +6,7 @@ SHELL = /bin/sh
 
 # Executables
 ALL = clipboard$(EXEEXT) \
+      draggable-group$(EXEEXT) \
       fltk-versions$(EXEEXT) \
       howto-add_fd-and-popen$(EXEEXT) \
       howto-browser-with-icons$(EXEEXT) \
@@ -41,4 +42,3 @@ clean:
 	$(RM) $(ALL)
 	$(RM) *.o
 	$(RM) core
-
diff --git a/examples/draggable-group.cxx b/examples/draggable-group.cxx
new file mode 100644
index 000000000..043ed5896
--- /dev/null
+++ b/examples/draggable-group.cxx
@@ -0,0 +1,259 @@
+//
+// "$Id$"
+//
+// Demonstrate deriving a class with draggable children.
+//
+// Copyright 2017 by Bill Spitzak and others.
+//
+// This library is free software. Distribution and use rights are outlined in
+// the file "COPYING" which should have been included with this file.  If this
+// file is missing or damaged, see the license at:
+//
+//     http://www.fltk.org/COPYING.php
+//
+// Please report all bugs and problems on the following page:
+//
+//     http://www.fltk.org/str.php
+//
+
+// K Dmitrij <kdiman@...> wrote on Wed, 26 Jul 2017 19:54:12 +0000 in
+// fltk.general, thread "[fltk.general] Draggable Group for examples FLTK":
+//
+// "Here is class for drag widgets and/or their children inside its parent
+//  widget. You can include it into examples of FLTK (and to adapt/modify
+//  if needs)".
+//
+// Thanks to Dmitrij for this contribution.
+
+// Use `fltk-config --compile draggable-group.cxx' to build this example.
+
+
+#include <FL/Fl.H>
+#include <FL/Fl_Double_Window.H>
+#include <FL/Fl_Box.H>
+#include <FL/Fl_Button.H>
+
+#include <stdio.h>
+
+/** \class DraggableGroup
+    \brief Class with draggable children, derived from Fl_Group.
+
+  Use this class if you want the user to be able to drag the children
+  of a group inside the borders of the group. DraggableGroup widgets
+  can be nested, but only direct children of the DraggableGroup widget
+  can be dragged.
+
+  Design decisions:
+    - Widgets can be dragged with the right mouse button.
+      This was chosen to avoid conflicts with other mouse button
+      events such as clicking a button.
+    - The dragged widget is raised to the top within its group for better
+      visual feedback while dragging by making it the last child of the group.
+    - The order of widgets is restored when the mouse button is released.
+      This can result in hiding the widget behind another widget, but this
+      was chosen to keep the order given by the programmer. If this
+      is not desired it can be changed easily.
+*/
+class DraggableGroup : public Fl_Group {
+
+protected:
+  int xoff, yoff;         // start offsets while dragging
+  int drag_index;         // index of dragged child
+  Fl_Widget *drag_widget; // dragged child widget
+
+public:
+  DraggableGroup(int X, int Y, int W, int H, const char *L = 0)
+    : Fl_Group(X, Y, W, H, L)
+    , xoff(0)
+    , yoff(0)
+    , drag_index(0)
+    , drag_widget(0) {
+    box(FL_UP_BOX);
+  }
+
+  /** Raise the dragged widget to the top (last child) of its group.
+
+    This ensures that the widget is always visible while it is dragged.
+    The original index is saved in 'drag_index' and restored when the
+    mouse button is released.
+
+    \internal
+    Since we allow only direct children of the DraggableGroup widget
+    to be dragged the argument 'q' is always a child of 'this'.
+    Note: add(q) first removes the widget from its parent group ('this')
+    and then adds it again as its last child.
+    This is the same as insert(*q, children()).
+  */
+  void top_level(Fl_Widget *q) {
+    drag_index = find(q); // save the widget's current index
+    add(q);               // raise to top (make it the last child)
+  }
+
+  /** Handle FL_PUSH, FL_DRAG, and FL_RELEASE events.
+
+    All other events are handled in Fl_Group::handle().
+    Dragged widgets are limited inside the borders of their parent group.
+  */
+  virtual int handle(int e) {
+
+    switch (e) {
+
+      case FL_PUSH: {
+	if (Fl::event_button() == FL_RIGHT_MOUSE) {
+	  if (Fl::belowmouse()->parent() == this) {
+	    drag_widget = Fl::belowmouse();
+
+	    // save pointer offsets relative to drag_widget's x/y position
+	    xoff = Fl::event_x() - drag_widget->x();
+	    yoff = Fl::event_y() - drag_widget->y();
+
+	    top_level(drag_widget); // raise to top for visible feedback
+	    redraw();
+	    return 1;
+	  }
+	}
+	break;
+      }
+
+      case FL_DRAG: {
+	if (!drag_widget)
+	  break;
+
+	int nX = Fl::event_x() - xoff; // new x coordinate
+	int nY = Fl::event_y() - yoff; // new y coordinate
+
+	int bbx = Fl::box_dx(box()); // left and right border width
+	int bby = Fl::box_dy(box()); // top and bottom border width
+
+	// keep the widget inside its parent's borders
+
+	if (nX < x() + bbx) {
+	  nX = x() + bbx;
+	} else if (nX + drag_widget->w() > x() + w() - bbx) {
+	  nX = x() + w() - drag_widget->w() - bbx;
+	}
+
+	if (nY < y() + bby) {
+	  nY = y() + bby;
+	} else if (nY + drag_widget->h() > y() + h() - bby) {
+	  nY = y() + h() - drag_widget->h() - bby;
+	}
+
+	drag_widget->position(nX, nY); // set the new position
+	redraw();
+	return 1;
+      }
+
+      case FL_RELEASE: {
+	if (drag_widget && Fl::event_button() == FL_RIGHT_MOUSE) {
+
+	  // Optional: restore the original widget order in the group.
+	  // Remove the next statement (or comment it out) if not desired.
+	  insert(*drag_widget, drag_index);
+
+	  init_sizes(); // save widget positions for later resizing
+	  drag_widget = 0;
+	  redraw();
+	  if (parent())
+	    parent()->redraw();
+	  return 1;
+	}
+	break;
+      }
+
+      default:
+	break;
+    } // switch(e)
+
+    return Fl_Group::handle(e);
+  }
+};
+
+// clear status message box after timeout
+void clear_status(void *v) {
+  Fl_Box *status = (Fl_Box *)v;
+  status->label("");
+  status->redraw();
+}
+
+// button callback: display status message for two seconds
+void button_cb(Fl_Widget *w, void *v) {
+  static char buf[128];
+  sprintf(buf, "button_cb: '%s'.\n", w->label());
+  Fl_Box *status = (Fl_Box *)v;
+  status->label(buf);
+  status->redraw();
+  Fl::remove_timeout(clear_status); // remove any pending timeout
+  Fl::add_timeout(2.0, clear_status, v);
+}
+
+int main() {
+
+  Fl_Double_Window win(500, 500, "Drag children within their parent group");
+
+  DraggableGroup area(0, 0, 500, 400, "Use the right mouse button (MB3)\nto drag objects");
+  area.align(FL_ALIGN_INSIDE);
+
+  // draggable group inside draggable area
+  DraggableGroup dobj(5, 5, 140, 140, "DraggableGroup");
+  dobj.align(FL_ALIGN_INSIDE);
+  Fl_Box b1(25, 25, 20, 20);
+  b1.color(FL_RED);
+  b1.box(FL_FLAT_BOX);
+  Fl_Box b2(105, 105, 20, 20);
+  b2.color(FL_GREEN);
+  b2.box(FL_FLAT_BOX);
+  dobj.end();
+
+  // regular group inside draggable area
+  Fl_Group dobj2(5, 280, 110, 110, "Fl_Group");
+  dobj2.box(FL_DOWN_BOX);
+  dobj2.align(FL_ALIGN_INSIDE);
+  Fl_Box b3(15, 290, 20, 20);
+  b3.color(FL_BLUE);
+  b3.box(FL_FLAT_BOX);
+  Fl_Box b4(85, 360, 20, 20);
+  b4.color(FL_YELLOW);
+  b4.box(FL_FLAT_BOX);
+  dobj2.end();
+
+  // draggable group inside draggable area
+  DraggableGroup dobj3(245, 5, 150, 150, "DraggableGroup");
+  dobj3.align(FL_ALIGN_INSIDE);
+
+  // nested draggable group
+  DraggableGroup dobj4(250, 10, 50, 50);
+  Fl_Box b5(255, 15, 15, 15);
+  b5.color(FL_BLACK);
+  b5.box(FL_FLAT_BOX);
+  Fl_Box b6(275, 30, 15, 15);
+  b6.color(FL_WHITE);
+  b6.box(FL_FLAT_BOX);
+  dobj4.end();
+
+  dobj3.end();
+
+  Fl_Button button1(200, 350, 180, 40, "Fl_Button inside DraggableGroup");
+  button1.align(FL_ALIGN_INSIDE | FL_ALIGN_WRAP);
+
+  area.end();
+
+  Fl_Button button2(200, 410, 180, 40, "Fl_Button outside DraggableGroup");
+  button2.align(FL_ALIGN_INSIDE | FL_ALIGN_WRAP);
+
+  Fl_Box *status = new Fl_Box(0, 460, win.w(), 40, "Messages ...");
+  status->box(FL_DOWN_BOX);
+
+  button1.callback(button_cb, status);
+  button2.callback(button_cb, status);
+
+  win.end();
+  win.resizable(win);
+  win.show();
+
+  return Fl::run();
+}
+
+//
+// End of "$Id$".
+//