Changes to solve STR#2426;

1) Hitting ENTER to select an item should make sure the item is
	   displayed if off-screen (Mayank Malik, pointing out similar behavior in Fl_Browser_)

        2) show_item() without a positional argument will invoke show_item_top()
	   if the item is off-screen.

	3) Added new method displayed() (to match Fl_Browser_'s)



git-svn-id: file:///fltk/svn/fltk/branches/branch-1.3@7893 ea41ed52-d2ee-0310-a9c1-e6b18d33e121

FL/Fl_Tree.H

@@ -803,7 +803,9 @@ public:
   void selectmode(Fl_Tree_Select val) {
     _prefs.selectmode(val);
   }
-  void show_item(Fl_Tree_Item *item, int yoff=0);
+  int displayed(Fl_Tree_Item *item);
+  void show_item(Fl_Tree_Item *item, int yoff);
+  void show_item(Fl_Tree_Item *item);
   void show_item_bottom(Fl_Tree_Item *item);
   void show_item_middle(Fl_Tree_Item *item);
   void show_item_top(Fl_Tree_Item *item);

src/Fl_Tree.cxx

@@ -520,6 +520,7 @@ int Fl_Tree::handle(int e) {
 	    case FL_KP_Enter:
 	      if ( when() & ~FL_WHEN_ENTER_KEY) {
 		select_only(_item_focus);
+		show_item(_item_focus);		// STR #2426
 		return(1);
 	      }
 	      break;
@@ -789,6 +790,27 @@ void Fl_Tree::show_item(Fl_Tree_Item *item, int yoff) {
   redraw();
 }
 
+/// See if \p item is currently displayed on-screen (visible within the widget).
+/// This can be used to detect if the item is scrolled off-screen.
+/// Checks to see if the item's vertical position is within the top and bottom
+/// edges of the display window. This does NOT take into account the hide()/show()
+/// status of the item.
+///
+int Fl_Tree::displayed(Fl_Tree_Item *item) {
+  return( (item->y() >= y() && item->y() <= (y()+h()-item->h())) ? 1 : 0);
+}
+
+/// Adjust the vertical scroll bar to show \p item at the top
+/// of the display IF it is currently off-screen (eg. show_item_top()).
+/// If it is already on-screen, no change is made.
+///
+/// \see show_item_top(), show_item_middle(), show_item_bottom()
+///
+void Fl_Tree::show_item(Fl_Tree_Item *item) {
+  if ( displayed(item) ) return;
+  show_item_top(item);
+}
+
 /// Adjust the vertical scrollbar so that \p item is at the top of the display.
 void Fl_Tree::show_item_top(Fl_Tree_Item *item) {
   item = item ? item : first();

test/tree.fl

@@ -142,7 +142,7 @@ Function {} {open
 } {
   Fl_Window window {
     label tree open
-    xywh {1099 53 580 695} type Double visible
+    xywh {1153 115 580 695} type Double visible
   } {
     Fl_Group tree {
       user_data 1234
@@ -538,38 +538,49 @@ switch ( whenmode_chooser->value() ) {
     Fl_Box showitem_box {
       label {show_item()
 }
-      xywh {468 423 60 77} box GTK_DOWN_BOX color 47 labelsize 11 align 1
+      xywh {480 425 70 82} box GTK_DOWN_BOX color 47 labelsize 11 align 1
+    }
+    Fl_Button {} {
+      label Show
+      callback {Fl_Tree_Item *item = tree->next_selected_item();
+tree->show_item(item);} selected
+      tooltip {Tests show_item() with no position specified.
+Makes the selected item visible IF it is off-screen.
+No change made if it is not off-screen.} xywh {495 434 40 17} labelsize 11
     }
     Fl_Button {} {
       label Top
       callback {Fl_Tree_Item *item = tree->next_selected_item();
 tree->show_item_top(item);}
-      tooltip {Scrolls selected item to the top of the display
+      tooltip {Test show_item_top().
+Scrolls selected item to the top of the display
 (only works if scrollbar showing)
 To use:
 1) open '500 items'
 2) select item 0010
-3) Hit Top/Mid/Bot} xywh {478 433 40 16} labelsize 11
+3) Hit Top/Mid/Bot} xywh {495 451 40 16} labelsize 11
     }
     Fl_Button {} {
       label Mid
       callback {Fl_Tree_Item *item = tree->next_selected_item();
 tree->show_item_middle(item);}
-      tooltip {Scrolls the selected item to the middle of the display
+      tooltip {Tests show_item_middle().
+Scrolls the selected item to the middle of the display
 To use:
   1) open '500 items'
   2) select 'item 0010'
-  3) Hit Top/Mid/Bot} xywh {478 453 40 16} labelsize 11
+  3) Hit Top/Mid/Bot} xywh {495 467 40 16} labelsize 11
     }
     Fl_Button {} {
       label Bot
       callback {Fl_Tree_Item *item = tree->next_selected_item();
 tree->show_item_bottom(item);}
-      tooltip {Scrolls the selected item to the bottom of the display
+      tooltip {Tests show_item_bottom().
+Scrolls the selected item to the bottom of the display
 To use:
   1) open '500 items'
   2) select 'item 0010'
-  3) Hit Top/Mid/Bot} xywh {478 473 40 16} labelsize 11
+  3) Hit Top/Mid/Bot} xywh {495 483 40 16} labelsize 11
     }
     Fl_Box docallback_box {
       label {Selection State Changes}
@@ -848,6 +859,5 @@ window->size_range(window->w(), window->h(), 0, 0);
 
      if ( tree->when() == FL_WHEN_CHANGED ) whenmode_chooser->value(0);
 else if ( tree->when() == FL_WHEN_RELEASE ) whenmode_chooser->value(1);
-else if ( tree->when() == FL_WHEN_NEVER   ) whenmode_chooser->value(2);} {selected
-  }
+else if ( tree->when() == FL_WHEN_NEVER   ) whenmode_chooser->value(2);} {}
 }