Sequencer: Implement simple undo.

sequencer/src/grid.C

@@ -977,6 +977,24 @@ Grid::mode ( void ) const
     return _mode;
 }
 
+void
+Grid::undo ( void )
+{
+    if ( ! _history.size() )
+        return;
+
+    data *d = _history.back();
+    
+    _history.pop_back();
+
+    // swap the copy back in (atomically).
+    _rd = (const data *)d;
+    
+    _rw = NULL;
+    
+    if ( ! _suspend_update )
+        signal_events_change();
+}
 
 /** return a pointer to a copy of grid's event list in raw form */
 event_list *

sequencer/src/grid.H

@@ -28,7 +28,7 @@ class smf;
 
 #include "debug.h"
 
-const int MAX_UNDO = 10;
+const int MAX_UNDO = 50;
 
 #include <list>
 
@@ -248,6 +248,8 @@ public:
     void copy ( void );
     void paste ( int offset );
 
+    void undo ( void );
+
     virtual tick_t default_length ( void ) const
         {
             return PPQN;

sequencer/src/gui/ui.fl

@@ -109,7 +109,7 @@ Function {init_colors()} {open private C return_type {static void}
 } 
 
 widget_class Visual_Metronome {open
-  xywh {1242 936 100 100} type Double visible
+  xywh {1244 936 100 100} type Double visible
 } {
   Fl_Slider progress {
     private xywh {139 115 1149 23} type Horizontal box FLAT_BOX color 7 selection_color 54
@@ -414,7 +414,7 @@ if ( Fl::event() == FL_SHORTCUT && Fl::event_key() == FL_Escape )
 	 
 if ( maybe_save_song() )
 	quit();} open
-      xywh {492 227 865 805} type Double color 47 resizable
+      xywh {494 231 865 805} type Double color 47 resizable
       code0 {o->color( FL_BACKGROUND_COLOR );}
       code1 {o->draw_overlay_callback( &UI::draw_overlay, this );}
       code2 {o->xclass( APP_NAME );}
@@ -1311,7 +1311,7 @@ ab.run();}
             }
           }
           Submenu edit_menu {
-            label {&Edit} open selected
+            label {&Edit} open
             xywh {0 0 68 18}
           } {
             MenuItem {} {
@@ -1424,6 +1424,13 @@ w->copy();}
 w->paste();}
               xywh {120 120 34 18} shortcut 0x40076
             }
+            MenuItem {} {
+              label Undo
+              callback {Canvas *w = current_canvas();
+
+w->grid()->undo();} selected
+              xywh {110 110 34 18} shortcut 0x4007a
+            }
           }
         }
         Fl_Button sm_indicator {