TfpgWidget: adds support for new event, OnDragStartDetected

1 files changed, 17 insertions, 0 deletions

diff --git a/src/corelib/fpg_widget.pas b/src/corelib/fpg_widget.pas
index 3f5204ed..7a95b92b 100644
--- a/src/corelib/fpg_widget.pas
+++ b/src/corelib/fpg_widget.pas
@@ -47,6 +47,7 @@ type
     FOnDragDrop: TfpgDragDropEvent;
     FOnDragEnter: TfpgDragEnterEvent;
     FOnDragLeave: TNotifyEvent;
+    FOnDragStartDetected: TNotifyEvent;
     FOnEnter: TNotifyEvent;
     FOnExit: TNotifyEvent;
     FOnMouseDown: TMouseButtonEvent;
@@ -59,6 +60,8 @@ type
     FOnResize: TNotifyEvent;
     FOnScreen: boolean;
     FOnShowHint: THintEvent;
+    FDragStartPos: TfpgPoint;
+    FDragActive: boolean;
     procedure   SetActiveWidget(const AValue: TfpgWidget);
     function    IsShowHintStored: boolean;
     procedure   SetFormDesigner(const AValue: TObject);
@@ -136,6 +139,7 @@ type
     { property events }
     property    OnClick: TNotifyEvent read FOnClick write FOnClick;
     property    OnDoubleClick: TMouseButtonEvent read FOnDoubleClick write FOnDoubleClick;
+    property    OnDragStartDetected: TNotifyEvent read FOnDragStartDetected write FOnDragStartDetected;
     property    OnEnter: TNotifyEvent read FOnEnter write FOnEnter;
     property    OnExit: TNotifyEvent read FOnExit write FOnExit;
     property    OnKeyPress: TKeyPressEvent read FOnKeyPress write FOnKeyPress;
@@ -428,6 +432,7 @@ begin
   FBackgroundColor := clWindowBackground;
   FTextColor      := clText1;
   FAcceptDrops    := False;
+  FDragActive     := False;
 
   inherited Create(AOwner);
 
@@ -585,6 +590,7 @@ begin
   case msg.Params.mouse.Buttons of
     MOUSE_LEFT:
       begin
+        FDragStartPos.SetPoint(msg.Params.mouse.x, msg.Params.mouse.y);
         mb := mbLeft;
         HandleLMouseDown(msg.Params.mouse.x, msg.Params.mouse.y, msg.Params.mouse.shiftstate);
       end;
@@ -611,6 +617,7 @@ var
   IsDblClick: boolean;
 begin
 //  writeln('TfpgWidget.MsgMouseUp');
+  FDragActive := False;
   if InDesigner then
   begin
     FFormDesigner.Dispatch(msg);
@@ -675,6 +682,16 @@ begin
       Exit;
   end;
 
+  if (msg.Params.mouse.Buttons and MOUSE_LEFT) = MOUSE_LEFT then
+  begin
+    if not FDragActive and (FDragStartPos.ManhattanLength(fpgPoint(msg.Params.mouse.x, msg.Params.mouse.y)) > fpgApplication.StartDragDistance) then
+    begin
+      FDragActive := True;
+      if Assigned(OnDragStartDetected) then
+        OnDragStartDetected(self);
+    end;
+  end;
+
   HandleMouseMove(msg.Params.mouse.x, msg.Params.mouse.y, msg.Params.mouse.Buttons, msg.Params.mouse.shiftstate);
   if Assigned(OnMouseMove) then
     OnMouseMove(self, msg.Params.mouse.shiftstate,