Q&A - Question

Limiting Mouse-Wheel Zoom to the Viewer

Question
Crag Cox asked on September 08, 2016, keyword: Developer Kernel
I have incorporated the mouse-wheel zoom into my Delphi project, but how do I limit the zoom response to when the mouse is within the viewer only.  As it stands now, my users attempt to use the mouse wheel to migrate through the legend control only to have zoom response in the viewer.  
Answers
Artur Redzko (TatukGIS) replied September 08, 2016
Assuming that you are using the form MouseWheelDown and FormMouseWheelUp events you can check inside procedures handling these events if the mouse position is over the viewer, e.g.:

procedure TfrmMain.FormMouseWheelDown(Sender: TObject; Shift: TShiftState;
  MousePos: TPoint; var Handled: Boolean);
var
  pt : TPoint;
begin
  pt := GIS.ScreenToClient(MousePos);
  if PtInRect(GIS.ClientRect, pt) then
    GISMouseWheelDown( Sender, Shift, MousePos, Handled ) ;
end;
 
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