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Move an image on your form depending on the scrollbar positions
- place two TScrollBars on your form
- in the object Inspector change the first scrollbar properties "Name" in "sbVert", "Child" in "sbVertical" and "Align" in "alRight"
- in the object Inspector change the second scrollbar properties "Name" in "sbHori" and "Align" in "alBottom"
- add a TPaintBox (additional component palette) to the form and set its "align" on "alClient"
- add a TImageList (common controls component palette) to the form
- upload an image in the ImageList:
- right-click the ImageList1 and select the ImageList Editor... from the pop-up menu
- Click on add and select an image (preferably a small icon 16 x 16 for example, Lazarus/images/icons/lazarus16x16)
- finish your selection with OK
- Choose your PaintBox, in the object inspector under events, create the event handler for the event OnPaint and write following code:
procedure TForm1.PaintBox1Paint(Sender: TObject); begin ImageList1.Draw( Paintbox1.Canvas, sbHori.Position * (PaintBox1.ClientWidth - ImageList1.Width) div sbHori.Max, sbVert.Position * (Paintbox1.ClientHeight - ImageList1.Height) div sbVert.Max, 0); end;
- Now let any change of the scrollbar positions repaint the form: create the event handler OnChange for a scrollbar and also call this for the other scrollbar:
procedure TForm1.sbVertChange(Sender: TObject); begin RePaint; end;
Your little program could look like: