[SOLVED] Clearing GDI+ drawings

[andybiochem]

Hi!,

I want to know how to clear GDI+ drawings from a GUI, without clearing the whole GUI.

Currently, using "_GDIPlus_GraphicsClear" causes the whole GUI to turn black (or whatever color selected).

In this reproducer (below) I want the GDI+ line to appear for 3 seconds, and then go away when I shut down GDI+.

The button (and any other controls in the GUI) should remain throughout.

#include <GuiConstantsEx.au3>
#include <GDIPlus.au3>

_Main()

Func _Main()
    Local $hGUI, $hWnd, $hGraphic, $hPen

    ; Create GUI
    $hGUI = GUICreate("GDI+", 400, 300)
    $hWnd = WinGetHandle("GDI+")
    GUICtrlCreateButton("Button",20,20,50,15)
    GUISetState()

    ; Draw line
    _GDIPlus_Startup ()
    $hGraphic = _GDIPlus_GraphicsCreateFromHWND ($hWnd)
    $hPen = _GDIPlus_PenCreate ()
    _GDIPlus_GraphicsDrawLine ($hGraphic, 10, 150, 390, 150, $hPen)

    ; Show line for 3 seconds
    Sleep(3000)

    ; Remove line & Clean up resources
    _GDIPlus_GraphicsClear($hGraphic) ;HOW TO CLEAR PROPERLY??????????????
    _GDIPlus_PenDispose ($hPen)
    _GDIPlus_GraphicsDispose ($hGraphic)
    _GDIPlus_Shutdown ()

    ; Loop until user exits
    Do
    Until GUIGetMsg() = $GUI_EVENT_CLOSE

EndFunc   ;==>_Main

I've trawled the forum and MSDN, but can't find a suitable approach.

Thanks for any advice!

Edited October 22, 2009 by andybiochem

[Authenticity]

_WinAPI_InvalidateRect($hWnd)

..or _WinAPI_RedrawWindow().

[andybiochem]

Genius.

"_WinAPI_InvalidateRect" ... how on earth did I miss that?

Thank you!!!

[monoceres]

Another way if you want to draw only to certain parts of the GUI is to create a label, get the handle to the label and use it as a regular window.