GDIPlus Arrow without the GUI showing.

[guinness]

The example works only when the GUISetState()'s are swapped around. I am creating a program which has a Parent GUI and then a Child GUI ($WS_EX_MDICHILD) that is hidden on initial start. The example is a strip down version, because "normally speaking" with other Controls it doesn't matter where GUISetState(@SW_SHOW) is put, before the Controls or after the Controls. Yet, in this case it seems to be a problem. If someone knows of the particular Function that I am missing it would be much appreciated.

Thanks.

Example:

#AutoIt3Wrapper_Au3Check_Parameters=-d -w 1 -w 2 -w 3 -w 4 -w 5 -w 6
#include <GDIPlus.au3>

_GDIPlus_Startup()
_Main()

Func _Main()
    Local $GUI
    $GUI = GUICreate("GDI+", 400, 300)

;~  GUISetState(@SW_SHOW) ; <<<<< Un-Comment and it will show.
    _CreateArrow($GUI, 10, 10)
    GUISetState(@SW_SHOW) ; <<<<< Comment and it will not show the Arrow.

    Do
    Until GUIGetMsg() = -3
    _GDIPlus_Shutdown()
EndFunc   ;==>_Main

Func _CreateArrow($cHandle, $cLeft, $cTop)
    Local $cSize = 3
    Local $cGraphic = _GDIPlus_GraphicsCreateFromHWND($cHandle)
    Local $cPen = _GDIPlus_PenCreate(0xFF000000, 2)
    Local $cEndCap = _GDIPlus_ArrowCapCreate($cSize, 6)
    _GDIPlus_PenSetCustomEndCap($cPen, $cEndCap)
    _GDIPlus_GraphicsDrawLine($cGraphic, $cLeft - $cSize, $cTop, $cLeft, $cTop, $cPen)
    _GDIPlus_ArrowCapDispose($cEndCap)
    _GDIPlus_PenDispose($cPen)
    _GDIPlus_GraphicsDispose($cGraphic)
EndFunc   ;==>_CreateArrow

[guinness]

No that was all the code I had for this small example (I hate to post without giving it a go first.)

But thanks for pointing me towards WM_PAINT. I had heard of this Windows Message but didn't have an idea of what it was used for until now.

I updated the code, it now paints on Startup and after the GUI has been minimised and restored. But after all this I think perhaps it would be easier (for what I want to do) is just embed an image in the EXE and use Zedna's Resource UDF, because I am going to want to have 5 Arrows that are constantly being deleted and re-created. I love a challenge, but I think opting for less code (which I know won't fail) is a better option. Cheers for taking the time to look at my code.

expandcollapse popup

#AutoIt3Wrapper_Au3Check_Parameters=-d -w 1 -w 2 -w 3 -w 4 -w 5 -w 6
#include <GDIPlus.au3>
#include <WinAPI.au3>
#include <WindowsConstants.au3>

Global $Global_GUI, $Global_Graphic, $Global_Image

_GDIPlus_Startup()
_Main()

Func _Main()
    Local $GUI
    $GUI = GUICreate("GDI+", 400, 300)
    $Global_GUI = $GUI
    GUIRegisterMsg(0x000F, "WM_PAINT") ; WM_PAINT
    GUIRegisterMsg(0x0085, "WM_PAINT") ; WM_NCPAINT
    _CreateArrow($GUI, 10, 10)

    GUISetState(@SW_SHOW)

    Do
    Until GUIGetMsg() = -3
    _GDIPlus_Shutdown()
EndFunc   ;==>_Main

Func _CreateArrow($cHandle, $cLeft, $cTop)
    Local $cSize = 3
    Local $cGraphicGUI = _GDIPlus_GraphicsCreateFromHWND(WinGetHandle($cHandle))

    ; Create Double Buffer
    Local $cBMPBuff = _GDIPlus_BitmapCreateFromGraphics(400, 300, $cGraphicGUI)
    Local $cGraphic = _GDIPlus_ImageGetGraphicsContext($cBMPBuff)
    $Global_Graphic = $cGraphicGUI
    ; End Double Buffer

    Local $cPen = _GDIPlus_PenCreate(0xFF000000, 2)
    $Global_Image = $cPen
    Local $cEndCap = _GDIPlus_ArrowCapCreate($cSize, 6)
    _GDIPlus_PenSetCustomEndCap($cPen, $cEndCap)
    _GDIPlus_GraphicsDrawLine($cGraphic, $cLeft - $cSize, $cTop, $cLeft, $cTop, $cPen)
EndFunc   ;==>_CreateArrow

Func WM_PAINT($hWnd, $iMsg, $iwParam, $ilParam)
    #forceref $iMsg, $iwParam, $ilParam
    If $hWnd = $Global_GUI Then
        _GDIPlus_GraphicsDrawLine($Global_Graphic, 10 - 3, 10, 10, 10, $Global_Image)
        _WinAPI_RedrawWindow($Global_GUI, "", "", BitOR($RDW_INVALIDATE, $RDW_UPDATENOW, $RDW_FRAME))
    EndIf
    Return "GUI_RUNDEFMSG"
EndFunc   ;==>WM_PAINT

Edited December 17, 2010 by guinness