Clearing a graphic drawn over a background image

[AndyK]

I'm trying to develop an application that draws a graphic when a spot on a background image is clicked. Unfortunately, when I try to clear the previously drawn graphic, it also clears the background image to black. I believe I understand this is happening because my graphic object is derived from the actual window, but so how would i fix this? I also need to be able to capture the coordinates of the mouse click relative to the image, which works fine as I have implemented it but might influence a fix for my problem. Im still trying to understand some of the features of AutoIt, so if you could explain what I'm doing wrong so that I understand, that would be great. Maybe this has been answered in another topic, but everything I have found so far was too complex for me to understand currently (I am a contractor who specializes in things that go bang).

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#include <GuiConstantsEx.au3>
#include <WindowsConstants.au3>
#include <AVIConstants.au3>
#include <TreeViewConstants.au3>
#include <GDIPlus.au3>
Opt("MouseCoordMode",2)

$settingsFile="c:\RHCV\IMS\settings.ini"
Local $settingsData[3][2] = [ ["LocationImage",""], ["LocationX",0], ["LocationY",0] ]
IniWriteSection($settingsFile,"Settings",$settingsData,0)

$file = FileOpenDialog("Please select a BMP, GIF or JPG...","C:\Users\user\Pictures\", "Images (*.jpg;*.bmp;*.gif)", 1+4+8)
IniWrite($settingsFile,"Settings","LocationImage",$file)

_GDIPlus_Startup()
$hImage = _GDIPlus_ImageLoadFromFile($file)
$iX = _GDIPlus_ImageGetWidth($hImage)
$iY = _GDIPlus_ImageGetHeight($hImage)
_GDIPlus_ImageDispose($hImage)


$looping = True
While $looping
    If @DesktopHeight < $iY Then
        $iX *= 0.75
        $iY *= 0.75
    ElseIf @DesktopWidth < $iX Then
        $iX *= 0.75
        $iY *= 0.75
    Else
        $looping = False
    EndIf
WEnd

$hWnd = GUICreate("TEST TEST TEST", $iX, $iY)
$pic = GUICtrlCreatePic("",0,0,$iX,$iY,$WS_CLIPSIBLINGS)
GUICtrlSetState(-1,$GUI_DISABLE)
GUICtrlSetImage($pic,$file)

$oGraphic = _GDIPlus_GraphicsCreateFromHWND($hWnd)
$hBrush = _GDIPlus_BrushCreateSolid(0xFF00FF00)

GUISetState(@SW_SHOW, $hWnd)

While 1
    $msg = GUIGetMsg(1)

    If $msg[0] = $GUI_EVENT_CLOSE Then ExitLoop

    If $msg[0] = $GUI_EVENT_PRIMARYDOWN Then
        If ($msg[3] >= 0) AND ($msg[3] <= $iX) AND ($msg[4] >= 0) AND ($msg[4] <= $iY) Then
            MsgBox(0,"","X: " & $msg[3] & "; Y: " & $msg[4])
            ;Really just need to update the original array with these values
            ;IniWrite($settingsFile,"Settings","LocationX",$msg[3])
            ;IniWrite($settingsFile,"Settings","LocationY",$msg[4])
            _GDIPlus_GraphicsClear($oGraphic,0x00FFFFFF)
            _GDIPlus_GraphicsFillRect($oGraphic, $msg[3]-4, $msg[4]-4, 9, 9, $hBrush)
        Else
            MsgBox(0,"","Please select a location on the actual picture.")
        EndIf
    EndIf

    ;$mouse = MouseGetPos()
    ;GUICtrlSetData($label,"X: " & $mouse[0] &"; Y: " & $mouse[1])
WEnd

_GDIPlus_BrushDispose($hBrush)
_GDIPlus_GraphicsDispose($oGraphic)
_GDIPlus_Shutdown()

Any help is appreciated...

Edited June 14, 2011 by AndyK

[UEZ]

Try this:

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#include <GuiConstantsEx.au3>
#include <WindowsConstants.au3>
#include <AVIConstants.au3>
#include <TreeViewConstants.au3>
#include <GDIPlus.au3>
Opt("MouseCoordMode",2)

$settingsFile="c:\RHCV\IMS\settings.ini"
Local $settingsData[3][2] = [ ["LocationImage",""], ["LocationX",0], ["LocationY",0] ]
IniWriteSection($settingsFile,"Settings",$settingsData,0)

$file = FileOpenDialog("Please select a BMP, GIF or JPG...","C:\Users\user\Pictures\", "Images (*.jpg;*.bmp;*.gif)", 1+4+8)
IniWrite($settingsFile,"Settings","LocationImage",$file)

_GDIPlus_Startup()
$hImage = _GDIPlus_ImageLoadFromFile($file)
$iX = _GDIPlus_ImageGetWidth($hImage)
$iY = _GDIPlus_ImageGetHeight($hImage)

$looping = True
While $looping
    If @DesktopHeight < $iY Then
        $iX *= 0.75
        $iY *= 0.75
    ElseIf @DesktopWidth < $iX Then
        $iX *= 0.75
        $iY *= 0.75
    Else
        $looping = False
    EndIf
WEnd

$hWnd = GUICreate("TEST TEST TEST", $iX, $iY)
$pic = GUICtrlCreatePic("",0,0,$iX,$iY,$WS_CLIPSIBLINGS)
GUICtrlSetState(-1,$GUI_DISABLE)
GUICtrlSetImage($pic,$file)

$oGraphic = _GDIPlus_GraphicsCreateFromHWND($hWnd)
$hBrush = _GDIPlus_BrushCreateSolid(0xFF00FF00)
GUISetState(@SW_SHOW, $hWnd)
_GDIPlus_GraphicsDrawImageRect($oGraphic, $hImage, 0, 0, $iX, $iY)

While 1
    $msg = GUIGetMsg(1)

    If $msg[0] = $GUI_EVENT_CLOSE Then ExitLoop

    If $msg[0] = $GUI_EVENT_PRIMARYDOWN Then
        If ($msg[3] >= 0) AND ($msg[3] <= $iX) AND ($msg[4] >= 0) AND ($msg[4] <= $iY) Then
            MsgBox(0,"","X: " & $msg[3] & "; Y: " & $msg[4])
            ;Really just need to update the original array with these values
            ;IniWrite($settingsFile,"Settings","LocationX",$msg[3])
            ;IniWrite($settingsFile,"Settings","LocationY",$msg[4])
;~             _GDIPlus_GraphicsClear($oGraphic,0xFF000000) ;not needed in this case
            _GDIPlus_GraphicsDrawImageRect($oGraphic, $hImage, 0, 0, $iX, $iY) ;comment this out if the drawn green squares shouldn't be cleaned
            _GDIPlus_GraphicsFillRect($oGraphic, $msg[3]-4, $msg[4]-4, 9, 9, $hBrush)
        Else
            MsgBox(0,"","Please select a location on the actual picture.")
        EndIf
    EndIf

    ;$mouse = MouseGetPos()
    ;GUICtrlSetData($label,"X: " & $mouse[0] &"; Y: " & $mouse[1])
WEnd
_GDIPlus_ImageDispose($hImage)
_GDIPlus_BrushDispose($hBrush)
_GDIPlus_GraphicsDispose($oGraphic)
_GDIPlus_Shutdown()

Br,

UEZ

[rover]

You can also replace GDIPlus_GraphicsClear() with _WinAPI_InvalidateRect($hPic, 0, False)

add this include

#include <WinAPI.au3>

and add this line below $pic = GUICtrlCreatePic()

Global $hPic = GUICtrlGetHandle($pic)

InvalidateRect() will force the pic control to be redrawn

Edited June 15, 2011 by rover

[UEZ]

It was too late yesterday evening to see that you display the picture in pic control.

However, disadvantage using pic control is that you cannot use png images.

Br,

UEZ

[AndyK]

Thank you both for the help...

@ UEZ

_GDIPlus_GraphicsDrawImageRect($oGraphic,$hImage, 0, 0, $iX, $iY) ;comment this out if the drawn green squares shouldn't be cleaned

Just so I understand, is this line basically just printing the image on top of everything that was previously drawn, thereby 'erasing' it?

Edited June 15, 2011 by AndyK

[UEZ]

With _GDIPlus_GraphicsDrawImageRect($oGraphic,$hImage, 0, 0, $iX, $iY) you are copying the image to the graphic handle again. That means it will erase previous screen. If you disable this line you will paint over that background image.

I hope I've explained it well.

Br,

UEZ

[AndyK]

Ah okay I see, yes that was a good explaination. Thanks again for the help.