GDIPlus, Images, and some unusual behavior

[YellowLab]

I have a script where I take an image and rotate that 90 or 180 degrees. I am having some issues with the image rotated 180 degrees. Here is (a portion) of the script I am using:

_GDIPlus_Startup()

$hImage1 = _GDIPlus_ImageLoadFromFile(@ScriptDir&'\PNGs\'&$sName&'.png')
$hGraphic1 = _GDIPlus_ImageGetGraphicsContext($hImage1)
$hImage2 = _GDIPlus_BitmapCreateFromGraphics($nW,$nH,$hGraphic1)
$hGraphic2 = _GDIPlus_ImageGetGraphicsContext($hImage2)

$matrix = _GDIPlus_MatrixCreate()
_GDIPlus_MatrixRotate($matrix, $nAngle)
_GDIPlus_GraphicsSetTransform($hGraphic2, $matrix)
_GDIPlus_GraphicsDrawImage($hGraphic2, $hImage1, $nXOffset+$nRotOffsetX, $nYOffset+$nRotOffsetY)
_GDIPlus_ImageSaveToFile($hImage2,@ScriptDir&'\test.bmp')

_GDIPlus_MatrixDispose($matrix)
_GDIPlus_GraphicsDispose($hGraphic1)
_GDIPlus_GraphicsDispose($hGraphic2)
_GDIPlus_ImageDispose($hImage1)
_GDIPlus_ImageDispose($hImage2)
_GDIPlus_Shutdown()

The image width in this case is 52 and the heigth is 98. The $nXOffset adn $nYOffset are negative width and heigth, in this instance ($nAngle=180 degree rotation). The $nRotOffSetY is 1 and the $nRotOffSetX is either 0 or 1, but neither work. XOffset1x3.jpg shows the image dump (@300%) when the RotOffsetX is equal to one. It is hard to see, but on the left side of the image there is a black line of missing pixels. Okay, so the offset should be zero. XOffset0x3.jpg shows the image dump (@300%) when RotOffsetX is zero. In this image, you can see that the black line has shifted to the other side. It appears as if the image has become one pixel narrower when rotated 180 degrees. The 90 degree rotation of the image works fine (RotOffsetX=0,RotOffsetY=1) - it comes out to be a 98 by 52 image, edge to edge. (Start1.png shows the original file that is subject to rotation.)

The issue I have is that I am applying the images to a control and conecting a bunch together. With the change in size, they all become misaligned and the end result doesn't look as good as when the images are prerotated.

I don't know if I am missing something in the functions, if this is a bug, or a limitation of the way this script works. Any help would be greatly appreciated. Thanks!

[martin]

Can you post a script which we could try? (Even if we need to use our own png.)

[YellowLab]

Download the "start1.png" attachment in the first post and place it in the script directory:

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#include-once
#include <WinAPI.au3>
#include <GDIPlus.au3>
$nX=52
$nY=98

$hMain=GUICreate("Rotate Test",350,250,0,0)
GUISetBkColor(0x000000)
$hLabel=GUICtrlCreateLabel("",10,10,$nX,$nY)
GUICtrlSetBkColor(-1,0xFF00FF)
$hPicture=GUICtrlCreatePic("",10,10,$nX,$nY)

_GDIPlus_Startup()
$hImage1 = _GDIPlus_ImageLoadFromFile(@ScriptDir&'\start1.png')
$hBMP1=_GDIPlus_BitmapCreateHBITMAPFromBitmap($hImage1)
_WinAPI_DeleteObject(GUICtrlSendMsg($hPicture, 0x0172, 0, $hBMP1))
_GDIPlus_ImageDispose($hImage1)

$hOriginal = GUICtrlCreateButton("Original",200,10,80,30)
$h90 = GUICtrlCreateButton("90 Rotation",200,50,80,30)
$h180_0=GUICtrlCreateButton("180 Rotation, 0",200,90,80,30)
$h180_1=GUICtrlCreateButton("180 Rotation, 1",200,130,80,30)

GUISetState(@SW_SHOW,$hMain)
While 1
    $nMsg=GUIGetMsg()
    Switch $nMsg
        Case -3
            Exit
        Case $hOriginal
            $nX=52
            $nY=98
            GUICtrlDelete($hPicture)
            GUICtrlDelete($hLabel)
            $hLabel=GUICtrlCreateLabel("",10,10,$nX,$nY)
            GUICtrlSetBkColor(-1,0xFF00FF)
            $hPicture=GUICtrlCreatePic("",10,10,$nX,$nY)
            $hImage1 = _GDIPlus_ImageLoadFromFile(@ScriptDir&'\start1.png')
            $hBMP1=_GDIPlus_BitmapCreateHBITMAPFromBitmap($hImage1)
            _WinAPI_DeleteObject(GUICtrlSendMsg($hPicture, 0x0172, 0, $hBMP1))
            _GDIPlus_ImageDispose($hImage1)
        Case $h90
            $nX=98
            $nY=52
            $nAngle=90
            $nRotOffsetX=0
            $nRotOffsetY=1
            $nXOffset=0
            $nYOffset=-$nX
            _Rotate($nX,$nY,$nAngle,$nRotOffsetX,$nRotOffsetY,$nXOffset,$nYOffset)
        Case $h180_0
            $nX=52
            $nY=98
            $nAngle=180
            $nRotOffsetX=0
            $nRotOffsetY=1
            $nXOffset=-$nX
            $nYOffset=-$nY
            _Rotate($nX,$nY,$nAngle,$nRotOffsetX,$nRotOffsetY,$nXOffset,$nYOffset)
        Case $h180_1
            $nX=52
            $nY=98
            $nAngle=180
            $nRotOffsetX=1
            $nRotOffsetY=1
            $nXOffset=-$nX
            $nYOffset=-$nY
            _Rotate($nX,$nY,$nAngle,$nRotOffsetX,$nRotOffsetY,$nXOffset,$nYOffset)
    EndSwitch
WEnd

GUIDelete($hMain)
_GDIPlus_Shutdown()

Func _Rotate($nW,$nH,$nAngle,$nRotOffsetX,$nRotOffsetY,$nXOffset,$nYOffset)
    GUICtrlDelete($hPicture)
    GUICtrlDelete($hLabel)
    
    $hLabel=GUICtrlCreateLabel("",10,10,$nX,$nY)
    GUICtrlSetBkColor(-1,0xFF00FF)
    $hPicture=GUICtrlCreatePic("",10,10,$nX,$nY)
    
    $hImage1 = _GDIPlus_ImageLoadFromFile(@ScriptDir&'\start1.png')
    $hGraphic1 = _GDIPlus_ImageGetGraphicsContext($hImage1)
    $hImage2 = _GDIPlus_BitmapCreateFromGraphics($nW,$nH,$hGraphic1)
    $hGraphic2 = _GDIPlus_ImageGetGraphicsContext($hImage2)
    $matrix = _GDIPlus_MatrixCreate()
    _GDIPlus_MatrixRotate($matrix, $nAngle)
    _GDIPlus_GraphicsSetTransform($hGraphic2, $matrix)
    _GDIPlus_GraphicsDrawImage($hGraphic2, $hImage1, $nXOffset+$nRotOffsetX, $nYOffset+$nRotOffsetY)
    Local $hBMP1=_GDIPlus_BitmapCreateHBITMAPFromBitmap($hImage2)
    _WinAPI_DeleteObject(GUICtrlSendMsg($hPicture, 0x0172, 0, $hBMP1))
    
    _GDIPlus_MatrixDispose($matrix)
    _GDIPlus_GraphicsDispose($hGraphic1)
    _GDIPlus_GraphicsDispose($hGraphic2)
    _GDIPlus_ImageDispose($hImage1)
    _GDIPlus_ImageDispose($hImage2)
EndFunc

This will draw a GUI with a black background. A pink rectangle the same size as the image will be drawn underneath. The buttons will rotate the image and the rectangle. I found with this that the 90 degree rotation also has the same problem - dropped pixels on the the right side. This can clearly be seen with this script - the pink line on the right side of the image after rotation. I am begining to think that there is a flaw in how this rotation is completed that results in the dropped pixels.

Edit: Not the most efficient code - but demonstrates the point

Edited January 19, 2010 by YellowLab

[YellowLab]

Thank the light for the internet. Digging around MSDN I found this function: GDIPlus RotateFlip. It seemed to be what I wanted and doing a search for the function lead me to this autoit post:

http://www.autoitscript.com/forum/index.php?showtopic=101283

Implementing that function works like a charm:

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#include-once
#include <WinAPI.au3>
#include <GDIPlus.au3>

Global enum _
    $RotateNoneFlipNone = 0 , _
    $Rotate90FlipNone = 1 , _
    $Rotate180FlipNone = 2 , _
    $Rotate270FlipNone = 3 , _
    $RotateNoneFlipX = 4 , _
    $Rotate90FlipX = 5 , _
    $Rotate180FlipX = 6 , _
    $Rotate270FlipX = 7 , _
    $RotateNoneFlipY = 6 , _
    $Rotate90FlipY = 7 , _
    $Rotate180FlipY = 4 , _
    $Rotate270FlipY = 5 , _
    $RotateNoneFlipXY = 6 , _
    $Rotate90FlipXY = 7 , _
    $Rotate180FlipXY = 0 , _
    $Rotate270FlipXY = 1


$nX=52
$nY=98

$hMain=GUICreate("Rotate Test",350,250,0,0)
GUISetBkColor(0x000000)
$hLabel=GUICtrlCreateLabel("",10,10,$nX,$nY)
GUICtrlSetBkColor(-1,0xFF00FF)
$hPicture=GUICtrlCreatePic("",10,10,$nX,$nY)

_GDIPlus_Startup()
$hImage1 = _GDIPlus_ImageLoadFromFile(@ScriptDir&'\start1.png')
$hBMP1=_GDIPlus_BitmapCreateHBITMAPFromBitmap($hImage1)
_WinAPI_DeleteObject(GUICtrlSendMsg($hPicture, 0x0172, 0, $hBMP1))

$hOriginal = GUICtrlCreateButton("Original",200,10,80,30)
$h90 = GUICtrlCreateButton("90 Rotation",200,50,80,30)
$h180_0=GUICtrlCreateButton("180 Rotation, 0",200,90,80,30)
$h180_1=GUICtrlCreateButton("180 Rotation, 1",200,130,80,30)

GUISetState(@SW_SHOW,$hMain)
While 1
    $nMsg=GUIGetMsg()
    Switch $nMsg
        Case -3
            Exit
        Case $hOriginal
            $nX=52
            $nY=98
            GUICtrlDelete($hPicture)
            GUICtrlDelete($hLabel)
            $hLabel=GUICtrlCreateLabel("",10,10,$nX,$nY)
            GUICtrlSetBkColor(-1,0xFF00FF)
            $hPicture=GUICtrlCreatePic("",10,10,$nX,$nY)
            $hImage1 = _GDIPlus_ImageLoadFromFile(@ScriptDir&'\start1.png')
            $hBMP1=_GDIPlus_BitmapCreateHBITMAPFromBitmap($hImage1)
            _WinAPI_DeleteObject(GUICtrlSendMsg($hPicture, 0x0172, 0, $hBMP1))
            _GDIPlus_ImageDispose($hImage1)
        Case $h90
            $nX=98
            $nY=52
            $nAngle=$Rotate90FlipNone
            _RotateImage($nX,$nY,$nAngle)
        Case $h180_0
            $nX=52
            $nY=98
            $nAngle=$Rotate180FlipNone
            _RotateImage($nX,$nY,$nAngle)
        Case $h180_1
            $nX=52
            $nY=98
            $nAngle=$Rotate180FlipNone
            _RotateImage($nX,$nY,$nAngle)
    EndSwitch
WEnd

GUIDelete($hMain)
_GDIPlus_ImageDispose($hImage1)
_GDIPlus_Shutdown()

Func _RotateImage($nW,$nH,$nRotation)
    GUICtrlDelete($hPicture)
    GUICtrlDelete($hLabel)
    
    $hLabel=GUICtrlCreateLabel("",10,10,$nW,$nH)
    GUICtrlSetBkColor(-1,0xFF00FF)
    $hPicture=GUICtrlCreatePic("",10,10,$nW,$nH)
    
    $hImage1 = _GDIPlus_ImageLoadFromFile(@ScriptDir&'\start1.png')
    DllCall($ghGDIPDll,"int","GdipImageRotateFlip","hwnd",$hImage1,"long",$nAngle)
    Local $hBMP1=_GDIPlus_BitmapCreateHBITMAPFromBitmap($hImage1)
    _WinAPI_DeleteObject(GUICtrlSendMsg($hPicture, 0x0172, 0, $hBMP1))
EndFunc

While it solves my problem of the image rotation, it doesn't answer the original question of where the missing pixels went.