#include <File.au3>
#include <GUIConstants.au3>
#include <GUIConstantsEx.au3>
#include <WindowsConstants.au3>
#include <StaticConstants.au3>
#include <EditConstants.au3>
#include <Misc.au3>
#include <Array.au3>
#include <GDIPlus.au3>

;User Changeable Variables
;========================================================================
$pictureFolder = "D:\Wallpapers"
$changeTime = 5 ;Seconds
Global $smWidth = 1600
Global $smHeight = 900
Global $monitorPosition = "Right"
;Global $monitorPosition = "Left"
;========================================================================
Global $imageList = _FileListToArray($pictureFolder)
Global $imageCount = $imageList[0]
Global $imageHeight, $imageWidth, $pHeight, $pWidth, $pic, $gdiPic

_GDIPlus_Startup()
OnAutoItExitRegister("CloseProgram")

$GUIStyle = BitOR($WS_POPUP, $WS_VISIBLE, $HWND_BOTTOM) ;Popup, Visible, Window on Bottom
$GUIStyleEx = BitOR($WS_EX_TRANSPARENT, $WS_EX_TOOLWINDOW) ;Allow Passthrough, Hide from Alt+Tab
$Parent = WinGetHandle('Program Manager', '') ;Sets parent to the program manager, allowing you to right click the desktop
If $monitorPosition = "Right" Then
	$GUI = GUICreate("Secondary Wallpaper", $smWidth, $smHeight, @DesktopWidth, 0, $GUIStyle, $GUIStyleEx, $Parent)
Else
	$GUI = GUICreate("Secondary Wallpaper", $smWidth, $smHeight, (-1 * @DesktopWidth), 0, $GUIStyle, $GUIStyleEx, $Parent)
EndIf
GUISetBkColor(0, $GUI)
_WinAPI_SetWindowPos($GUI, $HWND_BOTTOM, 0, 0, 0, 0, BitOR($SWP_NOACTIVATE, $SWP_NOMOVE, $SWP_NOSIZE, $SWP_SHOWWINDOW)) ;Forces window to bottom of screen
WinSetTrans($GUI, '', 255) ;Sets Window Visible Transparency: Required for mouse passthrough
ChangeImage()
GUISetState(@SW_SHOW) ;Show GUI

While 1
	Sleep($changeTime * 1000)
	ChangeImage()
WEnd

Func ChangeImage()
	$picName = Random(1, $imageCount, 1)
	;Get Dimensions of image
	GetDimensions($imageList[$picName])
	$imageHeight = $pHeight
	$imageWidth = $pWidth

	;Turn them all into integers. (Fixes glitch that caused some images to skip resizing)
	$imageHeight = Int($imageHeight)
	$imageWidth = Int($imageWidth)
	$smHeight = Int($smHeight)
	$smWidth = Int($smWidth)


		;Adjust the image size
	;-----------------------------------------------
	;If the image is bigger than the screen, adjust it
	If $imageWidth > $smWidth = 1 Or $imageHeight > $smHeight = 1 Then
		;Calculate Aspect Ratio of image
		$aspectRatioX = $smWidth / $imageWidth
		$aspectRatioY = $smHeight / $imageHeight
		If $aspectRatioX < $aspectRatioY Then
			$scaleFactor = $aspectRatioX
		Else
			$scaleFactor = $aspectRatioY
		EndIf
		$imageHeight = $imageHeight * $scaleFactor
		$imageWidth = $imageWidth * $scaleFactor
	;Else
		;Image is smaller/same size as monitor
	EndIf

	;Calculate Center of monitor
	;(Monitor size - image size) / 2
	$smCenterX = ($smWidth - $imageWidth) / 2
	$smCenterY = ($smHeight - $imageHeight) / 2

	;Resize the image
	$hHBmp = $pictureFolder & "\" & $imageList[$picName]
	$gdiPic = _GDIPlus_BitmapCreateFromFile($hHBmp) ;convert GDI bitmap to GDI+ bitmap
		_GDIPlus_BitmapDispose($pic)
	$pic = _GDIPlus_ImageResize($gdiPic, $imageWidth, $imageHeight) ;resize image
	_GDIPlus_BitmapDispose($gdiPic)

	GUISetBkColor(0, $GUI)
	Local $hGraphics = _GDIPlus_GraphicsCreateFromHWND($GUI) ;create a graphics object from a window handle
	$gdiPic = _GDIPlus_BitmapCreateFromFile($pictureFolder & "\" & $imageList[$picName])

	_GDIPlus_GraphicsDrawImage($hGraphics, $pic, $smCenterX, $smCenterY) ;display scaled image
	_GDIPlus_GraphicsDispose($hGraphics) ;Garbage Cleanup
EndFunc   ;==>ChangeImage


Func GetDimensions($picName)
	Local $prop, $dArray, $fileSize, $imageDimensionsGDI

	$path = $pictureFolder & "\" & $picName
	$fileSize = FileGetSize($path)
	;Save information to registry for faster access. Compare size of picture to verify changes to picture
	If $fileSize <> RegRead("HKEY_CURRENT_USER\Software\Secondary Wallpaper\Pictures", $picName & " Size") Then
		;File sizes do not match
		RegWrite("HKEY_CURRENT_USER\Software\Secondary Wallpaper\Pictures", $picName & " Size", "REG_SZ", $fileSize)
		$imageDimensionsGDI = _GDIPlus_ImageLoadFromFile($path)
		$pWidth = _GDIPlus_ImageGetWidth($imageDimensionsGDI)
		$pHeight = _GDIPlus_ImageGetHeight($imageDimensionsGDI)
		_GDIPlus_ImageDispose($imageDimensionsGDI)
		RegWrite("HKEY_CURRENT_USER\Software\Secondary Wallpaper\Pictures", $picName & " Width", "REG_SZ", $pWidth)
		RegWrite("HKEY_CURRENT_USER\Software\Secondary Wallpaper\Pictures", $picName & " Height", "REG_SZ", $pHeight)
	Else
		;File sizes match
		$pWidth = RegRead("HKEY_CURRENT_USER\Software\Secondary Wallpaper\Pictures", $picName & " Width")
		$pHeight = RegRead("HKEY_CURRENT_USER\Software\Secondary Wallpaper\Pictures", $picName & " Height")
		If $pWidth = "-1" Or $pHeight = "-1" Then
			RegWrite("HKEY_CURRENT_USER\Software\Secondary Wallpaper\Pictures", $picName & " Size", "REG_SZ", $fileSize)
			$imageDimensionsGDI = _GDIPlus_ImageLoadFromFile($path)
			$pWidth = _GDIPlus_ImageGetWidth($imageDimensionsGDI)
			$pHeight = _GDIPlus_ImageGetHeight($imageDimensionsGDI)
			_GDIPlus_ImageDispose($imageDimensionsGDI)
			RegWrite("HKEY_CURRENT_USER\Software\Secondary Wallpaper\Pictures", $picName & " Width", "REG_SZ", $pWidth)
			RegWrite("HKEY_CURRENT_USER\Software\Secondary Wallpaper\Pictures", $picName & " Height", "REG_SZ", $pHeight)
		EndIf
	EndIf

EndFunc   ;==>GetDimensions



Func CloseProgram()
	;Garbage Cleanup
	_GDIPlus_GraphicsDispose($gdiPic)
	_GDIPlus_Shutdown()
EndFunc   ;==>CloseProgram