GDIpHelper.ahk

JustTheBasics() {
	global
	
	; Start gdi+
	If !pToken := Gdip_Startup()
	{
		MsgBox, 48, gdiplus error!, Gdiplus failed to start. Please ensure you have gdiplus on your system
		ExitApp
	}
	OnExit, Exit
	return
	
	
	Exit:
	; gdi+ may now be shutdown on exiting the program
	Gdip_Shutdown(pToken)
	ExitApp
	Return

}

SetUpGDIP(iWidth=-1, iHeight=-1) {
	global
	Width := iWidth
	Height := iHeight
	If (iWidth < 0) {
		Width := A_ScreenWidth
	}
	if (iHeight < 0) {
		height := A_ScreenHeight
	}
	
	
	JustTheBasics()
	
	; Create a layered window (+E0x80000 : must be used for UpdateLayeredWindow to work!) that is always on top (+AlwaysOnTop), has no taskbar entry or caption
	Gui, 1: -Caption +E0x80000 +LastFound +AlwaysOnTop +ToolWindow +OwnDialogs

	; Show the window
	Gui, 1: Show, NA

	; Get a handle to this window we have created in order to update it later
	hwnd1 := WinExist()
	return
}

StartDrawGDIP() {
	global
	
	; Create a gdi bitmap with width and height of what we are going to draw into it. This is the entire drawing area for everything
	hbm := CreateDIBSection(Width, Height)

	; Get a device context compatible with the screen
	hdc := CreateCompatibleDC()

	; Select the bitmap into the device context
	obm := SelectObject(hdc, hbm)

	; Get a pointer to the graphics of the bitmap, for use with drawing functions
	G := Gdip_GraphicsFromHDC(hdc)	
}

EndDrawGDIP() {
	global
	
	; Update the specified window we have created (hwnd1) with a handle to our bitmap (hdc), specifying the x,y,w,h we want it positioned on our screen
	; So this will position our gui at (0,0) with the Width and Height specified earlier
	UpdateLayeredWindow(hwnd1, hdc, 0, 0, Width, Height)


	; Select the object back into the hdc
	SelectObject(hdc, obm)

	; Now the bitmap may be deleted
	DeleteObject(hbm)

	; Also the device context related to the bitmap may be deleted
	DeleteDC(hdc)

	; The graphics may now be deleted
	Gdip_DeleteGraphics(G)
}

ClearDrawGDIP() {
	global
	Gdip_GraphicsClear(G)
}