#include <GDIPlus.au3>
#include <GUIConstantsEx.au3>
#include <MsgBoxConstants.au3>
#include <WindowsConstants.au3>

Opt("GUIOnEventMode", 1)

Global $g_idCombo, $g_hGfx_Buffer, $g_hGfx_Buffer_H, $g_hGui, $g_hGraphics, $g_hGraphics_H, $g_hBmp_Buffer_H, $g_hImage, $g_hBmp_Buffer, $g_hGui_Histogram
Global $g_tChannel, $g_iMaxLum

_Example()

Func _Example()
    Local $sFile = FileOpenDialog("Sélectionnez une image", "", "Images (*.bmp;*.png;*.jpg;*.gif;*.tif)")
    If @error Or Not FileExists($sFile) Then Return

    If Not _GDIPlus_Startup() Then
        MsgBox($MB_SYSTEMMODAL, "ERROR", "GDIPlus.dll v1.1 not available")
        Return
    EndIf

    $g_hImage = _GDIPlus_ImageLoadFromFile($sFile)

    Local $iWidth = 600
    Local $iHeight = _GDIPlus_ImageGetHeight($g_hImage) * 600 / _GDIPlus_ImageGetWidth($g_hImage)

    $g_hGui = GUICreate("GDI+ v1.1", $iWidth, $iHeight)
    GUISetOnEvent($GUI_EVENT_CLOSE, "_Exit")
    $g_hGraphics = _GDIPlus_GraphicsCreateFromHWND($g_hGui)
    $g_hBmp_Buffer = _GDIPlus_BitmapCreateFromScan0($iWidth, $iHeight)
    $g_hGfx_Buffer = _GDIPlus_ImageGetGraphicsContext($g_hBmp_Buffer)
    _GDIPlus_GraphicsDrawImageRect($g_hGfx_Buffer, $g_hImage, 0, 0, $iWidth, $iHeight)

    $g_hGui_Histogram = GUICreate("Histogram", 266, 160)
    GUISetOnEvent($GUI_EVENT_CLOSE, "_Exit")
    $g_idCombo = GUICtrlCreateCombo("", 10, 132, 246, 20)
    GUICtrlSetData(-1, "Alpha|Red|Green|Blue|Grey", "Red")
    GUICtrlSetOnEvent(-1, "_CreateHistogram")
    $g_hGraphics_H = _GDIPlus_GraphicsCreateFromHWND($g_hGui_Histogram)
    $g_hBmp_Buffer_H = _GDIPlus_BitmapCreateFromScan0(259, 122)
    $g_hGfx_Buffer_H = _GDIPlus_ImageGetGraphicsContext($g_hBmp_Buffer_H)
    _GDIPlus_GraphicsSetSmoothingMode($g_hGfx_Buffer_H, 2)

    $g_iMaxLum = _GetHistogramMaxLum()
    _CreateHistogram()

    GUIRegisterMsg($WM_PAINT, "WM_PAINT")
    GUIRegisterMsg($WM_ERASEBKGND, "WM_PAINT")
    GUISetState(@SW_SHOW, $g_hGui)
    GUISetState(@SW_SHOW, $g_hGui_Histogram)

    GUISetOnEvent($GUI_EVENT_MOUSEMOVE, "_ToolTip", $g_hGui_Histogram)

    While Sleep(10)
    WEnd

EndFunc   ;==>_Example

Func _ToolTip()
    Local $aInfo = GUIGetCursorInfo($g_hGui_Histogram)
    If IsArray($aInfo) Then
        If $aInfo[0] < 0 Or $aInfo[0] > 266 Or $aInfo[1] < 0 Or $aInfo[1] > 160 Then Return

        Local $iIndex = $aInfo[0] - 5
        If $iIndex < 1 Then
            $iIndex = 1
        ElseIf $iIndex > 256 Then
            $iIndex = 256
        EndIf

        Local $iValue = DllStructGetData($g_tChannel, 1, $iIndex)

        ToolTip("Index: " & $iIndex & ", Value: " & $iValue)
    EndIf
EndFunc   ;==>_ToolTip

Func _GetHistogramMaxLum()
    Local $iSize = _GDIPlus_BitmapGetHistogramSize($GDIP_HistogramFormatGray)
    Local $tChannel_Grey = DllStructCreate("uint[" & $iSize & "];")
    _GDIPlus_BitmapGetHistogram($g_hImage, $GDIP_HistogramFormatGray, $iSize, $tChannel_Grey)

    Local $iMaxLum = 0
    For $i = 1 To $iSize
        If DllStructGetData($tChannel_Grey, 1, $i) > $iMaxLum Then $iMaxLum = DllStructGetData($tChannel_Grey, 1, $i)
    Next
    Return $iMaxLum
EndFunc   ;==>_GetHistogramMaxLum

Func _CreateHistogram()
    Local $iHistogramFormat, $iColor

    Switch GUICtrlRead($g_idCombo)
        Case "Alpha"
            $iHistogramFormat = $GDIP_HistogramFormatA
            $iColor = 0xFFFF00FF
        Case "Red"
            $iHistogramFormat = $GDIP_HistogramFormatR
            $iColor = 0xFFFF0000
        Case "Green"
            $iHistogramFormat = $GDIP_HistogramFormatG
            $iColor = 0xFF00FF00
        Case "Blue"
            $iHistogramFormat = $GDIP_HistogramFormatB
            $iColor = 0xFF0000FF
        Case "Grey"
            $iHistogramFormat = $GDIP_HistogramFormatGray
            $iColor = 0xFFFFFFFF
        Case Else
            Return
    EndSwitch

    Local $iSize = _GDIPlus_BitmapGetHistogramSize($iHistogramFormat)
    $g_tChannel = DllStructCreate("uint[" & $iSize & "];")

    _GDIPlus_BitmapGetHistogram($g_hImage, $iHistogramFormat, $iSize, $g_tChannel)

    Local $fScale = 1 / $g_iMaxLum * 100
    Local $aPoly[$iSize + 3][2] = [[$iSize + 2]]
    For $i = 1 To $iSize
        $aPoly[$i][0] = $i
        $aPoly[$i][1] = 100 - DllStructGetData($g_tChannel, 1, $i) * $fScale
    Next
    $aPoly[$iSize + 1][0] = $iSize + 1
    $aPoly[$iSize + 1][1] = 100
    $aPoly[$iSize + 2][0] = 1
    $aPoly[$iSize + 2][1] = 100

    _GDIPlus_GraphicsClear($g_hGfx_Buffer_H, 0xFFFFFFFF)
    Local $hBrush = _GDIPlus_LineBrushCreate(1, 0, 258, 0, 0xFF000000, $iColor)
    _GDIPlus_GraphicsFillPolygon($g_hGfx_Buffer_H, $aPoly, $hBrush)
    _GDIPlus_GraphicsFillRect($g_hGfx_Buffer_H, 1, 104, 256, 16, $hBrush)
    _GDIPlus_BrushDispose($hBrush)

    Local $hPen = _GDIPlus_PenCreate(0xFF000000)
    _GDIPlus_GraphicsDrawPolygon($g_hGfx_Buffer_H, $aPoly, $hPen)
    _GDIPlus_GraphicsDrawRect($g_hGfx_Buffer_H, 0, 0, 258, 100, $hPen)
    _GDIPlus_GraphicsDrawRect($g_hGfx_Buffer_H, 0, 103, 258, 18, $hPen)
    _GDIPlus_PenDispose($hPen)

    _GDIPlus_GraphicsDrawImage($g_hGraphics_H, $g_hBmp_Buffer_H, 4, 4)
EndFunc   ;==>_CreateHistogram

Func WM_PAINT($hWnd, $iMsgm, $wParam, $lParam)
    #forceref $iMsgm, $wParam, $lParam
    Switch $hWnd
        Case $g_hGui
            _GDIPlus_GraphicsDrawImage($g_hGraphics, $g_hBmp_Buffer, 0, 0)
        Case $g_hGui_Histogram
            _GDIPlus_GraphicsDrawImage($g_hGraphics_H, $g_hBmp_Buffer_H, 4, 4)
    EndSwitch
    Return $GUI_RUNDEFMSG
EndFunc   ;==>WM_PAINT

Func _Exit()
    _GDIPlus_ImageDispose($g_hImage)
    _GDIPlus_GraphicsDispose($g_hGfx_Buffer_H)
    _GDIPlus_BitmapDispose($g_hBmp_Buffer_H)
    _GDIPlus_GraphicsDispose($g_hGraphics_H)
    _GDIPlus_GraphicsDispose($g_hGfx_Buffer)
    _GDIPlus_BitmapDispose($g_hBmp_Buffer)
    _GDIPlus_GraphicsDispose($g_hGraphics)
    _GDIPlus_Shutdown()
    Exit
EndFunc   ;==>_Exit