資訊好好玩

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來源:cww

本範例是以一個stdPicture物件來存圖形，之後於PictureBox中以特殊效果來顯示。
因為我們想顯示的只有一個圖，所以不想多用另一個PictureBox來存原始圖，而後
再畫到另一個PictureBox上，那只有用StdPicture 物件來取代PictureBox(存來源圖)
，但是BitBlt這個繪圖函式需來源與目的的hDc，而StdPicture物件沒有hDc，它只有
一個Handle值，以本例來說，這Handle值便是圖形的hBitmap值。所以我們只好使用
MemoryDC的方式來做，產生一個MemoryDc後將BitMap圖放於其上，之後便可以使用
BitBlt來繪圖了。

'需求一個PictureBox( Named picture2)，一個Command按鍵)
Option Explicit
Private Declare Function BitBlt Lib "gdi32" (ByVal hDestDC As Long, _
                ByVal x As Long, ByVal y As Long, ByVal nWidth As Long, _
                ByVal nHeight As Long, ByVal hSrcDC As Long, _
                ByVal xSrc As Long, ByVal ySrc As Long, _
                ByVal dwRop As Long) As Long
Private Declare Function CreateCompatibleDC Lib "gdi32" _
                (ByVal hdc As Long) As Long
Private Declare Function SelectObject Lib "gdi32"  _
                (ByVal hdc As Long, ByVal hObject As Long) As Long
Private Declare Function DeleteDC Lib "gdi32" (ByVal hdc As Long) As Long
Const SRCCOPY = &HCC0020
Private Picture1 As New StdPicture

Private Sub Command1_Click()
Dim i As Long
Dim j As Long
Dim height5 As Long, width5 As Long
Dim hMemDc As Long

'stdPicture物件的度量單位是Himetric所以要轉換成Pixel
height5 = ScaleY(Picture1.Height, vbHimetric, vbPixels)
If height5 > Picture2.ScaleHeight Then
   height5 = Picture2.ScaleHeight
End If
width5 = ScaleX(Picture1.Width, vbHimetric, vbPixels)
If width5 > Picture2.ScaleWidth Then
   width5 = Picture2.ScaleWidth
End If
'Create Memory DC
hMemDc = CreateCompatibleDC(Picture2.hdc)
'將Picture1的BitMap圖指定給hMemDc
Call SelectObject(hMemDc, Picture1.Handle)
For i = height5 To 1 Step -1
    Call BitBlt(Picture2.hdc, 0, i, width5, 1, _
                hMemDc, 0, i, SRCCOPY)
    For j = i - 1 To 1 Step -1
        Call BitBlt(Picture2.hdc, 0, j, width5, 1, _
                hMemDc, 0, i, SRCCOPY)
    Next j
Next
Call DeleteDC(hMemDc)
End Sub

Private Sub Form_Load()
Dim i As Long
Picture2.ScaleMode = 3 '設定成Pixel的度量單位
'設定待Display的圖
Set Picture1 = LoadPicture("c:\windows\素還真.bmp")
'                          ^^^^^^^^^^^^^^^^^^^^^^
'              Load the picture we want to show
End Sub