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雨滴式的顯示圖片
? 本范例是以一個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 $#@62; Picture2.ScaleHeight Then
height5 = Picture2.ScaleHeight
End If
width5 = ScaleX(Picture1.Width, vbHimetric, vbPixels)
If width5 $#@62; 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 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
作者:http://www.zhujiangroad.com
來源:http://www.zhujiangroad.com
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