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  • vb教程之雨滴式的顯示圖片

  • 2017-09-21 16:28 來源:未知
 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,而后再畫到另一個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\aaa.bmp") 

' ^^^^^^^^^^^^^^^^^^^^^^ 

' Load the picture we want to show 

End Sub 
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