圖形縮放

利用Image類別提供的相關功能或是利用PictureBox我們可以很簡單的載入或是顯示圖形在畫面上，那麼如果要縮/放圖形的話應該要怎麼做呢？請參考看看下面程式碼

Dim img As Image
img = Image.FromFile(Application.StartupPath & "\MyImages\9F.jpg")
Dim G As Graphics = PictureBox2.CreateGraphics
Dim P(2) As Point
''左上
P(0) = New Point(0, 0)
''右上
P(1) = New Point(100, 0)
''左下
P(2) = New Point(0, 100)
G.DrawImage(img, P)

相關參考
ms-help://MS.VSCC.v80/MS.MSDN.v80/MS.NETDEVFX.v20.cht/cpref8/html/M_System_Drawing_Graphics_DrawImage_1_d482ade5.htm
或是可以直接上MSDN查詢有關DrawImage相關的部分
如果要把修改後的圖存成另外的檔案可以參考下面程式碼

Dim img As Image
Dim B As New Bitmap(100, 100)
img = Image.FromFile(Application.StartupPath & "\MyImages\9F.jpg")
Dim G As Graphics = Graphics.FromImage(B)
Dim P(2) As Point
''左上
P(0) = New Point(0, 0)
''右上
P(1) = New Point(100, 0)
''左下
P(2) = New Point(0, 100)
G.DrawImage(img, P)
B.Save(Application.StartupPath & "\tmp.jpg")

如果想要存到MemoryStream裡面可以參考下面程式碼，其實都是大同小異

Dim img As Image
Dim B As New Bitmap(100, 100)
img = Image.FromFile(Application.StartupPath & "\MyImages\9F.jpg")
Dim G As Graphics = Graphics.FromImage(B)
Dim P(2) As Point
''左上
P(0) = New Point(0, 0)
''右上
P(1) = New Point(100, 0)
''左下
P(2) = New Point(0, 100)
G.DrawImage(img, P)
Dim MS As New IO.MemoryStream
B.Save(MS, Imaging.ImageFormat.Jpeg)