HOW TO：使用區域的裁剪
更新：2007 年 11 月
Graphics 類別的其中一個屬性就是裁剪區域 (Clip Region)。由指定 Graphics 物件進行的所有繪製工作都限定只能在該 Graphics 物件的裁剪區域中。您可以藉由呼叫 SetClip 方法來設定裁剪區域。
範例
下列範例會建構只包含單一多邊形的路徑。然後程式碼會根據這個路徑來建構區域。這個區域會傳遞至 Graphics 物件的 SetClip 方法，然後繪製兩個字串。
下圖顯示的是裁剪的字串。
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' Create a path that consists of a single polygon.
Dim polyPoints As Point() = { _
New Point(10, 10), _
New Point(150, 10), _
New Point(100, 75), _
New Point(100, 150)}
Dim path As New GraphicsPath()
path.AddPolygon(polyPoints)
' Construct a region based on the path.
Dim [region] As New [Region](path)
' Draw the outline of the region.
Dim pen As Pen = Pens.Black
e.Graphics.DrawPath(pen, path)
' Set the clipping region of the Graphics object.
e.Graphics.SetClip([region], CombineMode.Replace)
' Draw some clipped strings.
Dim fontFamily As New FontFamily("Arial")
Dim font As New Font( _
fontFamily, _
36, _
FontStyle.Bold, _
GraphicsUnit.Pixel)
Dim solidBrush As New SolidBrush(Color.FromArgb(255, 255, 0, 0))
e.Graphics.DrawString( _
"A Clipping Region", _
font, _
solidBrush, _
New PointF(15, 25))
e.Graphics.DrawString( _
"A Clipping Region", _
font, _
solidBrush, _
New PointF(15, 68))
// Create a path that consists of a single polygon.
Point[] polyPoints = {
new Point(10, 10),
new Point(150, 10),
new Point(100, 75),
new Point(100, 150)};
GraphicsPath path = new GraphicsPath();
path.AddPolygon(polyPoints);
// Construct a region based on the path.
Region region = new Region(path);
// Draw the outline of the region.
Pen pen = Pens.Black;
e.Graphics.DrawPath(pen, path);
// Set the clipping region of the Graphics object.
e.Graphics.SetClip(region, CombineMode.Replace);
// Draw some clipped strings.
FontFamily fontFamily = new FontFamily("Arial");
Font font = new Font(
fontFamily,
36, FontStyle.Bold,
GraphicsUnit.Pixel);
SolidBrush solidBrush = new SolidBrush(Color.FromArgb(255, 255, 0, 0));
e.Graphics.DrawString(
"A Clipping Region",
font, solidBrush,
new PointF(15, 25));
e.Graphics.DrawString(
"A Clipping Region",
font,
solidBrush,
new PointF(15, 68));
編譯程式碼
上述範例是專為與 Windows Form 搭配使用而設計的，而且它需要 PaintEventArgs e (即 PaintEventHandler 的參數)。