HOW TO：複製影像
更新：2007 年 11 月
.NET Compact Framework 不支援 Image.Clone 方法，但您仍可複製影像和影像的某個部分。下列範例顯示如何執行下列作業：
定義用以建立點陣圖的方法
定義多載方法，以便複製一個點陣圖或複製點陣圖的某個部分
可藉由覆寫表單的 OnPaint 方法，呼叫這些方法並將影像繪製到螢幕
若要建立點陣圖
- 這個方法會建立點陣圖，以供示範使用。
' Creates a bitmap for copying.
Function CreateBitmap(sideSize As Integer) As Bitmap
Dim bmp As New Bitmap(sideSize, sideSize)
Dim g As Graphics = Graphics.FromImage(bmp)
g.FillEllipse(New SolidBrush(Color.Red), 0, 0, sideSize, sideSize)
g.DrawLine(New Pen(Color.Black), 0, 0, sideSize, sideSize)
g.DrawLine(New Pen(Color.Black), sideSize, 0, 0, sideSize)
g.Dispose()
Return bmp
End Function
// Creates a bitmap for copying.
private Bitmap CreateBitmap(int sideSize)
{
Bitmap bmp = new Bitmap(sideSize, sideSize);
Graphics g = Graphics.FromImage(bmp);
g.FillEllipse(new SolidBrush(Color.Red), 0, 0, sideSize, sideSize);
g.DrawLine(new Pen(Color.Black), 0, 0, sideSize, sideSize);
g.DrawLine(new Pen(Color.Black), sideSize, 0, 0, sideSize);
g.Dispose();
return bmp;
}
若要複製點陣圖
- 這個方法多載會將來源點陣圖當做參數，並將點陣圖做為複本傳回。
' Copies the entire bitmap.
Overloads Function CopyBitmap(source As Bitmap) As Bitmap
Return New Bitmap(source)
End Function
// Copies the entire bitmap.
protected Bitmap CopyBitmap(Bitmap source)
{
return new Bitmap(source);
}
若要複製點陣圖的某個部分
- 這個方法多載會將 Rectangle 當做參數，以決定要傳回之點陣圖部分的維度。
' Copies a part of the bitmap.
Overloads Function CopyBitmap(source As Bitmap, part As Rectangle) As Bitmap
Dim bmp As New Bitmap(part.Width, part.Height)
Dim g As Graphics = Graphics.FromImage(bmp)
g.DrawImage(source, 0, 0, part, GraphicsUnit.Pixel)
g.Dispose()
Return bmp
End Function
// Copies a part of a bitmap.
protected Bitmap CopyBitmap(Bitmap source, Rectangle part)
{
Bitmap bmp = new Bitmap(part.Width, part.Height);
Graphics g = Graphics.FromImage(bmp);
g.DrawImage(source,0,0,part,GraphicsUnit.Pixel);
g.Dispose();
return bmp;
}
若要建立、複製和繪製點陣圖
- 這個 OnPaint 方法多載會呼叫用以建立點陣圖，然後複製其中某部分的方法。它還會將所複製的點陣圖儲存至檔案。
' Draws the bitmaps on the form.
Protected Overrides Sub OnPaint(e As PaintEventArgs)
Dim arialFont As Font
Dim blackBrush As Brush
arialFont = New Font("Arial", 10, FontStyle.Regular)
blackBrush = New SolidBrush(Color.Black)
' Set the size of the sides of the bitmap,
' and get one-third of it for the center bitmap.
Dim sidesize As Integer = 75
Dim third As Integer = CInt(sidesize / 3)
' Create bitmap.
Dim source As Bitmap = CreateBitmap(sidesize)
' Copy entirely as a clone.
Dim clone As Bitmap = CopyBitmap(source)
' Copy the center part of the bitmap.
Dim center As Bitmap = _
CopyBitmap(source, New Rectangle(third, third, third, third))
' Save the bitmap to a file.
clone.Save("newbitmap.bmp", ImageFormat.Bmp)
' Draw the source, clone, and partial
' bitmaps vertically down the screen.
Dim y As Integer = 10
e.Graphics.DrawString("source bitmap:", ArialFont, BlackBrush, 10, y)
y += 20
e.Graphics.DrawImage(source, 10, y)
y += source.Height + 10
e.Graphics.DrawString("clone bitmap:", ArialFont, BlackBrush, 10, y)
y += 20
e.Graphics.DrawImage(clone, 10, y)
y += clone.Height + 10
e.Graphics.DrawString("center part of bitmap:", ArialFont, BlackBrush, 10, y)
y += 20
e.Graphics.DrawImage(center, 10, y)
y += center.Height + 10
' Dispose graphic objects.
arialFont.Dispose()
blackBrush.Dispose()
End Sub
// Draws the bitmaps on the form.
protected override void OnPaint(PaintEventArgs e)
{
Font arialFont;
Brush blackBrush;
arialFont = new Font("Arial", 10, FontStyle.Regular);
blackBrush = new SolidBrush(Color.Black);
// Set the size of the sides of the bitmap,
// and get one-third of it for the center bitmap.
int sidesize = 75;
int third = (int) sidesize/3;
// Create bitmap.
source = CreateBitmap(sidesize);
// Copy entirely as a clone.
clone = CopyBitmap(source);
// Copy the center part of the bitmap.
center = CopyBitmap(source, new Rectangle(third, third, third, third));
// Save the bitmap to a file.
clone.Save("newbitmap.bmp", ImageFormat.Bmp);
// Draw the source, clone, and partial
// bitmaps vertically down the screen.
int y = 10;
e.Graphics.DrawString("source bitmap:", arialFont, blackBrush, 10, y);
y += 20;
e.Graphics.DrawImage(source, 10, y);
y += source.Height + 10;
e.Graphics.DrawString("clone bitmap:", arialFont, blackBrush, 10, y);
y += 20;
e.Graphics.DrawImage(clone, 10, y);
y += clone.Height + 10;
e.Graphics.DrawString("center part of bitmap:", arialFont, blackBrush, 10, y);
y += 20;
e.Graphics.DrawImage(center, 10, y);
y += center.Height + 10;
// Dispose graphic objects.
arialFont.Dispose();
blackBrush.Dispose();
}
編譯程式碼
這個範例需要下列命名空間的參考：
穩固程式設計
請注意，Font 和 Brush 物件已在 OnPaint 方法多載中明確地加以處置。由 PaintEventArgs 物件的 Graphics 屬性傳回的 Graphics 物件，可由記憶體回收行程終結，而不需要明確地加以處置。