CopyFromScreen 是一個非常有用的方法，它可以將屏幕上的某個區域復制到一個 Bitmap 對象中。這在創建屏幕截圖、錄制屏幕或進行自動化測試時非常有用。以下是一些使用 CopyFromScreen 的技巧和示例：

1. 創建屏幕截圖：

using System.Drawing;
using System.Windows.Forms;

public Bitmap CaptureScreen()
{
    Rectangle screenBounds = Screen.GetBounds(Point.Empty);
    Bitmap screenshot = new Bitmap(screenBounds.Width, screenBounds.Height, PixelFormat.Format32bppArgb);

    using (Graphics g = Graphics.FromImage(screenshot))
    {
        g.CopyFromScreen(Point.Empty, Point.Empty, screenBounds.Size);
    }

    return screenshot;
}

2. 創建指定區域的截圖：

public Bitmap CaptureRegion(Rectangle region)
{
    Bitmap screenshot = new Bitmap(region.Width, region.Height, PixelFormat.Format32bppArgb);

    using (Graphics g = Graphics.FromImage(screenshot))
    {
        g.CopyFromScreen(region.Location, Point.Empty, region.Size);
    }

    return screenshot;
}

3. 創建透明背景的截圖：

public Bitmap CaptureTransparentScreenshot(Rectangle region)
{
    Bitmap screenshot = new Bitmap(region.Width, region.Height, PixelFormat.Format32bppArgb);

    using (Graphics g = Graphics.FromImage(screenshot))
    {
        g.CopyFromScreen(region.Location, Point.Empty, region.Size, CopyPixelOperation.SourceCopy);
    }

    return screenshot;
}

4. 在截圖中高亮顯示特定區域：

public Bitmap HighlightRegion(Bitmap screenshot, Rectangle region, Color highlightColor)
{
    using (Graphics g = Graphics.FromImage(screenshot))
    {
        using (Pen pen = new Pen(highlightColor, 5))
        {
            g.DrawRectangle(pen, region);
        }
    }

    return screenshot;
}

5. 將截圖保存為文件：

public void SaveScreenshot(Bitmap screenshot, string filePath)
{
    screenshot.Save(filePath, ImageFormat.Png);
}

6. 將截圖顯示在窗體上：

public void DisplayScreenshot(Form form, Bitmap screenshot)
{
    form.BackgroundImage = screenshot;
    form.ClientSize = screenshot.Size;
}

這些技巧和示例可以幫助你更好地使用 CopyFromScreen 方法。記住，當你處理大量圖像時，要確保正確地釋放資源，以避免內存泄漏。