从 BufferedGraphics C# 制作位图

Question

我在 C# WinForms 中制作了一个简单的程序，类似于 MSPaint。我目前卡住的一件事是我想从我正在绘制的 BufferedGraphics 制作 Bitmap 然后保存它。但是当我保存的时候，文件里什么也没有，只有一张空白的图片。

代码如下：

private BufferedGraphics picture;

    public Form1()
    {
        InitializeComponent();
        picture = BufferedGraphicsManager.Current.Allocate(MainPanel.CreateGraphics(), MainPanel.DisplayRectangle);
        picture.Graphics.FillRectangle(Brushes.White, MainPanel.DisplayRectangle);
        picture.Graphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;
        picture.Graphics.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
    }

    private void Draw()
    {
        if (mouseDown)
        {
            Point cursorPos = MainPanel.PointToClient(Cursor.Position);
            picture.Graphics.FillEllipse(selectedColor, cursorPos.X - slider.Value / 2, cursorPos.Y - slider.Value / 2, slider.Value, slider.Value);
            picture.Render();
        }
    }

    private void Save()
    {
        Bitmap result = new Bitmap(MainPanel.Width, MainPanel.Height, picture.Graphics);

        result.Save("image.png", System.Drawing.Imaging.ImageFormat.Png);

    }

Answer 1

检查下面的代码片段；

BufferedGraphics buffer;
int bufferWidth, bufferHeight;

using (Bitmap bitmap = new Bitmap(bufferWidth, bufferHeight))
{
  using (Graphics graphics = Graphics.FromImage(bitmap))
  {
    buffer.Render(graphics);
  }

  bitmap.Save("a.png", ImageFormat.Png);
}

从 BufferedGraphics C# 制作位图

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