如何使用打印预览打印分组框？

Question

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下面的代码在打印预览中显示了分组框的一半：

private void printDocument1_PrintPage(object sender, System.Drawing.Printing.PrintPageEventArgs e) {
  //  Bitmap bmp = new Bitmap(groupBox1.ClientRectangle.Width, groupBox1.ClientRectangle.Height);
  //  groupBox1.DrawToBitmap(bmp, groupBox1.ClientRectangle);
  //  e.Graphics.DrawImage(bmp, 0, 0);

  Bitmap bmp = new Bitmap(groupBox1.Width, groupBox1.Height, System.Drawing.Imaging.PixelFormat.Format32bppArgb);
  groupBox1.DrawToBitmap(bmp, new Rectangle(0, 0, groupBox1.Width, groupBox1.Height));
  e.Graphics.DrawImage((Image) bmp, 0, 0);
}

private void button1_Click(object sender, EventArgs e) {
  PrintPreviewDialog ppd = new PrintPreviewDialog();
  PrintDocument Pd = new PrintDocument();

  Pd.PrintPage += this.printDocument1_PrintPage;
  ppd.Document = Pd;
  ppd.ShowDialog();
}

Answer 1

你需要在页面的边界内进行绘制。

private void printDocument1_PrintPage(object sender, System.Drawing.Printing.PrintPageEventArgs e)
{
    var g = e.Graphics;
    var srcRect = new Rectangle(0, 0, groupBox1.Width, groupBox1.Height);
    var desRect = new Rectangle(e.PageBounds.X, e.PageBounds.Y, e.PageBounds.Width, srcRect.Height);
    //Or to draw within the margin
    //var desRect = new Rectangle(e.MarginBounds.X, e.MarginBounds.Y, e.MarginBounds.Width, srcRect.Height);

    using (var bmp = new Bitmap(srcRect.Width, srcRect.Height))
    {
        groupBox1.DrawToBitmap(bmp, srcRect);
        g.DrawImage(bmp, desRect, srcRect, GraphicsUnit.Pixel);
    }
}

此外，创建PrintDocument对象并在窗体的构造函数或Load事件中注册其PrintPage事件，以避免在button1_Click事件中重复此操作。别忘了丢弃一次性物品。