如何将图形转换为位图并将其保存在 c# 中？

Question

目前我正在学习使用图形方法绘制条形码并将其处理为位图。但是当我要保存的时候，虽然可以保存成功，但是结果是黑色的，什么都看不到。到底是什么问题？

    private void buttonDraw_Click(object sender, EventArgs e)
    {
        System.Drawing.Graphics g = this.pictureBoxBarcode.CreateGraphics();
        g.FillRectangle(new System.Drawing.SolidBrush(System.Drawing.SystemColors.Control),
        new Rectangle(0, 0, pictureBoxBarcode.Width, pictureBoxBarcode.Height));
        ean13.DrawEan13Barcode(g, new System.Drawing.Point(0, 0));
        g.Dispose();

    }

这是我的保存功能

    public void Save(Bitmap original)
    {
        // Displays a SaveFileDialog so the user can save the Image
        // assigned to Button2.
        SaveFileDialog saveFileDialog1 = new SaveFileDialog();
        saveFileDialog1.Filter = "JPeg Image|*.jpg|Bitmap Image|*.bmp|Gif Image|*.gif|Png Image|*.png";
        saveFileDialog1.Title = "Save an Image File";
        saveFileDialog1.ShowDialog();

        // If the file name is not an empty string open it for saving.
        if (saveFileDialog1.FileName != "")
        {
            // Saves the Image via a FileStream created by the OpenFile method.
            System.IO.FileStream fs =
               (System.IO.FileStream)saveFileDialog1.OpenFile();
            // Saves the Image in the appropriate ImageFormat based upon the
            // File type selected in the dialog box.
            // NOTE that the FilterIndex property is one-based.

            switch (saveFileDialog1.FilterIndex)
            {
                case 1:
                    original.Save(fs,
                       System.Drawing.Imaging.ImageFormat.Jpeg);
                    break;

                case 2:
                    original.Save(fs,
                       System.Drawing.Imaging.ImageFormat.Bmp);
                    break;

                case 3:
                    original.Save(fs,
                       System.Drawing.Imaging.ImageFormat.Gif);
                    break;

                case 4:
                    original.Save(fs,
                       System.Drawing.Imaging.ImageFormat.Png);
                    break;
            }
            fs.Close();
        }
    }

我无法提供任何图片来证明我的声誉不足以证明这一点。对不起。

Answer 1

要绘制到Bitmap，请使用以下代码：

private void buttonDraw_Click(object sender, EventArgs e)
{
    Bitmap bmp = new Bitmap(pictureBoxBarcode.ClientSize.Width,
                            pictureBoxBarcode.ClientSize.Height);
    using (Graphics g = Graphics.FromImage(bmp))
    {
       g.Clear(SystemColors.Control);
       ean13.DrawEan13Barcode(g, new System.Drawing.Point(0, 0));
    }
    // display:
    pictureBoxBarcode.Image = bmp;
    // save:
    bmp.Save(yourfilename,  ImageFormat.Png);
    // ..or..: 
    Save(bmp);
}

或者：

private void buttonSave_Click(object sender, EventArgs e)
{
    Save( (Bitmap) pictureBoxBarcode.Image);
}

我已经复制了你的绘图代码。

我不知道你为什么要让它看起来是灰色的..？

我假设ean13.DrawEan13Barcode 是一个函数，它使用传入的Graphics 对象在与Graphics 对象关联的Bitmap 上绘制一些东西。