c# - 如何将位图图像保存为 JPEG

Question

问题是文件没有保存为 JPEG。只是一个普通文件。

到目前为止，这是我的代码:

private void btnSave_Click(object sender, EventArgs e)
{
    saveDialog.FileName = txtModelName.Text;

    if (saveDialog.ShowDialog() == DialogResult.OK)
    {
        Bitmap bmp = new Bitmap(pnlDraw.Width, pnlDraw.Height);

        pnlDraw.DrawToBitmap(bmp, new Rectangle(0, 0,
            pnlDraw.Width, pnlDraw.Height));

        bmp.Save(saveDialog.FileName, System.Drawing.Imaging.ImageFormat.Jpeg);
    }
}

Answer 1

保存前检查文件名是否有.jpg扩展名如何？

您还可以将 saveDialog 更改为仅允许用户选择 .jpg 图像。

private void btnSave_Click(object sender, EventArgs e)
{
    saveDialog.FileName = txtModelName.Text;
    saveDialog.DefaultExt = "jpg";
    saveDialog.Filter = "JPG images (*.jpg)|*.jpg";    

    if (saveDialog.ShowDialog() == DialogResult.OK)
    {
        Bitmap bmp = new Bitmap(pnlDraw.Width, pnlDraw.Height);

        pnlDraw.DrawToBitmap(bmp, new Rectangle(0, 0,
            pnlDraw.Width, pnlDraw.Height));

        var fileName = saveDialog.FileName;
        if(!System.IO.Path.HasExtension(fileName) || System.IO.Path.GetExtension(fileName) != "jpg")
            fileName = fileName + ".jpg";

        bmp.Save(fileName, System.Drawing.Imaging.ImageFormat.Jpeg);
    }
}