Blurry and large image barcode being generated using a plugin in Windows Form

问题

Going through the steps mentioned here and using IDAutomationCode39, I am getting the barcode image, however they are very blurr and only scans bigger size images. My barcode id will be upto 30 characters long, which is causing a very wide barcode image. Where could the problem lie? Is it the IDAutomationCode39 or my setting in my button click event below?

private void button1_Click(object sender, EventArgs e)
    {
        string abbre = GenerateProdCodeFromProductName();
        txt2.Text = abbre;

        string barcode = txt1.Text;

        Bitmap bitm = new Bitmap(barcode.Length * 45, 160);
        bitm.SetResolution(240, 240);
        using (Graphics graphic = Graphics.FromImage(bitm))
        {
            Font newfont = new Font("IDAutomationHC39M", 6);
            PointF point = new PointF(5f, 5f);
            SolidBrush black = new SolidBrush(Color.Black);
            SolidBrush white = new SolidBrush(Color.White);
            graphic.FillRectangle(white, 0, 0, bitm.Width, bitm.Height);
            graphic.DrawString("*" + barcode + "*", newfont, black, point);
        }

        using (MemoryStream Mmst = new MemoryStream())
        {
            bitm.Save("ms", ImageFormat.Jpeg);
            pictureBox1.Image = bitm;
            pictureBox1.Width = bitm.Width;
            pictureBox1.Height = bitm.Height;
        }
    }

Thank you.

回答1:

I don't see any PlugIn reference in your code, you are just using a Code39 ASCII font to print a Barcode on a Bitmap.

The problem I see is that the size of the resulting Bitmap is unscaled.
What I mean is, you let the size of the Barcode determine the size of the final graphic image.
It is usually the opposite. You have some defined dimensions for a Bitmap, because of layout constraints: you have to print the barcode to a label, for example.
If the generated Barcode is wider than its container, you have to normalize it (scale it to fit).

Here is what I propose. The size of the Bitmap if fixed (300, 150). When the Barcode is generated, its size is scaled to fit the Bitmap size.
The quality of the image is preserved, using an Bicubic Interpolation in case of down scaling. The resulting graphics is also Anti-Aliased.
(Anti-Alias has a good visual render. May not be the best choice for printing. It also depends on the printer.)

The generated Bitmap is then passed to a PictureBox for visualization and saved to disk as a PNG image (this format because of its loss-less compression).

Here is the result:

string Barcode = "*8457QK3P9*";

using (Bitmap bitmap = new Bitmap(300, 150))
{
    bitmap.SetResolution(240, 240);
    using (Graphics graphics = Graphics.FromImage(bitmap))
    {
        Font font = new Font("IDAutomationSHC39M", 10, FontStyle.Regular, GraphicsUnit.Point);

        graphics.Clear(Color.White);
        StringFormat stringformat = new StringFormat(StringFormatFlags.NoWrap);
        graphics.TextRenderingHint = TextRenderingHint.AntiAliasGridFit;
        graphics.TextContrast = 10;

        PointF TextPosition = new PointF(10F, 10F);
        SizeF TextSize = graphics.MeasureString(Barcode, font, TextPosition, stringformat);

        if (TextSize.Width > bitmap.Width)
        {
            float ScaleFactor = (bitmap.Width - (TextPosition.X / 2)) / TextSize.Width;
            graphics.InterpolationMode = InterpolationMode.HighQualityBicubic;
            graphics.ScaleTransform(ScaleFactor, ScaleFactor);
        }

        graphics.DrawString(Barcode, font, new SolidBrush(Color.Black), TextPosition, StringFormat.GenericTypographic);

        bitmap.Save(@"[SomePath]\[SomeName].png", ImageFormat.Png);
        this.pictureBox1.Image = (Bitmap)bitmap.Clone();
        font.Dispose();
    }
}

来源：https://stackoverflow.com/questions/49267169/blurry-and-large-image-barcode-being-generated-using-a-plugin-in-windows-form