Epson.PrintImage taking a lot of time

[nk-alex]

I'm using ESCPOS_NET 3.0.0 on my .NET 9.0 Maui application. Following #111 I tried to convert the given code to .NET Maui (Without using System.Drawing). I ended up with this:

IList<byte[]> data = new List<byte[]>
{
    Epson.CenterAlign()
};

byte[] logoBytes = System.Convert.FromBase64String(Helpers.Settings.Logo);
int size = 256;

SKImage image = SKImage.FromEncodedData(logoBytes);
SKBitmap imageBitmap = SKBitmap.FromImage(image);

for (int i = 0; i < Math.Round((double)image.Height / size, 0, MidpointRounding.ToPositiveInfinity); i++)
{
    int width = image.Width;
    int height = size * (i + 1) <= image.Height ? size : image.Height - (size * i);

    SKBitmap newImage = new SKBitmap(width, height);

    using (SKCanvas canvas = new SKCanvas(newImage))
    {
        canvas.DrawBitmap(imageBitmap, new SKRect(0, 0, width, height), new SKRect(0, i * size, width, height));

        using (MemoryStream memoryStream = new MemoryStream())
        {
            SKData newImageData = newImage.Encode(SKEncodedImageFormat.Webp, 10);
            newImageData.SaveTo(memoryStream);
            data.Add(Epson.PrintImage(newImageData.ToArray(), true, true, 512, 0));
        }
    }
}

return ByteSplicer.Combine(data.ToArray());

My problem is with Epson.PrintImage(newImageData.ToArray(), true, true, 512, 0) no matter the parameters I try, it takes like 10 seconds to return everytime it's called. Is there anyway to speedup this process?

[lukevp]

Could you make a minimal repo or gist + image that reproduces this issue?

What OS are you using?

What exactly is slow, is it the call to PrintImage, the overall time to execute this whole code block, or is it the time it takes to start printing from when you call the library?

How do you have the printer connected?

Have you tried doing all the gyrations you're doing to convert it to the proper image data separately from the call to printing? These logos are typically not very large and can be stored as a byte array in memory, then reused whenever you need to print the logo. It's a bit wasteful to do all the image processing right before printing the image each time.

[nk-alex]

Hi @lukevp thanks for the quick response.

Here you can find a sample repo. The image I'm using is the same as #111. It's inside the project already, it will be automatically loaded.
You can find the code above specifically here.

To test the feature, I have created one function that tries to print logo the same way it's specified in docs and a second function that is trying to print the logo the same way it's specified in #111.

What OS are you using?

• I'm testing it on Android 15

What exactly is slow, is it the call to PrintImage, the overall time to execute this whole code block, or is it the time it takes to start printing from when you call the library?

• The call to PrintImage is what takes the long time to return. After calling await Printer.WriteAsync(bytes); the printing happens instantly.

How do you have the printer connected?

• I'm using ImmediateNetworkPrinterSettings to connect to a printer in my network.

Have you tried doing all the gyrations you're doing to convert it to the proper image data separately from the call to printing? These logos are typically not very large and can be stored as a byte array in memory, then reused whenever you need to print the logo. It's a bit wasteful to do all the image processing right before printing the image each time.

• You are right about that. I have also seen that my logo has 73 Kbytes originally and after something like Epson.PrintImage(ms.ToArray(), true, true, 512, 0), the result has less than 20 Kbytes. My only concern is if somehow this PrintImage process could be sped up somehow.