如何以xamarin形式获取位图的字节[]数据？

Question

I want to read an image into a byte array.

using my xaml, I have a binding for my image:

    <Image x:Name="myImageView"
           Source="triangles.bmp"
           Aspect="AspectFit" 
           VerticalOptions="Center"
           HorizontalOptions="FillAndExpand"/>

I would like to have the data from myImageView into a byte array. What code can accomplish this on xamarin forms ?

I have found solutions for the other way around (which i haven't tested yet), but I need this way (bound image->byte[], not byte[]->Image).

My usage will be, for example, to apply a bluring convolution filter, or to find the max pixel value.

Thanks.

Answer 1

Since you're using PCL, you can achieve this by using the interface I created below and registering it with Xamarin DependencyService.

I provided methods to get bytes from an URIImageSource & FileImageSource

In Your PCL Project

private void ABCDEFGHIJKLMNOPQRSTUVWXYZ(){
    var link = new Uri("https://xamarin.com/content/images/pages/forms/example-app.png");
    var goNative = DependencyService.Get<IStackoverflow>();
    var bytes = goNative.GetImageBytes(link);   // Your Bytes As Requested
}

public interface IStackoverflow  // Create an interface to access platform specific
{
    byte[] GetImageBytes(string filepath);
    byte[] GetImageBytes(Uri uri);
}

In your native project make sure you inherit from the above interface.

If you're not accessing it from your PCL project then,

imagePath = Resources.GetDrawable(Resource.Drawable.triangles.bmp);      

public byte[] GetImageBytes(string imagePath)
{
    var fileStream = new FileStream(imagePath, FileMode.Open, FileAccess.Read);
    var buffer = new byte[fileStream.Length];
    fileStream.Read(buffer, 0, (int)fileStream.Length);
    fileStream.Close();
    return buffer;
}

public byte[] GetImageBytes(Uri uri)
{
    var myWebClient = new WebClient();
    return  myWebClient.DownloadData(uri);
}

If you're unfamiliar with Xamarin DependencyService, here is their documentation Xamarin DependencyService