Forum› Xamarin.Forms

Set image from bitmap

KirillRadchenkoKirillRadchenko RUMember ✭✭
edited August 2015 in Xamarin.Forms 
Image image = new Image ();
Bitmap bitmap = Bitmap.CreateBitmap (200, 100, Bitmap.Config.Argb8888);
Canvas canvas = new Canvas(bitmap);

var paint = new Paint();
paint.Color = Android.Graphics.Color.Red;
paint.SetStyle(Paint.Style.Fill);

Rect rect = new Rect(0, 0, 200, 100);
canvas.DrawRect(rect, paint);

Android.Widget.ImageView contains method SetImageBitmap.
What the best way to set Xamarin.Forms.Image from my bitmap?

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  • KirillRadchenkoKirillRadchenko RUMember ✭✭
    edited August 2015

    http://stackoverflow.com/questions/32092476/set-image-from-bitmap

    Java.Nio.ByteBuffer buffer = Java.Nio.ByteBuffer.Allocate(bitmap.ByteCount);
bitmap.CopyPixelsToBuffer(buffer);
buffer.Rewind();

IntPtr classHandle = JNIEnv.FindClass("java/nio/ByteBuffer");
IntPtr methodId = JNIEnv.GetMethodID(classHandle, "array", "()[B");
IntPtr resultHandle = JNIEnv.CallObjectMethod(buffer.Handle, methodId);
byte[] byteArray = JNIEnv.GetArray<byte>(resultHandle);
JNIEnv.DeleteLocalRef(resultHandle);

var stream = new MemoryStream(byteArray);
image.Source = ImageSource.FromStream(stream);

    Is this the best way?

  • adamkempadamkemp USInsider, Developer Group Leader mod

    That code is obviously platform-specific. This kind of thing can't be done in a PCL in a cross-platform way. You will have to use a DependencyService to implement this feature so that you can do the platform-specific code in the platform-specific project.

  • KirillRadchenkoKirillRadchenko RUMember ✭✭

    OK, but how I can set data in my image from the bitmap in cross-platform situation? I can't find this information

  • KirillRadchenkoKirillRadchenko RUMember ✭✭

    OK. Thanks for the help!

  • ahmedkhanahmedkhan USUniversity ✭✭

    Is there some code or example available as a working solution to this?? I have been search for a way to convert an Android Bitmap image to Xamarin.Forms ImageSource

  • EmmanuelOluwagbemigaEmmanuelOluwagbemiga USMember ✭✭

    This is coming late but can be useful to anyone who needs it now:

    @adamkemp said:
    The actual code that deals with the bitmap has to be in platform-specific code. You can write a DependencyService that gives you a Stream, and you can use that stream in the PCL. What you can't do in the PCL is actually draw the bitmap. That requires platform-specific APIs.

    I created a Github gist that implements what @adamkemp described above

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