从位图设置图像

Question

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包含方法SetImageBitmap。从我的位图
设置Xamarin.Forms.Image的最佳方法是什么？

Answer 1

通过http://forums.xamarin.com/discussion/5950/how-to-convert-from-bitmap-to-byte-without-bitmap-compress转换Bitmap为byte[]

提到了两种解决方案。

1. var byteArray = ByteBuffer.Allocate(bitmap.ByteCount);
   bitmap.CopyPixelsToBuffer(byteArray);
   byte[] bytes = byteArray.ToArray<byte>();
   return bytes;
   

2. （如果第一个解决方案仍然损坏）

   ByteBuffer buffer = 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);
   

然后使用

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

创建一个Image.