Xamarin（Android - 带有大位图的OutOfMemory异常 - 如何解决（））

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我正在拍摄一张图像，解码由byte array方法生成的TakePicture然后旋转bitmap 270度。问题是我似乎耗尽了内存，我不知道如何解决它。这是代码：

Bitmap image = BitmapFactory.DecodeByteArray (data, 0, data.Length); data = https://www.songbingjia.com/android/null; Bitmap rotatedBitmap = Bitmap.CreateBitmap (image, 0, 0, image.Width, image.Height, matrix, true);

答案请查看官方Load Large Bitmaps Efficiently文档中的Xamarin，它解释了如何将大图像加载到内存中，而不会通过在内存中加载较小的子样本版本来投掷OutOfMemoryException。
读取位图尺寸和类型

async Task< BitmapFactory.Options> GetBitmapOptionsOfImageAsync() { BitmapFactory.Options options = new BitmapFactory.Options { InJustDecodeBounds = true }; // The result will be null because InJustDecodeBounds == true. Bitmap result=await BitmapFactory.DecodeResourceAsync(Resources, Resource.Drawable.someImage, options); int imageHeight = options.OutHeight; int imageWidth = options.OutWidth; _originalDimensions.Text = string.Format("Original Size= {0}x{1}", imageWidth, imageHeight); return options; }

将缩小版本加载到内存中

public static int CalculateInSampleSize(BitmapFactory.Options options, int reqWidth, int reqHeight) { // Raw height and width of image float height = options.OutHeight; float width = options.OutWidth; double inSampleSize = 1D; if (height > reqHeight || width > reqWidth) { int halfHeight = (int)(height / 2); int halfWidth = (int)(width / 2); // Calculate a inSampleSize that is a power of 2 - the decoder will use a value that is a power of two anyway. while ((halfHeight / inSampleSize) > reqHeight & & (halfWidth / inSampleSize) > reqWidth) { inSampleSize *= 2; } }return (int)inSampleSize; }

将图像加载为异步

public async Task< Bitmap> LoadScaledDownBitmapForDisplayAsync(Resources res, BitmapFactory.Options options, int reqWidth, int reqHeight) { // Calculate inSampleSize options.InSampleSize = CalculateInSampleSize(options, reqWidth, reqHeight); // Decode bitmap with inSampleSize set options.InJustDecodeBounds = false; return await BitmapFactory.DecodeResourceAsync(res, Resource.Drawable.someImage, options); }

并将其称为加载图像，例如在OnCreate中

protected async override void OnCreate(Bundle bundle) { base.OnCreate(bundle); SetContentView(Resource.Layout.Main); _imageView = FindViewById< ImageView> (Resource.Id.resized_imageview); BitmapFactory.Options options = await GetBitmapOptionsOfImageAsync(); Bitmap bitmapToDisplay = await LoadScaledDownBitmapForDisplayAsync (Resources, options, 150,//for 150 X 150 resolution 150); _imageView.SetImageBitmap(bitmapToDisplay); }

【Xamarin（Android - 带有大位图的OutOfMemory异常 - 如何解决（））】希望能帮助到你。