How to get free hard cap?

[1748995976]

背景

开发过程中发现图片太大会导致内存溢出，使用BasePostprocessor重写方法降低图片的宽高比，结果出现Pool hard cap violation的问题

val request: ImageRequest = ImageRequestBuilder.newBuilderWithSource(uri)
            .setPostprocessor(object : BasePostprocessor(){

                override fun process(destBitmap: Bitmap?, sourceBitmap: Bitmap?) {
                    destBitmap ?: return
                    sourceBitmap ?: return
                    internalCopyBitmap(destBitmap, sourceBitmap)
                    process(destBitmap)
                }

                override fun process(
                    sourceBitmap: Bitmap?,
                    bitmapFactory: PlatformBitmapFactory?
                ): CloseableReference<Bitmap> {
                    if(sourceBitmap == null || bitmapFactory == null){
                        return super.process(sourceBitmap, bitmapFactory)
                    }
                    val sourceBitmapConfig = sourceBitmap.config ?: FALLBACK_BITMAP_CONFIGURATION
                    val allocationByteCount = sourceBitmap.allocationByteCount
                   // to do: optimize maxAllocationByteCount's value
                    val maxAllocationByteCount  = 50 * 1024 *1024
                    val scale = if(allocationByteCount > maxAllocationByteCount){
                        maxAllocationByteCount.toFloat() / allocationByteCount.toFloat()
                    }else{
                        1f
                    }
                    val destBitmapRef = bitmapFactory.createBitmapInternal(
                        (sourceBitmap.width * scale).toInt(),
                        (sourceBitmap.height * scale).toInt(),
                        sourceBitmapConfig
                    )
                    return try {
                        process(destBitmapRef.get(), sourceBitmap)
                        CloseableReference.cloneOrNull(destBitmapRef)!!
                    } finally {
                        CloseableReference.closeSafely(destBitmapRef)
                    }
                }
            }
            )
            .build()

详细描述

看源码发现ArtBitmapFactory.createBitmapInternal -> mBitmapPool.get(sizeInBytes) -> canAllocate最后返回了false

问题

我想通过获取canAllocate的最大值，赋值给maxAllocationByteCount从而得到 满足内存 且 失真最低 的缩放比