Android 基于Bitmap的四种图片压缩方式

fun showBitmapinfo(bitmap: Bitmap){
        Log.d("Tag","压缩后的图片大小：${bitmap.byteCount/1024/1024}MB,宽度：${bitmap.width}，高度：${bitmap.height}")
}

public boolean compress(CompressFORMat format, int quality, OutputStream stream) {
}

fun getCompressBitmap(bitmap: Bitmap,quality:Int): Bitmap {
    val baos = ByteArrayOutputStream()
    bitmap.compress(Bitmap.CompressFormat.JPEG, quality, baos)
    val byte = baos.toByteArray()
    val ins = ByteArrayInputStream(byte)
    val bm = BitmapFactory.decodeStream(ins)
    ins.close()
    baos.close()
    return bm
}

val baos = ByteArrayOutputStream()
bitmap.compress(Bitmap.CompressFormat.JPEG, quality, baos)
val byte = baos.toByteArray()
Log.d("Tag","quality=$quality,byte-size=${byte.size}")

 public int inSampleSize;

    
    fun calculateInSampleSize(options: BitmapFactory.Options, reqWidth: Int, reqHeight: Int): Int {
        val height = options.outHeight
        val width = options.outWidth
        var inSampleSize = 1
        if (height > reqHeight || width > reqWidth) {
            val heightRatio = round(height.toFloat() / reqHeight.toFloat()).toInt()
            val widthRatio = round(width.toFloat() / reqWidth.toFloat()).toInt()
            inSampleSize = if (heightRatio < widthRatio) heightRatio else widthRatio
        }
        return inSampleSize
    }

    
    fun getSmallBitmap(filePath: String,reqWidth: Int,reqHeight: Int): Bitmap {
        val options = BitmapFactory.Options()
        options.inJustDecodeBounds = true //不加载 bitmap 进内存，只获取他的基本信息
        BitmapFactory.decodeFile(filePath, options)
        options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight)
        options.inJustDecodeBounds = false
        return BitmapFactory.decodeFile(filePath, options)
    }

    
    fun matrixBitmap(bitmap: Bitmap,scale:Float):Bitmap{
        val matrix = Matrix()
        matrix.setScale(scale,scale)
        var bm = Bitmap.createBitmap(bitmap,0,0,bitmap.width,bitmap.height,matrix,true)
        return bm
    }

fun rgb565Bitmap(filePath: String):Bitmap{
        val options = BitmapFactory.Options()
        options.inPreferredConfig = Bitmap.Config.RGB_565
        var bitmap = BitmapFactory.decodeFile(filePath,options)
        return bitmap
}