YUV420SP（NV21）旋轉和轉bitmap

轉載1：https://blog.csdn.net/qq1137830424/article/details/81980673

在調Camera的時候有個回調方法onPreviewFrame是返回攝像頭每一幀的圖像數據的，當我們需要對圖像數據做處理時就需要Nv21轉Bitmap，下面介紹兩種方式第一種方式只需要幾毫秒時間，第二種方式需要幾十毫秒。

第一種方式（高效）

package com.my.camerademo;

import android.content.Context;
import android.graphics.Bitmap;
import android.renderscript.Allocation;
import android.renderscript.Element;
import android.renderscript.RenderScript;
import android.renderscript.ScriptIntrinsicYuvToRGB;
import android.renderscript.Type;

public class NV21ToBitmap {

    private RenderScript rs;
    private ScriptIntrinsicYuvToRGB yuvToRgbIntrinsic;
    private Type.Builder yuvType, rgbaType;
    private Allocation in, out;

    public NV21ToBitmap(Context context) {
        rs = RenderScript.create(context);
        yuvToRgbIntrinsic = ScriptIntrinsicYuvToRGB.create(rs, Element.U8_4(rs));
    }

    public Bitmap nv21ToBitmap(byte[] nv21, int width, int height){
        if (yuvType == null){
            yuvType = new Type.Builder(rs, Element.U8(rs)).setX(nv21.length);
            in = Allocation.createTyped(rs, yuvType.create(), Allocation.USAGE_SCRIPT);

            rgbaType = new Type.Builder(rs, Element.RGBA_8888(rs)).setX(width).setY(height);
            out = Allocation.createTyped(rs, rgbaType.create(), Allocation.USAGE_SCRIPT);
        }

        in.copyFrom(nv21);

        yuvToRgbIntrinsic.setInput(in);
        yuvToRgbIntrinsic.forEach(out);

        Bitmap bmpout = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
        out.copyTo(bmpout);

        return bmpout;

    }

}

第二種方式

    private static Bitmap nv21ToBitmap(byte[] nv21, int width, int height) {
        Bitmap bitmap = null;
        try {
            YuvImage image = new YuvImage(nv21, ImageFormat.NV21, width, height, null);
            ByteArrayOutputStream stream = new ByteArrayOutputStream();
            image.compressToJpeg(new Rect(0, 0, width, height), 80, stream);
            bitmap = BitmapFactory.decodeByteArray(stream.toByteArray(), 0, stream.size());
            stream.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return bitmap;
    }

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轉載2： https://blog.csdn.net/xh2009cn/article/details/44258715

旋轉NV21且不出現翻轉

private static void yuv420spRotate90(byte[] des, byte[] src,
                                         int width, int height) {
        int wh = width * height;
        int k = 0;
        for(int i = 0; i < width; i++) {
            for(int j = height - 1; j >= 0; j--)
            {
                des[k] = src[width * j + i];
                k++;
            }
        }
        for(int i = 0; i < width; i += 2) {
            for(int j = height / 2 - 1; j >= 0; j--)
            {
                des[k] = src[wh+ width * j + i];
                des[k+1] = src[wh + width * j + i + 1];
                k+=2;
            }
        }
    }
 
private static void YUV420spRotate180(byte[] des,byte[] src,int width,int height)
    {
        int n = 0;
        int uh = height >> 1;
        int wh = width * height;
        //copy y
        for(int j = height - 1; j >= 0; j--)
        {
            for(int i = width - 1; i >= 0; i--)
            {
                des[n++] = src[width * j + i];
            }
        }
 
 
        for(int j = uh - 1;j >= 0; j--)
        {
            for(int i = width - 1; i > 0; i -= 2)
            {
                des[n] = src[wh + width * j + i - 1];
                des[n + 1] = src[wh + width * j + i];
                n += 2;
            }
        }
    }
 
private static void YUV420spRotate270(byte[] des,byte[] src,int width,int height)
    {
        int n = 0;
        int uvHeight = height >> 1;
        int wh = width * height;
        //copy y
        for(int j = width - 1; j >= 0; j--)
        {
            for(int i = 0; i < height;i++)
            {
                des[n++] = src[width * i + j];
            }
        }
 
        for(int j = width - 1; j > 0;j -= 2)
        {
            for(int i = 0; i < uvHeight; i++)
            {
                des[n++] = src[wh + width * i + j - 1];
                des[n++] = src[wh + width * i + j];
            }
        }
    }