银行/订单签名View，可回退上一笔，可清空，可保存

package com.ycq.customerview.view;

import android.content.Context;
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.os.Environment;
import android.util.AttributeSet;
import android.util.TypedValue;
import android.view.MotionEvent;
import android.view.View;
import android.widget.Toast;

import androidx.annotation.Nullable;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.util.ArrayList;
import java.util.List;

/**
 * 签名View，可回退上一笔，可清空，可保存
 */
public class SignatureView extends View {

    /**
     * 画笔
     */
    private Paint mPaint;
    /**
     * 路径
     */
    private Path mPath;
    /**
     * 所有路径/笔画集合，每一个item为一笔
     */
    private final List<Path> mLists = new ArrayList<>();
    /**
     * 图片保存路径
     * Android/data/应用包名/files/Pictures/XXX1659508032166.jpg
     */
    private String mSavePath;

    public SignatureView(Context context) {
        this(context, null);
    }

    public SignatureView(Context context, @Nullable AttributeSet attrs) {
        this(context, attrs, -1);
    }

    public SignatureView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init();
    }

    private void init() {
        //设置白色背景，否则保存的图片是黑色的
        setBackgroundColor(Color.WHITE);
        mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        mPaint.setStyle(Paint.Style.STROKE);
        mPaint.setColor(Color.BLACK);
        mPaint.setStrokeWidth(dp2px(8f));
        mPaint.setStrokeJoin(Paint.Join.ROUND);
        mPaint.setStrokeCap(Paint.Cap.ROUND);
        mPath = new Path();
    }

    private float dp2px(float dp) {
        return TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dp, Resources.getSystem().getDisplayMetrics());
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        canvas.drawPath(mPath, mPaint);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                float x = event.getX();
                float y = event.getY();
                //创建新的路径，即新的笔画
                Path path = new Path();
                path.moveTo(x, y);
                mLists.add(path);
                //移动到笔画的起点
                mPath.moveTo(x, y);
                break;
            case MotionEvent.ACTION_MOVE:
                float x1 = event.getX();
                float y1 = event.getY();
                if (mLists != null && mLists.size() != 0) {
                    Path path1 = mLists.get(mLists.size() - 1);
                    path1.lineTo(x1, y1);
                }
                //笔画的每一个点
                mPath.lineTo(x1, y1);
                invalidate();
                break;
            case MotionEvent.ACTION_UP:
                break;
        }
        return true;
    }

    /**
     * 回退一笔
     */
    public void goBackOne() {
        //重置路径
        mPath.reset();
        if (mLists != null && mLists.size() != 0) {
            //去掉最后一笔
            mLists.remove(mLists.size() - 1);
            if (mLists.size() != 0) {
                for (Path path : mLists) {
                    mPath.addPath(path);
                }
            }
        }
        invalidate();
    }

    /**
     * 清空
     */
    public void clear() {
        mPath.reset();
        mLists.clear();
        invalidate();
    }

    public Bitmap saveCanvas(Context context) {
        return saveCanvas(context, "");
    }

    public Bitmap saveCanvas(Context context, String picName) {
        if (mLists != null && mLists.size() != 0) {
            long time = System.currentTimeMillis();//系统时间
            File filesDir = context.getExternalFilesDir(Environment.DIRECTORY_PICTURES);

            StringBuilder sb = new StringBuilder();
            sb.append(filesDir.getAbsolutePath());
            if (picName.equals("")) {
                sb.append("/signature");
            } else {
                sb.append("/").append(picName);
            }
            mSavePath = sb.append(time).append(".jpg").toString();
            setDrawingCacheEnabled(true);
            //生成图片并保存
            Bitmap bitmap = getDrawingCache();
            bitmap = Bitmap.createBitmap(bitmap);
            try {
                FileOutputStream fos = new FileOutputStream(new File(mSavePath));
                bitmap.compress(Bitmap.CompressFormat.JPEG, 100, fos);//保存
                fos.flush();
                fos.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
            setDrawingCacheEnabled(false);
            Toast.makeText(context, "文件已保存到：" + mSavePath, Toast.LENGTH_LONG).show();
            System.out.println("文件已保存到：" + mSavePath);

            Bitmap bitmap1 = null;
            FileInputStream fis = null;
            try {
                fis = new FileInputStream(mSavePath);
                bitmap1 = BitmapFactory.decodeStream(fis);
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            }

            return bitmap1;
        }
        Toast.makeText(context, "画点什么吧......", Toast.LENGTH_LONG).show();
        return null;
    }


    public String getSavePath() {
        return mSavePath;
    }

}