手写签名--自定义View

先自定义view

package com.example.zhilongzhang.myapplication;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.PorterDuff;
import android.support.annotation.ColorInt;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;


public class LinePathView extends View {
private Context mContext;

/**
 * 笔画X坐标起点
 */
private float mX;
/**
 * 笔画Y坐标起点
 */
private float mY;
/**
 * 手写画笔
 */
private final Paint mGesturePaint = new Paint();
/**
 * 路径
 */
private final Path mPath = new Path();
/**
 * 签名画笔
 */
private Canvas cacheCanvas;
/**
 * 签名画布
 */
private Bitmap cachebBitmap;
/**
 * 是否已经签名
 */
private boolean isTouched = false;
/**
 * 画笔宽度 px；
 */
private int mPaintWidth = 10;
/**
 * 前景色
 */
private int mPenColor = Color.BLACK;
/**
 * 背景色（指最终签名结果文件的背景颜色，默认为透明色）
 */
private int mBackColor = Color.TRANSPARENT;

//签名开始与结束
private Touch touch;

public LinePathView(Context context) {
    super(context);
    init(context);
}

public LinePathView(Context context, AttributeSet attrs) {
    super(context, attrs);
    init(context);
}

public LinePathView(Context context, AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
    init(context);
}

public void init(Context context) {
    this.mContext = context;
    //设置抗锯齿
    mGesturePaint.setAntiAlias(true);
    //设置签名笔画样式
    mGesturePaint.setStyle(Paint.Style.STROKE);
    //设置笔画宽度
    mGesturePaint.setStrokeWidth(mPaintWidth);
    //设置签名颜色
    mGesturePaint.setColor(mPenColor);
}

@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
    super.onSizeChanged(w, h, oldw, oldh);
    //创建跟view一样大的bitmap，用来保存签名
    cachebBitmap = Bitmap.createBitmap(getWidth(), getHeight(), Bitmap.Config.ARGB_8888);
    cacheCanvas = new Canvas(cachebBitmap);
    cacheCanvas.drawColor(mBackColor);
    isTouched = false;
}

@Override
public boolean onTouchEvent(MotionEvent event) {
    if (touch != null) touch.OnTouch(true);
    switch (event.getAction()) {
        case MotionEvent.ACTION_DOWN:
            touchDown(event);
            break;
        case MotionEvent.ACTION_MOVE:
            isTouched = true;
            if (touch != null) touch.OnTouch(false);
            touchMove(event);
            break;
        case MotionEvent.ACTION_UP:
            //将路径画到bitmap中，即一次笔画完成才去更新bitmap，而手势轨迹是实时显示在画板上的。
            cacheCanvas.drawPath(mPath, mGesturePaint);
            mPath.reset();
            break;
    }
    // 更新绘制
    invalidate();
    return true;
}

@Override
protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    //画此次笔画之前的签名
    canvas.drawBitmap(cachebBitmap, 0, 0, mGesturePaint);
    // 通过画布绘制多点形成的图形
    canvas.drawPath(mPath, mGesturePaint);
}

// 手指点下屏幕时调用
private void touchDown(MotionEvent event) {
    // 重置绘制路线
    mPath.reset();
    float x = event.getX();
    float y = event.getY();
    mX = x;
    mY = y;
    // mPath绘制的绘制起点
    mPath.moveTo(x, y);
}

// 手指在屏幕上滑动时调用
private void touchMove(MotionEvent event) {
    final float x = event.getX();
    final float y = event.getY();
    final float previousX = mX;
    final float previousY = mY;
    final float dx = Math.abs(x - previousX);
    final float dy = Math.abs(y - previousY);
    // 两点之间的距离大于等于3时，生成贝塞尔绘制曲线
    if (dx >= 3 || dy >= 3) {
        // 设置贝塞尔曲线的操作点为起点和终点的一半
        float cX = (x + previousX) / 2;
        float cY = (y + previousY) / 2;
        // 二次贝塞尔，实现平滑曲线；previousX, previousY为操作点，cX, cY为终点
        mPath.quadTo(previousX, previousY, cX, cY);
        // 第二次执行时，第一次结束调用的坐标值将作为第二次调用的初始坐标值
        mX = x;
        mY = y;
    }
}

/**
 * 清除画板
 */
public void clear() {
    if (cacheCanvas != null) {
        isTouched = false;
        //更新画板信息
        mGesturePaint.setColor(mPenColor);
        cacheCanvas.drawColor(mBackColor, PorterDuff.Mode.CLEAR);
        mGesturePaint.setColor(mPenColor);
        invalidate();
    }
}

public interface Touch {
    void OnTouch(boolean isTouch);
}

public Touch getTouch() {
    return touch;
}

public void setTouch(Touch touch) {
    this.touch = touch;
}

/**
 * 保存画板
 *
 * @param path 保存到路径
 */
public void save(String path) throws IOException {
    save(path, false,0);
}

/**
 * 保存画板
 *
 * @param path       保存到路径
 * @param clearBlank 是否清除边缘空白区域
 * @param blank      要保留的边缘空白距离
 */
public void save(String path, boolean clearBlank, int blank) throws IOException {

    Bitmap bitmap = cachebBitmap;
    //BitmapUtil.createScaledBitmapByHeight(srcBitmap, 300);//  压缩图片
    if (clearBlank) {
        bitmap = clearBlank(bitmap, blank);
    }
    ByteArrayOutputStream bos = new ByteArrayOutputStream();
    bitmap.compress(Bitmap.CompressFormat.PNG, 100, bos);
    byte[] buffer = bos.toByteArray();
    if (buffer != null) {
        File file = new File(path);
        if (file.exists()) {
            file.delete();
        }
        OutputStream outputStream = new FileOutputStream(file);
        outputStream.write(buffer);
        outputStream.close();
    }
}

/**
 * 获取画板的bitmap
 *
 * @return
 */
public Bitmap getBitMap() {
    setDrawingCacheEnabled(true);
    buildDrawingCache();
    Bitmap bitmap = getDrawingCache();
    setDrawingCacheEnabled(false);
    return bitmap;
}

/**
 * 逐行扫描 清楚边界空白。
 *
 * @param bp
 * @param blank 边距留多少个像素
 * @return
 */
private Bitmap clearBlank(Bitmap bp, int blank) {
    int HEIGHT = bp.getHeight();
    int WIDTH = bp.getWidth();
    int top = 0, left = 0, right = 0, bottom = 0;
    int[] pixs = new int[WIDTH];
    boolean isStop;
    //扫描上边距不等于背景颜色的第一个点
    for (int y = 0; y < HEIGHT; y++) {
        bp.getPixels(pixs, 0, WIDTH, 0, y, WIDTH, 1);
        isStop = false;
        for (int pix : pixs) {
            if (pix != mBackColor) {
                top = y;
                isStop = true;
                break;
            }
        }
        if (isStop) {
            break;
        }
    }
    //扫描下边距不等于背景颜色的第一个点
    for (int y = HEIGHT - 1; y >= 0; y--) {
        bp.getPixels(pixs, 0, WIDTH, 0, y, WIDTH, 1);
        isStop = false;
        for (int pix : pixs) {
            if (pix != mBackColor) {
                bottom = y;
                isStop = true;
                break;
            }
        }
        if (isStop) {
            break;
        }
    }
    pixs = new int[HEIGHT];
    //扫描左边距不等于背景颜色的第一个点
    for (int x = 0; x < WIDTH; x++) {
        bp.getPixels(pixs, 0, 1, x, 0, 1, HEIGHT);
        isStop = false;
        for (int pix : pixs) {
            if (pix != mBackColor) {
                left = x;
                isStop = true;
                break;
            }
        }
        if (isStop) {
            break;
        }
    }
    //扫描右边距不等于背景颜色的第一个点
    for (int x = WIDTH - 1; x > 0; x--) {
        bp.getPixels(pixs, 0, 1, x, 0, 1, HEIGHT);
        isStop = false;
        for (int pix : pixs) {
            if (pix != mBackColor) {
                right = x;
                isStop = true;
                break;
            }
        }
        if (isStop) {
            break;
        }
    }
    if (blank < 0) {
        blank = 0;
    }
    //计算加上保留空白距离之后的图像大小
    left = left - blank > 0 ? left - blank : 0;
    top = top - blank > 0 ? top - blank : 0;
    right = right + blank > WIDTH - 1 ? WIDTH - 1 : right + blank;
    bottom = bottom + blank > HEIGHT - 1 ? HEIGHT - 1 : bottom + blank;
    return Bitmap.createBitmap(bp, left, top, right - left, bottom - top);
}

/**
 * 设置画笔宽度 默认宽度为10px
 *
 * @param mPaintWidth
 */
public void setPaintWidth(int mPaintWidth) {
    mPaintWidth = mPaintWidth > 0 ? mPaintWidth : 10;
    this.mPaintWidth = mPaintWidth;
    mGesturePaint.setStrokeWidth(mPaintWidth);

}


public void setBackColor(@ColorInt int backColor) {
    mBackColor = backColor;
}


/**
 * 设置画笔颜色
 *
 * @param mPenColor
 */
public void setPenColor(int mPenColor) {
    this.mPenColor = mPenColor;
    mGesturePaint.setColor(mPenColor);
}

/**
 * 是否有签名
 *
 * @return
 */
public boolean getTouched() {
    return isTouched;
}
}

//在MXL中的使用

//在Activity中的使用

 LinePathView mPathView;
 mPathView=findViewById(R.id.meview);
    //修改背景、笔宽、颜色
    mPathView.setBackColor(Color.WHITE);
    mPathView.setPaintWidth(20);
    mPathView.setPenColor(Color.BLACK);
    //清除
    findViewById(R.id.clean).setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            mPathView.clear();
            mPathView.setBackColor(Color.WHITE);
            mPathView.setPaintWidth(20);
            mPathView.setPenColor(Color.BLACK);
        }
    });
    //保存
    findViewById(R.id.sure).setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            if (mPathView.getTouched()) {
                try {
                    mPathView.save("/sdcard/qm.png", true, 10);
                    setResult(100);
                } catch (IOException e) {
                    e.printStackTrace();
                }
            } else {
                Toast.makeText(MainActivity.this, "您没有签名~", Toast.LENGTH_SHORT).show();
            }
        }
    });
}

*记得申请全权限