Android 自定义View手写签名并保存图片

/**
 * created by yyyyq on 2020/3/5.
 * 电子签名
 */
public class signatureview extends view {

    private context context;
    //x轴起点
    private float x;
    //y轴起点
    private float y;
    //画笔
    private final paint paint = new paint();
    //路径
    private final path path = new path();
    //画布
    private canvas canvas;
    //生成的图片
    private bitmap bitmap;
    //画笔的宽度
    private int paintwidth = 10;
    //签名颜色
    private int paintcolor = color.black;
    //背景颜色
    private int backgroundcolor = color.white;
    //是否已经签名
    private boolean istouched = false;

    //签名开始与结束
    public interface touch {
        void ontouch(boolean istouch);
    }

    private touch touch;


    public signatureview(context context) {
        super(context);
        init(context);
    }

    public signatureview(context context, @nullable attributeset attrs) {
        super(context, attrs);
        init(context);
    }

    public signatureview(context context, @nullable attributeset attrs, int defstyleattr) {
        super(context, attrs, defstyleattr);
        init(context);
    }

    private void init(context context) {
        this.context = context;
        //抗锯齿
        paint.setantialias(true);
        //样式
        paint.setstyle(paint.style.stroke);
        //画笔颜色
        paint.setcolor(paintcolor);
        //画笔宽度
        paint.setstrokewidth(paintwidth);
    }

    @override
    protected void onsizechanged(int w, int h, int oldw, int oldh) {
        super.onsizechanged(w, h, oldw, oldh);
        //创建于view大小一致的bitmap
        bitmap = bitmap.createbitmap(getwidth(), getheight(), bitmap.config.argb_8888);
        canvas = new canvas(bitmap);
        canvas.drawcolor(backgroundcolor);
        istouched = false;
    }


    @override
    public boolean ontouchevent(motionevent event) {
        if (touch != null) touch.ontouch(true);
        switch (event.getaction()) {
            //手指按下
            case motionevent.action_down:
                touchdwon(event);
                break;
            //手指移动
            case motionevent.action_move:
                istouched = true;
                if (touch != null) touch.ontouch(false);
                touchmove(event);
                break;
            //手指抬起
            case motionevent.action_up:
                canvas.drawpath(path, paint);
                path.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(bitmap, 0, 0, paint);
        // 通过画布绘制多点形成的图形
        canvas.drawpath(path, paint);
    }


    //手指按下的方法
    private void touchdwon(motionevent event) {
        //重置绘制路径
        path.reset();
        float downx = event.getx();
        float downy = event.gety();
        x = downx;
        y = downy;
        //绘制起点
        path.moveto(downx, downy);
    }

    //手指滑动的方法
    private void touchmove(motionevent event) {
        //当前的x,y坐标点
        final float movex = event.getx();
        final float movey = event.gety();
        //之前的x,y坐标点
        final float previousx = x;
        final float previousy = y;
        //获取绝对值
        final float dx = math.abs(movex - previousx);
        final float dy = math.abs(movey - previousy);
        if (dx >= 3 || dy >= 3) {
            float cx = (movex + previousx) / 2;
            float cy = (movey + previousy) / 2;
            path.quadto(previousx, previousy, cx, cy);
            x = movex;
            y = movey;
        }
    }

    /**
     * 设置画笔颜色
     *
     * @param paintcolor
     */
    public void setpaintcolor(int paintcolor) {
        this.paintcolor = paintcolor;
        paint.setcolor(paintcolor);
    }

    /**
     * 设置画笔宽度
     *
     * @param paintwidth
     */
    public void setpaintwidth(int paintwidth) {
        this.paintwidth = paintwidth;
        paint.setstrokewidth(paintwidth);
    }

    /**
     * 设置画板颜色
     *
     * @param canvascolor
     */
    public void setcanvascolor(int canvascolor) {
        this.backgroundcolor = canvascolor;
    }


    /**
     * 清除画板
     */
    public void clear() {
        if (canvas != null) {
            istouched = false;
            //更新画板
            paint.setcolor(paintcolor);
            paint.setstrokewidth(paintwidth);
            canvas.drawcolor(backgroundcolor, porterduff.mode.clear);
            invalidate();
        }
    }

    /**
     * 获取画板的bitmap
     *
     * @return
     */
    public bitmap getbitmap() {
        setdrawingcacheenabled(true);
        builddrawingcache();
        bitmap bitmap = getdrawingcache();
        setdrawingcacheenabled(false);
        return bitmap;
    }

    /**
     * 是否有签名
     *
     * @return
     */
    public boolean getsigstatus() {
        return istouched;
    }

    /**
     * 保存画板
     *
     * @param path 保存到路径
     */
    @suppresslint("wrongthread")
    public boolean save(string path) throws ioexception {
        bitmap bitmap = this.bitmap;
        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();
            return true;
        } else {
            return false;
        }
    }


}

<?xml version="1.0" encoding="utf-8"?>
<linearlayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <!--自定义view的绝对路径-->
    <com.example.customviewdemo.view.signatureview
        android:id="@+id/signature"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"
        android:background="#fff" />

    <linearlayout
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:layout_margin="20dp"
        android:orientation="horizontal">

        <button
            android:id="@+id/clear"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:gravity="center"
            android:text="清除" />

        <button
            android:id="@+id/issignature"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_marginleft="10dp"
            android:layout_weight="1"
            android:gravity="center"
            android:text="是否签名" />

        <button
            android:id="@+id/save"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_marginleft="10dp"
            android:layout_weight="1"
            android:gravity="center"
            android:text="保存" />

    </linearlayout>

</linearlayout>

/**
 * created by yyyyq on 2020/3/9.
 */
public class signatureactivity extends appcompatactivity {


    @override
    protected void oncreate(@nullable bundle savedinstancestate) {
        super.oncreate(savedinstancestate);
        setcontentview(r.layout.activity_signature);
        signatureview signatureview = findviewbyid(r.id.signature);
        //设置画笔颜色(可以不设置--默认画笔宽度10,画笔颜色黑,背景颜色白)
        signatureview.setpaintcolor(color.black);
        signatureview.setpaintwidth(20);
        signatureview.setcanvascolor(color.white);
        //清除
        button clear = findviewbyid(r.id.clear);
        clear.setonclicklistener(view -> {
            signatureview.clear();
            //设置画笔颜色(可以不设置--默认画笔宽度10,画笔颜色黑,背景颜色白)
            signatureview.setpaintcolor(color.black);
            signatureview.setpaintwidth(20);
            signatureview.setcanvascolor(color.white);
        });
        //是否含有签名
        button issignature = findviewbyid(r.id.issignature);
        issignature.setonclicklistener(view -> {
            if (signatureview.getsigstatus()) {
                toast.maketext(signatureactivity.this, "有签名", toast.length_short).show();
            } else {
                toast.maketext(signatureactivity.this, "无签名", toast.length_short).show();
            }
        });
        //保存
        button save = findviewbyid(r.id.save);
        save.setonclicklistener(view -> {
            try {
                if (signatureview.save("/sdcard/yyyyq.png")) {
                    toast.maketext(signatureactivity.this, "保存成功", toast.length_short).show();
                } else {
                    toast.maketext(signatureactivity.this, "保存失败", toast.length_short).show();
                }

            } catch (ioexception e) {
                e.printstacktrace();
            }

        });

    }
}