Android进阶之自定义View实战(二)九宫格手势解锁实现

一.引言

在上篇博客Android进阶之自定义View实战(一)仿iOS UISwitch控件实现中我们主要介绍了自定义View的最基本的实现方法。作为自定义View的入门篇，仅仅介绍了Canvas的基本使用方法，而对用户交互层面仅仅处理了单击事件接口，在实际的业务中，常常涉及到手势操作，本篇博客以九宫格手势解锁View为例，来说明自定义View如何根据需求处理用户的手势操作。虽然九宫格手势解锁自定义View网上资料有很多，实现原理大同小异，但这里我只是根据自己觉得最优的思路来实现它，目的是让更多的初学者能看清我的思想，更快的掌握它的套路。话不多说，先看效果图,本人纯种工科男，颜色大家看看就好~_~!（ps:as的录屏效果有一半屏幕是花的，所以上图片将就一下。。）；
1.手指滑动状态

2.手指释放后，校验失败

3.手指释放后，校验成功

二.案例分析

根据上面的三张图，可以看出手势锁有下面几个要素:
1.九宫格阵列状态，每个格子有三种状态:空闲、击中、校验失败、校验成功，其中击中状态是在手指移动过程中产生，后面的校验状态是手指释放后产生。格子状态的改变都在View的触摸事件里处理。
2.九宫格的绘制元素,每个格子有半透明大圆、深色小圆、三角；在移动过程中的手指路径，包括两个：格子与格子之间的连线和路径的”尾巴”：动态探测线。
3.触摸事件所需要处理的逻辑主要有每个格子的状态处理和路径规划。
1>根据手指的位置，确定击中的节点，在down和move事件改变它的状态;
2>在move事件中，探测击中的节点，如果探测到则绘制连线，否则绘制探测线。
3>在up或者cancel事件中，取消探测线，并根据击中的节点校验密码，更新状态，计算三角的方向，重绘节点。

三.范例代码

1.通过第二节的分析，格子(Block)是这个View的基本构成单元，包含状态、位置、大小半径、三角等元素，触摸事件的处理都是真的Block的处理。Block代码:

package com.star.gesturelock;

import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;

/**
 * 一个阵列的基本组成单元
 * Created by kakaixcm on 16/6/7.
 */
public class Block {
    float mCenterPointX;//圆心x
    float mCenterPointY;//圆心y
    float mBigRadius;//大圆半径
    float mLittleRadius;//小圆半径
    BlockSate mState = BlockSate.IDLE;//默认空闲

    int mId;//索引

    //空闲状态颜色
    int mIdleBigCircleColor = Color.parseColor("#110000ff");
    int mIdleLittleCircleColor = Color.parseColor("#0000ff");

    //选中状态颜色
    int mHittedBigCircleColor = Color.parseColor("#1100ff00");
    int mHittedLittleCircleColor = Color.parseColor("#00ff00");

    //密码通过的颜色
    int mSuccessBigCircleColor = Color.parseColor("#1100ff00");
    int mSuccessdLittleCircleColor = Color.parseColor("#00ff00");

    //密码错误时的颜色
    int mErroBigCircleColor = Color.parseColor("#11ff0000");
    int mErroLittleCircleColor = Color.parseColor("#ff0000");

    //三角
    Path mArrow = new Path();
    //三角指向角度,水平向右为0度，顺时针方向为正
    double mArrowAngle;

    public void setArrowAngle(double angle){
        mArrowAngle = angle;
    }

    public void drawArrow(Canvas canvas, Paint paint){
        //没有松手，则不画三角
        if(mState != BlockSate.SUCCESS && mState != BlockSate.ERRO){
            return;
        }

        float arrowLen = (mBigRadius - mLittleRadius)*0.5f;
        float arrowLeftX = mCenterPointX + mLittleRadius + (mBigRadius - mLittleRadius - arrowLen)/2;
        float arrowRightX = arrowLeftX + arrowLen;
        float topY = mCenterPointY - arrowLen;
        float bottomY = mCenterPointY + arrowLen;
        mArrow.moveTo(arrowRightX, mCenterPointY);
        mArrow.lineTo(arrowLeftX, topY);
        mArrow.lineTo(arrowLeftX, bottomY);
        mArrow.close();

        canvas.save();
        canvas.rotate((float) mArrowAngle, mCenterPointX, mCenterPointY);
        canvas.drawPath(mArrow, paint);
        canvas.restore();
    }
    public enum BlockSate {
        IDLE,//空闲
        HITTED,//手指触摸
        ERRO,//密码错误
        SUCCESS;//密码正确
    }

}

说明：drawArrow实现根据指向下一节点的方向绘制三角，三角形采用Path实现，三角形的方向调整则通过canvas.rotate方法实现。每个节点的指引角度是在手势释放后，根据击中的节点列表来依次计算。
2.GestureLockView实现:

package com.star.gesturelock;

import android.content.Context;
import android.content.res.Resources;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.text.TextUtils;
import android.util.AttributeSet;
import android.util.Log;
import android.util.TypedValue;
import android.view.MotionEvent;
import android.view.View;

import java.util.ArrayList;
import java.util.List;

/**
 * Created by kakaxicm on 16/6/7.
 */
public class GestureLockView extends View {
    private float mSize;//w=h

    private final float MBIGRADIUSFRACTION = 40/300.0f;
    private final float MLITTLERADIUSFRACTION = 15/300.0f;

    private float mLittleRadius;//小圆半径
    private float mBigRadius;//大圆半径

    private List<Block> mBaseBlocks = new ArrayList<>();
    private List<Integer> mSelectedIds = new ArrayList<>();

    private Paint mBigCirclePaint;
    private Paint mSmallCirclePaint;
    private Paint mLinePaint;//滑动过程中的折线和指引线paint

    private Path mPath;//滑动过程中的折线
    private float mNodeLineX;//折线的节点位置
    private float mNodeLineY;
    private float mLineTmpX;//指引线的终点
    private float mLineTmpY;

    String mAnswer = "012543678";//预设密码

    /**
     * 手势锁回调
     */
    public interface OnGestureLockListener{
        void onBlockHitted(int index);//block被触摸到
        void onGestureLockSuccess(String password);
        void onGestureLockFail();
    }

    private OnGestureLockListener mGestureLockListener;

    public void setmGestureLockListener(OnGestureLockListener listener){
        mGestureLockListener = listener;
    }

    public GestureLockView(Context context, AttributeSet attrs) {
        super(context, attrs);
        setBackgroundColor(Color.GRAY);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        int wMode = MeasureSpec.getMode(widthMeasureSpec);
        int hMode = MeasureSpec.getMode(heightMeasureSpec);
        int wSize = MeasureSpec.getSize(widthMeasureSpec);
        int hSize = MeasureSpec.getSize(heightMeasureSpec);
        int resultWidth = wSize;
        int resultHeight = hSize;
        Resources r = Resources.getSystem();
        //lp = wrapcontent时 指定默认值
        if(wMode == MeasureSpec.AT_MOST){
            resultWidth =  (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 300, r.getDisplayMetrics());
        }
        if(hMode == MeasureSpec.AT_MOST){
            resultHeight = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 300, r.getDisplayMetrics());
        }
        int size = resultWidth>resultHeight?resultHeight:resultWidth;
        setMeasuredDimension(size, size);
        initParams();
    }

    /**
     * 绘制涉及参量的初始化操作
     */
    private void initParams(){
        mSize = getMeasuredWidth();
        mBigRadius = MBIGRADIUSFRACTION*mSize;
        mLittleRadius = MLITTLERADIUSFRACTION*mSize;

        mBigCirclePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        mSmallCirclePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        mLinePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        mLinePaint.setStyle(Paint.Style.STROKE);
        mLinePaint.setStrokeCap(Paint.Cap.ROUND);
        mLinePaint.setStrokeJoin(Paint.Join.ROUND);
        mLinePaint.setStrokeWidth(mLittleRadius*2);
        mLinePaint.setColor(Color.parseColor("#4400ff00"));

        mPath = new Path();
        //blocks初始化
        if(mBaseBlocks.size() == 0){
            for(int i = 0; i < 3; i++){
                for(int j = 0; j < 3; j++){
                    //构建3*3 block
                    Block block = new Block();
                    float centerX = mSize*(1+j*2)/6;
                    float centerY = mSize*(1+i*2)/6;
                    block.mCenterPointX = centerX;
                    block.mCenterPointY = centerY;
                    block.mBigRadius = mBigRadius;
                    block.mLittleRadius = mLittleRadius;
                    block.mId = i*3+j;
                    mBaseBlocks.add(block);
                }
            }
        }

    }

    /**
     * 绘制blocks、折线、指引线
     * @param canvas
     */
    @Override
    protected void onDraw(Canvas canvas) {
       for(int i = 0; i < mBaseBlocks.size(); i++){
           Block block = mBaseBlocks.get(i);
           drawBlock(canvas, block);
       }
        //绘制折线和指引线
        canvas.drawPath(mPath, mLinePaint);
        if(mSelectedIds.size()>0){
            canvas.drawLine(mNodeLineX, mNodeLineY, mLineTmpX, mLineTmpY, mLinePaint);
        }

    }

    /**
     * 绘制基本单元
     * 1.大、小圆
     * 2.三角指示
     * @param canvas
     * @param block
     */
    private void drawBlock(Canvas canvas, Block block){
        if(block.mState == Block.BlockSate.IDLE){
            mBigCirclePaint.setColor(block.mIdleBigCircleColor);
            mSmallCirclePaint.setColor(block.mIdleLittleCircleColor);
        }else if(block.mState == Block.BlockSate.HITTED){
            mBigCirclePaint.setColor(block.mHittedBigCircleColor);
            mSmallCirclePaint.setColor(block.mHittedLittleCircleColor);
        }else if(block.mState == Block.BlockSate.SUCCESS){
            mBigCirclePaint.setColor(block.mSuccessBigCircleColor);
            mSmallCirclePaint.setColor(block.mSuccessdLittleCircleColor);
        }else if(block.mState == Block.BlockSate.ERRO){
            mBigCirclePaint.setColor(block.mErroBigCircleColor);
            mSmallCirclePaint.setColor(block.mErroLittleCircleColor);
        }

        canvas.drawCircle(block.mCenterPointX,block.mCenterPointY, block.mBigRadius, mBigCirclePaint);
        canvas.drawCircle(block.mCenterPointX,block.mCenterPointY, block.mLittleRadius, mSmallCirclePaint);

        //画三角指示符
        if(mSelectedIds.size() > 0){
            if(block.mId != mSelectedIds.get(mSelectedIds.size()-1)){//最后一个不画三角
                block.drawArrow(canvas,mSmallCirclePaint);
            }
        }
    }

    /**
     * 核心代码，控制手势监听的逻辑
     * step1:ACTION_DOWN 做复位操作
     * setp2:ACTION_MOVE 监测手指滑到哪个block，同时更新block状态、指引线及折线
     * step3:ACTION_UP 校验密码、更新选中的block状态、设置选中的block三角角度
     * srep4:前三步都会更改绘制涉及的参数，需要重绘操作
     * @param event
     * @return
     */
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        switch (event.getAction()){
            case MotionEvent.ACTION_DOWN:
                reset();
                break;
            case MotionEvent.ACTION_MOVE:
                float x = event.getX();
                float y = event.getY();
                Block block = checkHitBlock(x, y);
                //探测未选中的block
                if(block != null && !mSelectedIds.contains(block.mId)){//探测到
                    if(mGestureLockListener != null){
                        mGestureLockListener.onBlockHitted(block.mId);
                    }
                    //手指触摸到block,作以下处理:
                    //1.block状态处理
                    //2.path的节点设置为block的中心
                    //3.指引线的终点设为节点位置
                    block.mState = Block.BlockSate.HITTED;
                    mSelectedIds.add(block.mId);
                    mNodeLineX = block.mCenterPointX;
                    mNodeLineY = block.mCenterPointY;//折线变为block的圆心

                    if(mSelectedIds.size() == 1){//手指第一次选中block
                        mPath.moveTo(mNodeLineX, mNodeLineY);
                    }else{
                        mPath.lineTo(mNodeLineX, mNodeLineY);
                    }
                    mLineTmpX = mNodeLineX;
                    mLineTmpY = mNodeLineY;
                }else{//未探测到
                    //手指未触摸到block,则只需要设置指引线终点即可
                    mLineTmpX = x;
                    mLineTmpY = y;
                }

                break;
            case MotionEvent.ACTION_UP:
                //选中的block 改为error/success状态
                changeReleaseBlockState();
                //折线处理,终点回退到节点,实现取消指引线的效果
                mLineTmpX = mNodeLineX;
                mLineTmpY = mNodeLineY;
                //三角角度设置
                configBlockArrowAngles();
                break;
            default:
                break;
        }
        invalidate();
        return true;
    }

    /**
     * 手指松开时，根据选中的block，设置三角的角度
     */
    private void configBlockArrowAngles(){
        for(int i = 0; i < mSelectedIds.size()-1; i++){
            int index = mSelectedIds.get(i);
            int nextIndex = mSelectedIds.get(i+1);
            Block curBlock = mBaseBlocks.get(index);
            Block nextBlock = mBaseBlocks.get(nextIndex);

            float offsetX = nextBlock.mCenterPointX - curBlock.mCenterPointX;
            float offsetY = nextBlock.mCenterPointY - curBlock.mCenterPointY;
            double angle = Math.toDegrees(Math.atan2(offsetY,offsetX));
            curBlock.setArrowAngle(angle);
            Log.e("ANGLES",angle+"");
        }
    }

    /**
     * 松手时，检测结果，修改选中的block状态
     */
    private void changeReleaseBlockState(){
        StringBuilder sb = new StringBuilder();
        for(int i = 0;i < mSelectedIds.size();i++){
            sb.append(mSelectedIds.get(i));
        }

        boolean isSuccess = TextUtils.equals(mAnswer, sb.toString());

        if(mGestureLockListener != null){
            if(isSuccess){
                mGestureLockListener.onGestureLockSuccess(mAnswer);
            }else {
                mGestureLockListener.onGestureLockFail();
            }
        }
        //设置选中的block的状态
        for(int i = 0; i < mBaseBlocks.size(); i++){
            Block block = mBaseBlocks.get(i);
            if(mSelectedIds.contains(block.mId)){
                if(isSuccess){
                    block.mState = Block.BlockSate.SUCCESS;
                }else{
                    block.mState = Block.BlockSate.ERRO;
                }
            }
        }
    }

    /**
     * 复位所有block、path、指引线状态
     */
    private void reset(){
        mPath.reset();
        mSelectedIds.clear();
        for(int i = 0; i < mBaseBlocks.size(); i++){
            Block block = mBaseBlocks.get(i);
            block.mState = Block.BlockSate.IDLE;
            block.mArrowAngle = 0;
        }

        mLineTmpX = 0;
        mLineTmpY = 0;
        mNodeLineX = 0;
        mNodeLineY = 0;
    }

    /**
     * 检测位置落在哪个block上
     * @param x
     * @param y
     * @return
     */
    private Block checkHitBlock(float x, float y){
        for(int i = 0; i < mBaseBlocks.size(); i++){
            Block block = mBaseBlocks.get(i);
            float startX = block.mCenterPointX - block.mBigRadius;
            float endX = block.mCenterPointX + block.mBigRadius;
            float startY = block.mCenterPointY - block.mBigRadius;
            float endY = block.mCenterPointY + block.mBigRadius;

            if(x >= startX && x <=endX && y >= startY && y <= endY){
                return block;
            }
        }
        return null;
    }
}

说明:
1>initParams方法初始化了各个画笔、连接点。核心是初始化3*3的Block阵列。
2>核心逻辑处理逻辑在onTouchEvent中:
ACTION_DOWN方法复位整个View的状态；
ACTION_MOVE做探测击中的节点，如果探测到，则更新连线节点、探测线的起点以及节点状态(Hitted)，如果未探测到，则只需更新探测线的终点；
ACTION_UP校验密码并更新所有被选中的节点的状态和三角箭头方向、取消探测线绘制。上面的操作均改变了绘制涉及的参量，所以都唤起View重绘。
3> configBlockArrowAngles方法根据两个节点的位置计算三角箭头的方向；changeReleaseBlockState()主要做密码校验用；checkHitBlock做从手指位置到节点的探测；drawBlock主要实现不同状态下的节点和三角器绘制；onDraw方法调用每个节点的绘制和折线、探测线的绘制。
用例：

  GestureLockView lockView = (GestureLockView) findViewById(R.id.gesturelock);
        lockView.setmGestureLockListener(new GestureLockView.OnGestureLockListener() {
            @Override
            public void onBlockHitted(int index) {
                Log.e("GestureLockView",index+"");
            }

            @Override
            public void onGestureLockSuccess(String password) {
                Log.e("GestureLockView",password);
            }

            @Override
            public void onGestureLockFail() {
                Log.e("GestureLockView","erro");
            }
        });

希望大家通过这篇博客的分享，能在自定义View过程中对基本的触摸事件的处理如鱼得水！如有问题和更好的实现方案，希望大家指正。