android 多功能自定义画板控件(用于解决特定需求)

在项目中需要做一个可以自定义轨迹，但始终只有一条线，并且支持撤销（撤销单位为MotionEvent的down事件到up事件），还要支持动画预览等功能，最重要的是能够按照间隔像素来获取所有点的坐标，用于项目的其他功能。

整体的思路

1.项目中的应用场景需要画板是一个圆形的，这个好实现用canvas画圆就好

2.始终一条线，这个也好实现，在onTouchEvent中做文章（如果只是单纯的画一条线估计有不少的选择，但是后续要求能够起点终点转换以及预览动画）因此选择Path来实现

3.能够动画预览，需要借助于PathMeasure和ValueAnimator来完成

4.撤销功能，撤销指的是撤销一个单位，比如在word中指的是一次输入，因此在这个画板中，定义一个down多个move和一个up为一个操作单位，这些点作为一个路径存储起来，这样每次绘画的时候都会产生一个path，撤销的时候就是对这个集合进行remove操作即可

5.起点终点转换，因为集合中有多个path，因此在转换的时候就老老实实的用PathMeasure来倒序遍历所有的路径，并且每个路径从的getLength开始获取坐标，然后创建一个新的path来装所有的点(结合lineto 和 moveto)

6.按照间隔像素获取点集合，通过PathMeasure来获取点集合

7.清空功能.这个最好实现，直接对路径集合清空即可

8.自定义颜色配置，通过attr自定义属性实现

以下贴上效果动画

1.画线

2.预览

3.转换起点终点之后预览

4.撤销功能

5.产生点用于其他界面来小图展示

以上是效果图，现贴上源码

1.布局文件使用

2.自定义属性可直接配置

3.代码

package com.bubblelab.bubbledrip.views.custom;

import android.animation.Animator;
import android.animation.ValueAnimator;
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.DashPathEffect;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.PathMeasure;
import android.graphics.RectF;
import android.util.AttributeSet;
import android.util.TypedValue;
import android.view.MotionEvent;
import android.view.View;
import android.view.animation.LinearInterpolator;

import com.bubblelab.bubbledrip.R;
import com.bubblelab.bubbledrip.utils.T;

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

/**
 * 控件功能列表
 * 1.可清空
 * 2.支持起点终点转换
 * 3.始终为一条线
 * 4.支持从绘画的第一个点到最后一个点的预览动画,可以停止预览
 * 5.支持撤销操作(一个操作单位为从down - up)
 * 6.圆形画板
 * 7.可在布局文件中自定义属性
 * 8.可以用控件源的半径以及从控件源得到的点等比例初始化控件
 * 9.可设置该控件是否为仅用于显示或者是可操作
 * 10.可以按照点到点的间隔来获取集合点
 */
public class PaletteView extends View {
    public static int DEFAULT_CIRCLE_RADIUS = 0;//dp
    public static int DEFAULT_CIRCLE_LINE_COLOR = Color.GRAY;
    public static int DEFAULT_CIRCLE_BACKGROUND = Color.parseColor("#ffEEEEEE");
    public static int DEFAULT_CIRCLE_LINE_WIDTH = 2;//;dp
    public static int DEFAULT_LINE_COLOR = Color.BLACK;
    public static int DEFAULT_LINE_WIDTH = 10;//dp
    public static int DEFAULT_PREVIEW_TIME = 5;//默认预览时间为5秒

    private Paint mPaint;//画笔
    private Path mPath;//当前绘制的path
    private List mPaths;//可以用来撤销的path
    public int mCircleRadius = (int) dip2px(DEFAULT_CIRCLE_RADIUS);//背景圆的半径 由控件的宽和高指定 因此不要把控件的width和height设置为wrap_content

    //以下为自定义控件支持的属性集
    public int mCircleLineColor = DEFAULT_CIRCLE_LINE_COLOR;//背景圆的边线颜色
    public int mCircleBackgroung = DEFAULT_CIRCLE_BACKGROUND;//背景圆的背景色
    public int mCircleLineWidth = (int) dip2px(DEFAULT_CIRCLE_LINE_WIDTH);//背景圆的边线宽度
    public int mLineColor = DEFAULT_LINE_COLOR;//内容线的颜色
    public int mLineWidth = (int) dip2px(DEFAULT_LINE_WIDTH);//内容线的宽度
    public int mStartCircleColor = Color.parseColor("#73C7F7");//开始logo的圆颜色
    public int mEndRectColor = Color.parseColor("#73C7F7");//结束logo的矩形颜色
    public int mStartCircleRadius = (int) dip2px(5);//开始logo的圆半径
    public int mEndRectWith = (int) dip2px(8);//结束logo的矩形边长
    public int mPreviewStartRadius = mStartCircleRadius;//预览时的开始圆圈的半径
    public int mPreviewEndWidth = mEndRectWith;//预览时的结束矩形的边长
    public int mPreviewStartCircleColor = mStartCircleColor;//预览时的开始圆圈的颜色
    public int mPreviewEndRectColor = mEndRectColor;//预览时的结束矩形的颜色
    public int mPreviewLineColor = mLineColor;//预览时的线的颜色
    public int mPreviewLineWidth = mLineWidth;//预览时的线的宽度
    public boolean isOnlyShow = false;//是否为仅为显示模式 默认为可操作 true为不可操作


    public RectF mEndRectF = new RectF();//表示开始logo的矩形rectf对象
    public boolean isTouching = false;//是否在触摸该控件中
    private boolean isPreview = false;//手否在预览中
    PathMeasure mPathMeasure = new PathMeasure();//控件对象使用的pathmeasure
    private float mPreviewStartX, mPreviewStartY;//预览的开始圆圈的x,y坐标
    private ValueAnimator mPreviewAnimator;//预览的动画


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

    public PaletteView(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public PaletteView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        setDrawingCacheEnabled(true);
        TypedArray ta = getContext().obtainStyledAttributes(attrs, R.styleable.PaletteView);
        mCircleLineColor = ta.getColor(R.styleable.PaletteView_circle_line_color, mCircleLineColor);
        mCircleBackgroung = ta.getColor(R.styleable.PaletteView_circle_background, mCircleBackgroung);
        mCircleLineWidth = (int) ta.getDimension(R.styleable.PaletteView_circle_line_width, mCircleLineWidth);
        mLineColor = ta.getColor(R.styleable.PaletteView_line_color, mLineColor);
        mLineWidth = (int) ta.getDimension(R.styleable.PaletteView_line_width, mLineWidth);
        mStartCircleRadius = (int) ta.getDimension(R.styleable.PaletteView_start_circle_radius, mStartCircleRadius);
        mStartCircleColor = ta.getColor(R.styleable.PaletteView_start_circle_color, mStartCircleColor);
        mEndRectWith = (int) ta.getDimension(R.styleable.PaletteView_end_rect_width, mEndRectWith);
        mEndRectColor = ta.getColor(R.styleable.PaletteView_end_rect_color, mEndRectColor);
        isOnlyShow = ta.getBoolean(R.styleable.PaletteView_is_only_show, isOnlyShow);
        mPreviewStartRadius = (int) ta.getDimension(R.styleable.PaletteView_preview_start_circle_radius, mStartCircleRadius);
        mPreviewStartCircleColor = ta.getColor(R.styleable.PaletteView_preview_start_circle_color, mStartCircleColor);
        mPreviewEndWidth = (int) ta.getDimension(R.styleable.PaletteView_preview_end_rect_width, mEndRectWith);
        mPreviewEndRectColor = ta.getColor(R.styleable.PaletteView_preview_end_rect_color, mEndRectColor);
        mPreviewLineColor = ta.getColor(R.styleable.PaletteView_preview_line_color, mLineColor);
        mPreviewLineWidth = (int) ta.getDimension(R.styleable.PaletteView_preview_line_width, mLineWidth);
        ta.recycle();
        init();
    }

    private void init() {
        mPaint = new Paint();
        mPaint.setDither(true);
        mPaint.setAntiAlias(true);
        mPaint.setStrokeJoin(Paint.Join.ROUND);
        mPaint.setStrokeCap(Paint.Cap.ROUND);
        mPaths = new ArrayList<>();
        mPath = new Path();
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        setMeasuredDimension(MeasureSpec.getSize(widthMeasureSpec), MeasureSpec.getSize(heightMeasureSpec));
        mCircleRadius = Math.min((getMeasuredWidth() - getPaddingLeft() - getPaddingRight() - mCircleLineWidth * 2) / 2, (getMeasuredHeight() - getPaddingBottom() - getPaddingTop() - mCircleLineWidth * 2) / 2);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        //画背景圆
        mPaint.setColor(mCircleBackgroung);
        mPaint.setStyle(Paint.Style.FILL);
        canvas.drawCircle(getWidth() / 2, getHeight() / 2, mCircleRadius, mPaint);

        //画虚线
        mPaint.setStyle(Paint.Style.STROKE);
        mPaint.setColor(mCircleLineColor);
        mPaint.setStrokeWidth(mCircleLineWidth);
        mPaint.setPathEffect(new DashPathEffect(new float[]{13, 13}, 0));//先画长度为3的实线，再间隔长度为2的空白，之后一直重复这个单元。这个数组的长度只要大于等于2就行，你可以设置多个数值，产生不同效果，最后这个0指的是与起始位置的偏移量。
        canvas.drawCircle(getWidth() / 2, getHeight() / 2, mCircleRadius, mPaint);

        //画path点
        mPaint.setStyle(Paint.Style.STROKE);
        if (isPreview) {//设置预览时的paint的颜色和宽度
            mPaint.setColor(mPreviewLineColor);
            mPaint.setStrokeWidth(mPreviewLineWidth);

        } else {
            mPaint.setColor(mLineColor);
            mPaint.setStrokeWidth(mLineWidth);
        }
        mPaint.setPathEffect(null);
        for (Path path : mPaths) {
            canvas.drawPath(path, mPaint);
        }
        canvas.drawPath(mPath, mPaint);


        float[] headPos = getEndsPoints();
        if (headPos != null) {
            //按照第一个点为中心 画开始圆圈
            mPaint.setStyle(Paint.Style.FILL);
            mPaint.setStrokeWidth(1);
            mPaint.setPathEffect(null);

            if (isPreview) {
                mPaint.setColor(mPreviewStartCircleColor);
                canvas.drawCircle(mPreviewStartX, mPreviewStartY, mPreviewStartRadius, mPaint);
            } else {
                mPaint.setColor(mStartCircleColor);
                canvas.drawCircle(headPos[0], headPos[1], mStartCircleRadius, mPaint);
            }
            if (!isTouching) {//在手指不接触的时候再去绘制最后的小方块
                if (isPreview) {
                    mPaint.setColor(mPreviewEndRectColor);
                    mEndRectF.set(headPos[2] - mPreviewEndWidth / 2, headPos[3] - mPreviewEndWidth / 2, headPos[2] + mPreviewEndWidth / 2, headPos[3] + mPreviewEndWidth / 2);
                } else {
                    //按照最后一个点为中心 画结束的方块
                    mPaint.setColor(mEndRectColor);
                    mEndRectF.set(headPos[2] - mEndRectWith / 2, headPos[3] - mEndRectWith / 2, headPos[2] + mEndRectWith / 2, headPos[3] + mEndRectWith / 2);
                }
                canvas.drawRect(mEndRectF, mPaint);
            }
        }
    }


    /**
     * 获取绘画出来的轨迹的两端的点的值
     *
     * @return {firstX,firstY,lastX,lastY} 以数组形式返回两个端点的坐标值 如果没有画 则返回null
     */
    public float[] getEndsPoints() {
        float[] firstPos = new float[2];
        float[] lastPos = new float[2];
        if (mPaths.size() == 0) {
            return null;
        } else {
            Path firstPath = mPaths.get(0);
            Path lastPath = mPaths.get(mPaths.size() - 1);
            mPathMeasure.setPath(firstPath, false);
            mPathMeasure.getPosTan(0, firstPos, null);
            mPathMeasure.setPath(lastPath, false);
            mPathMeasure.getPosTan(mPathMeasure.getLength(), lastPos, null);
        }
        return new float[]{firstPos[0], firstPos[1], lastPos[0], lastPos[1]};
    }


    @Override
    public boolean onTouchEvent(MotionEvent e) {
        if (isOnlyShow) {
            return super.onTouchEvent(e);
        }
        if (isPreview) {
            return false;
        }
        float x = e.getX();
        float y = e.getY();
        A:
        switch (e.getAction()) {
            case MotionEvent.ACTION_DOWN:
                if (getDistanceWithCenter(x, y) >= (mCircleRadius - mLineWidth / 2)) {
                    break A;
                }
                isTouching = true;
                if (mPaths.size() == 0) {
                    mPath.moveTo(x, y);
                } else {
                    mPath.lineTo(x, y);
                }
                break;
            case MotionEvent.ACTION_MOVE:
                if (getDistanceWithCenter(x, y) >= (mCircleRadius - mLineWidth / 2)) {
                    break A;
                }
                mPath.lineTo(x, y);
                break;
            case MotionEvent.ACTION_UP:
                PathMeasure pathMeasure = new PathMeasure(mPath, false);
                if (pathMeasure.getLength() == 0) {
                    if (getDistanceWithCenter(x, y) >= (mCircleRadius - mLineWidth / 2)) {
                        break A;
                    } else {
                        mPath.lineTo(x + 0.1f, y + 0.1f);
                    }
                }
                processUp();
                isTouching = false;
                break;
        }
        invalidate();
        return true;
    }

    /**
     * 当up的时候 将path添加到path集合中
     */
    private void processUp() {
        Path path = new Path(mPath);
        mPaths.add(path);
        mPath.reset();
        mPath.moveTo(getEndsPoints()[2], getEndsPoints()[3]);
    }

    //撤销操作
    public boolean undo() {
        if (isPreview || isTouching) {
            T.showToast("请在无操作时清空", 100);
            return false;
        }

        if (isCanUndo()) {
            mPaths.remove(mPaths.size() - 1);
            invalidate();
            return true;
        } else return false;
    }


    //是否可以撤销
    public boolean isCanUndo() {
        if (mPaths != null && mPaths.size() > 0)
            return true;
        else return false;
    }

    /**
     * 清空画板的操作 在预览以及在触摸中无法清空
     */
    public void clear() {
        if (isPreview || isTouching) {
            return;
        }
        mPaths.clear();
        mPath.reset();
        invalidate();
    }

    /**
     * 交换头尾坐标
     */
    public void swapEndsPoints() {
        if (isPreview || isTouching) {
            T.showToast("请在无操作时清空", 100);
            return;
        }
        if (mPaths == null || mPaths.size() == 0) {
            return;
        }
        changePath();
        mPath.moveTo(getEndsPoints()[2], getEndsPoints()[3]);
        invalidate();
    }

    /**
     * 将mUndoPath中的点绘制到一个path中 然后删除掉mUndopath中的点 并将这个path存储到mundopath中,然后invaledate
     */
    private void changePath() {
        if (mPaths == null || mPaths.size() == 0) {
            return;
        }
        float[] pos = new float[2];
        Path path = new Path();
        PathMeasure pathMeasure = new PathMeasure();
        for (int index = mPaths.size() - 1; index >= 0; index--) {
            Path p = mPaths.get(index);
            pathMeasure.setPath(p, false);
            for (float start = pathMeasure.getLength(); start >= 0; start--) {
                pathMeasure.getPosTan(start, pos, null);
                if (index == mPaths.size() - 1 && start == pathMeasure.getLength()) {
                    path.moveTo(pos[0], pos[1]);
                } else {
                    path.lineTo(pos[0], pos[1]);
                }
            }
        }
        mPaths.clear();
        mPaths.add(path);
    }


    /**
     * 获取点到中心的距离
     *
     * @param x
     * @param y
     * @return
     */
    public int getDistanceWithCenter(float x, float y) {
        int centerX = getWidth() / 2;
        int centerY = getHeight() / 2;
        return (int) Math.sqrt(Math.pow(x - centerX, 2) + Math.pow(y - centerY, 2));
    }


    /**
     * @return 每隔distanceInterval就获取一个点, 然后转换为按照中心点的平面坐标集合
     */
    public ArrayList getCenterCPs(float distanceInterval) {
        if (mPaths == null || mPaths.size() == 0) {
            T.showToast("没有内容", 100);
            return null;
        }
        ArrayList val = new ArrayList<>();
        float centerX = getWidth() / 2;
        float centerY = getHeight() / 2;
        float[] temppos = new float[2];
        float x, y;
        PathMeasure pathMeasure = new PathMeasure();
        for (Path path : mPaths) {
            pathMeasure.setPath(path, false);
            for (float start = 0; start < pathMeasure.getLength(); ) {
                pathMeasure.getPosTan(start, temppos, null);
                x = temppos[0] - centerX;
                y = centerY - temppos[1];
                val.add(new CP(x, y));
                start += distanceInterval;
            }
            pathMeasure.getPosTan(pathMeasure.getLength(), temppos, null);
            x = temppos[0] - centerX;
            y = centerY - temppos[1];
            val.add(new CP(x, y));
        }
        return val;
    }


    /**
     * 通过源view的点和半径来等比例的显示path
     *
     * @param res
     * @param circleradius
     */
    public void initView(List res, float circleradius) {
        if (res == null || res.size() == 0) {
            return;
        }
        if (mCircleRadius == 0) {
            mCircleRadius = Math.min((getWidth() - getPaddingLeft() - getPaddingRight() - mCircleLineWidth * 2) / 2, (getHeight() - getPaddingBottom() - getPaddingTop() - mCircleLineWidth * 2) / 2);
        }
        float scale = mCircleRadius / circleradius;
        Path path = new Path();
        for (int index = 0; index < res.size(); index++) {
            CP cp = res.get(index);
            float newx = (float) (scale * cp.x);
            float newy = (float) (scale * cp.y);
            newx += getWidth() / 2;
            newy = getHeight() / 2 - newy;
            if (index == 0) {
                path.moveTo(newx, newy);
            } else {
                path.lineTo(newx, newy);
            }
            if (index == res.size() - 1) {
                mPath.moveTo(newx, newy);
            }
        }
        mPaths.add(path);
        invalidate();
    }

    /**
     * 开始预览
     *
     * @param time 设置预览时间  默认为5秒
     */
    public void startPreview(double time) {
        isPreview = true;
        final float[] pos = new float[2];
        final float[] tan = new float[2];
        if (mPaths.size() < 1) {
            return;
        }
        float length = 0;
        for (Path path : mPaths) {
            mPathMeasure.setPath(path, false);
            length += mPathMeasure.getLength();
        }
        mPreviewAnimator = ValueAnimator.ofFloat(0, length).setDuration((long) ((time == 0 ? DEFAULT_PREVIEW_TIME : time) * 1000));
        mPreviewAnimator.setInterpolator(new LinearInterpolator());
        mPreviewAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
            @Override
            public void onAnimationUpdate(ValueAnimator animation) {
                float animatedFraction = (float) animation.getAnimatedValue();
                float length = 0;
                for (int index = 0; index < mPaths.size(); index++) {
                    mPathMeasure.setPath(mPaths.get(index), false);
                    length += mPathMeasure.getLength();
                    if (animatedFraction < length) {
                        mPathMeasure.getPosTan(animatedFraction - (length - mPathMeasure.getLength()), pos, tan);
                        mPreviewStartX = pos[0];
                        mPreviewStartY = pos[1];
                        postInvalidate();
                        break;
                    }
                }
            }
        });
        mPreviewAnimator.setRepeatCount(0);
        mPreviewAnimator.addListener(new Animator.AnimatorListener() {
            @Override
            public void onAnimationStart(Animator animation) {
            }
            @Override
            public void onAnimationEnd(Animator animation) {
                isPreview = false;
                T.showToast("预览结束", 100);
                if (mPreviewListener != null) {
                    mPreviewListener.onPreviewEnd();
                }
                invalidate();
            }
            @Override
            public void onAnimationCancel(Animator animation) {
            }
            @Override
            public void onAnimationRepeat(Animator animation) {
            }
        });
        mPreviewAnimator.start();
    }

    /**
     * 预览完毕回调接口
     */
    public interface PreviewListener {
        public void onPreviewEnd();
    }
    public PreviewListener mPreviewListener;
    public void setOnPreViewListener(PreviewListener preViewListener) {
        mPreviewListener = preViewListener;
    }
    /**
     * 结束预览
     */
    public void stopPreview() {
        mPreviewAnimator.cancel();
        isPreview = false;
        invalidate();
    }
    public float dip2px(float dpVal) {
        return TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dpVal, getContext().getResources().getDisplayMetrics());
    }
    public float sp2px(float spVal) {
        return TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP, spVal, getContext().getResources().getDisplayMetrics());
    }
}