android仿百度福袋红包界面

马上到双十一，红包来袭，时间又是充裕，抢红包的时候意外发现了百度的福袋界面还不错，想想还要专门写一篇博文来完成其界面。

当然啦，这其实就是解锁界面的进化版本。不过其包含的知识点还是挺多的，写篇博文记录一下看看具体有哪些技术点啦。看

看百度的效果图：

1.编程思路

看看界面，不难发现，其就是一个放入九张图片的容器，绘制其实可以在其上面另创建一个透明View负责绘制线与圆圈。下面我们将介绍一下实现过程。

㈠自定义ViewGroup

我们知道，自定义ViewGroup一定需要实现其onLayout()方法。该方法是设置子View位置与尺寸的时候调用。还有一个onMeasure()方法，该方法是测量view及其内容来确定view的宽度和高度。

㈡存储其点与圆的位置及绘制参数

当重回界面的时候，是不会保存上一次绘制界面的内容，必须存储以备重绘时候绘制到界面

㈢简单的缩放动画

㈣自定义View实现绘制界面

㈤绘制完成时，清除界面绘制内容，并且保证不连接重复图片

下面我们将完成这些步骤。

2.自定义ViewGroup

开始的任务就是将九张图片平均分布到图片的位置，显示在手机界面中。其代码如下：

public class LYJViewGroup extends ViewGroup implements LYJGestureDrawline.OnAnimationCallback{
  
  private int childWidth;
  
  private Context context;
  
  private List<LYJGesturePoint> list;
  
  private LYJGestureView gestureDrawline;
  private int baseNum = 5;
  public LYJViewGroup(Context context) {
    super(context);
    this.context = context;
    this.list = new ArrayList<>();
    DisplayMetrics metric = new DisplayMetrics();
    ((Activity) context).getWindowManager().getDefaultDisplay().getMetrics(metric);
    childWidth = metric.widthPixels / 3;   // 屏幕宽度（像素）
    addChild();
    // 初始化一个可以画线的view
    gestureDrawline = new LYJGestureView(context, list);
    gestureDrawline.setAnimationCallback(this);
  }
  public void setParentView(ViewGroup parent){
    // 得到屏幕的宽度
    DisplayMetrics metric = new DisplayMetrics();
    ((Activity) context).getWindowManager().getDefaultDisplay().getMetrics(metric);
    int width = metric.widthPixels;
    LayoutParams layoutParams = new LayoutParams(width, width);
    this.setLayoutParams(layoutParams);
    gestureDrawline.setLayoutParams(layoutParams);
    parent.addView(this);
    parent.addView(gestureDrawline);
  }
  @Override
  protected void onLayout(boolean changed, int l, int t, int r, int b) {
    for (int i = 0; i < getChildCount(); i++) {
      //第几行
      int rowspan = i / 3;
      //第几列
      int column = i % 3;
      Android.view.View v = getChildAt(i);
      v.layout(column * childWidth + childWidth / baseNum, rowspan * childWidth + childWidth / baseNum,
          column * childWidth + childWidth - childWidth / baseNum, rowspan * childWidth + childWidth - childWidth / baseNum);
    }
  }
  @Override
  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    // 遍历设置每个子view的大小
    for (int i = 0; i < getChildCount(); i++) {
      View v = getChildAt(i);
      v.measure(widthMeasureSpec, heightMeasureSpec);
    }
  }
  private void addChild() {
    for (int i = 0; i < 9; i++) {
      ImageView image = new ImageView(context);
      image.setBackgroundResource(R.drawable.marker);
      this.addView(image);
      invalidate();
      // 第几行
      int rowspan = i / 3;
      // 第几列
      int column = i % 3;
      // 定义点的左上角与右下角的坐标
      int leftX = column * childWidth + childWidth / baseNum;
      int topY = rowspan * childWidth + childWidth / baseNum;
      int rightX = column * childWidth + childWidth - childWidth / baseNum;
      int bottomY = rowspan * childWidth + childWidth - childWidth / baseNum;
      LYJGesturePoint p = new LYJGesturePoint(leftX, topY, rightX,bottomY,i);
      this.list.add(p);
    }
  }
  @Override
  public void startAnimationImage(int i) {
    Animation animation= AnimationUtils.loadAnimation(getContext(), R.anim.gridlayout_child_scale_anim);
    getChildAt(i).startAnimation(animation);
  }
}

3.自定义点类

顾名思义，就是为了获取点的相关的属性，其中基础属性图片左上角坐标与右下角坐标，计算图片中心位置以便获取图片中心点。状态标记，表示该点是否绘制到图片。下面是其实体类：

public class LYJGesturePoint {
  private Point pointLeftTop;//左上角坐标
  private Point pointRightBottom;//右下角坐标
  private int centerX;//图片中心点X坐标
  private int centerY;//图片中心点Y坐标
  private int pointState;//是否点击了该图片
  private int num;
  public int getNum() {
    return num;
  }
  public int getPointState() {
    return pointState;
  }
  public void setPointState(int pointState) {
    this.pointState = pointState;
  }
  public Point getPointLeftTop() {
    return pointLeftTop;
  }
  public Point getPointRightBottom() {
    return pointRightBottom;
  }
  public LYJGesturePoint(int left,int top,int right,int bottom,int i){
    this.pointLeftTop=new Point(left,top);
    this.pointRightBottom=new Point(right,bottom);
    this.num=i;
  }
  public int getCenterX() {
    this.centerX=(this.pointLeftTop.x+this.pointRightBottom.x)/2;
    return centerX;
  }
  public int getCenterY() {
    this.centerY=(this.pointLeftTop.y+this.pointRightBottom.y)/2;
    return centerY;
  }
}
4.自定义圆类
这个类较简单就三个属性而已（圆中心点坐标及半径），代码如下：
public class LYJCirclePoint {
  private int roundX;//圆中心点X坐标
  private int roundY;//圆中心点Y坐标
  private int radiu;//圆半径
  public int getRadiu() {
    return radiu;
  }
  public int getRoundX() {
    return roundX;
  }
  public int getRoundY() {
    return roundY;
  }
  public LYJCirclePoint(int roundX,int roundY,int radiu){
    this.roundX=roundX;
    this.roundY=roundY;
    this.radiu=radiu;
  }
}

5.实现自定义绘制类View

代码如下：

public class LYJGestureView extends android.view.View {
  
  private Paint paint;
  
  private Paint circlePaint;
  
  private canvas canvas;
  
  private Bitmap bitmap;
  
  private List<LYJGesturePoint> list;
  
  private List<Pair<LYJGesturePoint, LYJGesturePoint>> lineList;
  
  private List<LYJCirclePoint> circlePoints;
  
  private LYJGesturePoint currentPoint;
  
  private OnAnimationCallback animationCallback;
  public interface OnAnimationCallback{
    public void startAnimationImage(int i);
  }
  public void setAnimationCallback(OnAnimationCallback animationCallback) {
    this.animationCallback = animationCallback;
  }
  public LYJGestureView(Context context, List<LYJGesturePoint> list){
    super(context);
    Log.i(getClass().getName(), "GestureDrawline");
    paint = new Paint(Paint.DITHER_FLAG);// 创建一个画笔
    circlePaint=new Paint(Paint.DITHER_FLAG);
    DisplayMetrics metric = new DisplayMetrics();
    ((Activity)context).getWindowManager().getDefaultDisplay().getMetrics(metric);
    Log.i(getClass().getName(), "widthPixels" + metric.widthPixels);
    Log.i(getClass().getName(), "heightPixels" + metric.heightPixels);
    bitmap = Bitmap.createBitmap(metric.widthPixels, metric.heightPixels, Bitmap.Config.ARGB_8888); // 设置位图的宽高
    canvas = new Canvas();
    canvas.setBitmap(bitmap);
    paint.setStyle(Paint.Style.STROKE);// 设置非填充
    paint.setStrokeWidth(20);// 笔宽20像素
    paint.setColor(Color.rgb(245, 142, 33));// 设置默认连线颜色
    paint.setAntiAlias(true);// 不显示锯齿
    circlePaint.setStyle(Paint.Style.FILL);
    circlePaint.setStrokeWidth(1);
    circlePaint.setAntiAlias(true);
    circlePaint.setColor(Color.rgb(245, 142, 33));
    this.list = list;
    this.lineList = new ArrayList<>();
    this.circlePoints=new ArrayList<>();
  }
  @Override
  public boolean onTouchEvent(MotionEvent event) {
    switch (event.getAction()){
      case MotionEvent.ACTION_DOWN:
        // 判断当前点击的位置是处于哪个点之内
        currentPoint = getPointAt((int) event.getX(), (int) event.getY());
        if (currentPoint != null) {
          currentPoint.setPointState(Constants.POINT_STATE_SELECTED);
          this.animationCallback.startAnimationImage(currentPoint.getNum());
          canvas.drawCircle(currentPoint.getCenterX(), currentPoint.getCenterY(), 20, circlePaint);
          circlePoints.add(new LYJCirclePoint(currentPoint.getCenterX(),currentPoint.getCenterY(),20));
        }
        invalidate();
        break;
      case MotionEvent.ACTION_MOVE:
        clearScreenAndDrawList();
        // 得到当前移动位置是处于哪个点内
        LYJGesturePoint pointAt = getPointAt((int) event.getX(), (int) event.getY());
        if (currentPoint == null && pointAt == null) {//你把手指按在屏幕滑动，如果终点与起点都不图片那么返回
          return true;
        } else {// 代表用户的手指移动到了点上
          if (currentPoint == null) {// 先判断当前的point是不是为null
            // 如果为空，那么把手指移动到的点赋值给currentPoint
            currentPoint = pointAt;
            // 把currentPoint这个点设置选中状态;
            currentPoint.setPointState(Constants.POINT_STATE_SELECTED);
          }
        }
        //如果移动到的点不为图片区域或者移动到自己的地方，或者该图片已经为选中状态，直接画直线就可以了
        if(pointAt == null || currentPoint.equals(pointAt) || Constants.POINT_STATE_SELECTED == pointAt.getPointState()){
          canvas.drawCircle(currentPoint.getCenterX(), currentPoint.getCenterY(), 20, circlePaint);
          circlePoints.add(new LYJCirclePoint(currentPoint.getCenterX(), currentPoint.getCenterY(), 20));
          canvas.drawLine(currentPoint.getCenterX(), currentPoint.getCenterY(), event.getX(), event.getY(), paint);
        }else{//其他情况画两点相连直线，并且保存绘制圆与直线，并调用按下图片的缩放动画
          canvas.drawCircle(pointAt.getCenterX(),pointAt.getCenterY(),20,circlePaint);
          circlePoints.add(new LYJCirclePoint(pointAt.getCenterX(), pointAt.getCenterY(), 20));
          this.animationCallback.startAnimationImage(pointAt.getNum());
          pointAt.setPointState(Constants.POINT_STATE_SELECTED);
          canvas.drawLine(currentPoint.getCenterX(), currentPoint.getCenterY(), pointAt.getCenterX(), pointAt.getCenterY(), paint);
          Pair<LYJGesturePoint, LYJGesturePoint> pair = new Pair<>(currentPoint, pointAt);
          lineList.add(pair);
          currentPoint=pointAt;//设置选中点为当前点。
        }
        invalidate();//重绘
        break;
      case MotionEvent.ACTION_UP:
        clearScreenAndDrawList();//防止多出一条没有终点的直线
        new Handler().postDelayed(new clearLineRunnable(), 1000);//1秒后清空绘制界面
        invalidate();//重绘
        break;
      default:
        break;
    }
    return true;
  }
  class clearLineRunnable implements Runnable {
    public void run() {
      // 清空保存点与圆的集合
      lineList.clear();
      circlePoints.clear();
      // 重新绘制界面
      clearScreenAndDrawList();
      for (LYJGesturePoint p : list) {
        //设置其为初始化不选中状态
        p.setPointState(Constants.POINT_STATE_NORMAL);
      }
      invalidate();
    }
  }
  
  private LYJGesturePoint getPointAt(int x, int y) {
    for (LYJGesturePoint point : list) {
      // 先判断点是否在图片的X坐标内
      int leftX = point.getPointLeftTop().x;
      int rightX = point.getPointRightBottom().x;
      if (!(x >= leftX && x < rightX)) {
        // 如果为假，则跳到下一个对比
        continue;
      }
      //在判断点是否在图片的Y坐标内
      int topY = point.getPointLeftTop().y;
      int bottomY = point.getPointRightBottom().y;
      if (!(y >= topY && y < bottomY)) {
        // 如果为假，则跳到下一个对比
        continue;
      }
      // 如果执行到这，那么说明当前点击的点的位置在遍历到点的位置这个地方
      return point;
    }
    return null;
  }
  
  private void clearScreenAndDrawList() {
    canvas.drawColor(Color.TRANSPARENT, PorterDuff.Mode.CLEAR);
    for (Pair<LYJGesturePoint, LYJGesturePoint> pair : lineList) {
      canvas.drawLine(pair.first.getCenterX(), pair.first.getCenterY(),
          pair.second.getCenterX(), pair.second.getCenterY(), paint);// 画线
    }
    for(LYJCirclePoint lyjCirclePoint : circlePoints){
      canvas.drawCircle(lyjCirclePoint.getRoundX(),lyjCirclePoint.getRoundY(), lyjCirclePoint.getRadiu(),circlePaint);
    }
  }
  //绘制用bitmap创建出来的画布
  @Override
  protected void onDraw(Canvas canvas) {
    canvas.drawBitmap(bitmap, 0, 0, null);
  }
}

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