自定义recyclerView实现时光轴效果

本文主要是介绍自定义recyclerView实现时光轴效果，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

时光轴效果在很多app上都有出现，例如淘宝中快递的跟踪，本文将使用recyclerView实现时光轴效果，我们会到自定义控件，首先先看一下效果图：

接下来是步骤分析

1自定义属性

这个大家应该都了解了，根据我们之前的分析，直接在attrs.xml中进行声明

<declare-styleable name="TimeLine"><attr name="beginLine" format="reference|color"></attr><attr name="endLine" format="reference|color"></attr><attr name="lineWidth" format="dimension"></attr><attr name="timeLineImage" format="color|reference"></attr><attr name="timeLineImageSize" format="dimension"></attr>
</declare-styleable>

进行一下各个属性的声明

•   beginLine:开始的线条

•   endLine:下面的线条

•   lineWidth:线条的宽度

•   timeLineImage:中间的圆形

•  timeLineImageSize:中间的圆形的大小，这里默认他的宽高一致

2.自定义TimeLine继承View，构造方法如下

private int lineWidth;
private Drawable mBeginLine;
private Drawable mEndLine;
private Drawable mTimeLineImage;
private int mTimeLineImageSize;public TimeLine(Context context) {this(context,null);
}public TimeLine(Context context, AttributeSet attrs) {this(context,attrs,0);
}public TimeLine(Context context, AttributeSet attrs, int defStyleAttr) {super(context, attrs, defStyleAttr);TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.TimeLine);lineWidth = a.getDimensionPixelOffset(R.styleable.TimeLine_lineWidth,15);mBeginLine = a.getDrawable(R.styleable.TimeLine_beginLine);mEndLine = a.getDrawable(R.styleable.TimeLine_endLine);mTimeLineImage = a.getDrawable(R.styleable.TimeLine_timeLineImage);mTimeLineImageSize = a.getDimensionPixelSize(R.styleable.TimeLine_timeLineImageSize,25);a.recycle();}

3.复写onMeasure方法

我们都知道自定义控件，一般需要重写onMeasure，onDraw,onLayout方法,这里onMeasure需要对wrap_content的情况进行特殊处理，具体原因请看源码

protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {super.onMeasure(widthMeasureSpec, heightMeasureSpec);int w = timeLineMarkerSize + getPaddingLeft() + getPaddingRight();int h = timeLineMarkerSize + getPaddingTop() + getPaddingBottom();int widthSize = resolveSizeAndState(w, widthMeasureSpec, 0);int heightSize = resolveSizeAndState(h, heightMeasureSpec, 0);int widthSpecMode = MeasureSpec.getMode(widthMeasureSpec);int widthSpecSize = MeasureSpec.getSize(widthMeasureSpec);int heightSpecMode = MeasureSpec.getMode(heightMeasureSpec);int heightSpecSize = MeasureSpec.getSize(heightMeasureSpec);// 处理宽高都为 wrap_content 的情况if (widthSpecMode == MeasureSpec.AT_MOST && heightSpecMode == MeasureSpec.AT_MOST) {setMeasuredDimension(DEFAULT_WIDTH, DEFAULT_HEIGHT);}// 处理宽为 wrap_content 的情况else if (widthSpecMode == MeasureSpec.AT_MOST) {setMeasuredDimension(DEFAULT_WIDTH, widthSize);}// 处理高为 wrap_content 的情况else if (heightSpecMode == MeasureSpec.AT_MOST) {setMeasuredDimension(heightSize, DEFAULT_HEIGHT);}}

看过View源码的同学应该知道，在控件进行测量的时候，需要根据

specMode来进行具体的操作，View中提供了resolveSizeAndState方法来进行判断，该方法源码如下：

public static int resolveSizeAndState(int size, int measureSpec, int childMeasuredState) {int result = size;int specMode = MeasureSpec.getMode(measureSpec);int specSize =  MeasureSpec.getSize(measureSpec);switch (specMode) {case MeasureSpec.UNSPECIFIED:result = size;break;case MeasureSpec.AT_MOST:if (specSize < size) {result = specSize | MEASURED_STATE_TOO_SMALL;} else {result = size;}break;case MeasureSpec.EXACTLY:result = specSize;break;}return result | (childMeasuredState&MEASURED_STATE_MASK);}

4.onDraw方法

@Override
protected void onDraw(Canvas canvas) {super.onDraw(canvas);if (mBeginLine != null) {mBeginLine.draw(canvas);}if (mEndLine != null) {mEndLine.draw(canvas);}if (mTimeLineImage!=null){mTimeLineImage.draw(canvas);}
}

5.onSizeChange

@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {int paddingLeft = getPaddingLeft();int paddingRight = getPaddingRight();int paddingTop = getPaddingTop();int paddingBottom = getPaddingBottom();//父容器的宽高int width = getWidth();int height = getHeight();int childWidth = width - paddingLeft - paddingRight;int childHeight = height - paddingTop - paddingBottom;mTimeLineImageSize = Math.min(mTimeLineImageSize, Math.min(childHeight, childWidth));if (mTimeLineImage != null) {mTimeLineImage.setBounds(paddingLeft, paddingTop, paddingLeft + mTimeLineImageSize, paddingTop + mTimeLineImageSize);bounds = mTimeLineImage.getBounds();} else {bounds = new Rect(paddingLeft, paddingTop, paddingLeft + childWidth, paddingTop + childHeight);}if (mBeginLine != null) {int lineLeft = mTimeLineImage.getBounds().centerX() - (lineWidth >> 1);mBeginLine.setBounds(lineLeft, 0, lineLeft + lineWidth, mTimeLineImage.getBounds().top);}if (mEndLine != null) {int lineLeft = mTimeLineImage.getBounds().centerX() - (lineWidth >> 1);mEndLine.setBounds(lineLeft, mTimeLineImage.getBounds().bottom, lineLeft + lineWidth, height);}
}

这里需要说明的是，我们的mBeginLine的长度，其实是我们自定义控件的paddingTop高度，同理mEndLine的长度是paddingBottom高度，所以我们在使用这个控件时，一般都会设置paddingTop和paddingBottom

6.使用TimeLine控件

以下是recyclerView中一个item的布局，多个item拼接起来就是一条时光轴，这里需要说明的是，我们的 LinearLayout使用的高度模式是wrap_content，这里我的TextView设置了android:paddingTop="30dp"，如果不对TextView设置android:paddingTop，会发现TimeLineView控件是看不见的，这是由于父控件wrap_content，那么父控件包裹TextView的内容，那么父控件的高度就是TextView的高度，这样TimeLineView设置了android:paddingTop="34dp"，这个高度是大于父控件的高度的，所以就看不到TimeLineView了，除非我们给LinearLayout的android:layout_height="wrap_content"，修改成固定的高度

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"xmlns:app="http://schemas.android.com/apk/res-auto"android:layout_width="match_parent"android:layout_height="wrap_content"android:orientation="horizontal"android:paddingLeft="16dp"android:paddingRight="16dp"><com.example.jikeyoujikeyou.timelinedemo2.TimeLineViewandroid:id="@+id/timeLineView"android:layout_width="wrap_content"android:layout_height="match_parent"android:clickable="true"android:focusable="true"android:focusableInTouchMode="true"android:paddingBottom="8dp"android:paddingLeft="4dp"android:paddingRight="4dp"android:paddingTop="34dp"app:beginLine="#ff0000"app:endLine="#ff0000"app:lineWidth="3dp"app:timeLineMarker="@drawable/timeline_marker"app:timeLineMarkerSize="24dp" /><TextViewstyle="@style/Base.TextAppearance.AppCompat.Title"android:id="@+id/timeLineName"android:layout_width="wrap_content"android:layout_height="wrap_content"android:ellipsize="end"android:paddingTop="30dp"android:singleLine="true"android:text="name"android:textColor="@color/grey_700"android:textSize="16sp" />
</LinearLayout>

7.最后就是recyclerView的使用

recyclerView的使用大家应该都很熟悉了，无非就是设置adapter,viewHolder等，这里不再赘述，还有一点需要强调的是ItemViewType有四种情况，第一个，最后一个，中间，还有只有一个四种情况情况，根据这几种情况，有选择设置mBeginLine与 mEndLine是否进行绘制

TimeLineAdapter代码：

package com.example.jikeyoujikeyou.timelinedemo;import android.annotation.TargetApi;
import android.content.Context;
import android.graphics.drawable.Drawable;
import android.os.Build;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;import java.util.ArrayList;
import java.util.List;
import java.util.Random;/*** Created by jikeyoujikeyou on 16/7/22.*/
public class TimeLineAdapter extends RecyclerView.Adapter<TimeLineAdapter.ViewHolder> {private List<TimeLineItem> datas ;public TimeLineAdapter(List<TimeLineItem> datas) {super();this.datas = datas;}@Overridepublic ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {LayoutInflater layoutInflater = LayoutInflater.from(parent.getContext());View view = layoutInflater.inflate(R.layout.item_timeline, null);return new ViewHolder(view, parent.getContext(), viewType);}@Overridepublic void onBindViewHolder(ViewHolder holder, int position) {TimeLineItem timeLineItem = datas.get(position);holder.tv_name.setText(timeLineItem.getTimeLineName());}@Overridepublic int getItemCount() {return datas.size();}@Overridepublic int getItemViewType(int position) {int size = datas.size() - 1;if (size == 0) {return TimeLineItemType.ATOM;} else if (position == 0) {return TimeLineItemType.START;} else if (position == size) {return TimeLineItemType.END;} else {return TimeLineItemType.NORMAL;}}class ViewHolder extends RecyclerView.ViewHolder {private TextView tv_name;private TimeLine timeLine;public ViewHolder(View itemView, Context context, int viewType) {super(itemView);tv_name = (TextView) itemView.findViewById(R.id.name);timeLine = (TimeLine) itemView.findViewById(R.id.timeLineView);Drawable drawable = context.getResources().getDrawable(R.drawable.timeline_marker);Drawable drawable2 = context.getResources().getDrawable(R.drawable.timeline_marker2);Drawable drawable3 = context.getResources().getDrawable(R.drawable.timeline_marker3);Drawable drawable4 = context.getResources().getDrawable(R.drawable.timeline_marker4);Drawable drawable5 = context.getResources().getDrawable(R.drawable.timeline_marker5);Random random = new Random();final int i = random.nextInt(5);final Drawable drawables[] = {drawable, drawable2, drawable3, drawable4, drawable5};timeLine.setTimeLineImage(drawables[i]);if (viewType == TimeLineItemType.START) {timeLine.setBeginLine(null);} else if (viewType == TimeLineItemType.END) {timeLine.setEndLine(null);} else if (viewType == TimeLineItemType.ATOM) {timeLine.setBeginLine(null);timeLine.setEndLine(null);}}}class TimeLineItemType {//正常public final static int NORMAL = 0;//开始public final static int START = 1;//结束public final static int END = 2;//只有一条数据,那么beginLine和endLine都没有public final static int ATOM = 3;}}

MainActivity代码：

<pre name="code" class="java">public class MainActivity extends AppCompatActivity {private List<TimeLineItem> mDatas;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);initData();RecyclerView recyclerView = (RecyclerView) findViewById(R.id.recyclerview);LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);linearLayoutManager.setOrientation(LinearLayoutManager.VERTICAL);recyclerView.setLayoutManager(linearLayoutManager);TimeLineAdapter adapter = new TimeLineAdapter(mDatas);recyclerView.setAdapter(adapter);}private void initData() {mDatas = new ArrayList<>();mDatas.add(new TimeLineItem("爸爸生日"));mDatas.add(new TimeLineItem("妈妈生日"));mDatas.add(new TimeLineItem("姐姐生日"));mDatas.add(new TimeLineItem("女神生日"));mDatas.add(new TimeLineItem("前任生日"));}
}

运行项目，就会呈现本文一开始的效果

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