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
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
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{ private List datas ; public TimeLineAdapter(List datas) { super(); this.datas = datas; } @Override public 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); } @Override public void onBindViewHolder(ViewHolder holder, int position) { TimeLineItem timeLineItem = datas.get(position); holder.tv_name.setText(timeLineItem.getTimeLineName()); } @Override public int getItemCount() { return datas.size(); } @Override public 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： public class MainActivity extends AppCompatActivity { private ListmDatas; @Override protected 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。
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持脚本之家。