Android自定义TabLayout效果
周末就要到了,今天项目中遇到这样一个Tab,选中tab的背景是个圆角矩形,方向指向器没有了,这样普通的TabLayout不能满足我的要求,可能会想到动态的去设置选中Tab的背景不就可以了,但是那样的话太生硬了,没有动画效果,其实想想也还比较简单,今天就简单的说一说这个YzzTab。效果如下图:
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这里是四个Tab,一版只显示3个,这里假设有num个Tab,当滑动到第3个时,这里就需要考虑如何让TabLayout和指示器一起移动呢?
@Override public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) { if (positionOffset>1){ return; } int leftCop = (int) (positionOffset*(getMeasuredWidth()/mMaxLineNum)+position*getMeasuredWidth()/mMaxLineNum); if (leftCop!=leftForTabLayout){ //这里要做判断是否滑动,当选择的位置大于TabLayout中显示的最大数-1时,会向左右滑动,指示器也会 //跟这滑动,相对静止,否则指示器滑动,Tab布局不移动 if (position>=mMaxLineNum-1) { scrollContent += leftCop - leftForTabLayout; scrollTo(scrollContent, 0); //这里要重新layout update(); } leftForTabLayout = leftCop; invalidate(); } }
首先,在ViewPage的监听中,positionOffset有时候可能大于1,这点需要注意的,当两次left的坐标相等 时,我们就不进行绘制了,接下来就是
如何确定left的值了,对于这点我也想了很久,最后终于得出结论:
int leftCop = (int) (positionOffset*(getMeasuredWidth()/mMaxLineNum)+position*getMeasuredWidth()/mMaxLineNum);
因为当positionOffset的值在向右滑动80%左右的时候getCurrentItem()的值会发生变化,这点可以试验一下,所以getCurrentItem()方法不能用了,只能用参数position.Layout滑动的实际代码注释很详细了,我就不再阐述了,可以试试。在布局滑动了以后,必须要layout,不然View的属性不会变,点击没法应,但是也可以不更新,动态的告诉用户点击的真是Tab,这样也可以。
private void update() { for (int i = 0; i
接下来就是绘制了,ViewGroup是默认不调用onDraw(Canvas canvas)方法的,原因很简单,ViewGroup是个容器,主要作用是起承载作用,绘画就交给子View了,但是还是有办法让其调用该方法的,如下:
setWillNotDraw(false);
这就告诉该容器,需要绘制;
接下来就是绘制指向器和选中背景了,一个圆角矩形和一条线,比较简单,我就不再详细说明了。
@Override protected void onDraw(Canvas canvas) { //left = getMeasuredWidth() / mChildCount * mSelectPosition; super.onDraw(canvas); mPaint.setColor(Color.GREEN); int top = getMeasuredHeight() / 4; int right = leftForTabLayout + getMeasuredWidth() / mMaxLineNum; int bottom = getMeasuredHeight() - getMeasuredHeight() / 4; RectF rectF = new RectF(leftForTabLayout, top, right, bottom); mPaint.setAntiAlias(true); mPaint.setStyle(Paint.Style.FILL); canvas.drawRoundRect(rectF, 10, 10, mPaint); mPaint.setColor(Color.RED); mPaint.setStrokeWidth(5); canvas.drawLine(leftForTabLayout,getMeasuredHeight()-5,right,getMeasuredHeight()-5,mPaint); }
接下来介绍建与ViewPager建立关联的方法
/** * 于ViewPager建立联系,这里必须先要给ViewPager设置Adapter * * @param viewPager */ public void setUpWithViewPager(ViewPager viewPager) { mViewPager = viewPager; mChildCount = viewPager.getAdapter().getCount(); mSelectPosition = viewPager.getCurrentItem(); viewPager.setOnPageChangeListener(this); }
初始化的方法
/** * 为Tab添加View */ private void init() { setWillNotDraw(false); mPaint = new Paint(); for (int i = 0; i < mChildCount; i++) { final TextView tv = new TextView(getContext()); int w = getMeasuredWidth()/mMaxLineNum; LinearLayout.LayoutParams lp = new LayoutParams(w, ViewGroup.LayoutParams.MATCH_PARENT); tv.setText("tab" + i); tv.setGravity(Gravity.CENTER); tv.setLayoutParams(lp); final int finalI = i; tv.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { if (monTabSelecterListener != null){ monTabSelecterListener.selecter(finalI,tv); } } }); addView(tv); } }
这里只是很简单的加了几个TextView进去,也可以弄个方法,通过用户动态添加自己想要的View,都可以实现的。至于监听的话就很简单了.上面已经写到了。
YzzTab的代码
package a6he.android.yzz.com.mytablayout; import android.content.Context; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint; import android.graphics.Rect; import android.graphics.RectF; import android.support.v4.view.ViewPager; import android.util.AttributeSet; import android.util.Log; import android.view.Gravity; import android.view.View; import android.view.ViewGroup; import android.widget.LinearLayout; import android.widget.Switch; import android.widget.TextView; /** * Created by yzz on 2017/2/24 0024. * * 实现背景随着ViewPager的滑动跟着移动 */ public class YzzTab extends LinearLayout implements ViewPager.OnPageChangeListener { private ViewPager mViewPager; private Paint mPaint; //tab的数量 private int mChildCount; //tab选中的位置 private int mSelectPosition; //绘制指向器的左顶点 private int leftForTabLayout = 0; private int leftForInvidator = 0; private int mMaxLineNum = 3; private int scrollContent = 0; private onTabSelecterListener monTabSelecterListener; public YzzTab(Context context) { super(context); } public YzzTab(Context context, AttributeSet attrs) { super(context, attrs); } public YzzTab(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); } @Override protected void onFinishInflate() { super.onFinishInflate(); } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); init(); } /** * 于ViewPager建立联系,这里必须先要给ViewPager设置Adapter * * @param viewPager */ public void setUpWithViewPager(ViewPager viewPager) { mViewPager = viewPager; mChildCount = viewPager.getAdapter().getCount(); mSelectPosition = viewPager.getCurrentItem(); viewPager.setOnPageChangeListener(this); } /** * 为Tab添加View */ private void init() { setWillNotDraw(false); mPaint = new Paint(); for (int i = 0; i < mChildCount; i++) { final TextView tv = new TextView(getContext()); int w = getMeasuredWidth()/mMaxLineNum; LinearLayout.LayoutParams lp = new LayoutParams(w, ViewGroup.LayoutParams.MATCH_PARENT); tv.setText("tab" + i); tv.setGravity(Gravity.CENTER); tv.setLayoutParams(lp); final int finalI = i; tv.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { if (monTabSelecterListener != null){ monTabSelecterListener.selecter(finalI,tv); } } }); addView(tv); } } @Override protected void onDraw(Canvas canvas) { //left = getMeasuredWidth() / mChildCount * mSelectPosition; super.onDraw(canvas); mPaint.setColor(Color.GREEN); int top = getMeasuredHeight() / 4; int right = leftForTabLayout + getMeasuredWidth() / mMaxLineNum; int bottom = getMeasuredHeight() - getMeasuredHeight() / 4; RectF rectF = new RectF(leftForTabLayout, top, right, bottom); mPaint.setAntiAlias(true); mPaint.setStyle(Paint.Style.FILL); canvas.drawRoundRect(rectF, 10, 10, mPaint); mPaint.setColor(Color.RED); mPaint.setStrokeWidth(5); canvas.drawLine(leftForTabLayout,getMeasuredHeight()-5,right,getMeasuredHeight()-5,mPaint); } @Override public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) { if (positionOffset>1){ return; } int leftCop = (int) (positionOffset*(getMeasuredWidth()/mMaxLineNum)+position*getMeasuredWidth()/mMaxLineNum); if (leftCop!=leftForTabLayout){ //这里要做判断是否滑动,当选择的位置大于TabLayout中显示的最大数-1时,会向左右滑动,指示器也会 //跟这滑动,相对静止,否则指示器滑动,Tab布局不移动 if (position>=mMaxLineNum-1) { scrollContent += leftCop - leftForTabLayout; scrollTo(scrollContent, 0); //这里要重新layout update(); } leftForTabLayout = leftCop; invalidate(); } } private void update() { for (int i = 0; i
好啦,就介绍这么多,还有待完善,继续封装,完成更强大的功能。
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