亲宝软件园·资讯

展开

Android滑动导航条 Android自定义控件实现可左右滑动的导航条

凤求凰丶 人气:0
想了解Android自定义控件实现可左右滑动的导航条的相关内容吗,凤求凰丶在本文为您仔细讲解Android滑动导航条的相关知识和一些Code实例,欢迎阅读和指正,我们先划重点:Android左右滑动导航条,Android自定义控件,Android导航条,下面大家一起来学习吧。

先上效果图:

这个控件其实算是比较轻量级的,相信不少小伙伴都能做出来。因为项目中遇到了一些特殊的定制要求,所以就自己写了一个,这里放出来。

首先来分析下这个控件的功能:

•能够响应左右滑动,并且能响应快速滑动
•选择项和未选择项有不同的样式表现,比如前景色,背景色,字体大小变粗之内的
•在切换选项的时候,如果当前选项未完全呈现在界面前,则自动滚动直至当前选项完全暴露显示

前两条还有,简简单单就实现了,主要是第三点,这才是我自定义这个控件的原因!那么如果要实现这个控件,需要用到哪些知识呢? 
•用Scroller来实现控件的滚动
•用VelocityTracker来实现控件的快速滚动 

如果上面两种技术你都已经会了,那么我们就可以开始讲解代码了。首先是一些属性的Getter/Setter方法,这里采用的链式设置法:

 public IndicatorView color(int colorDefault, int colorSelected, int colorBg){
 this.colorDefault = colorDefault;
 this.colorSelected = colorSelected;
 this.colorBg = colorBg;
 return this;
 }

 public IndicatorView textSize(int textSize){
 this.textSize = textSize;
 return this;
 }

 public IndicatorView text(String[] texts){
 this.texts = texts;
 return this;
 }

 public IndicatorView padding(int[] padding){
 this.padding = padding;
 return this;
 }

 public IndicatorView defaultSelect(int defaultSelect){
 this.selectItem = defaultSelect;
 return this;
 }

 public IndicatorView lineHeight(int lineHeight){
 this.lineHeight = lineHeight;
 return this;
 }

 public IndicatorView listener(OnIndicatorChangedListener listener){
 this.listener = listener;
 return this;
 }

 public IndicatorView type(Type type){
 this.type = type;
 return this;
 }

这里我们将每一个选项抽象成了一个Item类:

 public class Item {
 String text;
 int colorDefault;
 int colorSelected;
 int textSize;
 boolean isSelected = false;
 int width;
 Point drawPoint;
 int[] padding = new int[4];
 Rect rect = new Rect();
 }

然后是控件的初始化操作,主要根据当前控件的宽高,以及设置的一些属性,进行Item选项的初始化:

 @Override
 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec){
 width = MeasureSpec.getSize(widthMeasureSpec);
 height = MeasureSpec.getSize(heightMeasureSpec);
 //初始化Item
 initItems();
 super.onMeasure(widthMeasureSpec, heightMeasureSpec);
 }

 private void initItems(){
 items.clear();
 measureWidth = 0;
 for(int i = 0; i < texts.length; i++){
  Item item = new Item();
  item.text = texts[i];
  item.colorDefault = colorDefault;
  item.colorSelected = colorSelected;
  item.textSize = textSize;
  for(int j = 0; j < item.padding.length; j++){
  item.padding[j] = padding[j];
  }
  mPaint.setTextSize(item.textSize);
  item.width = (int)mPaint.measureText(item.text);
  int dx = 0;
  if(i - 1 < 0){
  dx = 0;
  }else{
  for(int j = 0; j < i; j++){
   dx += items.get(j).padding[0] + items.get(j).width + items.get(j).padding[2];
  }
  }
  int startX = item.padding[0] + dx;
  Paint.FontMetrics metrics = mPaint.getFontMetrics();
  int startY = (int)(height / 2 + (metrics.bottom - metrics.top) / 2 - metrics.bottom);
  item.drawPoint = new Point(startX, startY);
  //设置区域
  item.rect.left = item.drawPoint.x - item.padding[0];
  item.rect.top = 0;
  item.rect.right = item.drawPoint.x + item.width + item.padding[2];
  item.rect.bottom = height;
  //设置默认
  if(i == selectItem){
  item.isSelected = true;
  }
  measureWidth += item.rect.width();
  items.add(item);
 }
 //重绘
 invalidate();
 }

 接下来是事件处理,逻辑很简单。在DOWN时间记录坐标值,在MOVE中处理控件的滚动,在UP中处理滚动超屏时的恢复操作,以及点击的操作。

 @Override
 public boolean onTouchEvent(MotionEvent event){
 if(mVelocityTracker == null) {
  mVelocityTracker = VelocityTracker.obtain();
 }
 mVelocityTracker.addMovement(event);
 switch(event.getAction()){
  case MotionEvent.ACTION_DOWN:
  mTouchX = (int)event.getX();
  mTouchY = (int)event.getY();
  mMoveX = mTouchX;
  return true;

  case MotionEvent.ACTION_MOVE:
  if(measureWidth > width){
   int dx = (int)event.getX() - mMoveX;
   if(dx > 0){ // 右滑
   if(mScroller.getFinalX() > 0){
    mScroller.startScroll(mScroller.getFinalX(), mScroller.getFinalY(), -dx, 0);
   }else{
    mScroller.setFinalX(0);
   }
   }else{ //左滑
   if(mScroller.getFinalX() + width - dx < measureWidth){
    mScroller.startScroll(mScroller.getFinalX(), mScroller.getFinalY(), -dx, 0);
   }else{
    mScroller.setFinalX(measureWidth - width);
   }
   }
   mMoveX = (int)event.getX();
   invalidate();
  }
  break;

  case MotionEvent.ACTION_UP:
  case MotionEvent.ACTION_CANCEL:
  if(measureWidth > width){
   mVelocityTracker.computeCurrentVelocity(1000);
   int max = Math.max(Math.abs(mScroller.getCurrX()), Math.abs(measureWidth - width - mScroller.getCurrX()));
   mScroller.fling(mScroller.getFinalX(), mScroller.getFinalY(), (int)-mVelocityTracker.getXVelocity(), (int)-mVelocityTracker.getYVelocity(), 0, max, mScroller.getFinalY(), mScroller.getFinalY());
   //手指抬起时,根据滚动偏移量初始化位置
   if(mScroller.getCurrX() < 0){
   mScroller.abortAnimation();
   mScroller.startScroll(mScroller.getCurrX(), mScroller.getCurrY(), -mScroller.getCurrX(), 0);
   }else if(mScroller.getCurrX() + width > measureWidth){
   mScroller.abortAnimation();
   mScroller.startScroll(mScroller.getCurrX(), mScroller.getCurrY(), measureWidth - width - mScroller.getCurrX(), 0);
   }
  }
  if(event.getAction() == MotionEvent.ACTION_UP){
   int mUpX = (int)event.getX();
   int mUpY = (int)event.getY();
   //模拟点击操作
   if(Math.abs(mUpX - mTouchX) <= mTouchSlop && Math.abs(mUpY - mTouchY) <= mTouchSlop){
   for(int i = 0; i < items.size(); i++){
    if(items.get(i).rect.contains(mScroller.getCurrX() + mUpX, getScrollY() + mUpY)){
    setSelected(i);
    return super.onTouchEvent(event);
    }
   }
   }
  }
  break;

  default:
  break;
 }
 return super.onTouchEvent(event);
 }

 接下来就是很重要的一段代码,因为这段代码,才可以让未完全显示的Item选项被选中时自动滚动至完全显示:

 public void setSelected(int position){
 if(position >= items.size()){
  return;
 }
 for(int i = 0; i < items.size(); i++){
  if(i == position){
  items.get(i).isSelected = true;
  if(i != selectItem){
   selectItem = i;
   //判断是否需要滑动到完全可见
   if(mScroller.getCurrX() + width < items.get(i).rect.right){
   mScroller.startScroll(mScroller.getFinalX(), mScroller.getFinalY(), items.get(i).rect.right - mScroller.getCurrX() - width, mScroller.getFinalY());
   }
   if(items.get(i).rect.left < mScroller.getCurrX()){
   mScroller.startScroll(mScroller.getFinalX(), mScroller.getFinalY(), items.get(i).rect.left - mScroller.getCurrX(), mScroller.getFinalY());
   }
   if(listener != null){
   listener.onChanged(selectItem);
   }
  }
  }else{
  items.get(i).isSelected = false;
  }
 }
 invalidate();
 }

然后就是绘制方法了,相当于完全代理给了Item来实现:

 @Override
 protected void onDraw(Canvas canvas){
 mPaint.setAntiAlias(true);
 canvas.drawColor(colorBg);
 for(Item item : items){
  mPaint.setTextSize(item.textSize);
  if(item.isSelected){
  if(type == Type.SelectByLine){
   //绘制红线
   mPaint.setColor(item.colorSelected);
   mPaint.setStyle(Paint.Style.FILL);
   canvas.drawRoundRect(new RectF(item.rect.left, item.rect.bottom - lineHeight, item.rect.right, item.rect.bottom), 3, 3, mPaint);
  }else if(type == Type.SelectByFill){
   //绘制红色背景
   mPaint.setColor(getContext().getResources().getColor(android.R.color.holo_red_light));
   mPaint.setStyle(Paint.Style.FILL);
   canvas.drawRoundRect(new RectF(item.rect.left + 6, item.rect.top, item.rect.right - 6, item.rect.bottom), item.rect.height() * 5 / 12, item.rect.height() * 5 / 12, mPaint);
  }
  mPaint.setColor(item.colorSelected);
  }else{
  mPaint.setColor(item.colorDefault);
  }
  canvas.drawText(item.text, item.drawPoint.x, item.drawPoint.y, mPaint);
 }
 }

接下来就是怎么使用这个控件了,布局文件:

 <?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:id="@+id/listView"
 android:layout_width="match_parent"
 android:layout_height="match_parent">

 <cc.wxf.androiddemo.indicator.IndicatorView
 android:id="@+id/indicator"
 android:layout_width="match_parent"
 android:layout_height="38dp" />
</RelativeLayout>

MainActvity中:

package cc.wxf.androiddemo;

import android.content.Context;
import android.content.res.Resources;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;

import cc.wxf.androiddemo.indicator.IndicatorView;

public class MainActivity extends FragmentActivity {

 private IndicatorView indicatorView;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main);
 initIndicator();
 }

 private void initIndicator(){
 indicatorView = (IndicatorView)findViewById(R.id.indicator);
 Resources resources = getResources();
 indicatorView.color(resources.getColor(android.R.color.black),
  resources.getColor(android.R.color.holo_red_light),
  resources.getColor(android.R.color.darker_gray))
  .textSize(sp2px(this, 16))
  .padding(new int[]{dip2px(this, 14), dip2px(this, 14), dip2px(this, 14), dip2px(this, 14)})
  .text(new String[]{"电视剧","电影","综艺","片花","动漫","娱乐","会员1","会员2","会员3","会员4","会员5","会员6"})
  .defaultSelect(0).lineHeight(dip2px(this, 3))
  .listener(new IndicatorView.OnIndicatorChangedListener(){

   @Override
   public void onChanged(int position){

   }
  }).commit();
 }

 public static int dip2px(Context context, float dipValue){
 final float scale = context.getResources().getDisplayMetrics().density;
 return (int)(dipValue * scale + 0.5f);
 }

 public static int sp2px(Context context, float spValue){
 final float scale = context.getResources().getDisplayMetrics().scaledDensity;
 return (int)(spValue * scale + 0.5f);
 }

 @Override
 protected void onDestroy() {
 super.onDestroy();
 indicatorView.release();
 }
}

加载全部内容

相关教程
猜你喜欢
用户评论