自定义侧滑栏

最新推荐文章于 2022-10-27 15:30:29 发布

子夜枯灯123

最新推荐文章于 2022-10-27 15:30:29 发布

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分类专栏： android 文章标签： Scroller 侧滑栏 android

本文链接：https://blog.youkuaiyun.com/huangyanbin123/article/details/24850587

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本文介绍了一个使用Android自定义视图实现侧滑效果的示例。通过继承LinearLayout并利用Scroller类，作者实现了基本的手势滑动效果，但遇到了滑动超出边界的问题。文章详细展示了如何监听触摸事件、计算滑动速度以及处理滑动动画。

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为了学习Scroller类，自己写了个自定义侧滑的demo，但是效果还是有点问题，主要是会滑出边界的问题。原来都是直接用别人的开源的项目来做效果，现在想自己也弄得玩。虽然达不到很好的效果。

package com.example.learnscroller;

import android.content.Context;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.View;
import android.view.ViewConfiguration;
import android.widget.LinearLayout;
import android.widget.Scroller;

public class MyScrollView extends LinearLayout {
	
	private static final String TAG = "MyScrollerView";
	private View mPerLayout;//主界面view
	private View mSliderLayout;//侧边栏view
	private int screenWidth; //屏幕宽度
	private int screenHeight;//屏幕高度
	private float scale = 0.5f;//侧边栏占比例
	private Scroller scroller;
	private int startX;//记录开始X位置
	public static final int SNAP_VELOCITY  = 200;//默认开始滑动像素点
	private VelocityTracker velocityTracker;
	private int mMaxVelocity;
	private int verlocity;
	private boolean isOpen = false;
	
	public MyScrollView(Context context) {
		this(context, null);
		
	}
	public MyScrollView(Context context, AttributeSet attrs) {
		super(context, attrs);
		initView(context);
		
	}

	
	@Override
	protected void onLayout(boolean changed, int l, int t, int r, int b) {
		super.onLayout(changed,l,t,r, b);
		mSliderLayout.layout((int) -(screenWidth*scale+100), 0, 0, screenHeight);
		mPerLayout.layout(0, 0, screenWidth, screenHeight);
	}

	
	@Override
	protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
		super.onMeasure(widthMeasureSpec, heightMeasureSpec);
		screenWidth = MeasureSpec.getSize(widthMeasureSpec);
		screenHeight = MeasureSpec.getSize(heightMeasureSpec);
		
	}
	
	@Override
	public boolean onTouchEvent(MotionEvent event) {
		int currentX = 0;
		addVelocityTracker(event);
		switch (event.getAction()) {
		case MotionEvent.ACTION_DOWN:
			startX = (int) event.getX();
			break;
		case MotionEvent.ACTION_MOVE:
			verlocity = getScrollXVelocity();
			currentX = (int) event.getX();
			Log.i(TAG, "getScrollX():"+getScrollX());
			if(Math.abs(verlocity)> SNAP_VELOCITY){
				if(getScrollX()>0||-getScrollX()>scale * screenWidth){
					return true;
				}
				scrollBy(-(currentX - startX), 0);
				
			}
			startX = currentX;
			break;
		case MotionEvent.ACTION_UP:
			verlocity = getScrollXVelocity();
			currentX = (int) event.getX();
			if(isOpen){
				if(-verlocity > 500 ||-getScrollX() <= scale * screenWidth/3 ){
					toLeftMove();
				}else{
					toRightMove();
				}
			}else{
				if(verlocity > 500 ||-getScrollX()>= 2 * scale * screenWidth/3){
					toRightMove();
				}else{
					toLeftMove();
				}
			}
			startX  = 0;
			removeVelocityTracker();
			break;
		}
		return true;
	}

	private void toLeftMove(){
		scroller.startScroll(getScrollX(), 0, -getScrollX(), 0);
		postInvalidate();
		isOpen = false;
		
	}
	private void toRightMove() {
		scroller.startScroll(getScrollX(), 0, -getScrollX()-(int)(screenWidth*scale), 0);
		postInvalidate();
		isOpen = true;
	}
	
	@Override
	public void computeScroll() {
		super.computeScroll();
		if(scroller.computeScrollOffset()){
			scrollTo(scroller.getCurrX(), scroller.getCurrY());
			postInvalidate();
		}
		
	}
	
	public void setPerLayout(View perLayout) {
		mPerLayout = perLayout;
		addView(mPerLayout);
	}
	

	public void setSliderLayout(View sliderLayout) {
		mSliderLayout = sliderLayout;
		addView(mSliderLayout);
	}
	
	public void setScale(float scale) {
		this.scale = scale;
	}
	
	private void initView(Context context){
		scroller = new Scroller(context);
		ViewConfiguration.get(context);
		mMaxVelocity = ViewConfiguration.getMaximumFlingVelocity();
	}
	
	private void addVelocityTracker(MotionEvent event){
		if(velocityTracker == null){
			velocityTracker = VelocityTracker.obtain();
		}

		velocityTracker.addMovement(event);
	}
	
	private void removeVelocityTracker(){
		velocityTracker.recycle();

	}
	
	private int getScrollXVelocity(){
		velocityTracker.computeCurrentVelocity(1000,mMaxVelocity);
		  int velocity = (int) velocityTracker.getXVelocity();  
		return velocity;
		
	}
}