前言

之前写的一个LoadingBar，这次把LoadingBar加到下拉刷新的头部。从头写一个下拉刷新，附赠上拉加载更多。下面话不多说了，来一起看看详细的介绍吧。

效果图：

实现过程

首先是自定义属性，attrs.xml中定义头部的高度和上下的padding。

####attrs.xml####

然后是头部的文件，里面放了一个TextView和一个图片

header_layout.xml####

android:layout_width="match_parent"

android:layout_height="50dp"

android:orientation="vertical">

android:src="@mipmap/down"

android:layout_centerVertical="true"

android:id="@+id/icon"

android:layout_width="20dp"

android:layout_height="20dp"

android:layout_toLeftOf="@+id/text"

android:layout_marginRight="5dp"/>

android:id="@+id/text"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_centerInParent="true"

android:text="下拉刷新" />

然后是布局文件,让PPRefreshView作为父布局，下面可以放AbsListView的子类。

activity_main.xml####

xmlns:tools="http://schemas.android.com/tools"

android:layout_width="match_parent"

android:layout_height="match_parent"

android:background="@color/white" tools:context="top.greendami.greendami.MainActivity">

ppRefreshView:header_height="50dp"

ppRefreshView:header_padding="10dp"

android:id="@+id/swipeRefreshLayout"

android:layout_width="match_parent"

android:layout_height="match_parent"

android:background="#d4d4d4">

android:background="@color/white"

android:id="@+id/list" android:layout_width="match_parent" android:layout_height="match_parent">

最后是重点，下拉刷新的控件。

"精心"准备了一张图

####PPRefreshView.java####

package top.greendami.greendami;

package com.allrun.arsmartelevatorformanager.widget;

import android.content.Context;

import android.content.res.TypedArray;

import android.graphics.Canvas;

import android.support.v7.widget.RecyclerView;

import android.util.AttributeSet;

import android.view.LayoutInflater;

import android.view.MotionEvent;

import android.view.View;

import android.view.ViewConfiguration;

import android.view.ViewGroup;

import android.view.animation.Animation;

import android.view.animation.RotateAnimation;

import android.widget.ImageView;

import android.widget.TextView;

import com.allrun.arsmartelevatorformanager.R;

import com.allrun.arsmartelevatorformanager.util.DPUnitUtil;

/**

* Created by GreendaMI on 2017/3/21.

*/

public class PPRefreshView extends ViewGroup {

Context context;

RecyclerView mListView;

PPView mPPView;

View header;

TextView title;

ImageView mImage;//箭头

int listTop = 0;

float headerHeight = 10 + 30 + 10;//header的高度，上留白 + 文字(PPVIew)高度 + 下留白

float headerpadding = 10;//上留白,下留白

private int mYDown, mLastY;

//最短滑动距离

int a = 0;

RotateAnimation mRotateAnimation;

int state = 0; //0,正常;1,下拉;2,松开

public void setPPRefreshViewListener(PPRefreshViewListener mPPRefreshViewListener) {

this.mPPRefreshViewListener = mPPRefreshViewListener;

}

PPRefreshViewListener mPPRefreshViewListener;

public PPRefreshView(Context context) {

super(context);

this.context = context;

}

public PPRefreshView(Context context, AttributeSet attrs) {

super(context, attrs);

this.context = context;

//px转dp

a = DPUnitUtil.px2dip(context,ViewConfiguration.get(context).getScaledDoubleTapSlop());

TypedArray b = context.obtainStyledAttributes(attrs, R.styleable.PPRefreshView_header);

headerHeight = b.getDimension(R.styleable.PPRefreshView_header_header_height, 100);

headerpadding = b.getDimension(R.styleable.PPRefreshView_header_header_padding, 10);

b.recycle();

initAnima();

}

private void initAnima() {

//箭头旋转

mRotateAnimation = new RotateAnimation(0, 180, Animation.RELATIVE_TO_SELF,

0.5f, Animation.RELATIVE_TO_SELF, 0.5f);

mRotateAnimation.setFillAfter(true);

mRotateAnimation.setDuration(200);

}

@Override

protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {

if (mPPView != null) {

mPPView.measure(widthMeasureSpec,(int) (headerHeight- 2 * headerpadding));

}

if (header != null) {

header.measure(widthMeasureSpec, (int) (headerHeight- 2 * headerpadding));

}

super.onMeasure(widthMeasureSpec, heightMeasureSpec);

}

@Override

protected void onLayout(boolean changed, int l, int t, int r, int b) {

if (mListView == null && getChildCount() == 1) {

mListView = (RecyclerView)getChildAt(0);

mListView.setOnScrollListener(new RecyclerView.OnScrollListener() {

@Override

public void onScrolled(RecyclerView recyclerView, int dx, int dy) {

super.onScrolled(recyclerView, dx, dy);

if(!recyclerView.canScrollVertically(1)){

//添加外部回调

if(mPPRefreshViewListener != null){ mPPRefreshViewListener.LoadMore();

}

}

}

});

}

if (mListView != null) {

mListView.layout(l, listTop, getMeasuredWidth(), b);

}

if (mPPView != null) {

//top：文字(PPVIew)高度 + 下留白

mPPView.layout(l, (int)(listTop - headerHeight + headerpadding), r, listTop);

}

if (header != null) {

//top：文字(PPView)高度 + 下留白

header.layout(l, (int)(listTop - headerHeight + headerpadding), r, listTop);

}

}

@Override

protected void dispatchDraw(Canvas canvas) {

super.dispatchDraw(canvas);

//松开手指，list回到顶部

if (state == 2) {

listTop = listTop - 25;

if (listTop < headerHeight) {

listTop = (int)headerHeight;

}

requestLayout();

}

//刷新完毕，关闭header

if (state == 0 && listTop > 0) {

listTop = listTop - 25;

if (listTop < 0) {

listTop = 0;

}

requestLayout();

}

}

@Override

public boolean dispatchTouchEvent(MotionEvent event) {

final int action = event.getAction();

switch (action) {

case MotionEvent.ACTION_DOWN:

// 按下

mYDown = (int) event.getRawY();

break;

case MotionEvent.ACTION_MOVE:

// 移动

mLastY = (int) event.getRawY();

if (!mListView.canScrollVertically(-1) && mLastY > mYDown &&(mLastY - mYDown) > a) {

state = 1;

listTop = mLastY - mYDown;

if (mPPView != null) {

removeView(mPPView);

mPPView = null;

}

if (header == null) {

header = LayoutInflater.from(context).inflate(R.layout.header_layout, null, false);

title = ((TextView) header.findViewById(R.id.text));

mImage = ((ImageView) header.findViewById(R.id.icon));

addView(header);

}

if (title != null && (mLastY - mYDown) > a * 2f) {

title.setText("松开刷新");

if (mImage.getAnimation() == null) {

mImage.startAnimation(mRotateAnimation);

}

}

if (title != null && (mLastY - mYDown) < a * 2f) {

title.setText("下拉刷新");

mImage.setImageResource(R.mipmap.down);

}

requestLayout();

//已经判断是下拉刷新，拦截手势

return false;

}

break;

case MotionEvent.ACTION_UP:

// 抬起

// if (canLoad()) {

// loadData();

// }

//松手的时候，把文字标题去掉

if (header != null) {

removeView(header);

header = null;

}

//如果之前是下拉状态，就添加PPVIew

if (mPPView == null && state == 1) {

//添加外部回调

if(mPPRefreshViewListener != null){

mPPRefreshViewListener.onRefresh();

}

mPPView = new PPView(context);

addView(mPPView);

mYDown = 0;

mLastY = 0;

state = 2;

requestLayout();

}

break;

default:

break;

}

return super.dispatchTouchEvent(event);

}

/**

* 收起下拉刷新的header，刷新结束

*/

public void RefreshOver() {

if (mPPView != null) {

removeView(mPPView);

mPPView = null;

}

if (header != null) {

removeView(header);

header = null;

title = null;

mImage = null;

}

state = 0;

}

public void setRefreshing(boolean b) {

if(!b){

state = 0;

postInvalidate();

}else{

state = 2;

postInvalidate();

}

}

public interface PPRefreshViewListener{

void onRefresh();

void LoadMore();

}

}

主要思路是监听手势的滑动距离，如果ListView已经划到顶部，则ListView跟随手指位置，并添加Header。放开手指后,ListView慢慢回到顶部。

外部回调。监听下拉和上拉。

mSwipeRefreshLayout.setPPRefreshViewListener(new PPRefreshView.PPRefreshViewListener() {

@Override

public void onRefresh() {

Toast.makeText(MainActivity.this,"亲,刷新了",Toast.LENGTH_SHORT).show();

data.add("测试数据100");

mAdapter.notifyDataSetChanged();

}

@Override

public void LoadMore() {

Toast.makeText(MainActivity.this,"加载更多",Toast.LENGTH_SHORT).show();

}

});

refreshLayout.setRefreshing(false);;//刷新完毕

差点忘了粘连小球的View。

####PPView.java####

package top.greendami.greendami;

import android.content.Context;

import android.graphics.Canvas;

import android.graphics.Paint;

import android.graphics.Path;

import android.support.annotation.Nullable;

import android.util.AttributeSet;

import android.view.View;

/**

* Created by GreendaMi on 2017/3/17.

*/

public class PPView extends View {

String TAG = "PPView";

//动画开关

boolean isLoading = true;

Context mContext;

private int mWidth = 100;

private int mheight = 100;

public int mColor;

public Paint mPaint = new Paint();

float time = 0;

//小球与中间打球的最远距离

float distance = 100;

public PPView(Context context) {

super(context);

mContext = context;

mColor = context.getResources().getColor(R.color.colorPrimary);

init();

}

public PPView(Context context, @Nullable AttributeSet attrs) {

super(context, attrs);

mContext = context;

mColor = context.getResources().getColor(R.color.colorPrimary);

init();

}

private void init() {

mPaint.setAntiAlias(true);

mPaint.setColor(mColor);

}

@Override

protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {

super.onMeasure(widthMeasureSpec, heightMeasureSpec);

int widthSpecSize = MeasureSpec.getSize(widthMeasureSpec);

int heightSpecSize = MeasureSpec.getSize(heightMeasureSpec);

//宽度至少是高度的4倍

if (widthSpecSize < 4 * heightSpecSize) {

widthSpecSize = 4 * heightSpecSize;

}

mWidth = widthSpecSize;

mheight = heightSpecSize;

distance = 1.2f * mheight;

setMeasuredDimension(widthSpecSize, heightSpecSize);

}

@Override

protected void onDraw(Canvas canvas) {

super.onDraw(canvas);

if (isLoading) {

//大圆半径

float bigR = mheight * 0.32f + mheight * 0.03f * Math.abs((float) Math.sin(Math.toRadians(time)));

float smallR = mheight * 0.17f + mheight * 0.03f * Math.abs((float) Math.cos(Math.toRadians(time)));

float bigx = (getWidth()) / 2;

//画中间大圆

canvas.drawCircle(bigx, mheight / 2, bigR, mPaint);

float smalx = getSmallCenterX();

//画小圆

canvas.drawCircle(smalx, mheight / 2, smallR, mPaint);

//画链接

//小球在右侧

if (smalx > bigx) {

Path path = new Path();

//上面的贝塞尔曲线的第一个点，在大圆身上

float x1 = bigx + bigR * (float) Math.cos(Math.toRadians(time));

float y1 = mheight / 2 - bigR * (float) Math.sin(Math.toRadians(time));

if (y1 > mheight / 2 - smallR) {

y1 = mheight / 2 - smallR;

x1 = bigx + (float) (Math.sqrt(bigR * bigR - smallR * smallR));

}

//上面的贝塞尔曲线的第三个点，在小圆身上

float x2 = smalx - smallR * (float) Math.cos(Math.toRadians(time));

float y2 = mheight / 2 - smallR * (float) Math.sin(Math.toRadians(time));

if (y2 > mheight / 2 - smallR * 0.8) {

y2 = mheight / 2 - smallR * 0.8f;

x2 = smalx - smallR * (float) (Math.sqrt(1-0.64f));

}

//下面的贝塞尔曲线的第三个点，在小圆身上

float x3 = smalx - smallR * (float) Math.cos(Math.toRadians(time));

float y3 = mheight / 2 + smallR * (float) Math.sin(Math.toRadians(time));

if (y3 < mheight / 2 + smallR * 0.8) {

y3 = mheight / 2 + smallR * 0.8f;

x3 = smalx - smallR * (float) (Math.sqrt(1-0.64f));

}

//下面的贝塞尔曲线的第一个点，在大圆身上

float x4 = bigx + bigR * (float) Math.cos(Math.toRadians(time));

float y4 = mheight / 2 + bigR * (float) Math.sin(Math.toRadians(time));

if (y4 < mheight / 2 + smallR) {

y4 = mheight / 2 + smallR;

x4 = bigx + (float) (Math.sqrt(bigR * bigR - smallR * smallR));

}

path.moveTo(x1, y1);

path.quadTo((bigx + smalx) / 2, mheight / 2, x2, y2);

// 绘制贝赛尔曲线(Path)

path.lineTo(x3, y3);

path.quadTo((bigx + smalx) / 2, mheight / 2, x4, y4);

canvas.drawPath(path, mPaint);

}

//小球在左侧

if (smalx < bigx) {

Path path = new Path();

float x1 = bigx + bigR * (float) Math.cos(Math.toRadians(time));

float y1 = mheight / 2 - bigR * (float) Math.sin(Math.toRadians(time));

if (y1 > mheight / 2 - smallR) {

y1 = mheight / 2 - smallR;

x1 = bigx - (float) (Math.sqrt(bigR * bigR - smallR * smallR));

}

float x2 = smalx - smallR * (float) Math.cos(Math.toRadians(time));

float y2 = mheight / 2 - smallR * (float) Math.sin(Math.toRadians(time));

if (y2 > mheight / 2 - smallR * 0.8) {

y2 = mheight / 2 - smallR * 0.8f;

x2 = smalx + smallR * (float) (Math.sqrt(1-0.64f));

}

float x3 = smalx - smallR * (float) Math.cos(Math.toRadians(time));

float y3 = mheight / 2 + smallR * (float) Math.sin(Math.toRadians(time));

if (y3 < mheight / 2 + smallR * 0.8) {

y3 = mheight / 2 + smallR * 0.8f;

x3 = smalx + smallR * (float) (Math.sqrt(1-0.64f));

}

float x4 = bigx + bigR * (float) Math.cos(Math.toRadians(time));

float y4 = mheight / 2 + bigR * (float) Math.sin(Math.toRadians(time));

if (y4 < mheight / 2 + smallR) {

y4 = mheight / 2 + smallR;

x4 = bigx - (float) (Math.sqrt(bigR * bigR - smallR * smallR));

}

path.moveTo(x1, y1);

path.quadTo((bigx + smalx) / 2, mheight / 2, x2, y2);

// 绘制贝赛尔曲线(Path)

path.lineTo(x3, y3);

path.quadTo((bigx + smalx) / 2, mheight / 2, x4, y4);

canvas.drawPath(path, mPaint);

}

postInvalidate();

}

}

//计算小球的X坐标

private float getSmallCenterX() {

//此处控制速度

time = time + 4f;

return mWidth / 2 + distance * (float) Math.cos(Math.toRadians(time));

}

}

两张素材

总结

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