本篇文章给大家分享的是有关Android开发中利用ListView实现一个渐变式的下拉刷新动画，小编觉得挺实用的，因此分享给大家学习，希望大家阅读完这篇文章后可以有所收获，话不多说，跟着小编一起来看看吧。
主要要点
listview刷新过程中主要有三个步骤当前：状态为下拉刷新，当前状态为下拉刷新，当前状态为放开刷新，当前状态为正在刷新；主要思路为三个步骤分别对应三个自定义的view；即ibuRefreshFirstStepView，ibuRefreshSecondStepView，ibuRefreshThirdStepView。
效果图
ibuRefreshFirstStepView代码，例如：
private Bitmap initialBitmap;
private float mCurrentProgress;
private Bitmap scaledBitmap;
public ibuRefreshFirstStepView(Context context, AttributeSet attrs,
int defStyle) {
super(context, attrs, defStyle);
init(context);
}
public ibuRefreshFirstStepView(Context context, AttributeSet attrs) {
super(context, attrs);
init(context);
}
public ibuRefreshFirstStepView(Context context) {
super(context);
init(context);
}
private void init(Context context) {
//这个就是那个火箭图片
initialBitmap = Bitmap.createBitmap(BitmapFactory.decodeResource(getResources(), R.drawable.img_huojian1));
}
/**
* 重写onMeasure方法主要是设置wrap_content时 View的大小
* @param widthMeasureSpec
* @param heightMeasureSpec
*/
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
//根据设置的宽度来计算高度 设置为符合第二阶段娃娃图片的宽高比例
setMeasuredDimension(measureWidth(widthMeasureSpec),measureWidth(widthMeasureSpec)*initialBitmap.getHeight()/initialBitmap.getWidth());
}
/**
* 当wrap_content的时候，宽度即为第二阶段娃娃图片的宽度
* @param widMeasureSpec
* @return
*/
private int measureWidth(int widMeasureSpec){
int result = 0;
int size = MeasureSpec.getSize(widMeasureSpec);
int mode = MeasureSpec.getMode(widMeasureSpec);
if (mode == MeasureSpec.EXACTLY){
result = size;
}else{
result = initialBitmap.getWidth();
if (mode == MeasureSpec.AT_MOST){
result = Math.min(result,size);
}
}
return result;
}
/**
* 在onLayout里面获得测量后View的宽高
* @param changed
* @param left
* @param top
* @param right
* @param bottom
*/
@Override
protected void onLayout(boolean changed, int left, int top, int right,
int bottom) {
super.onLayout(changed, left, top, right, bottom);
// 给火箭图片进行等比例的缩放
scaledBitmap = Bitmap.createScaledBitmap(initialBitmap,89,110, false);
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
//这个方法是对画布进行缩放，从而达到椭圆形图片的缩放，第一个参数为宽度缩放比例，第二个参数为高度缩放比例，
// canvas.scale(mCurrentProgress, mCurrentProgress, measuredWidth/2, measuredHeight/2);
//将等比例缩放后的椭圆形画在画布上面
canvas.drawBitmap(scaledBitmap,90,dip2px(getContext(),80*mCurrentProgress),null);
}
/**
* 根据手机的分辨率从 dp 的单位 转成为 px(像素)
*/
public static int dip2px(Context context, float dpValue) {
final float scale = context.getResources().getDisplayMetrics().density;
return (int) (dpValue * scale + 0.5f);
}
/**
* 设置缩放比例，从0到1 0为最小 1为最大
* @param currentProgress
*/
public void setCurrentProgress(float currentProgress){
mCurrentProgress = currentProgress;
}
}ibuRefreshSecondStepView代码，例如：
private Bitmap endBitmap,scaledBitmap;
public ibuRefreshSecondStepView(Context context, AttributeSet attrs,
int defStyle) {
super(context, attrs, defStyle);
init();
}
public ibuRefreshSecondStepView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public ibuRefreshSecondStepView(Context context) {
super(context);
init();
}
private void init() {
endBitmap = Bitmap.createScaledBitmap(BitmapFactory.decodeResource(getResources(), R.drawable.img_huojian2), 89, 110, false);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
setMeasuredDimension(measureWidth(widthMeasureSpec), measureWidth(widthMeasureSpec) * endBitmap.getHeight() / endBitmap.getWidth());
}
@Override
protected void onLayout(boolean changed, int left, int top, int right,
int bottom) {
super.onLayout(changed, left, top, right, bottom);
scaledBitmap = Bitmap.createScaledBitmap(endBitmap, 89, 110, false);
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.drawBitmap(endBitmap, 90, dip2px(getContext(), 80 * 1), null);
}
/**
* 根据手机的分辨率从 dp 的单位 转成为 px(像素)
*/
public static int dip2px(Context context, float dpValue) {
final float scale = context.getResources().getDisplayMetrics().density;
return (int) (dpValue * scale + 0.5f);
}
private int measureWidth(int widthMeasureSpec){
int result = 0;
int size = MeasureSpec.getSize(widthMeasureSpec);
int mode = MeasureSpec.getMode(widthMeasureSpec);
if (mode == MeasureSpec.EXACTLY) {
result = size;
}else {
result = endBitmap.getWidth();
if (mode == MeasureSpec.AT_MOST) {
result = Math.min(result, size);
}
}
return result;
}
}ibuRefreshThirdStepView代码，例如：
private Bitmap endBitmap,scaledBitmap;
public ibuRefreshThirdStepView(Context context, AttributeSet attrs,
int defStyle) {
super(context, attrs, defStyle);
init();
}
public ibuRefreshThirdStepView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public ibuRefreshThirdStepView(Context context) {
super(context);
init();
}
private void init() {
endBitmap = Bitmap.createScaledBitmap(BitmapFactory.decodeResource(getResources(), R.drawable.img_huojian3), 89, 170, false);
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.drawBitmap(endBitmap, 90, dip2px(getContext(), 40 * 1), null);
}
/**
* 根据手机的分辨率从 dp 的单位 转成为 px(像素)
*/
public static int dip2px(Context context, float dpValue) {
final float scale = context.getResources().getDisplayMetrics().density;
return (int) (dpValue * scale + 0.5f);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
setMeasuredDimension(measureWidth(widthMeasureSpec), measureWidth(widthMeasureSpec)*endBitmap.getHeight()/endBitmap.getWidth());
}
private int measureWidth(int widthMeasureSpec){
int result = 0;
int size = MeasureSpec.getSize(widthMeasureSpec);
int mode = MeasureSpec.getMode(widthMeasureSpec);
if (mode == MeasureSpec.EXACTLY) {
result = size;
}else {
result = endBitmap.getWidth();
if (mode == MeasureSpec.AT_MOST) {
result = Math.min(result, size);
}
}
return result;
}代码块
IbuListView 代码，例如：
private static final int DONE = 0;
private static final int PULL_TO_REFRESH = 1;
private static final int RELEASE_TO_REFRESH = 2;
private static final int REFRESHING = 3;
private static final int RATIO = 3;
private RelativeLayout headerView;
private int headerViewHeight;
private float startY;
private float offsetY;
private TextView tv_pull_to_refresh;
private OnMeiTuanRefreshListener mOnRefreshListener;
private int state;
private int mFirstVisibleItem;
private boolean isRecord;
private boolean isEnd;
private boolean isRefreable;
private FrameLayout mAnimContainer;
// private Animation animation;
private SimpleDateFormat format;
private ibuRefreshFirstStepView mFirstView;
private ibuRefreshSecondStepView mSecondView;
private AnimationDrawable secondAnim;
private ibuRefreshThirdStepView mThirdView;
private AnimationDrawable thirdAnim;
public IbuListView(Context context) {
super(context);
init(context);
}
public IbuListView(Context context, AttributeSet attrs) {
super(context, attrs);
init(context);
}
public IbuListView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init(context);
}
public interface OnMeiTuanRefreshListener{
void onRefresh();
}
/**
* 回调接口，想实现下拉刷新的listview实现此接口
* @param onRefreshListener
*/
public void setOnMeiTuanRefreshListener(OnMeiTuanRefreshListener onRefreshListener){
mOnRefreshListener = onRefreshListener;
isRefreable = true;
}
/**
* 刷新完毕，从主线程发送过来，并且改变headerView的状态和文字动画信息
*/
public void setOnRefreshComplete(){
//一定要将isEnd设置为true，以便于下次的下拉刷新
isEnd = true;
state = DONE;
changeHeaderByState(state);
}
private ImageView imageViewBack,imageView_B;
private void init(Context context) {
setOverScrollMode(View.OVER_SCROLL_NEVER);
setOnScrollListener(this);
headerView = (RelativeLayout) LayoutInflater.from(context).inflate(R.layout.ibu_item, null, false);
imageViewBack= (ImageView) headerView.findViewById(R.id.icon_back);
imageView_B= (ImageView) headerView.findViewById(R.id.image_b);
mFirstView = (ibuRefreshFirstStepView) headerView.findViewById(R.id.first_view);
tv_pull_to_refresh = (TextView) headerView.findViewById(R.id.tv_pull_to_refresh);
mSecondView = (ibuRefreshSecondStepView) headerView.findViewById(R.id.second_view);
mThirdView = (ibuRefreshThirdStepView) headerView.findViewById(R.id.third_view);
measureView(headerView);
addHeaderView(headerView);
headerViewHeight = headerView.getMeasuredHeight();
headerView.setPadding(0, -headerViewHeight, 0, 0);
Log.i("zhangqi","headerViewHeight="+headerViewHeight);
state = DONE;
isEnd = true;
isRefreable = false;
}
@Override
public void onScrollStateChanged(AbsListView absListView, int i) {
}
@Override
public void onScroll(AbsListView absListView, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
mFirstVisibleItem = firstVisibleItem;
}
@Override
public boolean onTouchEvent(MotionEvent ev) {
if (isEnd) {//如果现在时结束的状态，即刷新完毕了，可以再次刷新了，在onRefreshComplete中设置
if (isRefreable) {//如果现在是可刷新状态 在setOnMeiTuanListener中设置为true
switch (ev.getAction()){
//用户按下
case MotionEvent.ACTION_DOWN:
//如果当前是在listview顶部并且没有记录y坐标
if (mFirstVisibleItem == 0 && !isRecord) {
//将isRecord置为true，说明现在已记录y坐标
isRecord = true;
//将当前y坐标赋值给startY起始y坐标
startY = ev.getY();
}
imageView_B.setVisibility(VISIBLE);
break;
//用户滑动
case MotionEvent.ACTION_MOVE:
//再次得到y坐标，用来和startY相减来计算offsetY位移值
float tempY = ev.getY();
//再起判断一下是否为listview顶部并且没有记录y坐标
if (mFirstVisibleItem == 0 && !isRecord) {
isRecord = true;
startY = tempY;
}
//如果当前状态不是正在刷新的状态，并且已经记录了y坐标
if (state!=REFRESHING && isRecord ) {
//计算y的偏移量
offsetY = tempY - startY;
//计算当前滑动的高度
float currentHeight = (-headerViewHeight+offsetY/3);
//用当前滑动的高度和头部headerView的总高度进行比 计算出当前滑动的百分比 0到1
float currentProgress = 1+currentHeight/headerViewHeight;
//如果当前百分比大于1了，将其设置为1，目的是让第一个状态的椭圆不再继续变大
if (currentProgress>=1) {
currentProgress = 1;
}
//如果当前的状态是放开刷新，并且已经记录y坐标
if (state == RELEASE_TO_REFRESH && isRecord) {
setSelection(0);
//如果当前滑动的距离小于headerView的总高度
if (-headerViewHeight+offsetY/RATIO<0) {
//将状态置为下拉刷新状态
state = PULL_TO_REFRESH;
//根据状态改变headerView，主要是更新动画和文字等信息
changeHeaderByState(state);
//如果当前y的位移值小于0，即为headerView隐藏了
}else if (offsetY<=0) {
//将状态变为done
state = DONE;
//根据状态改变headerView，主要是更新动画和文字等信息
changeHeaderByState(state);
}
}
//如果当前状态为下拉刷新并且已经记录y坐标
if (state == PULL_TO_REFRESH && isRecord) {
setSelection(0);
//如果下拉距离大于等于headerView的总高度
if (-headerViewHeight+offsetY/RATIO>=0) {
//将状态变为放开刷新
state = RELEASE_TO_REFRESH;
//根据状态改变headerView，主要是更新动画和文字等信息
changeHeaderByState(state);
//如果当前y的位移值小于0，即为headerView隐藏了
}else if (offsetY<=0) {
//将状态变为done
state = DONE;
//根据状态改变headerView，主要是更新动画和文字等信息
changeHeaderByState(state);
}
}
//如果当前状态为done并且已经记录y坐标
if (state == DONE && isRecord) {
//如果位移值大于0
if (offsetY>=0) {
//将状态改为下拉刷新状态
state = PULL_TO_REFRESH;
}
}
//如果为下拉刷新状态
if (state == PULL_TO_REFRESH) {
//则改变headerView的padding来实现下拉的效果
headerView.setPadding(0,(int)(-headerViewHeight+offsetY/RATIO) ,0,0);
//给第一个状态的View设置当前进度值
mFirstView.setCurrentProgress(currentProgress);
//重画
mFirstView.postInvalidate();
}
//如果为放开刷新状态
if (state == RELEASE_TO_REFRESH) {
//改变headerView的padding值
headerView.setPadding(0,(int)(-headerViewHeight+offsetY/RATIO) ,0, 0);
//给第一个状态的View设置当前进度值
mFirstView.setCurrentProgress(currentProgress);
//重画
mFirstView.postInvalidate();
}
}
break;
//当用户手指抬起时
case MotionEvent.ACTION_UP:
//如果当前状态为下拉刷新状态
if (state == PULL_TO_REFRESH) {
//平滑的隐藏headerView
this.smoothScrollBy((int)(-headerViewHeight+offsetY/RATIO)+headerViewHeight, 500);
//根据状态改变headerView
changeHeaderByState(state);
}
//如果当前状态为放开刷新
if (state == RELEASE_TO_REFRESH) {
//平滑的滑到正好显示headerView
this.smoothScrollBy((int)(-headerViewHeight+offsetY/RATIO), 500);
//将当前状态设置为正在刷新
state = REFRESHING;
//回调接口的onRefresh方法
mOnRefreshListener.onRefresh();
//根据状态改变headerView
changeHeaderByState(state);
}
//这一套手势执行完，一定别忘了将记录y坐标的isRecord改为false，以便于下一次手势的执行
isRecord = false;
break;
}
}
}
return super.onTouchEvent(ev);
}
private Animation animation;
/**
* 根据状态改变headerView的动画和文字显示
* @param state
*/
private void changeHeaderByState(int state){
switch (state) {
case DONE://如果的隐藏的状态
//设置headerView的padding为隐藏
headerView.setPadding(0, -headerViewHeight, 0, 0);
//第一状态的view显示出来
mFirstView.setVisibility(View.VISIBLE);
imageView_B.setVisibility(VISIBLE);
tv_pull_to_refresh.setText("下拉刷新");
//第二状态的view隐藏起来
mSecondView.setVisibility(View.GONE);
//停止第二状态的动画
secondAnim.stop();
//第三状态的view隐藏起来
mThirdView.setVisibility(View.GONE);
//停止第三状态的动画
thirdAnim.stop();
break;
case RELEASE_TO_REFRESH://当前状态为放开刷新
//文字显示为放开刷新
tv_pull_to_refresh.setText("放开刷新");
//第一状态view隐藏起来
mFirstView.setVisibility(View.GONE);
//第二状态view显示出来
mSecondView.setVisibility(View.VISIBLE);
//播放第二状态的动画
secondAnim.start();
//第三状态view隐藏起来
mThirdView.setVisibility(View.GONE);
//停止第三状态的动画
thirdAnim.stop();
break;
case PULL_TO_REFRESH://当前状态为下拉刷新
imageView_B.setVisibility(VISIBLE);
//设置文字为下拉刷新
tv_pull_to_refresh.setText("下拉刷新");
//第一状态view显示出来
mFirstView.setVisibility(View.VISIBLE);
//第二状态view隐藏起来
mSecondView.setVisibility(View.GONE);
//第二状态动画停止
secondAnim.stop();
//第三状态view隐藏起来
mThirdView.setVisibility(View.GONE);
//第三状态动画停止
thirdAnim.stop();
break;
case REFRESHING://当前状态为正在刷新
//文字设置为正在刷新
tv_pull_to_refresh.setText("正在刷新");
//第一状态view隐藏起来
mFirstView.setVisibility(View.GONE);
//第三状态view显示出来
mThirdView.setVisibility(View.VISIBLE);
//第二状态view隐藏起来
mSecondView.setVisibility(View.GONE);
//停止第二状态动画
secondAnim.stop();
//启动第三状态view
thirdAnim.start();
imageView_B.setVisibility(GONE);
animation = new TranslateAnimation(0, 0, 0, 600);
animation.setDuration(3000);
imageViewBack.setAnimation(animation);
break;
default:
break;
}
}
private void measureView(View child) {
ViewGroup.LayoutParams p = child.getLayoutParams();
if (p == null) {
p = new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,
ViewGroup.LayoutParams.WRAP_CONTENT);
}
int childWidthSpec = ViewGroup.getChildMeasureSpec(0, 0 + 0, p.width);
int lpHeight = p.height;
int childHeightSpec;
if (lpHeight > 0) {
childHeightSpec = MeasureSpec.makeMeasureSpec(lpHeight,
MeasureSpec.EXACTLY);
} else {
childHeightSpec = MeasureSpec.makeMeasureSpec(0,
MeasureSpec.UNSPECIFIED);
}
child.measure(childWidthSpec, childHeightSpec);
}
}以上就是Android开发中利用ListView实现一个渐变式的下拉刷新动画，小编相信有部分知识点可能是我们日常工作会见到或用到的。希望你能通过这篇文章学到更多知识。更多详情敬请关注亿速云行业资讯频道。
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