本文主要是介绍imageswitch的自动切换的一个工具类，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
主要代码
public class ImageSwitcher extends ViewGroup {
private String TAG = ImageSwitcher.class.getSimpleName();
private static final int SNAP_VELOCITY = 300;
private Scroller scroller;
private VelocityTracker mVelocityTracker;
private int mTouchSlop;
private float mMotionX;
private int mImageWidth;
private int imageCount;
private int mIndex;
private int mImageHeight;
private int[] imageItems;
private boolean forceToRelayout;
private int mTouchState = TOUCH_STATE_REST;
private static final int TOUCH_STATE_REST = 0;
private static final int TOUCH_STATE_SCROLLING = 1;
private static final int AUTO_MSG = 0;
private static final int START_MSG =2;
private static final int HANDLE_MSG = 1;
private static final long PHOTO_CHANGE_TIME = 4000;
private Handler mHandler = new Handler(){ //处理图片自动或者手动滚动操作
public void handleMessage(Message msg) {
switch (msg.what) {
case AUTO_MSG:
scrollToNext();
mHandler.sendEmptyMessageDelayed(AUTO_MSG, PHOTO_CHANGE_TIME);
break;
case START_MSG:
mHandler.sendEmptyMessageDelayed(AUTO_MSG, PHOTO_CHANGE_TIME);
break;
case HANDLE_MSG:
mHandler.removeMessages(AUTO_MSG);
mHandler.sendEmptyMessageDelayed(AUTO_MSG, PHOTO_CHANGE_TIME);
default:
break;
}
}
};
/**
* 表示滚动到下一张图片这个动作
*/
private static final int SCROLL_NEXT = 0;
/**
* 表示滚动到上一张图片这个动作
*/
private static final int SCROLL_PREVIOUS = 1;
private static final int SCROLL_BACK = 2;
public ImageSwitcher(Context context, AttributeSet attrs) {
super(context, attrs);
scroller = new Scroller(context);
mTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();
}
/**
* 当View被添加到Window容器的时候才开始执行:生命周期依次先后 onMeasure > onLayout > onDraw >onAttachedToWindow
*/
@Override
protected void onAttachedToWindow(){
super.onAttachedToWindow();
mHandler.sendEmptyMessage(START_MSG); //发送消息让图片自动开始滚动
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
if(changed || forceToRelayout){
imageCount = getChildCount();
mImageWidth = getMeasuredWidth();
mImageHeight = getMeasuredHeight();
int marginLeft = 0;
scroller.abortAnimation(); //设置scroller为滚动状态
this.scrollTo(0, 0); //每次重新布局时候，重置滚动初始位置
int[] items = { getIndexForItem(1), getIndexForItem(2),
getIndexForItem(3), getIndexForItem(4),
getIndexForItem(5) };
imageItems = items;
for (int i = 0; i < items.length; i++) {
ImageView childView = (ImageView)getChildAt(items[i]);
childView.layout(marginLeft, 0, marginLeft
+ mImageWidth , mImageHeight);
marginLeft = marginLeft + mImageWidth;
}
refreshImageView();
forceToRelayout = false;
}
}
private void refreshImageView(){
for (int i = 0; i < imageItems.length; i++) {
ImageView childView = (ImageView)getChildAt(imageItems[i]);
childView.invalidate();
}
}
private int getIndexForItem(int item) {
int index = -1;
index = mIndex + item - 3;
while (index < 0) {
index = index + imageCount;
}
while (index > imageCount - 1) {
index = index - imageCount;
}
return index;
}
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
int action = ev.getAction();
if ((action == MotionEvent.ACTION_MOVE)
&& (mTouchState != TOUCH_STATE_REST)) {
return true;
}
float xLoc = ev.getX();
switch(action){
case MotionEvent.ACTION_DOWN:
mMotionX = xLoc;
mTouchState = TOUCH_STATE_REST;
Log.e(TAG, "onInterceptTouchEvent ACTION_DOWN");
break;
case MotionEvent.ACTION_MOVE:
Log.e(TAG, "onInterceptTouchEvent ACTION_MOVE");
int xDif = (int)Math.abs(mMotionX - xLoc);
if(xDif > mTouchSlop){ //当我们的水平距离滚动达到我们滚动的最小距离,开始拦截ViewGroup的事件给子控件分发
mTouchState = TOUCH_STATE_SCROLLING;
}
break;
case MotionEvent.ACTION_UP:
Log.e(TAG, "onInterceptTouchEvent ACTION_UP");
mTouchState = TOUCH_STATE_REST;
break;
case MotionEvent.ACTION_CANCEL:
Log.e(TAG, "onInterceptTouchEvent ACTION_CANCEL");
mTouchState = TOUCH_STATE_REST;
break;
default:
Log.e(TAG, "onInterceptTouchEvent DEFAULT");
mTouchState = TOUCH_STATE_REST;
break;
}
return mTouchState != TOUCH_STATE_REST;
}
@Override
public boolean onTouchEvent(MotionEvent event) {
if(scroller.isFinished()){ //scroller还没有开始或者已经完成，以下代码在手指滑动的时候才开始执行
if (mVelocityTracker == null) {
mVelocityTracker = VelocityTracker.obtain();
}
mVelocityTracker.addMovement(event);
int action = event.getAction();
float x = event.getX();
switch (action) {
case MotionEvent.ACTION_DOWN:
// 记录按下时的横坐标
mMotionX = x;
case MotionEvent.ACTION_MOVE:
int disX = (int)(mMotionX - x);
mMotionX = x;
scrollBy(disX, 0);
break;
case MotionEvent.ACTION_UP:
mVelocityTracker.computeCurrentVelocity(1000);
int velocityX = (int) mVelocityTracker.getXVelocity();
if (judeScrollToNext(velocityX)) {
// 下一张图
scrollToNext();
} else if (judeScrollToPrevious(velocityX)) {
//上一张图
scrollToPrevious();
} else {
// 当前图片
scrollBack();
}
if (mVelocityTracker != null) {
mVelocityTracker.recycle();
mVelocityTracker = null;
}
mHandler.sendEmptyMessageDelayed(HANDLE_MSG, PHOTO_CHANGE_TIME);
return true;
}
}
return false;
}
private void scrollBack() {
if (scroller.isFinished()) {
beginScroll(getScrollX(), 0, -getScrollX(), 0,SCROLL_BACK);
}
}
private void scrollToPrevious() {
if(scroller.isFinished()){
setImageSwitchIndex(SCROLL_PREVIOUS);
int disX = -mImageWidth - getScrollX();
beginScroll(getScrollX(), 0, disX, 0,SCROLL_PREVIOUS);
}
}
private void scrollToNext() {
if (scroller.isFinished()) {
setImageSwitchIndex(SCROLL_NEXT);
int disX = mImageWidth - getScrollX();
beginScroll(getScrollX(), 0, disX, 0,SCROLL_NEXT);
}
}
/**
* 图片开始滑动
*/
private void beginScroll(int startX, int startY, int dx, int dy,
final int action) {
int duration = (int) (700f / mImageWidth * Math.abs(dx));
scroller.startScroll(startX, startY, dx, dy, duration);
invalidate();
mHandler.postDelayed(new Runnable() {
@Override
public void run() {
if (action == SCROLL_NEXT || action == SCROLL_PREVIOUS) {
forceToRelayout = true;
requestLayout();
}
}
}, duration);
}
private void setImageSwitchIndex(int action) {
if(action == SCROLL_NEXT){
if(mIndex < imageCount){
mIndex++;
}else{
mIndex = 0;
}
}else if(action == SCROLL_PREVIOUS){
if(mIndex > 0){
mIndex--;
}else{
mIndex = imageCount -1;
}
}
}
/**
* 判断时候滑向前一个
* @param velocityX
* @return
*/
private boolean judeScrollToPrevious(int velocityX) {
return velocityX > SNAP_VELOCITY || getScrollX() < -mImageWidth / 2;
}
/**
* 判断时候滑向后一个
* @param velocityX
* @return
*/
private boolean judeScrollToNext(int velocityX) {
return velocityX < -SNAP_VELOCITY|| getScrollX() > mImageWidth / 2;
}
@Override
public void computeScroll() {
if (scroller.computeScrollOffset()) {
scrollTo(scroller.getCurrX(), scroller.getCurrY());
//刷新View 否则效果可能有误差
postInvalidate();
}
}
}
布局
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent">
<com.zhanglei.imageswitcher.ImageSwitcher
android:id="@+id/image_switch_view"
android:layout_width="match_parent"
android:layout_height="200dp" >
<ImageView
android:id="@+id/image1"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:scaleType="fitXY"
android:clickable="true"
android:src="@drawable/item01"/>
<ImageView
android:id="@+id/image2"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:scaleType="fitXY"
android:clickable="true"
android:src="@drawable/item02"/>
<ImageView
android:id="@+id/image3"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:scaleType="fitXY"
android:clickable="true"
android:src="@drawable/item03"/>
<ImageView
android:id="@+id/image4"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:scaleType="fitXY"
android:clickable="true"
android:src="@drawable/item04"/>
<ImageView
android:id="@+id/image5"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:scaleType="fitXY"
android:clickable="true"
android:src="@drawable/item05"/>
</com.zhanglei.imageswitcher.ImageSwitcher>
</RelativeLayout>
效果就不展示了，因为我不会录像，嘎嘎
拿来就可以用哦
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