IOS有側滑回退的功能,可以側滑回退到上一個Activity,并且在側滑時,底層的actvity是透明顯示的。下面代碼将實作該功能。
主要實作思路是讓Activity的整個容器滑動。
package com.tjpld.tonglingsafetyandroid.customview;
import java.util.LinkedList;
import java.util.List;
import android.app.Activity;
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.support.v4.view.ViewPager;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.ViewGroup;
import android.widget.FrameLayout;
import android.widget.Scroller;
import com.tjpld.tonglingsafetyandroid.R;
public class SwipeBackLayout extends FrameLayout {
private static final String TAG = SwipeBackLayout.class.getSimpleName();
//放置Activity的View
private View mContentView;
//側滑最小距離
private int mTouchSlop;
//按下的位置
private int downX;
private int downY;
//目前的位置
private int tempX;
private Scroller mScroller;
private int viewWidth;
//判斷是否為滑動
private boolean isSilding;
//是否完成
private boolean isFinish;
//側滑的陰影效果
private Drawable mShadowDrawable;
private Activity mActivity;
private List<ViewPager> mViewPagers = new LinkedList<ViewPager>();
public SwipeBackLayout(Context context, AttributeSet attrs) {
this(context, attrs, );
}
public SwipeBackLayout(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
//得到最小的距離
mTouchSlop = ViewConfiguration.get(context).getScaledTouchSlop();
//初始化滑動對象
mScroller = new Scroller(context);
//初始化陰影資源
mShadowDrawable = getResources().getDrawable(R.drawable.shadow_left);
}
//對外部提供的接口
public void attachToActivity(Activity activity) {
mActivity = activity;
TypedArray a = activity.getTheme().obtainStyledAttributes(
new int[]{android.R.attr.windowBackground});
int background = a.getResourceId(, );
a.recycle();
//從外界傳入的activity頁面的底層容器,setContentView設定的View的父容 器 父容器一般都是ViewGroup
ViewGroup decor = (ViewGroup) activity.getWindow().getDecorView();
//得到setContentView設定的View
ViewGroup decorChild = (ViewGroup) decor.getChildAt();
//設定它的背景色
decorChild.setBackgroundResource(background);
//移除到之前父容器中的布局view
decor.removeView(decorChild);
//為目前頁面父容器添加設定過背景色後的子view
addView(decorChild);
setContentView(decorChild);
decor.addView(this);
}
//得到從外部傳入的activity的布局容器
private void setContentView(View decorChild) {
mContentView = (View) decorChild.getParent();
}
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
ViewPager mViewPager = getTouchViewPager(mViewPagers, ev);
Log.i(TAG, "mViewPager = " + mViewPager);
//判斷是否攔截此次事件
if (mViewPager != null && mViewPager.getCurrentItem() != ) {
return super.onInterceptTouchEvent(ev);
}
switch (ev.getAction()) {
//當隻是按下去是,既非滑動事件,不對此事件做處理
case MotionEvent.ACTION_DOWN:
downX = tempX = (int) ev.getRawX();
downY = (int) ev.getRawY();
break;
//當移動時攔截次事件 調用onTouchEvent
case MotionEvent.ACTION_MOVE:
int moveX = (int) ev.getRawX();
//如果滑動的位置到我按下的位置之間的距離大于系統預設的最小距離 視為一次滑動
if (moveX - downX > mTouchSlop
&& Math.abs((int) ev.getRawY() - downY) < mTouchSlop) {
return true;
}
break;
}
return super.onInterceptTouchEvent(ev);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_MOVE:
//點選事件發生的位置
int moveX = (int) event.getRawX();
//滑動的距離,tempX目前的位置,在攔截事件裡進行了初始化,第一次是你按下的位置
int deltaX = tempX - moveX;
//目前位置就是view滑動後的位置
tempX = moveX;
//如果滑動後的位置到按下的位置 大于預設滑動距離 視為一次滑動
if (moveX - downX > mTouchSlop && Math.abs((int) event.getRawY() - downY) < mTouchSlop) {
isSilding = true;
}
//如果是一次滑動的話,就讓整個容器滑動
if (moveX - downX >= && isSilding) {
mContentView.scrollBy(deltaX, );
}
break;
case MotionEvent.ACTION_UP:
isSilding = false;
//向右滑動,值是負的 是以是小于等于整個view的寬的1/2時 代表完成了一次滑動 觸發事件
if (mContentView.getScrollX() <= -viewWidth / ) {
isFinish = true;
scrollRight();
} else {
scrollOrigin();
isFinish = false;
}
break;
}
return true;
}
private void getAlLViewPager(List<ViewPager> mViewPagers, ViewGroup parent) {
int childCount = parent.getChildCount();
for (int i = ; i < childCount; i++) {
View child = parent.getChildAt(i);
if (child instanceof ViewPager) {
mViewPagers.add((ViewPager) child);
} else if (child instanceof ViewGroup) {
getAlLViewPager(mViewPagers, (ViewGroup) child);
}
}
}
private ViewPager getTouchViewPager(List<ViewPager> mViewPagers, MotionEvent ev) {
if (mViewPagers == null || mViewPagers.size() == ) {
return null;
}
Rect mRect = new Rect();
for (ViewPager v : mViewPagers) {
v.getHitRect(mRect);
if (mRect.contains((int) ev.getX(), (int) ev.getY())) {
return v;
}
}
return null;
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
super.onLayout(changed, l, t, r, b);
if (changed) {
viewWidth = this.getWidth();
getAlLViewPager(mViewPagers, this);
Log.i(TAG, "ViewPager size = " + mViewPagers.size());
}
}
@Override
protected void dispatchDraw(Canvas canvas) {
super.dispatchDraw(canvas);
if (mShadowDrawable != null && mContentView != null) {
int left = mContentView.getLeft()
- mShadowDrawable.getIntrinsicWidth();
int right = left + mShadowDrawable.getIntrinsicWidth();
int top = mContentView.getTop();
int bottom = mContentView.getBottom();
mShadowDrawable.setBounds(left, top, right, bottom);
mShadowDrawable.draw(canvas);
}
}
//當滑動布局超過1/2擡手時,使用者擡手,但使用者認為這樣算是完成了操作,接下來隐藏另一部分contentView的工作由系統完成
private void scrollRight() {
//計算出剩餘的寬度 向右換滑動mContentView.getScrollX()負值
final int delta = (viewWidth + mContentView.getScrollX());
//參數,起止X,起止Y,目标X,目标Y,持續時間
//同時會調用computeScoller共同完成滑動 mScroller.startScroll(mContentView.getScrollX(), 0, -delta + 1, 0,
Math.abs(delta));
postInvalidate();
}
private void scrollOrigin() {
int delta = mContentView.getScrollX();
mScroller.startScroll(mContentView.getScrollX(), , -delta, ,
Math.abs(delta));
postInvalidate();
}
@Override
public void computeScroll() {
if (mScroller.computeScrollOffset()) { mContentView.scrollTo(mScroller.getCurrX(), mScroller.getCurrY());
postInvalidate();
//完成滑動時銷毀頁面
if (mScroller.isFinished() && isFinish) {
mActivity.finish();
}
}
}
}
使用的時候讓Activity繼承SwipeBackActivity 這是一個空實作的Activity
public class SwipeBackActivity extends AppCompatActivity {
protected SwipeBackLayout layout;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
layout = (SwipeBackLayout) LayoutInflater.from(this).inflate(
R.layout.base, null);
layout.attachToActivity(this);
}
@Override
public void startActivity(Intent intent) {
super.startActivity(intent);
overridePendingTransition(R.anim.base_slide_right_in, R.anim.base_slide_remain);
}
// Press the back button in mobile phone
@Override
public void onBackPressed() {
super.onBackPressed();
overridePendingTransition(, R.anim.base_slide_right_out);
//第一動畫代表下一個即将出來的頁的進入動畫效果,第二個代表目前頁的退出動畫效果
// overridePendingTransition(R.anim.base_slide_right_in,R.anim.base_slide_left_out );
}
}
注意:在style中設定activity的容器層的(window層)ViewGroup的背景為透明
<style name="Theme.AppCompat.Translucent" parent="AppTheme">
<item name="android:windowBackground">@android:color/transparent</item>
<item name="android:colorBackgroundCacheHint">@null</item>
<item name="android:windowIsTranslucent">true</item>
<item name="android:windowAnimationStyle">@android:style/Animation</item>
</style>
同時給activity的layout布局View設定背景background.否則會使整個頁面為透明