android滑屏效果

① android Launcher的滑动效果怎么实现

滑动功能主要分两步：
1、在onInterceptTouchEvent中进行拦截。
2、在onTouchEvent中进行滑动。

1,onInterceptTouchEvent(MotionEvent en)
在这个方法中，决定了什么时候截获MotionEvent来实现滑动，避免了子View的其他事件的影响（如点击事件）。
[java] view plain
public boolean onInterceptTouchEvent(MotionEvent ev) {
/**
* This method JUST determines whether we want to intercept the motion.
* If we return true, onTouchEvent will be called and we do the actual
* scrolling there.
**/

//获取速度跟踪器，记录各个时刻的速度。并且添加当前的MotionEvent以记录更行速度值。
(ev);
......
/**
* Shortcut the most recurring case: the user is in the dragging
* state and he is moving his finger. We want to intercept this
* motion.
* 最常见的需要拦截的情况：用户已经进入滑动状态，并且正在滑动手指。
* 对这种情况直接进行拦截，执行onTouchEvent()继续执行滑动操作。
**/
final int action = ev.getAction();
if ((action == MotionEvent.ACTION_MOVE) &&
(mTouchState == TOUCH_STATE_SCROLLING)) {
return true;
}

switch (action & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_MOVE: {

/**
* mIsBeingDragged == false, otherwise the shortcut would have caught it. Check
* whether the user has moved far enough from his original down touch.
*/
/**
* 当在这里接受到ACTION_MOVE时，说明mTouchState!=TOUCH_STATE_SCROLLING并且mIsBeingDragged的值应该为false，
* 否则DragLayer就应该截获了MotionEvent用于实现拖拽。
* 此时还没有进入滑动状态，当mActivePointerId == INVALID_POINTER时，也就是在此之前没有接收到任何touch事件。
* 这种情况发生在Workspace变小时，也就是之前Workspace处于SPRING_LOADED状态。当出现这种情况时直接把当前的事件当作ACTION_DOWN进行处理。
* 反之，则通过determineScrollingStart()尝试能够进入滑动状态。
*/
if (mActivePointerId != INVALID_POINTER) {
determineScrollingStart(ev);
break;
}
// if mActivePointerId is INVALID_POINTER, then we must have missed an ACTION_DOWN
// event. in that case, treat the first occurence of a move event as a ACTION_DOWN
// i.e. fall through to the next case (don't break)
// (We sometimes miss ACTION_DOWN events in Workspace because it ignores all events
// while it's small- this was causing a crash before we checked for INVALID_POINTER)
}

case MotionEvent.ACTION_DOWN: {
final float x = ev.getX();
final float y = ev.getY();
// Remember location of down touch
//记录按下的x的坐标值
mDownMotionX = x;
//记录前次发生touch时的坐标
mLastMotionX = x;
mLastMotionY = y;
//因为在ScrollBy时只能使用int，而记录的x和y都是float，会产生误差，故这里用mLastMotionXRemainder记录余数
//用于消除误差
mLastMotionXRemainder = 0;
//x方向上的总位移
mTotalMotionX = 0;
mActivePointerId = ev.getPointerId(0);

//设置mAllowLongPress=true，允许LongClick事件发生。LongClick事件定义在Launcher中
//处理的内容包括启动对shortcut的拖拽或弹出壁纸选择的对话框，若mAllowLongPress=false，
//则不会响应以上事件。
mAllowLongPress = true;

/**
* If being flinged and user touches the screen, initiate drag;
* otherwise don't. mScroller.isFinished should be false when
* being flinged.
* 当屏幕处于flinged状态（快速滑动）时，若此时用户触摸了屏幕，需要使滑动停止。
* 并且初始化拖拽的条件
**/
final int xDist = Math.abs(mScroller.getFinalX() - mScroller.getCurrX());
final boolean finishedScrolling = (mScroller.isFinished() || xDist < mTouchSlop);
if (finishedScrolling) {
mTouchState = TOUCH_STATE_REST;
mScroller.abortAnimation();
} else {
mTouchState = TOUCH_STATE_SCROLLING;
}

// check if this can be the beginning of a tap on the side of the pages
// to scroll the current page
if (mTouchState != TOUCH_STATE_PREV_PAGE && mTouchState != TOUCH_STATE_NEXT_PAGE) {
if (getChildCount() > 0) {
if (hitsPreviousPage(x, y)) {
mTouchState = TOUCH_STATE_PREV_PAGE;
} else if (hitsNextPage(x, y)) {
mTouchState = TOUCH_STATE_NEXT_PAGE;
}
}
}
break;
}

case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_CANCEL:
mTouchState = TOUCH_STATE_REST;
mAllowLongPress = false;
mActivePointerId = INVALID_POINTER;
releaseVelocityTracker();
break;
case MotionEvent.ACTION_POINTER_UP:
onSecondaryPointerUp(ev);
releaseVelocityTracker();
break;
}

/**
* The only time we want to intercept motion events is if we are in the
* drag mode.
* 只有进入了滑动状态，才进行拦截，进入onTouchEvent执行滑动操作。当mTouchState != TOUCH_STATE_REST
* 时，就说明没有进入滑动状态。
**/
return mTouchState != TOUCH_STATE_REST;
}

2,onTouchEvent(MotionEvent en)

在这个方法中，执行各种关于滑动的工作的计算，界面的刷新等工作。
[java] view plain
public boolean onTouchEvent(MotionEvent ev) {
......
switch (action & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN:
/*
* If being flinged and user touches, stop the fling. isFinished
* will be false if being flinged.
*/
/**
* 如果Workspace此时已经被“掷出去”（靠惯性滑动）。
* 此时发生ACTION_DOWN则需要停止滑动。
*/
if (!mScroller.isFinished()) {
mScroller.abortAnimation();
}

// Remember where the motion event started
mDownMotionX = mLastMotionX = ev.getX();
mLastMotionXRemainder = 0;
mTotalMotionX = 0;
mActivePointerId = ev.getPointerId(0);
if (mTouchState == TOUCH_STATE_SCROLLING) {
pageBeginMoving();
}
break;

case MotionEvent.ACTION_MOVE:
if (mTouchState == TOUCH_STATE_SCROLLING) {
......
if (Math.abs(deltaX) >= 1.0f) {
......
if (!mDeferScrollUpdate) {
//调用scrollBy滑动桌面
scrollBy((int) deltaX, 0);
......
} else {
......
}
mLastMotionX = x;
mLastMotionXRemainder = deltaX - (int) deltaX;
} else {
awakenScrollBars();
}
} else {
/**
* 如果条件满足，则进入滑动状态，开始滑动。
*/
determineScrollingStart(ev);
}
break;
case MotionEvent.ACTION_UP:
if (mTouchState == TOUCH_STATE_SCROLLING) {
......
boolean isSignificantMove = Math.abs(deltaX) > MIN_LENGTH_FOR_MOVE;

boolean returnToOriginalPage = false;
final int pageWidth = getScaledMeasuredWidth(getPageAt(mCurrentPage));
if (Math.abs(deltaX) > pageWidth * RETURN_TO_ORIGINAL_PAGE_THRESHOLD &&
Math.signum(velocityX) != Math.signum(deltaX)) {
returnToOriginalPage = true;
}

boolean isFling = mTotalMotionX > MIN_LENGTH_FOR_FLING &&
Math.abs(velocityX) > snapVelocity;
int finalPage;

//判断拿起手指之后应该进入哪个分屏
if (((isSignificantMove && deltaX > 0 && !isFling) ||
(isFling && velocityX > 0)) && mCurrentPage > 0) {
finalPage = returnToOriginalPage ? mCurrentPage : mCurrentPage - 1;
snapToPageWithVelocity(finalPage, velocityX);
} else if (((isSignificantMove && deltaX < 0 && !isFling) ||
(isFling && velocityX < 0)) &&
mCurrentPage < getChildCount() - 1) {
finalPage = returnToOriginalPage ? mCurrentPage : mCurrentPage + 1;
snapToPageWithVelocity(finalPage, velocityX);
} else {
snapToDestination();
}
} else if (mTouchState == TOUCH_STATE_PREV_PAGE) {
//直接进入前一屏
int nextPage = Math.max(0, mCurrentPage - 1);
if (nextPage != mCurrentPage) {
snapToPage(nextPage);
} else {
snapToDestination();
}
} else if (mTouchState == TOUCH_STATE_NEXT_PAGE) {
//直接进入后一屏
int nextPage = Math.min(getChildCount() - 1, mCurrentPage + 1);
if (nextPage != mCurrentPage) {
snapToPage(nextPage);
} else {
snapToDestination();
}
} else {
onUnhandledTap(ev);
}
mTouchState = TOUCH_STATE_REST;
mActivePointerId = INVALID_POINTER;
releaseVelocityTracker();
break;

case MotionEvent.ACTION_CANCEL:
if (mTouchState == TOUCH_STATE_SCROLLING) {
snapToDestination();
}
mTouchState = TOUCH_STATE_REST;
mActivePointerId = INVALID_POINTER;
releaseVelocityTracker();
break;
case MotionEvent.ACTION_POINTER_UP:
onSecondaryPointerUp(ev);
break;
}
return true;
}

② android怎么实现滑动效果

工具/原料
ViewFlipper类和OnGestureListener接口
animation动画效果translate和alpha
方法/步骤

1、设置布局文件，其中使用到ViewFlipper控件，内容如下：
<?xml version="1.0" encoding="utf-8"?>
<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"
android:background="@drawable/background"
android:paddingBottom="@dimen/activity_optopns_vertical_margin"
android:paddingLeft="@dimen/activity_options_horizontal_margin"
android:paddingRight="@dimen/activity_options_horizontal_margin"
android:paddingTop="@dimen/activity_optopns_vertical_margin"
tools:context=".ImageFlipperActivity" >
<RelativeLayout
android:id="@id/rl_image_flipper_title"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal" >
<Button
android:id="@+id/btn_image_flipper_back"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_marginBottom="10dp"
android:background="@drawable/custom_button"
android:text="@string/back"
android:textColor="@color/textColor"
android:textSize="16sp"
android:visibility="visible" />
<TextView
android:id="@id/tv_image_flipper_title"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:text="@string/image_flipper"
android:textColor="@color/textColor"
android:textSize="30sp"
android:textStyle="bold" />
</RelativeLayout>
<LinearLayout
android:id="@id/ll_image_flipper_content"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_below="@id/rl_image_flipper_title"
android:layout_marginBottom="20dp"
android:layout_marginTop="20dp"
android:gravity="center"
android:orientation="vertical" >
<ViewFlipper
android:id="@id/vf_image_flipper"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</LinearLayout>
</RelativeLayout>

2、从左边进入的动画文件，其内容如下：
<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android" >
<!-- translate：画面转换位置移动动画效果 -->
<translate
android:ration="500"
android:fromXDelta="100%p"
android:toXDelta="0" />
<!-- alpha：渐变透明度动画效果 -->
<alpha
android:ration="500"
android:fromAlpha="0.1"
android:toAlpha="1.0" />
</set>

3、从左边退出的动画文件，其内容如下：
<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android" >
<translate
android:ration="500"
android:fromXDelta="0"
android:toXDelta="-100%p" />
<alpha
android:ration="500"
android:fromAlpha="1.0"
android:toAlpha="0.1" />
</set>

4、从右边进入的动画文件，其内容如下：
<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android" >
<translate
android:ration="500"
android:fromXDelta="-100%p"
android:toXDelta="0" />
<alpha
android:ration="500"
android:fromAlpha="0.1"
android:toAlpha="1.0" />
</set>

5、从右边退出的动画文件，其内容如下：
<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android" >
<translate
android:ration="500"
android:fromXDelta="0"
android:toXDelta="100%p" />
<alpha
android:ration="500"
android:fromAlpha="1.0"
android:toAlpha="0.1" />
</set>

6、加载布局文件和动画文件的类，其源码内容为：
/**
*
*/
package com.i114gbox.aglieguy;
import android.content.Context;
import android.os.Bundle;
import android.view.GestureDetector;
import android.view.GestureDetector.OnGestureListener;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.animation.AnimationUtils;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.ViewFlipper;
import com.i114gbox.sdk.activity.I114gBoxActivity;
import com.i114gbox.sdk.utils.I114gBoxCollectActivityUtils;
import com.i114gbox.sdk.utils.I114gBoxLogUtils;
import com.i114gbox.sdk.utils.I114gBoxResourceUtils;
/**
* 图片滑动Activity
*
* @author SJC
*
*/
public class ImageFlipperActivity extends I114gBoxActivity implements
OnGestureListener {
private static String TAG = "ImageFlipperActivity";
private Context ctx = null;
private GestureDetector gestureDetector;// 手势监听
private ViewFlipper viewFlipper;// 视图轮播
@Override
protected void onCreate(Bundle savedInstanceState) {
I114gBoxLogUtils.d(TAG, "The onCreate method execute.");
super.onCreate(savedInstanceState);
I114gBoxCollectActivityUtils.getInstance().addActivity(this);// 收集Activity
ctx = this;
setContentView(I114gBoxResourceUtils.getLayoutId(ctx,
"activity_image_flipper"));
gestureDetector = new GestureDetector(this);
viewFlipper = (ViewFlipper) findViewById(I114gBoxResourceUtils.getId(
ctx, "vf_image_flipper"));
viewFlipper.addView(addImageView(I114gBoxResourceUtils.getDrawableId(
ctx, "flipper_01")));
viewFlipper.addView(addImageView(I114gBoxResourceUtils.getDrawableId(
ctx, "flipper_02")));
viewFlipper.addView(addImageView(I114gBoxResourceUtils.getDrawableId(
ctx, "flipper_03")));
viewFlipper.addView(addImageView(I114gBoxResourceUtils.getDrawableId(
ctx, "flipper_04")));
viewFlipper.addView(addImageView(I114gBoxResourceUtils.getDrawableId(
ctx, "flipper_05")));
viewFlipper.addView(addImageView(I114gBoxResourceUtils.getDrawableId(
ctx, "flipper_06")));
// viewFlipper.addView(addImageView(R.drawable.one));
// viewFlipper.addView(addImageView(R.drawable.two));
// viewFlipper.addView(addImageView(R.drawable.three));
// viewFlipper.addView(addImageView(R.drawable.four));
// viewFlipper.addView(addImageView(R.drawable.five));
Button backButton = (Button) findViewById(I114gBoxResourceUtils.getId(
ctx, "btn_image_flipper_back"));
backButton.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
finish();
}
});
}
/** 添加ImageView控件 **/
private View addImageView(int id) {
ImageView imageView = new ImageView(this);
imageView.setImageResource(id);
return imageView;
}
@Override
public boolean onTouchEvent(MotionEvent event) {
I114gBoxLogUtils.d(TAG, "The onTouchEvent method execute.");
return gestureDetector.onTouchEvent(event);
}
@Override
public boolean onDown(MotionEvent e) {
I114gBoxLogUtils.d(TAG, "The onDown method execute.");
return false;
}
@Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
float velocityY) {
I114gBoxLogUtils.d(TAG, "The onFling method execute.");
I114gBoxLogUtils.i(TAG, "e1.x:" + e1.getX() + "|" + "e2.x:" + e2.getX()
+ "|" + "velocityX:" + velocityX + "|" + "velocityY:"
+ velocityY);
if (e1.getX() - e2.getX() > 120) {
this.viewFlipper.setInAnimation(AnimationUtils.loadAnimation(ctx,
R.anim.push_left_in));// 进入屏幕的动画
this.viewFlipper.setOutAnimation(AnimationUtils.loadAnimation(ctx,
R.anim.push_left_out));// 离开屏幕的动画
this.viewFlipper.showNext();// 手动显示下一个视图
return true;
} else if (e1.getX() - e2.getX() < -120) {
this.viewFlipper.setInAnimation(AnimationUtils.loadAnimation(ctx,
R.anim.push_right_in));
this.viewFlipper.setOutAnimation(AnimationUtils.loadAnimation(ctx,
R.anim.push_right_out));
this.viewFlipper.showPrevious();// 手动显示前一个视图
return true;
}
return false;
}
@Override
public void onLongPress(MotionEvent e) {
I114gBoxLogUtils.d(TAG, "The onLongPress method execute.");
}
@Override
public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX,
float distanceY) {
I114gBoxLogUtils.d(TAG, "The onScroll method execute.");
I114gBoxLogUtils.i(TAG, "e1.X:" + e1.getX() + "|" + "e2.X:" + e2.getX()
+ "|" + "distanceX:" + distanceX + "|" + "distanceY:"
+ distanceY);
return false;
}
@Override
public void onShowPress(MotionEvent e) {
I114gBoxLogUtils.d(TAG, "The onShowPress method execute.");
}
@Override
public boolean onSingleTapUp(MotionEvent e) {
I114gBoxLogUtils.d(TAG, "The onSingleTapUp method execute.");
return false;
}
}

③ android平台中页面切换时如果要用触摸屏左右滑动，怎么实现

左右滑动切换是通过viewPager来实现的，完整代码查看附件。

ViewPager的数据是通过PageAdapter来装载的：

1.调用adapter.notifyDataSetChanged(); 刷新控件，但是要覆盖PagerAdapter的getItemPosition方法，并返回return POSITION_NONE;

2.利用PagerAdapter的工作机制,就是PagerAdapter的执行顺序,PagerAdapter作为ViewPager的适配器，无论ViewPager有多少页，PagerAdapter在初始化时也只初始化开始的2个View，即调用2次instantiateItem方法。而接下来每当ViewPager滑动时，PagerAdapter都会调用destroyItem方法将距离该页2个步幅以上的那个View销毁，以此保证PagerAdapter最多只管辖3个View，且当前View是3个中的中间一个，如果当前View缺少两边的View，那么就instantiateItem，如里有超过2个步幅的就destroyItem。

3.每当Adapter调用instantiateItem时，运用View.setTag方法将该View标识。当需要更新这个View的数据时，通过调用ViewPager.findViewWithTag方法找到相应的View，然后更新View中的数据。