android滑屏效果

① android Launcher的滑動效果怎麼實現

滑動功能主要分兩步：
1、在onInterceptTouchEvent中進行攔截。
2、在onTouchEvent中進行滑動。

1,onInterceptTouchEvent(MotionEvent en)
在這個方法中，決定了什麼時候截獲MotionEvent來實現滑動，避免了子View的其他事件的影響（如點擊事件）。
[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.
**/

//獲取速度跟蹤器，記錄各個時刻的速度。並且添加當前的MotionEvent以記錄更行速度值。
(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.
* 最常見的需要攔截的情況：用戶已經進入滑動狀態，並且正在滑動手指。
* 對這種情況直接進行攔截，執行onTouchEvent()繼續執行滑動操作。
**/
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.
*/
/**
* 當在這里接受到ACTION_MOVE時，說明mTouchState!=TOUCH_STATE_SCROLLING並且mIsBeingDragged的值應該為false，
* 否則DragLayer就應該截獲了MotionEvent用於實現拖拽。
* 此時還沒有進入滑動狀態，當mActivePointerId == INVALID_POINTER時，也就是在此之前沒有接收到任何touch事件。
* 這種情況發生在Workspace變小時，也就是之前Workspace處於SPRING_LOADED狀態。當出現這種情況時直接把當前的事件當作ACTION_DOWN進行處理。
* 反之，則通過determineScrollingStart()嘗試能夠進入滑動狀態。
*/
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
//記錄按下的x的坐標值
mDownMotionX = x;
//記錄前次發生touch時的坐標
mLastMotionX = x;
mLastMotionY = y;
//因為在ScrollBy時只能使用int，而記錄的x和y都是float，會產生誤差，故這里用mLastMotionXRemainder記錄余數
//用於消除誤差
mLastMotionXRemainder = 0;
//x方向上的總位移
mTotalMotionX = 0;
mActivePointerId = ev.getPointerId(0);

//設置mAllowLongPress=true，允許LongClick事件發生。LongClick事件定義在Launcher中
//處理的內容包括啟動對shortcut的拖拽或彈出壁紙選擇的對話框，若mAllowLongPress=false，
//則不會響應以上事件。
mAllowLongPress = true;

/**
* If being flinged and user touches the screen, initiate drag;
* otherwise don't. mScroller.isFinished should be false when
* being flinged.
* 當屏幕處於flinged狀態（快速滑動）時，若此時用戶觸摸了屏幕，需要使滑動停止。
* 並且初始化拖拽的條件
**/
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.
* 只有進入了滑動狀態，才進行攔截，進入onTouchEvent執行滑動操作。當mTouchState != TOUCH_STATE_REST
* 時，就說明沒有進入滑動狀態。
**/
return mTouchState != TOUCH_STATE_REST;
}

2,onTouchEvent(MotionEvent en)

在這個方法中，執行各種關於滑動的工作的計算，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此時已經被「擲出去」（靠慣性滑動）。
* 此時發生ACTION_DOWN則需要停止滑動。
*/
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) {
//調用scrollBy滑動桌面
scrollBy((int) deltaX, 0);
......
} else {
......
}
mLastMotionX = x;
mLastMotionXRemainder = deltaX - (int) deltaX;
} else {
awakenScrollBars();
}
} else {
/**
* 如果條件滿足，則進入滑動狀態，開始滑動。
*/
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;

//判斷拿起手指之後應該進入哪個分屏
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) {
//直接進入前一屏
int nextPage = Math.max(0, mCurrentPage - 1);
if (nextPage != mCurrentPage) {
snapToPage(nextPage);
} else {
snapToDestination();
}
} else if (mTouchState == TOUCH_STATE_NEXT_PAGE) {
//直接進入後一屏
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怎麼實現滑動效果

工具/原料
ViewFlipper類和OnGestureListener介面
animation動畫效果translate和alpha
方法/步驟

1、設置布局文件，其中使用到ViewFlipper控制項，內容如下：
<?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、從左邊進入的動畫文件，其內容如下：
<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android" >
<!-- translate：畫面轉換位置移動動畫效果 -->
<translate
android:ration="500"
android:fromXDelta="100%p"
android:toXDelta="0" />
<!-- alpha：漸變透明度動畫效果 -->
<alpha
android:ration="500"
android:fromAlpha="0.1"
android:toAlpha="1.0" />
</set>

3、從左邊退出的動畫文件，其內容如下：
<?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、從右邊進入的動畫文件，其內容如下：
<?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、從右邊退出的動畫文件，其內容如下：
<?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、載入布局文件和動畫文件的類，其源碼內容為：
/**
*
*/
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;
/**
* 圖片滑動Activity
*
* @author SJC
*
*/
public class ImageFlipperActivity extends I114gBoxActivity implements
OnGestureListener {
private static String TAG = "ImageFlipperActivity";
private Context ctx = null;
private GestureDetector gestureDetector;// 手勢監聽
private ViewFlipper viewFlipper;// 視圖輪播
@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控制項 **/
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));// 進入屏幕的動畫
this.viewFlipper.setOutAnimation(AnimationUtils.loadAnimation(ctx,
R.anim.push_left_out));// 離開屏幕的動畫
this.viewFlipper.showNext();// 手動顯示下一個視圖
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();// 手動顯示前一個視圖
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平台中頁面切換時如果要用觸摸屏左右滑動，怎麼實現

左右滑動切換是通過viewPager來實現的，完整代碼查看附件。

ViewPager的數據是通過PageAdapter來裝載的：

1.調用adapter.notifyDataSetChanged(); 刷新控制項，但是要覆蓋PagerAdapter的getItemPosition方法，並返回return POSITION_NONE;

2.利用PagerAdapter的工作機制,就是PagerAdapter的執行順序,PagerAdapter作為ViewPager的適配器，無論ViewPager有多少頁，PagerAdapter在初始化時也只初始化開始的2個View，即調用2次instantiateItem方法。而接下來每當ViewPager滑動時，PagerAdapter都會調用destroyItem方法將距離該頁2個步幅以上的那個View銷毀，以此保證PagerAdapter最多隻管轄3個View，且當前View是3個中的中間一個，如果當前View缺少兩邊的View，那麼就instantiateItem，如里有超過2個步幅的就destroyItem。

3.每當Adapter調用instantiateItem時，運用View.setTag方法將該View標識。當需要更新這個View的數據時，通過調用ViewPager.findViewWithTag方法找到相應的View，然後更新View中的數據。