运行效果:
main.xml
<?xml version="1.0" encoding="utf-8"?><com.cn.ScrollLayout xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/ScrollLayoutTest" android:layout_width="fill_parent" android:layout_height="fill_parent"> <LinearLayout android:background="#FF00" android:layout_width="fill_parent" android:layout_height="fill_parent"></LinearLayout> <FrameLayout android:background="#F00F" android:layout_width="fill_parent" android:layout_height="fill_parent"> </FrameLayout> <LinearLayout android:layout_width="wrap_content" android:layout_height="wrap_content"> <Button android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Button2" /> </LinearLayout></com.cn.ScrollLayout>
MainActivity.java
package com.cn;import android.app.Activity;import android.os.Bundle;/** * * <p> * Title: MainActivity.java * </p> * <p> * E-Mail: [email protected] * </p> * <p> * QQ: 176291935 * </p> * <p> * Http: iaiai.iteye.com * </p> * <p> * Create time: 2011-10-13 * </p> * * @author 丸子 * @version 0.0.1 */public class MainActivity extends Activity { /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); }}
ScrollLayout.java
package com.cn;import android.content.Context;import android.util.AttributeSet;import android.util.Log;import android.view.MotionEvent;import android.view.VelocityTracker;import android.view.View;import android.view.ViewConfiguration;import android.view.ViewGroup;import android.widget.Scroller;/** * * <p> * Title: ScrollLayout.java * </p> * <p> * E-Mail: [email protected] * </p> * <p> * QQ: 176291935 * </p> * <p> * Http: iaiai.iteye.com * </p> * <p> * Create time: 2011-10-13 * </p> * * @author 丸子 * @version 0.0.1 */public class ScrollLayout extends ViewGroup { private static final String TAG = "ScrollLayout"; private Scroller mScroller; private VelocityTracker mVelocityTracker; private int mCurScreen; private int mDefaultScreen = 0; private static final int TOUCH_STATE_REST = 0; private static final int TOUCH_STATE_SCROLLING = 1; private static final int SNAP_VELOCITY = 600; private int mTouchState = TOUCH_STATE_REST; private int mTouchSlop; private float mLastMotionX; private float mLastMotionY; public ScrollLayout(Context context, AttributeSet attrs) { this(context, attrs, 0); } public ScrollLayout(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); mScroller = new Scroller(context); mCurScreen = mDefaultScreen; mTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop(); } @Override protected void onLayout(boolean changed, int l, int t, int r, int b) { if (changed) { int childLeft = 0; final int childCount = getChildCount(); for (int i = 0; i < childCount; i++) { final View childView = getChildAt(i); if (childView.getVisibility() != View.GONE) { final int childWidth = childView.getMeasuredWidth(); childView.layout(childLeft, 0, childLeft + childWidth, childView.getMeasuredHeight()); childLeft += childWidth; } } } } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { Log.e(TAG, "onMeasure"); super.onMeasure(widthMeasureSpec, heightMeasureSpec); final int width = MeasureSpec.getSize(widthMeasureSpec); final int widthMode = MeasureSpec.getMode(widthMeasureSpec); if (widthMode != MeasureSpec.EXACTLY) { throw new IllegalStateException( "ScrollLayout only canmCurScreen run at EXACTLY mode!"); } final int heightMode = MeasureSpec.getMode(heightMeasureSpec); if (heightMode != MeasureSpec.EXACTLY) { throw new IllegalStateException( "ScrollLayout only can run at EXACTLY mode!"); } // The children are given the same width and height as the scrollLayout final int count = getChildCount(); for (int i = 0; i < count; i++) { getChildAt(i).measure(widthMeasureSpec, heightMeasureSpec); } // Log.e(TAG, "moving to screen "+mCurScreen); scrollTo(mCurScreen * width, 0); } /** * * According to the position of current layout * * scroll to the destination page. */ public void snapToDestination() { final int screenWidth = getWidth(); final int destScreen = (getScrollX() + screenWidth / 2) / screenWidth; snapToScreen(destScreen); } public void snapToScreen(int whichScreen) { // get the valid layout page whichScreen = Math.max(0, Math.min(whichScreen, getChildCount() - 1)); if (getScrollX() != (whichScreen * getWidth())) { final int delta = whichScreen * getWidth() - getScrollX(); mScroller.startScroll(getScrollX(), 0, delta, 0, Math.abs(delta) * 2); mCurScreen = whichScreen; invalidate(); // Redraw the layout } } public void setToScreen(int whichScreen) { whichScreen = Math.max(0, Math.min(whichScreen, getChildCount() - 1)); mCurScreen = whichScreen; scrollTo(whichScreen * getWidth(), 0); } public int getCurScreen() { return mCurScreen; } @Override public void computeScroll() { if (mScroller.computeScrollOffset()) { scrollTo(mScroller.getCurrX(), mScroller.getCurrY()); postInvalidate(); } } @Override public boolean onTouchEvent(MotionEvent event) { if (mVelocityTracker == null) { mVelocityTracker = VelocityTracker.obtain(); } mVelocityTracker.addMovement(event); final int action = event.getAction(); final float x = event.getX(); final float y = event.getY(); switch (action) { case MotionEvent.ACTION_DOWN: Log.e(TAG, "event down!"); if (!mScroller.isFinished()) { mScroller.abortAnimation(); } mLastMotionX = x; break; case MotionEvent.ACTION_MOVE: int deltaX = (int) (mLastMotionX - x); mLastMotionX = x; scrollBy(deltaX, 0); break; case MotionEvent.ACTION_UP: Log.e(TAG, "event : up"); // if (mTouchState == TOUCH_STATE_SCROLLING) { final VelocityTracker velocityTracker = mVelocityTracker; velocityTracker.computeCurrentVelocity(1000); int velocityX = (int) velocityTracker.getXVelocity(); Log.e(TAG, "velocityX:" + velocityX); if (velocityX > SNAP_VELOCITY && mCurScreen > 0) { // Fling enough to move left Log.e(TAG, "snap left"); snapToScreen(mCurScreen - 1); } else if (velocityX < -SNAP_VELOCITY && mCurScreen < getChildCount() - 1) { // Fling enough to move right Log.e(TAG, "snap right"); snapToScreen(mCurScreen + 1); } else { snapToDestination(); } // if (velocityX > SNAP_VELOCITY && mCurScreen > 0) { // // // Fling enough to move left // // Log.e(TAG, "snap left"); // if (mCurScreen > getChildCount() - 1) { // View v1 = getChildAt(0); // View v2 = getChildAt(1); // View v3 = getChildAt(2); // // } // snapToScreen(mCurScreen - 1); // // } else if (velocityX < -SNAP_VELOCITY // // && mCurScreen < getChildCount() - 1) { // // // Fling enough to move right // // Log.e(TAG, "snap right"); // // snapToScreen(mCurScreen + 1); // // } else { // // snapToDestination(); // // } // // if (mVelocityTracker != null) { // // mVelocityTracker.recycle(); // // mVelocityTracker = null; // // } // } mTouchState = TOUCH_STATE_REST; break; case MotionEvent.ACTION_CANCEL: mTouchState = TOUCH_STATE_REST; break; } return true; } @Override public boolean onInterceptTouchEvent(MotionEvent ev) { Log.e(TAG, "onInterceptTouchEvent-slop:" + mTouchSlop + "; action = " + ev.getAction()); final int action = ev.getAction(); if ((action == MotionEvent.ACTION_MOVE) && (mTouchState != TOUCH_STATE_REST)) { Log.e(TAG, "onInterceptTouchEvent-action:" + action); return true; } final float x = ev.getX(); final float y = ev.getY(); switch (action) { case MotionEvent.ACTION_MOVE: final int xDiff = (int) Math.abs(mLastMotionX - x); Log.e(TAG, "onInterceptTouchEvent-move: xDiff = " + xDiff + "; mLastMotionX = " + mLastMotionX); if (xDiff > mTouchSlop) { mTouchState = TOUCH_STATE_SCROLLING; } break; case MotionEvent.ACTION_DOWN: mLastMotionX = x; mLastMotionY = y; Log.e(TAG, "onInterceptTouchEvent-down: x = " + x + "; y = " + y); mTouchState = mScroller.isFinished() ? TOUCH_STATE_REST : TOUCH_STATE_SCROLLING; break; case MotionEvent.ACTION_CANCEL: case MotionEvent.ACTION_UP: Log.e(TAG, "onInterceptTouchEvent-up: mLastMotionX = " + mLastMotionX); mTouchState = TOUCH_STATE_REST; break; } return mTouchState != TOUCH_STATE_REST; }}