Java tutorial
/* * (C) Copyright 2011-2013 li.jamling@gmail.com. * * This software is the property of li.jamling@gmail.com. * You have to accept the terms in the license file before use. * */ package cn.ieclipse.af.view; import android.content.Context; import android.content.res.TypedArray; import android.support.v4.view.ViewPager; 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; import cn.ieclipse.af.R; /** * LauncherWorkSapce???? * * @author jamling, Yao.GUET blog: http://blog.csdn.net/Yao_GUET date: * 2011-05-04 * */ public class ScrollLayout extends ViewGroup { private static final String TAG = "CScrollLayout"; private static final int TOUCH_STATE_REST = 0; private static final int TOUCH_STATE_SCROLLING = 1; private static final int SNAP_VELOCITY = 600; private boolean debug = false; private Scroller mScroller; private VelocityTracker mVelocityTracker; private int mCurScreen; private int mDefaultScreen = 0; private int mSnapVelocity; private int mTouchState = TOUCH_STATE_REST; private int mTouchSlop; private float mLastMotionX; private float mLastMotionY; private OnScreenChangeListener mScreenChangeListener; private ViewPager mViewPager; public void setOnScreenChangeListener(OnScreenChangeListener listener) { this.mScreenChangeListener = listener; } public void setViewPager(ViewPager viewPager) { this.mViewPager = viewPager; } public ScrollLayout(Context context, AttributeSet attrs) { this(context, attrs, 0); } public ScrollLayout(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); mCurScreen = mDefaultScreen; mScroller = new Scroller(context); mTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop(); init(context, attrs); } private void init(Context context, AttributeSet attrs) { if (attrs != null) { TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.ScrollLayout); debug = a.getBoolean(R.styleable.ScrollLayout_debug, false); mSnapVelocity = a.getInt(R.styleable.ScrollLayout_snapVelocity, SNAP_VELOCITY); a.recycle(); } } private void disableWipe(boolean disableWipe) { if (mViewPager != null) { if (mViewPager instanceof ViewPagerV4) { ((ViewPagerV4) mViewPager).setDisableWipe(disableWipe); } else { mViewPager.requestDisallowInterceptTouchEvent(disableWipe); } } } @Override protected void onLayout(boolean changed, int l, int t, int r, int b) { if (debug) { Log.v(TAG, String.format("onLayout changed=%b,l=%d,t=%d,r=%d,b=%d", changed, l, t, r, 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) { if (debug) { Log.v(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 if (mScreenChangeListener != null) { int count = getChildCount(); mScreenChangeListener.onScreenChange(mCurScreen, mCurScreen < count - 1, mCurScreen > 0); } } } public void setToScreen(int whichScreen) { whichScreen = Math.max(0, Math.min(whichScreen, getChildCount() - 1)); mCurScreen = whichScreen; scrollTo(whichScreen * getWidth(), 0); if (mScreenChangeListener != null) { int count = getChildCount(); mScreenChangeListener.onScreenChange(mCurScreen, mCurScreen < count - 1, mCurScreen > 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: if (debug) { Log.v(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: if (debug) { Log.v(TAG, "event : up"); } // if (mTouchState == TOUCH_STATE_SCROLLING) { final VelocityTracker velocityTracker = mVelocityTracker; velocityTracker.computeCurrentVelocity(1000); int velocityX = (int) velocityTracker.getXVelocity(); if (debug) { Log.v(TAG, "velocityX:" + velocityX); } if (velocityX > mSnapVelocity) { if (mCurScreen > 0) { // Fling enough to move left if (debug) { Log.v(TAG, "snap left"); } snapToScreen(mCurScreen - 1); } else { // TODO disableWipe(false); snapToDestination(); } } else if (velocityX < -mSnapVelocity) { if (mCurScreen < getChildCount() - 1) { // Fling enough to move right if (debug) { Log.v(TAG, "snap right"); } snapToScreen(mCurScreen + 1); } else { // TODO disableWipe(false); snapToDestination(); } } 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) { if (debug) { Log.e(TAG, "onInterceptTouchEvent-slop:" + mTouchSlop); } final int action = ev.getAction(); if ((action == MotionEvent.ACTION_MOVE) && (mTouchState != TOUCH_STATE_REST)) { 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); if (xDiff > mTouchSlop) { mTouchState = TOUCH_STATE_SCROLLING; } break; case MotionEvent.ACTION_DOWN: mLastMotionX = x; mLastMotionY = y; mTouchState = mScroller.isFinished() ? TOUCH_STATE_REST : TOUCH_STATE_SCROLLING; break; case MotionEvent.ACTION_CANCEL: case MotionEvent.ACTION_UP: mTouchState = TOUCH_STATE_REST; break; } return mTouchState != TOUCH_STATE_REST; } public static interface OnScreenChangeListener { void onScreenChange(int screen, boolean hasNext, boolean hasPreview); } }