屏幕滑动几张图片
import android.content.Context;import android.util.Log;import android.content.res.TypedArray;import android.util.AttributeSet;import android.view.MotionEvent;import android.view.VelocityTracker;import android.view.View;import android.view.ViewGroup;import android.view.ViewConfiguration;import android.widget.Scroller;public class DragableSpace extends ViewGroup { private Scroller mScroller; private VelocityTracker mVelocityTracker; private int mScrollX = 0; private int mCurrentScreen = 0; private float mLastMotionX; private static final String LOG_TAG = "DragableSpace"; private static final int SNAP_VELOCITY = 1000; private final static int TOUCH_STATE_REST = 0; private final static int TOUCH_STATE_SCROLLING = 1; private int mTouchState = TOUCH_STATE_REST; private int mTouchSlop = 0; public DragableSpace(Context context) { super(context); mScroller = new Scroller(context); mTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop(); this.setLayoutParams(new ViewGroup.LayoutParams( ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.FILL_PARENT)); } public DragableSpace(Context context, AttributeSet attrs) { super(context, attrs); mScroller = new Scroller(context); mTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop(); this.setLayoutParams(new ViewGroup.LayoutParams( ViewGroup.LayoutParams.WRAP_CONTENT , ViewGroup.LayoutParams.FILL_PARENT)); TypedArray a=getContext().obtainStyledAttributes(attrs,R.styleable.DragableSpace); mCurrentScreen = a.getInteger(R.styleable.DragableSpace_default_screen, 0); } @Override 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. */ /* * Shortcut the most recurring case: the user is in the dragging state * and he is moving his finger. We want to intercept this motion. */ final int action = ev.getAction(); if ((action == MotionEvent.ACTION_MOVE) && (mTouchState != TOUCH_STATE_REST)) { return true; } final float x = ev.getX(); switch (action) { 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. */ /* * Locally do absolute value. mLastMotionX is set to the y value * of the down event. */ final int xDiff = (int) Math.abs(x - mLastMotionX); boolean xMoved = xDiff > mTouchSlop; if (xMoved) { // Scroll if the user moved far enough along the X axis mTouchState = TOUCH_STATE_SCROLLING; } break; case MotionEvent.ACTION_DOWN: // Remember location of down touch mLastMotionX = x; /* * If being flinged and user touches the screen, initiate drag; * otherwise don't. mScroller.isFinished should be false when * being flinged. */ mTouchState = mScroller.isFinished() ? TOUCH_STATE_REST : TOUCH_STATE_SCROLLING; break; case MotionEvent.ACTION_CANCEL: case MotionEvent.ACTION_UP: // Release the drag mTouchState = TOUCH_STATE_REST; break; } /* * The only time we want to intercept motion events is if we are in the * drag mode. */ return mTouchState != TOUCH_STATE_REST; } @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(); switch (action) { case MotionEvent.ACTION_DOWN: Log.i(LOG_TAG, "event : down"); /* * If being flinged and user touches, stop the fling. isFinished * will be false if being flinged. */ if (!mScroller.isFinished()) { mScroller.abortAnimation(); } // Remember where the motion event started mLastMotionX = x; break; case MotionEvent.ACTION_MOVE: // Log.i(LOG_TAG,"event : move"); // if (mTouchState == TOUCH_STATE_SCROLLING) { // Scroll to follow the motion event final int deltaX = (int) (mLastMotionX - x); mLastMotionX = x; //Log.i(LOG_TAG, "event : move, deltaX " + deltaX + ", mScrollX " + mScrollX); if (deltaX < 0) { if (mScrollX > 0) { scrollBy(Math.max(-mScrollX, deltaX), 0); } } else if (deltaX > 0) { final int availableToScroll = getChildAt(getChildCount() - 1) .getRight() - mScrollX - getWidth(); if (availableToScroll > 0) { scrollBy(Math.min(availableToScroll, deltaX), 0); } } // } break; case MotionEvent.ACTION_UP: Log.i(LOG_TAG, "event : up"); // if (mTouchState == TOUCH_STATE_SCROLLING) { final VelocityTracker velocityTracker = mVelocityTracker; velocityTracker.computeCurrentVelocity(1000); int velocityX = (int) velocityTracker.getXVelocity(); if (velocityX > SNAP_VELOCITY && mCurrentScreen > 0) { // Fling hard enough to move left snapToScreen(mCurrentScreen - 1); } else if (velocityX < -SNAP_VELOCITY && mCurrentScreen < getChildCount() - 1) { // Fling hard enough to move right snapToScreen(mCurrentScreen + 1); } else { snapToDestination(); } if (mVelocityTracker != null) { mVelocityTracker.recycle(); mVelocityTracker = null; } // } mTouchState = TOUCH_STATE_REST; break; case MotionEvent.ACTION_CANCEL: Log.i(LOG_TAG, "event : cancel"); mTouchState = TOUCH_STATE_REST; } mScrollX = this.getScrollX(); return true; } private void snapToDestination() { final int screenWidth = getWidth(); final int whichScreen = (mScrollX + (screenWidth / 2)) / screenWidth; Log.i(LOG_TAG, "from des"); snapToScreen(whichScreen); } public void snapToScreen(int whichScreen) { Log.i(LOG_TAG, "snap To Screen " + whichScreen); mCurrentScreen = whichScreen; final int newX = whichScreen * getWidth(); final int delta = newX - mScrollX; mScroller.startScroll(mScrollX, 0, delta, 0, Math.abs(delta) * 2); invalidate(); } public void setToScreen(int whichScreen) { Log.i(LOG_TAG, "set To Screen " + whichScreen); mCurrentScreen = whichScreen; final int newX = whichScreen * getWidth(); mScroller.startScroll(newX, 0, 0, 0, 10); invalidate(); } @Override protected void onLayout(boolean changed, int l, int t, int r, int b) { int childLeft = 0; final int count = getChildCount(); for (int i = 0; i < count; i++) { final View child = getChildAt(i); if (child.getVisibility() != View.GONE) { final int childWidth = child.getMeasuredWidth(); child.layout(childLeft, 0, childLeft + childWidth, child .getMeasuredHeight()); childLeft += childWidth; } } } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); final int width = MeasureSpec.getSize(widthMeasureSpec); final int widthMode = MeasureSpec.getMode(widthMeasureSpec); if (widthMode != MeasureSpec.EXACTLY) { throw new IllegalStateException("error mode."); } final int heightMode = MeasureSpec.getMode(heightMeasureSpec); if (heightMode != MeasureSpec.EXACTLY) { throw new IllegalStateException("error mode."); } // The children are given the same width and height as the workspace final int count = getChildCount(); for (int i = 0; i < count; i++) { getChildAt(i).measure(widthMeasureSpec, heightMeasureSpec); } Log.i(LOG_TAG, "moving to screen "+mCurrentScreen); scrollTo(mCurrentScreen * width, 0); } @Override public void computeScroll() { if (mScroller.computeScrollOffset()) { mScrollX = mScroller.getCurrX(); scrollTo(mScrollX, 0); postInvalidate(); } }}?
<?xml version="1.0" encoding="utf-8"?><com.matthieu.launcher.DragableSpace xmlns:app="http://schemas.android.com/apk/res/com.matthieu.launcher" xmlns:android="http://schemas.android.com/apk/res/android"android:id="@+id/space"android:layout_width="fill_parent"android:layout_height="fill_parent"app:default_screen="1"><include android:id="@+id/left" layout="@layout/left_screen" /><include android:id="@+id/center" layout="@layout/initial_screen" /><include android:id="@+id/right" layout="@layout/right_screen" /></com.matthieu.launcher.DragableSpace>
?2.<com.matthieu.launcher.DragableSpace xmlns:app="http://schemas.android.com/apk/res/com.matthieu.launcher"
3. xmlns:android="http://schemas.android.com/apk/res/android"
4.android:id="@+id/space"
5.android:layout_width="fill_parent"
6.android:layout_height="fill_parent"
7.app:default_screen="1"
8.>
9.<include android:id="@+id/left" layout="@layout/left_screen" />
10.<include android:id="@+id/center" layout="@layout/initial_screen" />
11.<include android:id="@+id/right" layout="@layout/right_screen" />
12.</com.matthieu.launcher.DragableSpace>
可以解释下这个文件吗？？？ 3 楼 无忧鱼 2012-03-08 无图无真相啊！