实例介绍
【实例简介】
【实例截图】
【核心代码】
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Rect;
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;
/**
* @author Administrator
*
*/
public class ScrollableViewGroup extends ViewGroup {
private static final int INVALID_SCREEN = -1;
private static final int TOUCH_STATE_REST = 0;
private static final int TOUCH_STATE_SCROLLING = 1;
private static final int SNAP_VELOCITY = 1000;
private int mDefaultScreen;
private int mCurrentScreen;
private int mNextScreen = INVALID_SCREEN;
private int mMaximumVelocity;
private Scroller mScroller;
private int mTouchState;
private boolean mFirstLayout = true;
private float mLastMotionX;
private float mLastMotionY;
private int mTouchSlop;
private boolean mAllowLongPress;
private VelocityTracker mVelocityTracker;
private int mPaintFlag = 0;
private OnCurrentViewChangedListener mOnCurrentViewChangedListener;
public interface OnCurrentViewChangedListener {
public void onCurrentViewChanged(View view, int currentview);
};
/**
* @param context
*/
public ScrollableViewGroup(Context context) {
super(context);
initViewGroup();
}
/**
* @param context
* @param attrs
*/
public ScrollableViewGroup(Context context, AttributeSet attrs) {
super(context, attrs);
initViewGroup();
}
/**
* @param context
* @param attrs
* @param defStyle
*/
public ScrollableViewGroup(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
initViewGroup();
}
/*
* (non-Javadoc)
*
* @see android.view.ViewGroup#onLayout(boolean, int, int, int, int)
*/
@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;
}
}
}
/**
* Initializes various states for this viewgroup.
*/
private void initViewGroup() {
mScroller = new Scroller(getContext());
mCurrentScreen = mDefaultScreen;
final ViewConfiguration configuration = ViewConfiguration
.get(getContext());
mTouchSlop = configuration.getScaledTouchSlop();
// mMaximumVelocity = configuration.getScaledMaximumFlingVelocity();
}
public boolean isDefaultViewShowing() {
return mCurrentScreen == mDefaultScreen;
}
public int getCurrentView() {
return mCurrentScreen;
}
public void setCurrentView(int currentView) {
// snapToScreen(currentView);
mCurrentScreen = Math
.max(0, Math.min(currentView, getChildCount() - 1));
scrollTo(mCurrentScreen * getWidth(), 0);
if (mOnCurrentViewChangedListener != null)
mOnCurrentViewChangedListener.onCurrentViewChanged(this,
mCurrentScreen);
invalidate();
}
/*
* (non-Javadoc)
*
* @see android.view.View#computeScroll()
*/
@Override
public void computeScroll() {
// Log.d("Curt", "computeScroll");
if (mScroller.computeScrollOffset()) {
// FIXED 鍗峰姩鏃犳硶瑙﹀彂涓嬫鐨刢omputeScroll;
final int currx = mScroller.getCurrX(), curry = mScroller
.getCurrY(), scrx = getScrollX(), scry = getScrollY();
if (currx != scrx || curry != scry)
scrollTo(mScroller.getCurrX(), mScroller.getCurrY());
else
invalidate();
} else if (mNextScreen != INVALID_SCREEN) {
mCurrentScreen = Math.max(0, Math.min(mNextScreen,
getChildCount() - 1));
mNextScreen = INVALID_SCREEN;
mPaintFlag = 0;
clearChildrenCache();
final int scrx = getScrollX(), scry = getScrollY(), mCurrentScrollX = mCurrentScreen
* getWidth();
if (scrx != mCurrentScrollX)
scrollTo(mCurrentScrollX, scry);
if (mOnCurrentViewChangedListener != null)
mOnCurrentViewChangedListener.onCurrentViewChanged(this,
mCurrentScreen);
}
}
/*
* (non-Javadoc)
*
* @see android.view.ViewGroup#dispatchDraw(android.graphics.Canvas)
*/
@Override
protected void dispatchDraw(Canvas canvas) {
boolean fastDraw = mTouchState != TOUCH_STATE_SCROLLING
&& mNextScreen == INVALID_SCREEN;
// If we are not scrolling or flinging, draw only the current screen
if (fastDraw) {
drawChild(canvas, getChildAt(mCurrentScreen), getDrawingTime());
} else {
final long drawingTime = getDrawingTime();
// If we are flinging, draw only the current screen and the target
// screen
if (mNextScreen >= 0
&& mNextScreen < getChildCount()
&& (Math.abs(mCurrentScreen - mNextScreen) == 1 || mPaintFlag != 0)) {
final View viewCurrent = getChildAt(mCurrentScreen), viewNext = getChildAt(mNextScreen);
drawChild(canvas, viewCurrent, drawingTime);
if (mPaintFlag == 0) {
drawChild(canvas, viewNext, drawingTime);
} else {
Paint paint = new Paint();
if (mPaintFlag < 0) {
canvas.drawBitmap(viewNext.getDrawingCache(), -viewNext
.getWidth(), viewNext.getTop(), paint);
} else {
canvas.drawBitmap(viewNext.getDrawingCache(),
getWidth() * getChildCount(),
viewNext.getTop(), paint);
}
}
} else {
// If we are scrolling, draw all of our children
final int count = getChildCount();
for (int i = 0; i < count; i ) {
drawChild(canvas, getChildAt(i), drawingTime);
}
if (mPaintFlag != 0) {
final View viewNext;
Paint paint = new Paint();
if (mPaintFlag < 0) {
viewNext = getChildAt(getChildCount() - 1);
// Log.d("Curt", "dispatchDraw: " viewNext.getDrawingCache());
if (viewNext.getDrawingCache() == null) {
viewNext.buildDrawingCache();
}
canvas.drawBitmap(viewNext.getDrawingCache(), -viewNext
.getWidth(), viewNext.getTop(), paint);
} else {
viewNext = getChildAt(0);
canvas.drawBitmap(viewNext.getDrawingCache(),
getWidth() * getChildCount(),
viewNext.getTop(), paint);
}
}
}
}
}
/*
* (non-Javadoc)
*
* @see android.view.View#onMeasure(int, int)
*/
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
final int width = MeasureSpec.getSize(widthMeasureSpec);
final int count = getChildCount();
for (int i = 0; i < count; i ) {
getChildAt(i).measure(widthMeasureSpec, heightMeasureSpec);
}
if (mFirstLayout) {
scrollTo(mCurrentScreen * width, 0);
mFirstLayout = false;
}
}
/*
* (non-Javadoc)
*
* @see
* android.view.ViewGroup#requestChildRectangleOnScreen(android.view.View,
* android.graphics.Rect, boolean)
*/
@Override
public boolean requestChildRectangleOnScreen(View child, Rect rectangle,
boolean immediate) {
int screen = indexOfChild(child);
if (screen != mCurrentScreen || !mScroller.isFinished()) {
snapToScreen(screen);
return true;
}
return false;
}
/*
* (non-Javadoc)
*
* @see android.view.ViewGroup#onRequestFocusInDescendants(int,
* android.graphics.Rect)
*/
@Override
protected boolean onRequestFocusInDescendants(int direction,
Rect previouslyFocusedRect) {
int focusableScreen;
if (mNextScreen != INVALID_SCREEN) {
focusableScreen = mNextScreen;
} else {
focusableScreen = mCurrentScreen;
}
// Log.d("Curt", "onRequestFocusInDescendants: " focusableScreen);
boolean log = getChildAt(focusableScreen).requestFocus(direction,
previouslyFocusedRect);
// Log.d("Curt", "onRequestFocusInDescendants" log);
return false;
}
/*
* (non-Javadoc)
*
* @see android.view.ViewGroup#dispatchUnhandledMove(android.view.View, int)
*/
@Override
public boolean dispatchUnhandledMove(View focused, int direction) {
if (direction == View.FOCUS_LEFT) {
if (getCurrentView() > 0) {
snapToScreen(getCurrentView() - 1);
return true;
}
} else if (direction == View.FOCUS_RIGHT) {
if (getCurrentView() < getChildCount() - 1) {
snapToScreen(getCurrentView() 1);
return true;
}
}
return super.dispatchUnhandledMove(focused, direction);
}
/*
* (non-Javadoc)
*
* @see
* android.view.ViewGroup#onInterceptTouchEvent(android.view.MotionEvent)
*/
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
// Log.d("Curt", "onInterceptTouchEvent");
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(x - mLastMotionX);
final int yDiff = (int) Math.abs(y - mLastMotionY);
final int touchSlop = mTouchSlop;
boolean xMoved = xDiff > touchSlop;
boolean yMoved = yDiff > touchSlop;
if (xMoved || yMoved) {
if (xMoved) {
// Scroll if the user moved far enough along the X axis
mTouchState = TOUCH_STATE_SCROLLING;
enableChildrenCache();
}
// Either way, cancel any pending longpress
if (mAllowLongPress) {
mAllowLongPress = false;
// Try canceling the long press. It could also have been
// scheduled
// by a distant descendant, so use the mAllowLongPress flag
// to block
// everything
final View currentScreen = getChildAt(mCurrentScreen);
currentScreen.cancelLongPress();
}
}
break;
case MotionEvent.ACTION_DOWN:
// Remember location of down touch
mLastMotionX = x;
mLastMotionY = y;
mAllowLongPress = true;
/*
* 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:
mTouchState = TOUCH_STATE_REST;
mAllowLongPress = false;
break;
}
/*
* The only time we want to intercept motion events is if we are in the
* drag mode.
*/
return mTouchState != TOUCH_STATE_REST;
}
void enableChildrenCache() {
final int count = getChildCount();
for (int i = 0; i < count; i ) {
final View layout = getChildAt(i);
layout.setDrawingCacheEnabled(true);
if (layout instanceof ViewGroup) {
((ViewGroup) layout).setAlwaysDrawnWithCacheEnabled(true);
}
}
}
void clearChildrenCache() {
final int count = getChildCount();
for (int i = 0; i < count; i ) {
final View layout = getChildAt(i);
if (layout instanceof ViewGroup) {
((ViewGroup) layout).setAlwaysDrawnWithCacheEnabled(false);
}
}
}
/*
* (non-Javadoc)
*
* @see android.view.View#onTouchEvent(android.view.MotionEvent)
*/
@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:
/*
* 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;
mTouchState = TOUCH_STATE_SCROLLING;
break;
case MotionEvent.ACTION_MOVE:
// Log.d("Curt", "move : " mTouchState);
if (mTouchState == TOUCH_STATE_SCROLLING) {
// Scroll to follow the motion event
final int deltaX = (int) (mLastMotionX - x);
mLastMotionX = x;
if (deltaX < 0) {
/*
* if (getScrollX() > 0) { scrollBy(Math.max(-getScrollX(),
* deltaX), 0); }
*/
if (getScrollX() <= 0) {
mPaintFlag = -1;
}
scrollBy(deltaX, 0);
} else if (deltaX > 0) {
int availableToScroll = getChildAt(getChildCount() - 1)
.getRight()
- getScrollX() - getWidth();
/*
* if (availableToScroll > 0) {
* scrollBy(Math.min(availableToScroll, deltaX), 0); }
*/
if (availableToScroll <= 0) {
mPaintFlag = 1;
availableToScroll = getWidth() << 1;
}
if (availableToScroll > 0)
scrollBy(Math.min(availableToScroll, deltaX), 0);
}
}
break;
case MotionEvent.ACTION_UP:
if (mTouchState == TOUCH_STATE_SCROLLING) {
final VelocityTracker velocityTracker = mVelocityTracker;
// velocityTracker.computeCurrentVelocity(1000,
// mMaximumVelocity);
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.d("Curt", "cancel");
mTouchState = TOUCH_STATE_REST;
}
return true;
}
private void snapToDestination() {
final int screenWidth = getWidth();
final int scrollWidth = getScrollX() (screenWidth >> 1);
final int viewCount = getChildCount();
final int whichScreen;
if (scrollWidth < 0)
whichScreen = -1;
else if (scrollWidth > screenWidth * viewCount)
whichScreen = viewCount;
else
whichScreen = (getScrollX() (screenWidth / 2)) / screenWidth;
snapToScreen(whichScreen);
}
public void snapToScreen(int whichScreen) {
// Log.d("Curt", "snapToScreen");
if (whichScreen != mCurrentScreen) {
View child = getChildAt(mCurrentScreen);
if (child instanceof ImageViewTouch) {
ImageViewTouch touch = (ImageViewTouch) child;
if (touch.isSmaller) {
touch.zoomTo(1.0f);
touch.isSmaller = false;
}
}
} else {
View child = getChildAt(mCurrentScreen);
if (child instanceof ImageViewTouch) {
ImageViewTouch touch = (ImageViewTouch) child;
if (touch.isSmaller) {
touch.zoomTo(1.0f);
touch.isSmaller = false;
}
}
}
if (!mScroller.isFinished())
return;
enableChildrenCache();
final int viewCount = getChildCount() - 1;
final int oldWhichScreen = whichScreen;
if (whichScreen < 0) {
whichScreen = viewCount;
mPaintFlag = -1; // next screen should be painted before current
} else if (whichScreen > viewCount) {
whichScreen = 0;
mPaintFlag = 1;
} else
mPaintFlag = 0;
// whichScreen = Math.max(0, Math.min(whichScreen, getChildCount() -
// 1));
boolean changingScreens = whichScreen != mCurrentScreen;
mNextScreen = whichScreen;
View focusedChild = getFocusedChild();
Log.d("Curt", "snapToScreen: Child is: " focusedChild);
if (focusedChild != null && changingScreens
&& focusedChild == getChildAt(mCurrentScreen)) {
focusedChild.clearFocus();
}
//getChildAt(mCurrentScreen).requestFocus();
//Log.d("Curt", "snapToScreen: " mCurrentScreen);
final int newX = oldWhichScreen * getWidth();
final int delta = newX - getScrollX();
mScroller.startScroll(getScrollX(), 0, delta, 0, Math.abs(delta) * 2);
invalidate();
/*
* if (!mScroller.isFinished()) return; enableChildrenCache();
*
* whichScreen = Math.max(0, Math.min(whichScreen, getChildCount() -
* 1)); boolean changingScreens = whichScreen != mCurrentScreen;
*
* mNextScreen = whichScreen;
*
* View focusedChild = getFocusedChild(); if (focusedChild != null &&
* changingScreens && focusedChild == getChildAt(mCurrentScreen)) {
* focusedChild.clearFocus(); }
*
* final int newX = whichScreen * getWidth(); final int delta = newX -
* getScrollX(); mScroller.startScroll(getScrollX(), 0, delta, 0,
* Math.abs(delta) * 2);
*
* invalidate();
*/}
public void scrollLeft() {
if (mNextScreen == INVALID_SCREEN && mCurrentScreen > 0
&& mScroller.isFinished()) {
snapToScreen(mCurrentScreen - 1);
}
}
public void scrollRight() {
if (mNextScreen == INVALID_SCREEN
&& mCurrentScreen < getChildCount() - 1
&& mScroller.isFinished()) {
snapToScreen(mCurrentScreen 1);
}
}
public void moveToDefaultScreen() {
snapToScreen(mDefaultScreen);
getChildAt(mDefaultScreen).requestFocus();
}
public boolean isScrollFinish() {
return mTouchState != TOUCH_STATE_SCROLLING
&& mNextScreen == INVALID_SCREEN;
// return mScroller.isFinished();
}
public OnCurrentViewChangedListener getOnCurrentViewChangedListener() {
return mOnCurrentViewChangedListener;
}
public void setOnCurrentViewChangedListener(
OnCurrentViewChangedListener mOnCurrentViewChangedListener) {
this.mOnCurrentViewChangedListener = mOnCurrentViewChangedListener;
}
}
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