ViewGroup中调整大小的ImageView显示不佳

时间:2012-02-21 12:09:04

标签: android view viewgroup

我有一个自定义视图组和自定义的imageViews。使用它我可以用一个手势从一个图像视图滑动到另一个图像视图。

使用缩放缩放缩放ImageView时,视图组中无法使用缩放的某些方式,但根据缩放的空间。

enter code here
public class RealViewSwitcher extends ViewGroup {

public static boolean isAllowedToDispatchTouchEvents=false;

// TODO: This class does the basic stuff right now, but it would be cool to have certain things implemented,
// e.g. using an adapter for getting views instead of setting them directly, memory management and the
// possibility of scrolling vertically instead of horizontally. If you have ideas or patches, please visit
// my website and drop me a mail. :-)

/**
 * Listener for the event that the RealViewSwitcher switches to a new view.
 */
public static interface OnScreenSwitchListener {

    /**
     * Notifies listeners about the new screen. Runs after the animation completed.
     * 
     * @param screen The new screen index.
     */
    void onScreenSwitched(int screen);

}

private static final int SNAP_VELOCITY = 1000;
private static final int INVALID_SCREEN = -1;

private Scroller mScroller;
private VelocityTracker mVelocityTracker;

private final static int TOUCH_STATE_REST = 0;
private final static int TOUCH_STATE_SCROLLING = 1;

private int mTouchState = TOUCH_STATE_REST;

private float mLastMotionX;
private int mTouchSlop;
private int mMaximumVelocity;
private int mCurrentScreen;
private int mNextScreen = INVALID_SCREEN;

private boolean mFirstLayout = true;

private OnScreenSwitchListener mOnScreenSwitchListener;

public RealViewSwitcher(Context context) {
    super(context);
    init();
}

public RealViewSwitcher(Context context, AttributeSet attrs) {
    super(context, attrs);
    init();
}

private void init() {
    System.out.println("int()");
    mScroller = new Scroller(getContext());

    final ViewConfiguration configuration = ViewConfiguration.get(getContext());
    mTouchSlop = configuration.getScaledTouchSlop();
    mMaximumVelocity = configuration.getScaledMaximumFlingVelocity();
}

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    System.out.println("measured");
    final int width = MeasureSpec.getSize(widthMeasureSpec);
    final int widthMode = MeasureSpec.getMode(widthMeasureSpec);
    if (widthMode != MeasureSpec.EXACTLY) {
        throw new IllegalStateException("ViewSwitcher can only be used in EXACTLY mode.");
    }

    final int heightMode = MeasureSpec.getMode(heightMeasureSpec);
    if (heightMode != MeasureSpec.EXACTLY) {
        throw new IllegalStateException("ViewSwitcher can only be used in EXACTLY 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);
    }

    if (mFirstLayout) {
        scrollTo(mCurrentScreen * width, 0);
        mFirstLayout = false;
    }
}

@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
    int childLeft = 0;
    System.out.println("Layout set");
    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
public boolean onTouchEvent(MotionEvent ev) {
    Log.d("TouchEvent", "parent:motion event detected");
    if (mVelocityTracker == null) {
        mVelocityTracker = VelocityTracker.obtain();
    }
    mVelocityTracker.addMovement(ev);

    final int action = ev.getAction();
    final float x = ev.getX();

    switch (action) {
    case MotionEvent.ACTION_DOWN:

        Log.d("TouchEvent", "parent:motion event to 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 = mScroller.isFinished() ? TOUCH_STATE_REST : TOUCH_STATE_SCROLLING;

        break;

    case MotionEvent.ACTION_MOVE:

        Log.d("TouchEvent", "parent:motion event to move");
        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;
        }

        if (mTouchState == TOUCH_STATE_SCROLLING) {
            // Scroll to follow the motion event
            final int deltaX = (int) (mLastMotionX - x);
            mLastMotionX = x;

            final int scrollX = getScrollX();
            if (deltaX < 0) {
                if (scrollX > 0) {
                    scrollBy(Math.max(-scrollX, deltaX), 0);
                }
            } else if (deltaX > 0) {
                final int availableToScroll = getChildAt(getChildCount() - 1).getRight() - scrollX - getWidth();
                if (availableToScroll > 0) {
                    scrollBy(Math.min(availableToScroll, deltaX), 0);
                }
            }
        }
        break;

    case MotionEvent.ACTION_UP:

        Log.d("TouchEvent", "parent:motion event to 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("TouchEvent", "parent:motion event to cancel");
        mTouchState = TOUCH_STATE_REST;
    }

    return true;
}

private void snapToDestination() {
    final int screenWidth = getWidth();
    final int whichScreen = (getScrollX() + (screenWidth / 2)) / screenWidth;

    snapToScreen(whichScreen);
}

private void snapToScreen(int whichScreen) {
    if (!mScroller.isFinished())
        return;

    whichScreen = Math.max(0, Math.min(whichScreen, getChildCount() - 1));

    mNextScreen = whichScreen;

    final int newX = whichScreen * getWidth();
    final int delta = newX - getScrollX();
    mScroller.startScroll(getScrollX(), 0, delta, 0, Math.abs(delta) * 2);
    invalidate();
}

@Override
public void computeScroll() {

    if (mScroller.computeScrollOffset()) {
        scrollTo(mScroller.getCurrX(), mScroller.getCurrY());
        postInvalidate();

    } else if (mNextScreen != INVALID_SCREEN) {
        mCurrentScreen = Math.max(0, Math.min(mNextScreen, getChildCount() - 1));

        // notify observer about screen change
        if (mOnScreenSwitchListener != null)
            mOnScreenSwitchListener.onScreenSwitched(mCurrentScreen);

        Log.d("TouchEvent", "parent:motion event to Compute scroll");
        mNextScreen = INVALID_SCREEN;
    }
}

/**
 * Returns the index of the currently displayed screen.
 * 
 * @return The index of the currently displayed screen.
 */
public int getCurrentScreen() {
    return mCurrentScreen;
}

/**
 * Sets the current screen.
 * 
 * @param currentScreen The new screen.
 */
public void setCurrentScreen(int currentScreen) {
    mCurrentScreen = Math.max(0, Math.min(currentScreen, getChildCount() - 1));
    scrollTo(mCurrentScreen * getWidth(), 0);
    invalidate();
}

/**
 * Sets the {@link ViewSwitcher.OnScreenSwitchListener}.
 * 
 * @param onScreenSwitchListener The listener for switch events.
 */
public void setOnScreenSwitchListener(OnScreenSwitchListener onScreenSwitchListener) {
    mOnScreenSwitchListener = onScreenSwitchListener;
}

/* (non-Javadoc)
 * @see android.view.ViewGroup#onInterceptTouchEvent(android.view.MotionEvent)
 */

public boolean onInterceptTouchEvent(MotionEvent ev) 
{

    Log.d("TouchEvent", "parent:Intercept Touch Event");
    if(isAllowedToDispatchTouchEvents)
    {

    }onTouchEvent(ev);
    return isAllowedToDispatchTouchEvents;

}

}

0 个答案:

没有答案