I have a view with 3 pages in which the user can swipe both horizontally (to move from one page to the other) and vertically (up or down to see all content when needed). I use a class like the code I give below that handles the gestures (I found it mostly here-> http://www.jmstudio.org/archives/391 but now this link is down now). I also have a timer in all 3 views that counts time when user presses a “start” button. My problem: in the first view the start button is positioned way down because there is a lot of content. When user presses start, which makes counter to start, then the view is scrolled automatically up (I do not know if in some way it “wants” to show the timer that is updated in every second). When I try to move down again it goes up in every second. Note that this does not happen every time. After some moments, and if I navigate through views it may stop. Also it does not happen in an emulator I tried it, but it does in device. Can anyone have an idea why this is happening and how to fix? It drives me mad! Thank you in advance!
(below is the class)
public class FlingAndScrollViewer 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 = "FlingAndScrollViewer";
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 FlingAndScrollViewer(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 FlingAndScrollViewer(Context context, AttributeSet attrs) {
super(context, attrs);
TypedArray a = getContext().obtainStyledAttributes(attrs,
R.styleable.FlingAndScrollViewer);
mCurrentScreen = a.getInteger(
R.styleable.FlingAndScrollViewer_default_screen, 0);
mScroller = new Scroller(context);
mTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();
this.setLayoutParams(new ViewGroup.LayoutParams(
ViewGroup.LayoutParams.WRAP_CONTENT,
ViewGroup.LayoutParams.FILL_PARENT));
}
public void setInitialPosition(int initialPosition) {
mCurrentScreen = initialPosition;
}
@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.
*/
if(this.isEnabled()){
final int action;
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;
}
return false;
}
@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();
}
}
/**
* Return the parceable instance to be saved
*/
@Override
protected Parcelable onSaveInstanceState() {
final SavedState state = new SavedState(super.onSaveInstanceState());
state.currentScreen = mCurrentScreen;
return state;
}
/**
* Restore the previous saved current screen
*/
@Override
protected void onRestoreInstanceState(Parcelable state) {
SavedState savedState = (SavedState) state;
super.onRestoreInstanceState(savedState.getSuperState());
if (savedState.currentScreen != -1) {
mCurrentScreen = savedState.currentScreen;
}
}
// ========================= INNER CLASSES ==============================
public interface onViewChangedEvent {
void onViewChange(int currentViewIndex);
}
/**
* A SavedState which save and load the current screen
*/
public static class SavedState extends BaseSavedState {
int currentScreen = -1;
/**
* Internal constructor
*
* @param superState
*/
SavedState(Parcelable superState) {
super(superState);
}
/**
* Private constructor
*
* @param in
*/
private SavedState(Parcel in) {
super(in);
currentScreen = in.readInt();
}
/**
* Save the current screen
*/
@Override
public void writeToParcel(Parcel out, int flags) {
super.writeToParcel(out, flags);
out.writeInt(currentScreen);
}
/**
* Return a Parcelable creator
*/
public static final Parcelable.Creator<SavedState> CREATOR = new Parcelable.Creator<SavedState>() {
public SavedState createFromParcel(Parcel in) {
return new SavedState(in);
}
public SavedState[] newArray(int size) {
return new SavedState[size];
}
};
}
}
