@Override
public void computeScroll() {
if (mScroller.computeScrollOffset()) {
// This is called at drawing time by ViewGroup. We don't want to
// re-show the scrollbars at this point, which scrollTo will do,
// so we replicate most of scrollTo here.
//
// It's a little odd to call onScrollChanged from inside the drawing.
//
// It is, except when you remember that computeScroll() is used to
// animate scrolling. So unless we want to defer the onScrollChanged()
// until the end of the animated scrolling, we don't really have a
// choice here.
//
// I agree. The alternative, which I think would be worse, is to post
// something and tell the subclasses later. This is bad because there
// will be a window where mScrollX/Y is different from what the app
// thinks it is.
//
int oldX = getScrollX();
int oldY = getScrollY();
int x = mScroller.getCurrX();
int y = mScroller.getCurrY();
if (oldX != x || oldY != y) {
final int range = getScrollRange();
final int overscrollMode = getOverScrollMode();
final boolean canOverscroll =
overscrollMode == OVER_SCROLL_ALWAYS
|| (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0);
overScrollBy(x - oldX, y - oldY, oldX, oldY, range, 0, mOverflingDistance, 0, false);
onScrollChanged(getScrollX(), getScrollY(), oldX, oldY);
}
if (!awakenScrollBars()) {
postInvalidateOnAnimation();
}
} else {
int scrollX = getScrollX();
int finalX = getScrollXFromFinalX(scrollX);
if (!mIsBeingDragged && scrollX != finalX) {
if (mScroller.springBack(getScrollX(), getScrollY(), finalX, finalX, 0, 0)) {
postInvalidateOnAnimation();
}
}
}
}
private boolean touchEvent(MotionEvent ev) {
initVelocityTrackerIfNotExists();
mVelocityTracker.addMovement(ev);
final int action = ev.getAction();
switch (action & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN:
{
if (getChildCount() == 0 || !inScrollArea(ev)) {
return false;
}
if ((mIsBeingDragged = !mScroller.isFinished())) {
final ViewParent parent = getParent();
if (parent != null) {
parent.requestDisallowInterceptTouchEvent(true);
}
}
/*
* 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 = (int) ev.getX();
mActivePointerId = ev.getPointerId(0);
break;
}
case MotionEvent.ACTION_MOVE:
final int activePointerIndex = ev.findPointerIndex(mActivePointerId);
if (activePointerIndex == -1) {
Log.e(TAG, "Invalid pointerId=" + mActivePointerId + " in onTouchEvent");
break;
}
final int x = (int) ev.getX(activePointerIndex);
int deltaX = mLastMotionX - x;
if (!mIsBeingDragged && Math.abs(deltaX) > mTouchSlop) {
final ViewParent parent = getParent();
if (parent != null) {
parent.requestDisallowInterceptTouchEvent(true);
}
mIsBeingDragged = true;
if (deltaX > 0) {
deltaX -= mTouchSlop;
} else {
deltaX += mTouchSlop;
}
}
if (mIsBeingDragged) {
// Scroll to follow the motion event
mLastMotionX = x;
final int oldX = getScrollX();
final int oldY = getScrollY();
final int range = getScrollRange();
final int overscrollMode = getOverScrollMode();
final boolean canOverscroll =
overscrollMode == OVER_SCROLL_ALWAYS
|| (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0);
if (overScrollBy(deltaX, 0, getScrollX(), 0, range, 0, mOverscrollDistance, 0, true)) {
// Break our velocity if we hit a scroll barrier.
mVelocityTracker.clear();
}
onScrollChanged(getScrollX(), getScrollY(), oldX, oldY);
}
break;
case MotionEvent.ACTION_UP:
if (mIsBeingDragged) {
final VelocityTracker velocityTracker = mVelocityTracker;
velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity);
int initialVelocity = (int) velocityTracker.getXVelocity(mActivePointerId);
if (getChildCount() > 0) {
if ((Math.abs(initialVelocity) > mMinimumVelocity)) {
fling(-initialVelocity);
} else {
int finalX = getScrollX();
finalX = getScrollXFromFinalX(finalX);
if (mScroller.springBack(getScrollX(), getScrollY(), finalX, finalX, 0, 0)) {
postInvalidateOnAnimation();
}
}
}
mActivePointerId = INVALID_POINTER;
mIsBeingDragged = false;
recycleVelocityTracker();
}
break;
case MotionEvent.ACTION_CANCEL:
if (mIsBeingDragged && getChildCount() > 0) {
if (mScroller.springBack(getScrollX(), getScrollY(), 0, getScrollRange(), 0, 0)) {
postInvalidateOnAnimation();
}
mActivePointerId = INVALID_POINTER;
mIsBeingDragged = false;
recycleVelocityTracker();
}
break;
case MotionEvent.ACTION_POINTER_UP:
onSecondaryPointerUp(ev);
break;
}
return true;
}
@Override
public boolean onTouchEvent(MotionEvent event) {
// return super.onTouchEvent(event);
// int height = getHeight();
initVelocityTrackerIfNotExists();
mVelocityTracker.addMovement(event);
int action = event.getActionMasked();
if (action == MotionEvent.ACTION_DOWN) {
if (!mIsDown) {
mIsDown = true;
mDownPt.x = event.getX();
mDownPt.y = event.getY();
mDownedScrollPt.x = getScrollX();
mDownedScrollPt.y = getScrollY();
// initOrResetVelocityTracker();
// mVelocityTracker.addMovement(event);
if (!mScroller.isFinished()) {
mScroller.abortAnimation();
}
}
} else if (action == MotionEvent.ACTION_MOVE) {
if (mIsDown) {
float x = event.getX();
float y = event.getY();
float sx = -(x - mDownPt.x) + mDownedScrollPt.x;
float sy = -(y - mDownPt.y) + mDownedScrollPt.y;
scrollTo((int) sx, (int) sy);
// initVelocityTrackerIfNotExists();
// mVelocityTracker.addMovement(event);
}
} else if (action == MotionEvent.ACTION_UP) {
if (mIsDown) {
final VelocityTracker velocityTracker = mVelocityTracker;
velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity);
int initialVelocity = (int) velocityTracker.getYVelocity(event.getPointerId(0));
int initialVelocitx = (int) velocityTracker.getXVelocity(event.getPointerId(0));
fling(-initialVelocitx, -initialVelocity);
recycleVelocityTracker();
mIsDown = false;
}
} else if (action == MotionEvent.ACTION_CANCEL) {
if (mIsDown) {
if (mScroller.springBack(
getScrollX(), getScrollY(), 0, getScrollRangeX(), 0, getScrollRangeY())) {
// postInvalidateOnAnimation();
postInvalidate();
}
recycleVelocityTracker();
mIsDown = false;
}
}
return true;
}
private boolean interceptTouchEvent(MotionEvent ev) {
/*
* This method JUST determines whether we want to intercept the motion. If we
* return true, onMotionEvent 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) && (mIsBeingDragged)) {
return true;
}
switch (action & MotionEvent.ACTION_MASK) {
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 x value of the down
* event.
*/
final int activePointerId = mActivePointerId;
if (activePointerId == INVALID_POINTER) {
// If we don't have a valid id, the touch down wasn't on content.
break;
}
final int pointerIndex = ev.findPointerIndex(activePointerId);
if (pointerIndex == -1) {
Log.e(TAG, "Invalid pointerId=" + activePointerId + " in onInterceptTouchEvent");
break;
}
final int x = (int) ev.getX(pointerIndex);
final int xDiff = (int) Math.abs(x - mLastMotionX);
if (xDiff > mTouchSlop) {
setHorizontalScrollBarEnabled(true);
mIsBeingDragged = true;
mLastMotionX = x;
initVelocityTrackerIfNotExists();
mVelocityTracker.addMovement(ev);
if (getParent() != null) getParent().requestDisallowInterceptTouchEvent(true);
}
break;
}
case MotionEvent.ACTION_DOWN:
{
final int x = (int) ev.getX();
if (!inChild((int) x, (int) ev.getY())) {
mIsBeingDragged = false;
recycleVelocityTracker();
break;
}
/*
* Remember location of down touch. ACTION_DOWN always refers to pointer index
* 0.
*/
mLastMotionX = x;
mActivePointerId = ev.getPointerId(0);
initOrResetVelocityTracker();
mVelocityTracker.addMovement(ev);
/*
* If being flinged and user touches the screen, initiate drag; otherwise
* don't. mScroller.isFinished should be false when being flinged.
*/
mIsBeingDragged = false;
break;
}
case MotionEvent.ACTION_CANCEL:
case MotionEvent.ACTION_UP:
/* Release the drag */
mIsBeingDragged = false;
mActivePointerId = INVALID_POINTER;
if (mScroller.springBack(getScrollX(), getScrollY(), 0, getScrollRange(), 0, 0)) {
postInvalidateOnAnimation();
}
break;
case MotionEvent.ACTION_POINTER_DOWN:
{
final int index = ev.getActionIndex();
mLastMotionX = (int) ev.getX(index);
mActivePointerId = ev.getPointerId(index);
break;
}
case MotionEvent.ACTION_POINTER_UP:
onSecondaryPointerUp(ev);
mLastMotionX = (int) ev.getX(ev.findPointerIndex(mActivePointerId));
break;
}
/*
* The only time we want to intercept motion events is if we are in the drag mode.
*/
return mIsBeingDragged;
}
public boolean springBack(int startX, int startY, int minX, int maxX, int minY, int maxY) {
return mScroller.springBack(startX, startY, minX, maxX, minY, maxY);
}
