Add support for stretch overscroll to internal ViewPager (13cdf67f) · Commits · e / os / android_frameworks_base

core/java/com/android/internal/widget/ViewPager.java

+75 −9

Original line number	Diff line number	Diff line
		@@ -353,8 +353,8 @@ public class ViewPager extends ViewGroup {
		mTouchSlop = configuration.getScaledPagingTouchSlop();
		mMinimumVelocity = (int) (MIN_FLING_VELOCITY * density);
		mMaximumVelocity = configuration.getScaledMaximumFlingVelocity();
		mLeftEdge = new EdgeEffect(context);
		mRightEdge = new EdgeEffect(context);
		mLeftEdge = new EdgeEffect(context, attrs);
		mRightEdge = new EdgeEffect(context, attrs);

		mFlingDistance = (int) (MIN_DISTANCE_FOR_FLING * density);
		mCloseEnough = (int) (CLOSE_ENOUGH * density);
		@@ -386,6 +386,28 @@ public class ViewPager extends ViewGroup {
		}
		}

		/**
		* Returns the {@link EdgeEffect#getType()} for the edge effects.
		* @return the {@link EdgeEffect#getType()} for the edge effects.
		* @attr ref android.R.styleable#EdgeEffect_edgeEffectType
		*/
		@EdgeEffect.EdgeEffectType
		public int getEdgeEffectType() {
		// Both left and right edge have the same edge effect type
		return mLeftEdge.getType();
		}

		/**
		* Sets the {@link EdgeEffect#setType(int)} for the edge effects.
		* @param type The edge effect type to use for the edge effects.
		* @attr ref android.R.styleable#EdgeEffect_edgeEffectType
		*/
		public void setEdgeEffectType(@EdgeEffect.EdgeEffectType int type) {
		mLeftEdge.setType(type);
		mRightEdge.setType(type);
		invalidate();
		}

		/**
		* Set a PagerAdapter that will supply views for this pager as needed.
		*
		@@ -1891,7 +1913,7 @@ public class ViewPager extends ViewGroup {
		}
		if (mIsBeingDragged) {
		// Scroll to follow the motion event
		if (performDrag(x)) {
		if (performDrag(x, y)) {
		postInvalidateOnAnimation();
		}
		}
		@@ -1918,6 +1940,17 @@ public class ViewPager extends ViewGroup {
		mIsBeingDragged = true;
		requestParentDisallowInterceptTouchEvent(true);
		setScrollState(SCROLL_STATE_DRAGGING);
		} else if (mLeftEdge.getDistance() != 0
		\|\| mRightEdge.getDistance() != 0) {
		// Caught the edge glow animation
		mIsBeingDragged = true;
		setScrollState(SCROLL_STATE_DRAGGING);
		if (mLeftEdge.getDistance() != 0) {
		mLeftEdge.onPullDistance(0f, 1 - mLastMotionY / getHeight());
		}
		if (mRightEdge.getDistance() != 0) {
		mRightEdge.onPullDistance(0f, mLastMotionY / getHeight());
		}
		} else {
		completeScroll(false);
		mIsBeingDragged = false;
		@@ -2009,7 +2042,7 @@ public class ViewPager extends ViewGroup {
		// Scroll to follow the motion event
		final int activePointerIndex = ev.findPointerIndex(mActivePointerId);
		final float x = ev.getX(activePointerIndex);
		needsInvalidate \|= performDrag(x);
		needsInvalidate \|= performDrag(x, ev.getY(activePointerIndex));
		}
		break;
		case MotionEvent.ACTION_UP:
		@@ -2080,12 +2113,43 @@ public class ViewPager extends ViewGroup {
		}
		}

		private boolean performDrag(float x) {
		/**
		* If either of the horizontal edge glows are currently active, this consumes part or all of
		* deltaX on the edge glow.
		*
		* @param deltaX The pointer motion, in pixels, in the horizontal direction, positive
		* for moving down and negative for moving up.
		* @param y The vertical position of the pointer.
		* @return The amount of <code>deltaX</code> that has been consumed by the
		* edge glow.
		*/
		private float releaseHorizontalGlow(float deltaX, float y) {
		// First allow releasing existing overscroll effect:
		float consumed = 0;
		float displacement = y / getHeight();
		float pullDistance = (float) deltaX / getWidth();
		if (mLeftEdge.getDistance() != 0) {
		consumed = -mLeftEdge.onPullDistance(-pullDistance, 1 - displacement);
		} else if (mRightEdge.getDistance() != 0) {
		consumed = mRightEdge.onPullDistance(pullDistance, displacement);
		}
		return consumed * getWidth();
		}

		private boolean performDrag(float x, float y) {
		boolean needsInvalidate = false;

		final float dX = mLastMotionX - x;
		final int width = getPaddedWidth();
		final float deltaX = mLastMotionX - x;
		mLastMotionX = x;
		final float releaseConsumed = releaseHorizontalGlow(dX, y);
		final float deltaX = dX - releaseConsumed;
		if (releaseConsumed != 0) {
		needsInvalidate = true;
		}
		if (Math.abs(deltaX) < 0.0001f) { // ignore rounding errors from releaseHorizontalGlow()
		return needsInvalidate;
		}

		final EdgeEffect startEdge;
		final EdgeEffect endEdge;
		@@ -2128,14 +2192,14 @@ public class ViewPager extends ViewGroup {
		if (scrollStart < startBound) {
		if (startAbsolute) {
		final float over = startBound - scrollStart;
		startEdge.onPull(Math.abs(over) / width);
		startEdge.onPullDistance(over / width, 1 - y / getHeight());
		needsInvalidate = true;
		}
		clampedScrollStart = startBound;
		} else if (scrollStart > endBound) {
		if (endAbsolute) {
		final float over = scrollStart - endBound;
		endEdge.onPull(Math.abs(over) / width);
		endEdge.onPullDistance(over / width, y / getHeight());
		needsInvalidate = true;
		}
		clampedScrollStart = endBound;
		@@ -2228,7 +2292,9 @@ public class ViewPager extends ViewGroup {
		*/
		private int determineTargetPage(int currentPage, float pageOffset, int velocity, int deltaX) {
		int targetPage;
		if (Math.abs(deltaX) > mFlingDistance && Math.abs(velocity) > mMinimumVelocity) {
		if (Math.abs(deltaX) > mFlingDistance && Math.abs(velocity) > mMinimumVelocity
		&& mLeftEdge.getDistance() == 0 // don't fling while stretched
		&& mRightEdge.getDistance() == 0) {
		targetPage = currentPage - (velocity < 0 ? mLeftIncr : 0);
		} else {
		final float truncator = currentPage >= mCurItem ? 0.4f : 0.6f;