private void updateStateForChildFullyInBottomStack(
StackScrollAlgorithmState algorithmState,
float transitioningPositionStart,
StackViewState childViewState,
int childHeight,
AmbientState ambientState) {
Log.d(TAG, "updateStateForChildFullyInBottomStack: ");
float currentYPosition;
algorithmState.itemsInBottomStack += 1.0f;
if (algorithmState.itemsInBottomStack < MAX_ITEMS_IN_BOTTOM_STACK) {
// We are visually entering the bottom stack
currentYPosition =
transitioningPositionStart
+ mBottomStackIndentationFunctor.getValue(algorithmState.itemsInBottomStack)
- mPaddingBetweenElements;
childViewState.location = StackViewState.LOCATION_BOTTOM_STACK_PEEKING;
} else {
// we are fully inside the stack
if (algorithmState.itemsInBottomStack > MAX_ITEMS_IN_BOTTOM_STACK + 2) {
childViewState.alpha = 0.0f;
} else if (algorithmState.itemsInBottomStack > MAX_ITEMS_IN_BOTTOM_STACK + 1) {
childViewState.alpha = 1.0f - algorithmState.partialInBottom;
}
childViewState.location = StackViewState.LOCATION_BOTTOM_STACK_HIDDEN;
currentYPosition = ambientState.getInnerHeight();
}
childViewState.yTranslation = currentYPosition - childHeight;
clampPositionToTopStackEnd(childViewState, childHeight);
}
private void updateStateForTopStackChild(
StackScrollAlgorithmState algorithmState,
int numberOfElementsCompletelyIn,
int i,
int childHeight,
StackViewState childViewState,
float scrollOffset) {
Log.d(TAG, "updateStateForTopStackChild: ");
// First we calculate the index relative to the current stack window of size at most
// {@link #MAX_ITEMS_IN_TOP_STACK}
int paddedIndex = i - 1 - Math.max(numberOfElementsCompletelyIn - MAX_ITEMS_IN_TOP_STACK, 0);
if (paddedIndex >= 0) {
// We are currently visually entering the top stack
float distanceToStack =
(childHeight + mPaddingBetweenElements) - algorithmState.scrolledPixelsTop;
if (i == algorithmState.lastTopStackIndex
&& distanceToStack > (mTopStackTotalSize + mPaddingBetweenElements)) {
// Child is currently translating into stack but not yet inside slow down zone.
// Handle it like the regular scrollview.
childViewState.yTranslation = scrollOffset;
} else {
// Apply stacking logic.
float numItemsBefore;
if (i == algorithmState.lastTopStackIndex) {
numItemsBefore =
1.0f - (distanceToStack / (mTopStackTotalSize + mPaddingBetweenElements));
} else {
numItemsBefore = algorithmState.itemsInTopStack - i;
}
// The end position of the current child
float currentChildEndY =
mCollapsedSize
+ mTopStackTotalSize
- mTopStackIndentationFunctor.getValue(numItemsBefore);
childViewState.yTranslation = currentChildEndY - childHeight;
}
childViewState.location = StackViewState.LOCATION_TOP_STACK_PEEKING;
} else {
if (paddedIndex == -1) {
childViewState.alpha = 1.0f - algorithmState.partialInTop;
} else {
// We are hidden behind the top card and faded out, so we can hide ourselves.
childViewState.alpha = 0.0f;
}
childViewState.yTranslation = mCollapsedSize - childHeight;
childViewState.location = StackViewState.LOCATION_TOP_STACK_HIDDEN;
}
}
private void updateStateForChildTransitioningInBottom(
StackScrollAlgorithmState algorithmState,
float transitioningPositionStart,
float bottomPeakStart,
float currentYPosition,
StackViewState childViewState,
int childHeight) {
Log.d(TAG, "updateStateForChildTransitioningInBottom: ");
// This is the transitioning element on top of bottom stack, calculate how far we are in.
algorithmState.partialInBottom =
1.0f
- ((transitioningPositionStart - currentYPosition)
/ (childHeight + mPaddingBetweenElements));
// the offset starting at the transitionPosition of the bottom stack
float offset = mBottomStackIndentationFunctor.getValue(algorithmState.partialInBottom);
algorithmState.itemsInBottomStack += algorithmState.partialInBottom;
int newHeight = childHeight;
if (childHeight > mCollapsedSize && mIsSmallScreen) {
newHeight =
(int)
Math.max(
Math.min(
transitioningPositionStart
+ offset
- mPaddingBetweenElements
- currentYPosition,
childHeight),
mCollapsedSize);
childViewState.height = newHeight;
}
childViewState.yTranslation =
transitioningPositionStart + offset - newHeight - mPaddingBetweenElements;
// We want at least to be at the end of the top stack when collapsing
clampPositionToTopStackEnd(childViewState, newHeight);
childViewState.location = StackViewState.LOCATION_MAIN_AREA;
}
