/**
* Determine the positions for the views. This is the main part of the algorithm.
*
* @param resultState The result state to update if a change to the properties of a child occurs
* @param algorithmState The state in which the current pass of the algorithm is currently in
* @param ambientState The current ambient state
*/
private void updatePositionsForState(
StackScrollState resultState,
StackScrollAlgorithmState algorithmState,
AmbientState ambientState) {
Log.d(TAG, "updatePositionsForState: ");
// The starting position of the bottom stack peek
float bottomPeekStart = ambientState.getInnerHeight() - mBottomStackPeekSize;
// The position where the bottom stack starts.
float bottomStackStart = bottomPeekStart - mBottomStackSlowDownLength;
// The y coordinate of the current child.
float currentYPosition = 0.0f;
// How far in is the element currently transitioning into the bottom stack.
float yPositionInScrollView = 0.0f;
// If we have a heads-up higher than the collapsed height we need to add the difference to
// the padding of all other elements, i.e push in the top stack slightly.
ExpandableNotificationRow topHeadsUpEntry = ambientState.getTopHeadsUpEntry();
int childCount = algorithmState.visibleChildren.size();
int numberOfElementsCompletelyIn =
algorithmState.partialInTop == 1.0f
? algorithmState.lastTopStackIndex
: (int) algorithmState.itemsInTopStack;
for (int i = 0; i < childCount; i++) {
ExpandableView child = algorithmState.visibleChildren.get(i);
StackViewState childViewState = resultState.getViewStateForView(child);
childViewState.location = StackViewState.LOCATION_UNKNOWN;
int childHeight = getMaxAllowedChildHeight(child, ambientState);
float yPositionInScrollViewAfterElement =
yPositionInScrollView + childHeight + mPaddingBetweenElements;
float scrollOffset = yPositionInScrollView - algorithmState.scrollY + mCollapsedSize;
if (i == algorithmState.lastTopStackIndex + 1) {
// Normally the position of this child is the position in the regular scrollview,
// but if the two stacks are very close to each other,
// then have have to push it even more upwards to the position of the bottom
// stack start.
currentYPosition = Math.min(scrollOffset, bottomStackStart);
}
childViewState.yTranslation = currentYPosition;
// The y position after this element
float nextYPosition = currentYPosition + childHeight + mPaddingBetweenElements;
if (i <= algorithmState.lastTopStackIndex) {
// Case 1:
// We are in the top Stack
updateStateForTopStackChild(
algorithmState,
numberOfElementsCompletelyIn,
i,
childHeight,
childViewState,
scrollOffset);
clampPositionToTopStackEnd(childViewState, childHeight);
// check if we are overlapping with the bottom stack
if (childViewState.yTranslation + childHeight + mPaddingBetweenElements >= bottomStackStart
&& !mIsExpansionChanging
&& i != 0
&& mIsSmallScreen) {
// we just collapse this element slightly
int newSize =
(int)
Math.max(
bottomStackStart - mPaddingBetweenElements - childViewState.yTranslation,
mCollapsedSize);
childViewState.height = newSize;
updateStateForChildTransitioningInBottom(
algorithmState,
bottomStackStart,
bottomPeekStart,
childViewState.yTranslation,
childViewState,
childHeight);
}
clampPositionToBottomStackStart(childViewState, childViewState.height, ambientState);
} else if (nextYPosition >= bottomStackStart) {
// Case 2:
// We are in the bottom stack.
if (currentYPosition >= bottomStackStart) {
// According to the regular scroll view we are fully translated out of the
// bottom of the screen so we are fully in the bottom stack
updateStateForChildFullyInBottomStack(
algorithmState, bottomStackStart, childViewState, childHeight, ambientState);
} else {
// According to the regular scroll view we are currently translating out of /
// into the bottom of the screen
updateStateForChildTransitioningInBottom(
algorithmState,
bottomStackStart,
bottomPeekStart,
currentYPosition,
childViewState,
childHeight);
}
} else {
// Case 3:
// We are in the regular scroll area.
childViewState.location = StackViewState.LOCATION_MAIN_AREA;
clampYTranslation(childViewState, childHeight, ambientState);
}
// The first card is always rendered.
if (i == 0) {
childViewState.alpha = 1.0f;
childViewState.yTranslation = Math.max(mCollapsedSize - algorithmState.scrollY, 0);
if (childViewState.yTranslation + childViewState.height
> bottomPeekStart - mCollapseSecondCardPadding) {
childViewState.height =
(int)
Math.max(
bottomPeekStart - mCollapseSecondCardPadding - childViewState.yTranslation,
mCollapsedSize);
}
childViewState.location = StackViewState.LOCATION_FIRST_CARD;
}
if (childViewState.location == StackViewState.LOCATION_UNKNOWN) {
Log.wtf(LOG_TAG, "Failed to assign location for child " + i);
}
currentYPosition = childViewState.yTranslation + childHeight + mPaddingBetweenElements;
yPositionInScrollView = yPositionInScrollViewAfterElement;
if (ambientState.isShadeExpanded() && topHeadsUpEntry != null && child != topHeadsUpEntry) {
childViewState.yTranslation += topHeadsUpEntry.getHeadsUpHeight() - mCollapsedSize;
}
childViewState.yTranslation +=
ambientState.getTopPadding() + ambientState.getStackTranslation();
}
updateHeadsUpStates(resultState, algorithmState, ambientState);
}
