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PiecewiseLinearIndentationFunctor.javaAPI DocAndroid 5.1 API4843Thu Mar 12 22:22:42 GMT 2015com.android.systemui.statusbar.stack

PiecewiseLinearIndentationFunctor

public class PiecewiseLinearIndentationFunctor extends StackIndentationFunctor
A Functor which interpolates the stack distance linearly based on base values. The base values are based on an interpolation between a linear function and a quadratic function

Fields Summary
private final ArrayList
mBaseValues
private final float
mLinearPart
Constructors Summary
PiecewiseLinearIndentationFunctor(int maxItemsInStack, int peekSize, int distanceToPeekStart, float linearPart)

param
maxItemsInStack The maximum number of items which should be visible at the same time, i.e the function returns totalTransitionDistance for the element with index maxItemsInStack
param
peekSize The visual appearance of this is how far the cards in the stack peek out below the top card and it is measured in real pixels. Note that the visual appearance does not necessarily always correspond to the actual visual distance below the top card but is a maximum, achieved when the next card just starts transitioning into the stack and the stack is full. If distanceToPeekStart is 0, we directly start at the peek, otherwise the first element transitions between 0 and distanceToPeekStart. Visualization: --------------------------------------------------- --- | | | | FIRST ITEM | | <- distanceToPeekStart | | | |---------------------------------------------------| --- --- |__________________SECOND ITEM______________________| | <- peekSize |===================================================| _|_
param
distanceToPeekStart The distance to the start of the peak.
param
linearPart The interpolation factor between the linear and the quadratic amount taken. This factor must be somewhere in [0 , 1]

        super(maxItemsInStack, peekSize, distanceToPeekStart);
        mBaseValues = new ArrayList<Float>(maxItemsInStack+1);
        initBaseValues();
        mLinearPart = linearPart;
Methods Summary
private intgetSumOfSquares(int n)
Get the sum of squares up to and including n, i.e sum(i * i, 1, n)

param
n the maximum square to include
return

        return n * (n + 1) * (2 * n + 1) / 6;
public floatgetValue(float itemsBefore)

        if (mStackStartsAtPeek) {
            // We directly start at the stack, so no initial interpolation.
            itemsBefore++;
        }
        if (itemsBefore < 0) {
            return 0;
        } else if (itemsBefore >= mMaxItemsInStack) {
            return mTotalTransitionDistance;
        }
        int below = (int) itemsBefore;
        float partialIn = itemsBefore - below;

        if (below == 0) {
            return mDistanceToPeekStart * partialIn;
        } else {
            float result = mDistanceToPeekStart;
            float progress = mBaseValues.get(below - 1) * (1 - partialIn)
                    + mBaseValues.get(below) * partialIn;
            result += (progress * (1 - mLinearPart)
                    + (itemsBefore - 1) / (mMaxItemsInStack - 1)  * mLinearPart) * mPeekSize;
            return result;
        }
private voidinitBaseValues()

        int sumOfSquares = getSumOfSquares(mMaxItemsInStack-1);
        int totalWeight = 0;
        mBaseValues.add(0.0f);
        for (int i = 0; i < mMaxItemsInStack - 1; i++) {
            totalWeight += (mMaxItemsInStack - i - 1) * (mMaxItemsInStack - i - 1);
            mBaseValues.add((float) totalWeight / sumOfSquares);
        }