Example usage for android.widget EdgeEffect onPull

Introduction

In this page you can find the example usage for android.widget EdgeEffect onPull.

Prototype

public void onPull(float deltaDistance) 

Source Link

Document

A view should call this when content is pulled away from an edge by the user.

Usage

From source file:net.simonvt.staggeredgridview.StaggeredGridView.java

/**
 * @param deltaY Pixels that content should move by
 * @return true if the movement completed, false if it was stopped prematurely.
 *//*from   ww  w  .  j a va 2  s .  c o  m*/
private boolean trackMotionScroll(int deltaY, boolean allowOverScroll) {
    final boolean contentFits = contentFits();
    final int allowOverhang = Math.abs(deltaY);

    final int overScrolledBy;
    final int movedBy;
    if (!contentFits) {
        final int overhang;
        final boolean up;
        populating = true;
        if (deltaY > 0) {
            overhang = fillUp(firstPosition - 1, allowOverhang);
            up = true;
        } else {
            overhang = fillDown(firstPosition + getChildCount(), allowOverhang);
            up = false;
        }
        movedBy = Math.min(overhang, allowOverhang);
        offsetChildren(up ? movedBy : -movedBy);
        recycleOffscreenViews();
        populating = false;
        overScrolledBy = allowOverhang - overhang;
    } else {
        overScrolledBy = allowOverhang;
        movedBy = 0;
    }

    if (allowOverScroll) {
        final int overScrollMode = getOverScrollMode();

        if (overScrollMode == OVER_SCROLL_ALWAYS
                || (overScrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && !contentFits)) {

            if (overScrolledBy > 0) {
                EdgeEffect edge = deltaY > 0 ? topEdge : bottomEdge;
                edge.onPull((float) Math.abs(deltaY) / getHeight());
                postInvalidateOnAnimation();
            }
        }
    }

    if (!awakenScrollBars()) {
        invalidate();
    }

    correctTooLow();

    return deltaY == 0 || movedBy != 0;
}

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From source file:com.android.internal.widget.ViewPager.java

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

    final int width = getPaddedWidth();
    final float deltaX = mLastMotionX - x;
    mLastMotionX = x;/*from   ww  w  .  j a  v a  2  s  . c o m*/

    final EdgeEffect startEdge;
    final EdgeEffect endEdge;
    if (isLayoutRtl()) {
        startEdge = mRightEdge;
        endEdge = mLeftEdge;
    } else {
        startEdge = mLeftEdge;
        endEdge = mRightEdge;
    }

    // Translate scroll to relative coordinates.
    final float nextScrollX = getScrollX() + deltaX;
    final float scrollStart;
    if (isLayoutRtl()) {
        scrollStart = MAX_SCROLL_X - nextScrollX;
    } else {
        scrollStart = nextScrollX;
    }

    final float startBound;
    final ItemInfo startItem = mItems.get(0);
    final boolean startAbsolute = startItem.position == 0;
    if (startAbsolute) {
        startBound = startItem.offset * width;
    } else {
        startBound = width * mFirstOffset;
    }

    final float endBound;
    final ItemInfo endItem = mItems.get(mItems.size() - 1);
    final boolean endAbsolute = endItem.position == mAdapter.getCount() - 1;
    if (endAbsolute) {
        endBound = endItem.offset * width;
    } else {
        endBound = width * mLastOffset;
    }

    final float clampedScrollStart;
    if (scrollStart < startBound) {
        if (startAbsolute) {
            final float over = startBound - scrollStart;
            startEdge.onPull(Math.abs(over) / width);
            needsInvalidate = true;
        }
        clampedScrollStart = startBound;
    } else if (scrollStart > endBound) {
        if (endAbsolute) {
            final float over = scrollStart - endBound;
            endEdge.onPull(Math.abs(over) / width);
            needsInvalidate = true;
        }
        clampedScrollStart = endBound;
    } else {
        clampedScrollStart = scrollStart;
    }

    // Translate back to absolute coordinates.
    final float targetScrollX;
    if (isLayoutRtl()) {
        targetScrollX = MAX_SCROLL_X - clampedScrollStart;
    } else {
        targetScrollX = clampedScrollStart;
    }

    // Don't lose the rounded component.
    mLastMotionX += targetScrollX - (int) targetScrollX;

    scrollTo((int) targetScrollX, getScrollY());
    pageScrolled((int) targetScrollX);

    return needsInvalidate;
}

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