Combination with FadingActionBar possible?

[Zordid]

Hi!
I try to combine your sticky headers with a fading action bar as in FadingActionBar library. The problem is, that the headers "stick" behind the opaque action bar (because the action bar starts out transparent and fades to opaque) - which is of course contradicting the purpose of stuck headers.
I would need to tell your list to stick the headers right below the action bar even though the original measurement gives your list the impression it has more room on top which it kind of loses when the user scrolls down.
Is that possible? Do you see a way to maybe tell the headers where exactly to stick?
Thanks!
Olaf

[Zordid]

Just fyi, I did a small change to the method drawStickyHeader - adding a top offset like this in line 2:

int top = mHeaderBottomPosition - headerHeight + mHeaderTopOffset;

where mHeaderTopOffset is a new settable field that my onCreate method sets to exactly the size of the action bar.
This is of course not the solution, it just draws the stuck header at the desired position, but when scrolling to it, it does not yet work correctly... :-(

[Zordid]

Could you give me some hints on how to implement this myselff? I desparately need this feature. Or do you need more explanation on what I want to achieve?

[Zordid]

This picture demonstrates where the header gets fixed - behind the ActionBar

[emilsjolander]

I prioritised other issues before this one. Did you fix this in a good way you would like to share? :)

[Zordid]

Hi Emil,

yeah - I worked around that thing for my situation. I didn't really have
the time yet to get familiar with git at all. For all I know, I have to
clone the repo, commit to my and then issue a pull request - ist that
right??

Greetings,
OIaf

Am 26.10.2013 00:03, schrieb Emil Sjölander:

I prioritised other issues before this one. Did you fix this in a good
way you would like to share? :)

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#146 (comment).

[emilsjolander]

thats correct yes :)

[Zordid]

Okay! I will try! That would be my first time... give me a couple of
days, I'm not at my developer machine at the moment!

Am 06.11.2013 20:06, schrieb Emil Sjölander:

thats correct yes :)

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#146 (comment).

[iKiKi]

@Zordid
Hi, I'm currently exactly trying to combine StickyListHeaders with FadingActionBar, how about that.
What did you do to combine them ? Did you push a PR ?

[Zordid]

Not yet. I will use the holiday time to get at it again. I can explain how I combined them successfully!

KiKi notifications@github.com schrieb:

@Zordid
Hi, I'm currently exactly trying to combine StickyListHeaders with
FadingActionBar, how about that.
What did you do to combine them ? Did you push a PR ?

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#146 (comment)

[iKiKi]

I made changes in FadeActionBar lib to combine it with StickyListHeaders but sticky headers stay at the top of the frame, hidden by the ActionBar. I would be interested to have your explanation, how did you achieve to display sticky headers just above the ActionBar ?

[TannerPerrien]

+1 -- I would love to see a solution here!

[Zordid]

Within the old 1.x version of StickyListHeaders I was able to solve this by adding a member field

private int mHeaderTopOffset = 0;

to the class StickyListHeadersListView, along with a setter metho

public void setHeaderTopOffset(final int headerTopOffset) {
    mHeaderTopOffset = headerTopOffset;
}

This offset could be set to the height of the Action Bar like this:

listView.setHeaderTopOffset(Utils.getActionBarHeight(getActivity()));

using this helper method from StackOverflow:

/**
 * Determines the height of the action bar from the given context.
 * <p>
 * Taken from: http://stackoverflow.com/a/15476793/273456
 * 
 * @param context
 * @return the height in pixels
 */
public static int getActionBarHeight(final Context context) {
    int actionBarHeight = 0;
    final TypedValue tv = new TypedValue();
    final Theme theme = context.getTheme();
    final DisplayMetrics displayMetrics = context.getResources().getDisplayMetrics();
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
        if (theme.resolveAttribute(android.R.attr.actionBarSize, tv, true)) {
            actionBarHeight = TypedValue.complexToDimensionPixelSize(tv.data, displayMetrics);
        }
    } else if (theme.resolveAttribute(com.actionbarsherlock.R.attr.actionBarSize, tv, true)) {
        actionBarHeight = TypedValue.complexToDimensionPixelSize(tv.data, displayMetrics);
    }
    return actionBarHeight;
}

The real work within StickyListHeaders consisted of these changes:

1. adjust the top variable here:

private void drawStickyHeader(final Canvas canvas) {
    int headerHeight = getHeaderHeight();
    int top = mHeaderBottomPosition - headerHeight + mHeaderTopOffset;
    // clip the headers drawing region
    mClippingRect.left = getPaddingLeft();
    mClippingRect.right = getWidth() - getPaddingRight();
    mClippingRect.bottom = top + headerHeight;
    mClippingRect.top = mClippingToPadding ? getPaddingTop() : 0;

    canvas.save();
    canvas.clipRect(mClippingRect);
    canvas.translate(getPaddingLeft(), top);
    mHeader.draw(canvas);
    canvas.restore();
}

2. within scrollChanged (two changes: calling fixedFirstVisibleItemWithOffset instead of fixedFirstVisibleItem at the beginning and at the end, see use of the member field when calculating mHeaderBottomPosition)

private void scrollChanged(final int reportedFirstVisibleItem) {

    int adapterCount = mAdapter == null ? 0 : mAdapter.getCount();
    if (adapterCount == 0 || !mAreHeadersSticky) {
        return;
    }

    final int listViewHeaderCount = getHeaderViewsCount();
    int firstVisibleItem = fixedFirstVisibleItemWithOffset(reportedFirstVisibleItem) - listViewHeaderCount;

    if (firstVisibleItem < 0 || firstVisibleItem > adapterCount - 1) {
        reset();
        updateHeaderVisibilities();
        invalidate();
        return;
    }

    long newHeaderId = mAdapter.getHeaderId(firstVisibleItem);
    if (mCurrentHeaderId == null || mCurrentHeaderId != newHeaderId) {
        mHeaderPosition = firstVisibleItem;
        mCurrentHeaderId = newHeaderId;
        mHeader = mAdapter.getHeaderView(mHeaderPosition, mHeader, this);
        measureHeader();
    }

    int childCount = getChildCount();
    if (childCount != 0) {
        View viewToWatch = null;
        int watchingChildDistance = Integer.MAX_VALUE;
        boolean viewToWatchIsFooter = false;

        for (int i = 0; i < childCount; i++) {
            final View child = super.getChildAt(i);
            final boolean childIsFooter = mFooterViews != null && mFooterViews.contains(child);

            final int childDistance = child.getTop() - (mClippingToPadding ? getPaddingTop() : 0);
            if (childDistance < 0) {
                continue;
            }

            if (viewToWatch == null
                    || (!viewToWatchIsFooter && !((WrapperView) viewToWatch).hasHeader())
                    || ((childIsFooter || ((WrapperView) child).hasHeader()) && childDistance < watchingChildDistance)) {
                viewToWatch = child;
                viewToWatchIsFooter = childIsFooter;
                watchingChildDistance = childDistance;
            }
        }

        final int headerHeight = getHeaderHeight();
        if (viewToWatch != null && (viewToWatchIsFooter || ((WrapperView) viewToWatch).hasHeader())) {
            if (firstVisibleItem == listViewHeaderCount && super.getChildAt(0).getTop() > 0 && !mClippingToPadding) {
                mHeaderBottomPosition = 0;
            } else {
                final int paddingTop = mClippingToPadding ? getPaddingTop() : 0;
                mHeaderBottomPosition = Math
                        .min(viewToWatch.getTop() - mHeaderTopOffset, headerHeight + paddingTop);
                mHeaderBottomPosition = mHeaderBottomPosition < paddingTop ? headerHeight + paddingTop
                        : mHeaderBottomPosition;
            }
        } else {
            mHeaderBottomPosition = headerHeight + (mClippingToPadding ? getPaddingTop() : 0);
        }
    }
    updateHeaderVisibilities();
    invalidate();
}

3. adding the new helper method:

private int fixedFirstVisibleItemWithOffset(int firstVisibleItem) {
    if (mHeaderTopOffset == 0) {
        return fixedFirstVisibleItem(firstVisibleItem);
    }

    for (int i = 0; i < getChildCount(); i++) {
        if (getChildAt(i).getBottom() >= mHeaderTopOffset) {
            firstVisibleItem += i;
            break;
        }
    }

    // work around to fix bug with firstVisibleItem being to high because
    // listview does not take clipToPadding=false into account
    if (!mClippingToPadding && getPaddingTop() > 0) {
        if (super.getChildAt(0).getTop() > mHeaderTopOffset) {
            if (firstVisibleItem > 0) {
                firstVisibleItem -= 1;
            }
        }
    }
    return firstVisibleItem;
}

With these changes, StickyListHeaders worked flawlessly together with FadingActionBar!
I don't know how to add this in the new 2.x version, haven't looked at it yet!

[emilsjolander]

I was discussing a similar issue (transparent action bar) with a friend yesterday and we almost implemented a setStickyHeaderMarginTop() method but quickly saw the problem with this solution. The problem arises when a new header come into place, what should be done with the old header? It has no logical place to be. So that's the current issue, it's a minor issue from a library/code standpoint but a big issue from a user experience standpoint.

[Zordid]

Hi!
No, I can't see a problem there at all. Are we talking about the same situation? Fading Actionbar fades from transparent to opaque - the old header is not visible anymore.
Maybe that only works good because for this to look perfect you need a header image to leave enough room for something to scroll underneath the action bar. By the time the very first header reaches the action bar, it is already completely opaque.
Wanna see my app, I could mail it to you.

"Emil Sjölander" notifications@github.com schrieb:

I was discussing a similar issue (transparent action bar) with a friend
yesterday and we almost implemented a setStickyHeaderMarginTop()
method but quickly saw the problem with this solution. The problem
arises when a new header come into place, what should be done with the
old header? It has no logical place to be. So that's the current issue,
it's a minor issue from a library/code standpoint but a big issue from
a user experience standpoint.

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#146 (comment)

[emilsjolander]

Well no it's not a problem for integrating with FadingActionBar but when adding an api like this we must look at all it's use cases, one big use case would be having the header stick at the bottom of a translucent action bar. While you are thinking about this from the view point of your app (which is totally valid) i have to think of this from the view point of a very general library that can be used in all sorts of applications.