/*
* Copyright (C) 2013 Sergej Shafarenka, halfbit.de
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file kt in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.mhacks.android.views;
import android.content.Context;
import android.database.DataSetObserver;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.PointF;
import android.graphics.Rect;
import android.graphics.drawable.GradientDrawable;
import android.graphics.drawable.GradientDrawable.Orientation;
import android.os.Parcelable;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.SoundEffectConstants;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.accessibility.AccessibilityEvent;
import android.widget.AbsListView;
import android.widget.HeaderViewListAdapter;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SectionIndexer;
import com.mhacks.android.BuildConfig;
/**
* ListView, which is capable to pin section views at its top while the rest is still scrolled.
*/
public class PinnedSectionListView extends ListView {
//-- inner classes
/** List adapter to be implemented for being used with PinnedSectionListView adapter. */
public static interface PinnedSectionListAdapter extends ListAdapter {
/** This method shall return 'true' if views of given type has to be pinned. */
boolean isItemViewTypePinned(int viewType);
}
/** Wrapper class for pinned section view and its position in the list. */
static class PinnedSection {
public View view;
public int position;
public long id;
}
//-- class fields
// fields used for handling touch events
private final Rect mTouchRect = new Rect();
private final PointF mTouchPoint = new PointF();
private int mTouchSlop;
private View mTouchTarget;
private MotionEvent mDownEvent;
// fields used for drawing shadow under a pinned section
private GradientDrawable mShadowDrawable;
private int mSectionsDistanceY;
private int mShadowHeight;
/** Delegating listener, can be null. */
OnScrollListener mDelegateOnScrollListener;
/** Shadow for being recycled, can be null. */
PinnedSection mRecycleSection;
/** shadow instance with a pinned view, can be null. */
PinnedSection mPinnedSection;
/** Pinned view Y-translation. We use it to stick pinned view to the next section. */
int mTranslateY;
/** Scroll listener which does the magic */
private final OnScrollListener mOnScrollListener = new OnScrollListener() {
@Override public void onScrollStateChanged(AbsListView view, int scrollState) {
if (mDelegateOnScrollListener != null) { // delegate
mDelegateOnScrollListener.onScrollStateChanged(view, scrollState);
}
}
@Override
public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
if (mDelegateOnScrollListener != null) { // delegate
mDelegateOnScrollListener.onScroll(view, firstVisibleItem, visibleItemCount, totalItemCount);
}
// get expected adapter or fail fast
ListAdapter adapter = getAdapter();
if (adapter == null || visibleItemCount == 0) return; // nothing to do
final boolean isFirstVisibleItemSection =
isItemViewTypePinned(adapter, adapter.getItemViewType(firstVisibleItem));
if (isFirstVisibleItemSection) {
View sectionView = getChildAt(0);
if (sectionView.getTop() == getPaddingTop()) { // view sticks to the top, no need for pinned shadow
destroyPinnedShadow();
} else { // section doesn't stick to the top, make sure we have a pinned shadow
ensureShadowForPosition(firstVisibleItem, firstVisibleItem, visibleItemCount);
}
} else { // section is not at the first visible position
int sectionPosition = findCurrentSectionPosition(firstVisibleItem);
if (sectionPosition > -1) { // we have section position
ensureShadowForPosition(sectionPosition, firstVisibleItem, visibleItemCount);
} else { // there is no section for the first visible item, destroy shadow
destroyPinnedShadow();
}
}
};
};
/** Default change observer. */
private final DataSetObserver mDataSetObserver = new DataSetObserver() {
@Override public void onChanged() {
recreatePinnedShadow();
};
@Override public void onInvalidated() {
recreatePinnedShadow();
}
};
//-- constructors
public PinnedSectionListView(Context context, AttributeSet attrs) {
super(context, attrs);
initView();
}
public PinnedSectionListView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
initView();
}
private void initView() {
setOnScrollListener(mOnScrollListener);
mTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();
initShadow(true);
}
//-- public API methods
public void setShadowVisible(boolean visible) {
initShadow(visible);
if (mPinnedSection != null) {
View v = mPinnedSection.view;
invalidate(v.getLeft(), v.getTop(), v.getRight(), v.getBottom() + mShadowHeight);
}
}
//-- pinned section drawing methods
public void initShadow(boolean visible) {
if (visible) {
if (mShadowDrawable == null) {
mShadowDrawable = new GradientDrawable(Orientation.TOP_BOTTOM,
new int[] { Color.parseColor("#ffa0a0a0"), Color.parseColor("#50a0a0a0"), Color.parseColor("#00a0a0a0")});
mShadowHeight = (int) (8 * getResources().getDisplayMetrics().density);
}
} else {
if (mShadowDrawable != null) {
mShadowDrawable = null;
mShadowHeight = 0;
}
}
}
/** Create shadow wrapper with a pinned view for a view at given position */
void createPinnedShadow(int position) {
// try to recycle shadow
PinnedSection pinnedShadow = mRecycleSection;
mRecycleSection = null;
// create new shadow, if needed
if (pinnedShadow == null) pinnedShadow = new PinnedSection();
// request new view using recycled view, if such
View pinnedView = getAdapter().getView(position, pinnedShadow.view, PinnedSectionListView.this);
// read layout parameters
LayoutParams layoutParams = (LayoutParams) pinnedView.getLayoutParams();
if (layoutParams == null) { // create default layout params
layoutParams = new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
}
int heightMode = MeasureSpec.getMode(layoutParams.height);
int heightSize = MeasureSpec.getSize(layoutParams.height);
if (heightMode == MeasureSpec.UNSPECIFIED) heightMode = MeasureSpec.EXACTLY;
int maxHeight = getHeight() - getListPaddingTop() - getListPaddingBottom();
if (heightSize > maxHeight) heightSize = maxHeight;
// measure & layout
int ws = MeasureSpec.makeMeasureSpec(getWidth() - getListPaddingLeft() - getListPaddingRight(), MeasureSpec.EXACTLY);
int hs = MeasureSpec.makeMeasureSpec(heightSize, heightMode);
pinnedView.measure(ws, hs);
pinnedView.layout(0, 0, pinnedView.getMeasuredWidth(), pinnedView.getMeasuredHeight());
mTranslateY = 0;
// initialize pinned shadow
pinnedShadow.view = pinnedView;
pinnedShadow.position = position;
pinnedShadow.id = getAdapter().getItemId(position);
// store pinned shadow
mPinnedSection = pinnedShadow;
}
/** Destroy shadow wrapper for currently pinned view */
void destroyPinnedShadow() {
if (mPinnedSection != null) {
// keep shadow for being recycled later
mRecycleSection = mPinnedSection;
mPinnedSection = null;
}
}
/** Makes sure we have an actual pinned shadow for given position. */
void ensureShadowForPosition(int sectionPosition, int firstVisibleItem, int visibleItemCount) {
if (visibleItemCount < 2) { // no need for creating shadow at all, we have a single visible item
destroyPinnedShadow();
return;
}
if (mPinnedSection != null
&& mPinnedSection.position != sectionPosition) { // invalidate shadow, if required
destroyPinnedShadow();
}
if (mPinnedSection == null) { // create shadow, if empty
createPinnedShadow(sectionPosition);
}
// align shadow according to next section position, if needed
int nextPosition = sectionPosition + 1;
if (nextPosition < getCount()) {
int nextSectionPosition = findFirstVisibleSectionPosition(nextPosition,
visibleItemCount - (nextPosition - firstVisibleItem));
if (nextSectionPosition > -1) {
View nextSectionView = getChildAt(nextSectionPosition - firstVisibleItem);
final int bottom = mPinnedSection.view.getBottom() + getPaddingTop();
mSectionsDistanceY = nextSectionView.getTop() - bottom;
if (mSectionsDistanceY < 0) {
// next section overlaps pinned shadow, move it up
mTranslateY = mSectionsDistanceY;
} else {
// next section does not overlap with pinned, stick to top
mTranslateY = 0;
}
} else {
// no other sections are visible, stick to top
mTranslateY = 0;
mSectionsDistanceY = Integer.MAX_VALUE;
}
}
}
int findFirstVisibleSectionPosition(int firstVisibleItem, int visibleItemCount) {
ListAdapter adapter = getAdapter();
for (int childIndex = 0; childIndex < visibleItemCount; childIndex++) {
int position = firstVisibleItem + childIndex;
int viewType = adapter.getItemViewType(position);
if (isItemViewTypePinned(adapter, viewType)) return position;
}
return -1;
}
int findCurrentSectionPosition(int fromPosition) {
ListAdapter adapter = getAdapter();
if (adapter instanceof SectionIndexer) {
// try fast way by asking section indexer
SectionIndexer indexer = (SectionIndexer) adapter;
int sectionPosition = indexer.getSectionForPosition(fromPosition);
int itemPosition = indexer.getPositionForSection(sectionPosition);
int typeView = adapter.getItemViewType(itemPosition);
if (isItemViewTypePinned(adapter, typeView)) {
return itemPosition;
} // else, no luck
}
// try slow way by looking through to the next section item above
for (int position=fromPosition; position>=0; position--) {
int viewType = adapter.getItemViewType(position);
if (isItemViewTypePinned(adapter, viewType)) return position;
}
return -1; // no candidate found
}
void recreatePinnedShadow() {
destroyPinnedShadow();
ListAdapter adapter = getAdapter();
if (adapter != null && adapter.getCount() > 0) {
int firstVisiblePosition = getFirstVisiblePosition();
int sectionPosition = findCurrentSectionPosition(firstVisiblePosition);
if (sectionPosition == -1) return; // no views to pin, exit
ensureShadowForPosition(sectionPosition,
firstVisiblePosition, getLastVisiblePosition() - firstVisiblePosition);
}
}
@Override
public void setOnScrollListener(OnScrollListener listener) {
if (listener == mOnScrollListener) {
super.setOnScrollListener(listener);
} else {
mDelegateOnScrollListener = listener;
}
}
@Override
public void onRestoreInstanceState(Parcelable state) {
super.onRestoreInstanceState(state);
post(new Runnable() {
@Override public void run() { // restore pinned view after configuration change
recreatePinnedShadow();
}
});
}
@Override
public void setAdapter(ListAdapter adapter) {
// assert adapter in debug mode
if (BuildConfig.DEBUG && adapter != null) {
if (!(adapter instanceof PinnedSectionListAdapter))
throw new IllegalArgumentException("Does your adapter implement PinnedSectionListAdapter?");
if (adapter.getViewTypeCount() < 2)
throw new IllegalArgumentException("Does your adapter handle at least two types" +
" of views in getViewTypeCount() method: items and sections?");
}
// unregister observer at old adapter and register on new one
ListAdapter oldAdapter = getAdapter();
if (oldAdapter != null) oldAdapter.unregisterDataSetObserver(mDataSetObserver);
if (adapter != null) adapter.registerDataSetObserver(mDataSetObserver);
// destroy pinned shadow, if new adapter is not same as old one
if (oldAdapter != adapter) destroyPinnedShadow();
super.setAdapter(adapter);
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
super.onLayout(changed, l, t, r, b);
if (mPinnedSection != null) {
int parentWidth = r - l - getPaddingLeft() - getPaddingRight();
int shadowWidth = mPinnedSection.view.getWidth();
if (parentWidth != shadowWidth) {
recreatePinnedShadow();
}
}
}
@Override
protected void dispatchDraw(Canvas canvas) {
super.dispatchDraw(canvas);
if (mPinnedSection != null) {
// prepare variables
int pLeft = getListPaddingLeft();
int pTop = getListPaddingTop();
View view = mPinnedSection.view;
// draw child
canvas.save();
int clipHeight = view.getHeight() +
(mShadowDrawable == null ? 0 : Math.min(mShadowHeight, mSectionsDistanceY));
canvas.clipRect(pLeft, pTop, pLeft + view.getWidth(), pTop + clipHeight);
canvas.translate(pLeft, pTop + mTranslateY);
drawChild(canvas, mPinnedSection.view, getDrawingTime());
if (mShadowDrawable != null && mSectionsDistanceY > 0) {
mShadowDrawable.setBounds(mPinnedSection.view.getLeft(),
mPinnedSection.view.getBottom(),
mPinnedSection.view.getRight(),
mPinnedSection.view.getBottom() + mShadowHeight);
mShadowDrawable.draw(canvas);
}
canvas.restore();
}
}
//-- touch handling methods
@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
final float x = ev.getX();
final float y = ev.getY();
final int action = ev.getAction();
if (action == MotionEvent.ACTION_DOWN
&& mTouchTarget == null
&& mPinnedSection != null
&& isPinnedViewTouched(mPinnedSection.view, x, y)) { // create touch target
// user touched pinned view
mTouchTarget = mPinnedSection.view;
mTouchPoint.x = x;
mTouchPoint.y = y;
// copy down event for eventually be used later
mDownEvent = MotionEvent.obtain(ev);
}
if (mTouchTarget != null) {
if (isPinnedViewTouched(mTouchTarget, x, y)) { // forward event to pinned view
mTouchTarget.dispatchTouchEvent(ev);
}
if (action == MotionEvent.ACTION_UP) { // perform onClick on pinned view
super.dispatchTouchEvent(ev);
performPinnedItemClick();
clearTouchTarget();
} else if (action == MotionEvent.ACTION_CANCEL) { // cancel
clearTouchTarget();
} else if (action == MotionEvent.ACTION_MOVE) {
if (Math.abs(y - mTouchPoint.y) > mTouchSlop) {
// cancel sequence on touch target
MotionEvent event = MotionEvent.obtain(ev);
event.setAction(MotionEvent.ACTION_CANCEL);
mTouchTarget.dispatchTouchEvent(event);
event.recycle();
// provide correct sequence to super class for further handling
super.dispatchTouchEvent(mDownEvent);
super.dispatchTouchEvent(ev);
clearTouchTarget();
}
}
return true;
}
// call super if this was not our pinned view
return super.dispatchTouchEvent(ev);
}
private boolean isPinnedViewTouched(View view, float x, float y) {
view.getHitRect(mTouchRect);
// by taping top or bottom padding, the list performs on click on a border item.
// we don't add top padding here to keep behavior consistent.
mTouchRect.top += mTranslateY;
mTouchRect.bottom += mTranslateY + getPaddingTop();
mTouchRect.left += getPaddingLeft();
mTouchRect.right -= getPaddingRight();
return mTouchRect.contains((int)x, (int)y);
}
private void clearTouchTarget() {
mTouchTarget = null;
if (mDownEvent != null) {
mDownEvent.recycle();
mDownEvent = null;
}
}
private boolean performPinnedItemClick() {
if (mPinnedSection == null) return false;
OnItemClickListener listener = getOnItemClickListener();
if (listener != null) {
View view = mPinnedSection.view;
playSoundEffect(SoundEffectConstants.CLICK);
if (view != null) {
view.sendAccessibilityEvent(AccessibilityEvent.TYPE_VIEW_CLICKED);
}
listener.onItemClick(this, view, mPinnedSection.position, mPinnedSection.id);
return true;
}
return false;
}
public static boolean isItemViewTypePinned(ListAdapter adapter, int viewType) {
if (adapter instanceof HeaderViewListAdapter) {
adapter = ((HeaderViewListAdapter)adapter).getWrappedAdapter();
}
return ((PinnedSectionListAdapter) adapter).isItemViewTypePinned(viewType);
}
}