package
com.devsmart.android.ui;
import
java.util.LinkedList;
import
java.util.Queue;
import
android.content.Context;
import
android.database.DataSetObserver;
import
android.graphics.Rect;
import
android.util.AttributeSet;
import
android.view.GestureDetector;
import
android.view.GestureDetector.OnGestureListener;
import
android.view.MotionEvent;
import
android.view.View;
import
android.widget.AdapterView;
import
android.widget.ListAdapter;
import
android.widget.Scroller;
public
class
HorizontalListView
extends
AdapterView<ListAdapter> {
public
boolean
mAlwaysOverrideTouch =
true
;
protected
ListAdapter mAdapter;
private
int
mLeftViewIndex = -
1
;
private
int
mRightViewIndex =
0
;
protected
int
mCurrentX;
protected
int
mNextX;
private
int
mMaxX = Integer.MAX_VALUE;
private
int
mDisplayOffset =
0
;
protected
Scroller mScroller;
private
GestureDetector mGesture;
private
Queue<View> mRemovedViewQueue =
new
LinkedList<View>();
private
OnItemSelectedListener mOnItemSelected;
private
OnItemClickListener mOnItemClicked;
private
OnItemLongClickListener mOnItemLongClicked;
private
boolean
mDataChanged =
false
;
public
HorizontalListView(Context context, AttributeSet attrs) {
super
(context, attrs);
initView();
}
private
synchronized
void
initView() {
mLeftViewIndex = -
1
;
mRightViewIndex =
0
;
mDisplayOffset =
0
;
mCurrentX =
0
;
mNextX =
0
;
mMaxX = Integer.MAX_VALUE;
mScroller =
new
Scroller(getContext());
mGesture =
new
GestureDetector(getContext(), mOnGesture);
}
@Override
public
void
setOnItemSelectedListener(AdapterView.OnItemSelectedListener listener) {
mOnItemSelected = listener;
}
@Override
public
void
setOnItemClickListener(AdapterView.OnItemClickListener listener){
mOnItemClicked = listener;
}
@Override
public
void
setOnItemLongClickListener(AdapterView.OnItemLongClickListener listener) {
mOnItemLongClicked = listener;
}
private
DataSetObserver mDataObserver =
new
DataSetObserver() {
@Override
public
void
onChanged() {
synchronized
(HorizontalListView.
this
){
mDataChanged =
true
;
}
invalidate();
requestLayout();
}
@Override
public
void
onInvalidated() {
reset();
invalidate();
requestLayout();
}
};
@Override
public
ListAdapter getAdapter() {
return
mAdapter;
}
@Override
public
View getSelectedView() {
return
null
;
}
@Override
public
void
setAdapter(ListAdapter adapter) {
if
(mAdapter !=
null
) {
mAdapter.unregisterDataSetObserver(mDataObserver);
}
mAdapter = adapter;
mAdapter.registerDataSetObserver(mDataObserver);
reset();
}
private
synchronized
void
reset(){
initView();
removeAllViewsInLayout();
requestLayout();
}
@Override
public
void
setSelection(
int
position) {
}
private
void
addAndMeasureChild(
final
View child,
int
viewPos) {
LayoutParams params = child.getLayoutParams();
if
(params ==
null
) {
params =
new
LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT);
}
addViewInLayout(child, viewPos, params,
true
);
child.measure(MeasureSpec.makeMeasureSpec(getWidth(), MeasureSpec.AT_MOST),
MeasureSpec.makeMeasureSpec(getHeight(), MeasureSpec.AT_MOST));
}
@Override
protected
synchronized
void
onLayout(
boolean
changed,
int
left,
int
top,
int
right,
int
bottom) {
super
.onLayout(changed, left, top, right, bottom);
if
(mAdapter ==
null
){
return
;
}
if
(mDataChanged){
int
oldCurrentX = mCurrentX;
initView();
removeAllViewsInLayout();
mNextX = oldCurrentX;
mDataChanged =
false
;
}
if
(mScroller.computeScrollOffset()){
int
scrollx = mScroller.getCurrX();
mNextX = scrollx;
}
if
(mNextX <=
0
){
mNextX =
0
;
mScroller.forceFinished(
true
);
}
if
(mNextX >= mMaxX) {
mNextX = mMaxX;
mScroller.forceFinished(
true
);
}
int
dx = mCurrentX - mNextX;
removeNonVisibleItems(dx);
fillList(dx);
positionItems(dx);
mCurrentX = mNextX;
if
(!mScroller.isFinished()){
post(
new
Runnable(){
@Override
public
void
run() {
requestLayout();
}
});
}
}
private
void
fillList(
final
int
dx) {
int
edge =
0
;
View child = getChildAt(getChildCount()-
1
);
if
(child !=
null
) {
edge = child.getRight();
}
fillListRight(edge, dx);
edge =
0
;
child = getChildAt(
0
);
if
(child !=
null
) {
edge = child.getLeft();
}
fillListLeft(edge, dx);
}
private
void
fillListRight(
int
rightEdge,
final
int
dx) {
while
(rightEdge + dx < getWidth() && mRightViewIndex < mAdapter.getCount()) {
View child = mAdapter.getView(mRightViewIndex, mRemovedViewQueue.poll(),
this
);
addAndMeasureChild(child, -
1
);
rightEdge += child.getMeasuredWidth();
if
(mRightViewIndex == mAdapter.getCount()-
1
) {
mMaxX = mCurrentX + rightEdge - getWidth();
}
if
(mMaxX <
0
) {
mMaxX =
0
;
}
mRightViewIndex++;
}
}
private
void
fillListLeft(
int
leftEdge,
final
int
dx) {
while
(leftEdge + dx >
0
&& mLeftViewIndex >=
0
) {
View child = mAdapter.getView(mLeftViewIndex, mRemovedViewQueue.poll(),
this
);
addAndMeasureChild(child,
0
);
leftEdge -= child.getMeasuredWidth();
mLeftViewIndex--;
mDisplayOffset -= child.getMeasuredWidth();
}
}
private
void
removeNonVisibleItems(
final
int
dx) {
View child = getChildAt(
0
);
while
(child !=
null
&& child.getRight() + dx <=
0
) {
mDisplayOffset += child.getMeasuredWidth();
mRemovedViewQueue.offer(child);
removeViewInLayout(child);
mLeftViewIndex++;
child = getChildAt(
0
);
}
child = getChildAt(getChildCount()-
1
);
while
(child !=
null
&& child.getLeft() + dx >= getWidth()) {
mRemovedViewQueue.offer(child);
removeViewInLayout(child);
mRightViewIndex--;
child = getChildAt(getChildCount()-
1
);
}
}
private
void
positionItems(
final
int
dx) {
if
(getChildCount() >
0
){
mDisplayOffset += dx;
int
left = mDisplayOffset;
for
(
int
i=
0
;i<getChildCount();i++){
View child = getChildAt(i);
int
childWidth = child.getMeasuredWidth();
child.layout(left,
0
, left + childWidth, child.getMeasuredHeight());
left += childWidth + child.getPaddingRight();
}
}
}
public
synchronized
void
scrollTo(
int
x) {
mScroller.startScroll(mNextX,
0
, x - mNextX,
0
);
requestLayout();
}
@Override
public
boolean
dispatchTouchEvent(MotionEvent ev) {
boolean
handled =
super
.dispatchTouchEvent(ev);
handled |= mGesture.onTouchEvent(ev);
return
handled;
}
protected
boolean
onFling(MotionEvent e1, MotionEvent e2,
float
velocityX,
float
velocityY) {
synchronized
(HorizontalListView.
this
){
mScroller.fling(mNextX,
0
, (
int
)-velocityX,
0
,
0
, mMaxX,
0
,
0
);
}
requestLayout();
return
true
;
}
protected
boolean
onDown(MotionEvent e) {
mScroller.forceFinished(
true
);
return
true
;
}
private
OnGestureListener mOnGesture =
new
GestureDetector.SimpleOnGestureListener() {
@Override
public
boolean
onDown(MotionEvent e) {
return
HorizontalListView.
this
.onDown(e);
}
@Override
public
boolean
onFling(MotionEvent e1, MotionEvent e2,
float
velocityX,
float
velocityY) {
return
HorizontalListView.
this
.onFling(e1, e2, velocityX, velocityY);
}
@Override
public
boolean
onScroll(MotionEvent e1, MotionEvent e2,
float
distanceX,
float
distanceY) {
synchronized
(HorizontalListView.
this
){
mNextX += (
int
)distanceX;
}
requestLayout();
return
true
;
}
@Override
public
boolean
onSingleTapConfirmed(MotionEvent e) {
for
(
int
i=
0
;i<getChildCount();i++){
View child = getChildAt(i);
if
(isEventWithinView(e, child)) {
if
(mOnItemClicked !=
null
){
mOnItemClicked.onItemClick(HorizontalListView.
this
, child, mLeftViewIndex +
1
+ i, mAdapter.getItemId( mLeftViewIndex +
1
+ i ));
}
if
(mOnItemSelected !=
null
){
mOnItemSelected.onItemSelected(HorizontalListView.
this
, child, mLeftViewIndex +
1
+ i, mAdapter.getItemId( mLeftViewIndex +
1
+ i ));
}
break
;
}
}
return
true
;
}
@Override
public
void
onLongPress(MotionEvent e) {
int
childCount = getChildCount();
for
(
int
i =
0
; i < childCount; i++) {
View child = getChildAt(i);
if
(isEventWithinView(e, child)) {
if
(mOnItemLongClicked !=
null
) {
mOnItemLongClicked.onItemLongClick(HorizontalListView.
this
, child, mLeftViewIndex +
1
+ i, mAdapter.getItemId(mLeftViewIndex +
1
+ i));
}
break
;
}
}
}
private
boolean
isEventWithinView(MotionEvent e, View child) {
Rect viewRect =
new
Rect();
int
[] childPosition =
new
int
[
2
];
child.getLocationOnScreen(childPosition);
int
left = childPosition[
0
];
int
right = left + child.getWidth();
int
top = childPosition[
1
];
int
bottom = top + child.getHeight();
viewRect.set(left, top, right, bottom);
return
viewRect.contains((
int
) e.getRawX(), (
int
) e.getRawY());
}
};
}
