/*******************************************************************************
* Copyright (c) 2011 Adam Shanks (ChainsDD)
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except 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.
******************************************************************************/
/*
* Copyright (C) 2010 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except 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.noshufou.android.su.widget;
import android.content.Context;
import android.content.res.ColorStateList;
import android.graphics.Canvas;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.view.View;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.TextView;
/**
* A ListView that maintains a header pinned at the top of the list. The
* pinned header can be pushed up and dissolved as needed.
*/
public class PinnedHeaderListView extends ListView {
/**
* Adapter interface. The list adapter must implement this interface.
*/
public interface PinnedHeaderAdapter {
/**
* Pinned header state: don't show the header.
*/
public static final int PINNED_HEADER_GONE = 0;
/**
* Pinned header state: show the header at the top of the list.
*/
public static final int PINNED_HEADER_VISIBLE = 1;
/**
* Pinned header state: show the header. If the header extends beyond
* the bottom of the first shown element, push it up and clip.
*/
public static final int PINNED_HEADER_PUSHED_UP = 2;
/**
* Computes the desired state of the pinned header for the given
* position of the first visible list item. Allowed return values are
* {@link #PINNED_HEADER_GONE}, {@link #PINNED_HEADER_VISIBLE} or
* {@link #PINNED_HEADER_PUSHED_UP}.
*/
int getPinnedHeaderState(int position);
/**
* Configures the pinned header view to match the first visible list item.
*
* @param header pinned header view.
* @param position position of the first visible list item.
* @param alpha fading of the header view, between 0 and 255.
*/
void configurePinnedHeader(View header, int position, int alpha);
}
private static final int MAX_ALPHA = 255;
private PinnedHeaderAdapter mAdapter;
private View mHeaderView;
private boolean mHeaderViewVisible;
private int mHeaderViewWidth;
private int mHeaderViewHeight;
public PinnedHeaderListView(Context context) {
super(context);
}
public PinnedHeaderListView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public PinnedHeaderListView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
public void setPinnedHeaderView(View view) {
mHeaderView = view;
if (mHeaderView != null) {
setFadingEdgeLength(0);
}
requestLayout();
}
@Override
public void setAdapter(ListAdapter adapter) {
super.setAdapter(adapter);
mAdapter = (PinnedHeaderAdapter)adapter;
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
if (mHeaderView != null) {
measureChild(mHeaderView, widthMeasureSpec, heightMeasureSpec);
mHeaderViewWidth = mHeaderView.getMeasuredWidth();
mHeaderViewHeight = mHeaderView.getMeasuredHeight();
}
}
@Override
protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
super.onLayout(changed, left, top, right, bottom);
if (mHeaderView != null) {
mHeaderView.layout(0, 0, mHeaderViewWidth, mHeaderViewHeight);
configureHeaderView(getFirstVisiblePosition());
}
}
public void configureHeaderView(int position) {
if (mHeaderView == null || getCount() == 0) {
return;
}
int state = mAdapter.getPinnedHeaderState(position);
switch (state) {
case PinnedHeaderAdapter.PINNED_HEADER_GONE: {
mHeaderViewVisible = false;
break;
}
case PinnedHeaderAdapter.PINNED_HEADER_VISIBLE: {
mAdapter.configurePinnedHeader(mHeaderView, position, MAX_ALPHA);
if (mHeaderView.getTop() != 0) {
mHeaderView.layout(0, 0, mHeaderViewWidth, mHeaderViewHeight);
}
mHeaderViewVisible = true;
break;
}
case PinnedHeaderAdapter.PINNED_HEADER_PUSHED_UP: {
View firstView = getChildAt(0);
int bottom = firstView.getBottom();
int headerHeight = mHeaderView.getHeight();
int y;
int alpha;
if (bottom < headerHeight) {
y = (bottom - headerHeight);
alpha = MAX_ALPHA * (headerHeight + y) / headerHeight;
} else {
y = 0;
alpha = MAX_ALPHA;
}
mAdapter.configurePinnedHeader(mHeaderView, position, alpha);
if (mHeaderView.getTop() != y) {
mHeaderView.layout(0, y, mHeaderViewWidth, mHeaderViewHeight + y);
}
mHeaderViewVisible = true;
break;
}
}
}
@Override
protected void dispatchDraw(Canvas canvas) {
super.dispatchDraw(canvas);
if (mHeaderViewVisible) {
drawChild(canvas, mHeaderView, getDrawingTime());
}
}
public final static class PinnedHeaderCache {
public TextView titleView;
public ColorStateList textColor;
public Drawable background;
}
}