/*
* Copyright 2011 woozzu
*
* 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.yaoyumeng.v2ex.ui.widget;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.RectF;
import android.os.Handler;
import android.os.Message;
import android.os.SystemClock;
import android.support.v7.widget.RecyclerView;
import android.view.MotionEvent;
import android.widget.SectionIndexer;
public class IndexScroller {
private float mIndexbarWidth;
private float mIndexbarMargin;
private float mPreviewPadding;
private float mDensity;
private float mScaledDensity;
private float mAlphaRate;
private int mState = STATE_HIDDEN;
private int mListViewWidth;
private int mListViewHeight;
private int mCurrentSection = -1;
private boolean mIsIndexing = false;
private RecyclerView mRecyclerView = null;
private SectionIndexer mIndexer = null;
private String[] mSections = null;
private RectF mIndexbarRect;
private static final int STATE_HIDDEN = 0;
private static final int STATE_SHOWING = 1;
private static final int STATE_SHOWN = 2;
private static final int STATE_HIDING = 3;
public IndexScroller(Context context, RecyclerView lv) {
mDensity = context.getResources().getDisplayMetrics().density;
mScaledDensity = context.getResources().getDisplayMetrics().scaledDensity;
mRecyclerView = lv;
setAdapter(mRecyclerView.getAdapter());
mIndexbarWidth = 20 * mDensity;
mIndexbarMargin = 10 * mDensity;
mPreviewPadding = 5 * mDensity;
}
public void draw(Canvas canvas) {
if (mState == STATE_HIDDEN)
return;
// mAlphaRate determines the rate of opacity
Paint indexbarPaint = new Paint();
indexbarPaint.setColor(Color.BLACK);
indexbarPaint.setAlpha((int) (64 * mAlphaRate));
indexbarPaint.setAntiAlias(true);
canvas.drawRoundRect(mIndexbarRect, 5 * mDensity, 5 * mDensity, indexbarPaint);
if (mSections != null && mSections.length > 0) {
// Preview is shown when mCurrentSection is set
if (mCurrentSection >= 0) {
Paint previewPaint = new Paint();
previewPaint.setColor(Color.BLACK);
previewPaint.setAlpha(96);
previewPaint.setAntiAlias(true);
previewPaint.setShadowLayer(3, 0, 0, Color.argb(64, 0, 0, 0));
Paint previewTextPaint = new Paint();
previewTextPaint.setColor(Color.WHITE);
previewTextPaint.setAntiAlias(true);
previewTextPaint.setTextSize(50 * mScaledDensity);
float previewTextWidth = previewTextPaint.measureText(mSections[mCurrentSection]);
float previewSize = 2 * mPreviewPadding + previewTextPaint.descent() - previewTextPaint.ascent();
RectF previewRect = new RectF((mListViewWidth - previewSize) / 2
, (mListViewHeight - previewSize) / 2
, (mListViewWidth - previewSize) / 2 + previewSize
, (mListViewHeight - previewSize) / 2 + previewSize);
canvas.drawRoundRect(previewRect, 5 * mDensity, 5 * mDensity, previewPaint);
canvas.drawText(mSections[mCurrentSection], previewRect.left + (previewSize - previewTextWidth) / 2 - 1
, previewRect.top + mPreviewPadding - previewTextPaint.ascent() + 1, previewTextPaint);
}
Paint indexPaint = new Paint();
indexPaint.setColor(Color.WHITE);
indexPaint.setAlpha((int) (255 * mAlphaRate));
indexPaint.setAntiAlias(true);
indexPaint.setTextSize(12 * mScaledDensity);
float sectionHeight = (mIndexbarRect.height() - 2 * mIndexbarMargin) / mSections.length;
float paddingTop = (sectionHeight - (indexPaint.descent() - indexPaint.ascent())) / 2;
for (int i = 0; i < mSections.length; i++) {
float paddingLeft = (mIndexbarWidth - indexPaint.measureText(mSections[i])) / 2;
canvas.drawText(mSections[i], mIndexbarRect.left + paddingLeft
, mIndexbarRect.top + mIndexbarMargin + sectionHeight * i + paddingTop - indexPaint.ascent(), indexPaint);
}
}
}
public boolean onTouchEvent(MotionEvent ev) {
switch (ev.getAction()) {
case MotionEvent.ACTION_DOWN:
// If down event occurs inside index bar region, start indexing
if (mState != STATE_HIDDEN && contains(ev.getX(), ev.getY())) {
setState(STATE_SHOWN);
// It demonstrates that the motion event started from index bar
mIsIndexing = true;
// Determine which section the point is in, and move the list to that section
mCurrentSection = getSectionByPoint(ev.getY());
mRecyclerView.getLayoutManager().scrollToPosition(mIndexer.getPositionForSection(mCurrentSection));
return true;
}
break;
case MotionEvent.ACTION_MOVE:
if (mIsIndexing) {
// If this event moves inside index bar
if (contains(ev.getX(), ev.getY())) {
// Determine which section the point is in, and move the list to that section
mCurrentSection = getSectionByPoint(ev.getY());
mRecyclerView.getLayoutManager().scrollToPosition(mIndexer.getPositionForSection(mCurrentSection));
}
return true;
}
break;
case MotionEvent.ACTION_UP:
if (mIsIndexing) {
mIsIndexing = false;
mCurrentSection = -1;
}
if (mState == STATE_SHOWN)
setState(STATE_HIDING);
break;
}
return false;
}
public void onSizeChanged(int w, int h, int oldw, int oldh) {
mListViewWidth = w;
mListViewHeight = h;
mIndexbarRect = new RectF(w - mIndexbarMargin - mIndexbarWidth
, mIndexbarMargin
, w - mIndexbarMargin
, h - mIndexbarMargin);
}
public void show() {
if (mState == STATE_HIDDEN)
setState(STATE_SHOWING);
else if (mState == STATE_HIDING)
setState(STATE_HIDING);
}
public void hide() {
if (mState == STATE_SHOWN)
setState(STATE_HIDING);
}
public void setAdapter(RecyclerView.Adapter adapter) {
if (adapter instanceof SectionIndexer) {
mIndexer = (SectionIndexer) adapter;
mSections = (String[]) mIndexer.getSections();
}
}
private void setState(int state) {
if (state < STATE_HIDDEN || state > STATE_HIDING)
return;
mState = state;
switch (mState) {
case STATE_HIDDEN:
// Cancel any fade effect
mHandler.removeMessages(0);
break;
case STATE_SHOWING:
// Start to fade in
mAlphaRate = 0;
fade(0);
break;
case STATE_SHOWN:
// Cancel any fade effect
mHandler.removeMessages(0);
break;
case STATE_HIDING:
// Start to fade out after three seconds
mAlphaRate = 1;
fade(3000);
break;
}
}
public boolean contains(float x, float y) {
// Determine if the point is in index bar region, which includes the right margin of the bar
return (x >= mIndexbarRect.left && y >= mIndexbarRect.top && y <= mIndexbarRect.top + mIndexbarRect.height());
}
private int getSectionByPoint(float y) {
if (mSections == null || mSections.length == 0)
return 0;
if (y < mIndexbarRect.top + mIndexbarMargin)
return 0;
if (y >= mIndexbarRect.top + mIndexbarRect.height() - mIndexbarMargin)
return mSections.length - 1;
return (int) ((y - mIndexbarRect.top - mIndexbarMargin) / ((mIndexbarRect.height() - 2 * mIndexbarMargin) / mSections.length));
}
private void fade(long delay) {
mHandler.removeMessages(0);
mHandler.sendEmptyMessageAtTime(0, SystemClock.uptimeMillis() + delay);
}
private Handler mHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
super.handleMessage(msg);
switch (mState) {
case STATE_SHOWING:
// Fade in effect
mAlphaRate += (1 - mAlphaRate) * 0.2;
if (mAlphaRate > 0.9) {
mAlphaRate = 1;
setState(STATE_SHOWN);
}
mRecyclerView.invalidate();
fade(10);
break;
case STATE_SHOWN:
// If no action, hide automatically
setState(STATE_HIDING);
break;
case STATE_HIDING:
// Fade out effect
mAlphaRate -= mAlphaRate * 0.2;
if (mAlphaRate < 0.1) {
mAlphaRate = 0;
setState(STATE_HIDDEN);
}
mRecyclerView.invalidate();
fade(10);
break;
}
}
};
}