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The source code is released under:
GNU Lesser General Public License
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package com.woozzu.android.widget; /*w w w . ja v a2 s.c o m*/ /* * Copyright 2011 woozzu * * Modified in 2013 by Jos? Alcal? Correa * * 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. */ 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.view.MotionEvent; import android.widget.Adapter; import android.widget.ListView; 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 ListView mListView = null; private SectionIndexer mIndexer = 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, ListView lv) { mDensity = context.getResources().getDisplayMetrics().density; mScaledDensity = context.getResources().getDisplayMetrics().scaledDensity; mListView = lv; setAdapter(mListView.getAdapter()); mIndexbarWidth = 30 * 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); final Object [] sections = mIndexer.getSections(); if (sections != null && sections.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); String currentText = sections[mCurrentSection].toString(); float previewTextWidth = previewTextPaint.measureText(currentText); 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(currentText, 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) / sections.length; float paddingTop = (sectionHeight - (indexPaint.descent() - indexPaint.ascent())) / 2; for (int i = 0; i < sections.length; i++) { String text = sections[i].toString(); float paddingLeft = (mIndexbarWidth - indexPaint.measureText(text)) / 2; canvas.drawText(text, 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()); mListView.setSelection(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()); mListView.setSelection(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(Adapter adapter) { if (adapter instanceof SectionIndexer) { mIndexer = (SectionIndexer) adapter; } } 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; } } private 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) { Object [] sections = mIndexer.getSections(); if (sections == null || sections.length == 0) return 0; if (y < mIndexbarRect.top + mIndexbarMargin) return 0; if (y >= mIndexbarRect.top + mIndexbarRect.height() - mIndexbarMargin) return sections.length - 1; return (int) ((y - mIndexbarRect.top - mIndexbarMargin) / ((mIndexbarRect.height() - 2 * mIndexbarMargin) / sections.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); } mListView.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); } mListView.invalidate(); fade(10); break; } } }; }