ListView保持在列表的顶部固定View 案例分析 源码.zip

/* * Copyright (C) 2008 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.android.contacts; package com.miss.sos; import com.miss.sos.R; import android.content.Context; import android.content.res.Resources; import android.graphics.Canvas; import android.graphics.Paint; import android.graphics.RectF; import android.graphics.drawable.Drawable; import android.os.Handler; import android.os.SystemClock; import android.util.AttributeSet; import android.view.MotionEvent; import android.view.View; import android.view.ViewGroup.OnHierarchyChangeListener; import android.widget.AbsListView; import android.widget.Adapter; import android.widget.BaseAdapter; import android.widget.FrameLayout; import android.widget.HeaderViewListAdapter; import android.widget.ListView; import android.widget.AbsListView.OnScrollListener; /** * FastScrollView is meant for embedding {@link ListView}s that contain a large number of * items that can be indexed in some fashion. It displays a special scroll bar that allows jumping * quickly to indexed sections of the list in touch-mode. Only one child can be added to this * view group and it must be a {@link ListView}, with an adapter that is derived from * {@link BaseAdapter}. */ public class FastScrollView extends FrameLayout implements OnScrollListener, OnHierarchyChangeListener { private Drawable mCurrentThumb; private Drawable mOverlayDrawable; private int mThumbH; private int mThumbW; private int mThumbY; private RectF mOverlayPos; // Hard coding these for now private int mOverlaySize = 104; private boolean mDragging; private ListView mList; private boolean mScrollCompleted; private boolean mThumbVisible; private int mVisibleItem; private Paint mPaint; private int mListOffset; private Object [] mSections; private String mSectionText; private boolean mDrawOverlay; private ScrollFade mScrollFade; private Handler mHandler = new Handler(); private BaseAdapter mListAdapter; private boolean mChangedBounds; interface SectionIndexer { Object[] getSections(); int getPositionForSection(int section); int getSectionForPosition(int position); } public FastScrollView(Context context) { super(context); init(context); } public FastScrollView(Context context, AttributeSet attrs) { super(context, attrs); init(context); } public FastScrollView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); init(context); } private void useThumbDrawable(Drawable drawable) { mCurrentThumb = drawable; mThumbW = 64; //mCurrentThumb.getIntrinsicWidth(); mThumbH = 52; //mCurrentThumb.getIntrinsicHeight(); mChangedBounds = true; } private void init(Context context) { // Get both the scrollbar states drawables final Resources res = context.getResources(); useThumbDrawable(res.getDrawable( R.drawable.scrollbar_handle_accelerated_anim2)); mOverlayDrawable = res.getDrawable(R.drawable.dialog_full_dark); mScrollCompleted = true; setWillNotDraw(false); // Need to know when the ListView is added setOnHierarchyChangeListener(this); mOverlayPos = new RectF(); mScrollFade = new ScrollFade(); mPaint = new Paint(); mPaint.setAntiAlias(true); mPaint.setTextAlign(Paint.Align.CENTER); mPaint.setTextSize(mOverlaySize / 2); mPaint.setColor(0xFFFFFFFF); mPaint.setStyle(Paint.Style.FILL_AND_STROKE); } private void removeThumb() { mThumbVisible = false; // Draw one last time to remove thumb invalidate(); } @Override public void draw(Canvas canvas) { super.draw(canvas); if (!mThumbVisible) { // No need to draw the rest return; } final int y = mThumbY; final int viewWidth = getWidth(); final FastScrollView.ScrollFade scrollFade = mScrollFade; int alpha = -1; if (scrollFade.mStarted) { alpha = scrollFade.getAlpha(); if (alpha < ScrollFade.ALPHA_MAX / 2) { mCurrentThumb.setAlpha(alpha * 2); } int left = viewWidth - (mThumbW * alpha) / ScrollFade.ALPHA_MAX; mCurrentThumb.setBounds(left, 0, viewWidth, mThumbH); mChangedBounds = true; } canvas.translate(0, y); mCurrentThumb.draw(canvas); canvas.translate(0, -y); // If user is dragging the scroll bar, draw the alphabet overlay if (mDragging && mDrawOverlay) { mOverlayDrawable.draw(canvas); final Paint paint = mPaint; float descent = paint.descent(); final RectF rectF = mOverlayPos; canvas.drawText(mSectionText, (int) (rectF.left + rectF.right) / 2, (int) (rectF.bottom + rectF.top) / 2 + mOverlaySize / 4 - descent, paint); } else if (alpha == 0) { scrollFade.mStarted = false; removeThumb(); } else { invalidate(viewWidth - mThumbW, y, viewWidth, y + mThumbH); } } @Override protected void onSizeChanged(int w, int h, int oldw, int oldh) { super.onSizeChanged(w, h, oldw, oldh); if (mCurrentThumb != null) { mCurrentThumb.setBounds(w - mThumbW, 0, w, mThumbH); } final RectF pos = mOverlayPos; pos.left = (w - mOverlaySize) / 2; pos.right = pos.left + mOverlaySize; pos.top = h / 10; // 10% from top pos.bottom = pos.top + mOverlaySize; mOverlayDrawable.setBounds((int) pos.left, (int) pos.top, (int) pos.right, (int) pos.bottom); } public void onScrollStateChanged(AbsListView view, int scrollState) { } public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) { if (totalItemCount - visibleItemCount > 0 && !mDragging) { mThumbY = ((getHeight() - mThumbH) * firstVisibleItem) / (totalItemCount - visibleItemCount); if (mChangedBounds) { final int viewWidth = getWidth(); mCurrentThumb.setBounds(viewWidth - mThumbW, 0, viewWidth, mThumbH); mChangedBounds = false; } } mScrollCompleted = true; if (firstVisibleItem == mVisibleItem) { return; } mVisibleItem = firstVisibleItem; if (!mThumbVisible || mScrollFade.mStarted) { mThumbVisible = true; mCurrentThumb.setAlpha(ScrollFade.ALPHA_MAX); } mHandler.removeCallbacks(mScrollFade); mScrollFade.mStarted = false; if (!mDragging) { mHandler.postDelayed(mScrollFade, 1500); } } private void getSections() { Adapter adapter = mList.getAdapter(); if (adapter instanceof HeaderViewListAdapter) { mListOffset = ((HeaderViewListAdapter)adapter).getHeadersCount(); adapter = ((HeaderViewListAdapter)adapter).getWrappedAdapter();