Develop Reference

Android: Surface has been released

So this bit of code seems to be the problem:
public void surfaceCreated(final SurfaceHolder sh) {
loop = new Loop();
loop.setMethod(new LoopMethod() {
public void callMethod() {
Canvas canvas = sh.lockCanvas();
synchronized(sh) {
draw(canvas);
}
sh.unlockCanvasAndPost(canvas);
}
});
loop.setRunning(true);
loop.start();
}
This works fine up until the user backs out of the application, or opens up the Recent Items tray. Upon which I get the following error:
java.lang.IllegalStateException: Surface has already been released.
which points to this line:
sh.unlockCanvasAndPost(canvas);
Why is this occurring and how do I fix it?
EDIT: ENTIRE PROBLEMATIC CLASS
public class SplashScreen extends SurfaceView implements SurfaceHolder.Callback {
private SplashActivity splashActivity;
private Loop loop;
//Loading gif info
private Movie loadingGif;
private long gifStart;
private int gifW, gifH;
private boolean gifDone;
public SplashScreen(Context context, SplashActivity splashActivity) {
super(context);
getHolder().addCallback(this);
this.splashActivity = splashActivity;
//Load gif in
InputStream gifStream = context.getResources().openRawResource(+ R.drawable.load);
loadingGif = Movie.decodeStream(gifStream);
gifW = loadingGif.width();
gifH = loadingGif.height();
gifDone = false;
}
private void beginLoading() {
}
public void surfaceCreated(final SurfaceHolder sh) {
loop = new Loop();
loop.setMethod(new LoopMethod() {
public void callMethod() {
Canvas canvas = sh.lockCanvas();
synchronized(sh) {
draw(canvas);
}
sh.unlockCanvasAndPost(canvas);
}
});
loop.setRunning(true);
loop.start();
}
public void draw(Canvas canvas) {
if(canvas != null) {
super.draw(canvas);
canvas.save();
canvas.drawColor(Color.rgb(69, 69, 69));
Paint p = new Paint();
p.setAntiAlias(true);
long now = android.os.SystemClock.uptimeMillis();
if(gifStart == 0)
gifStart = now;
if(loadingGif != null) {
int dur = loadingGif.duration();
if(!gifDone) {
int relTime = (int) ((now - gifStart) % dur);
loadingGif.setTime(relTime);
}
else
loadingGif.setTime(dur);
if(now - gifStart > dur && !gifDone) {
gifDone = true;
loadingGif.setTime(dur);
beginLoading();
}
float scaleX = getWidth()/gifW*1f;
float scaleY = getHeight()/gifH*1f;
float centerX = getWidth()/2/scaleX - gifW/2;
float centerY = getHeight()/2/scaleY - gifH/2;
canvas.scale(scaleX, scaleY);
loadingGif.draw(canvas, centerX, centerY, p);
canvas.restore();
p.setColor(Color.WHITE);
p.setTypeface(Typeface.create("Segoe UI", Typeface.BOLD));
p.setTextSize(UsefulMethods.spToPx(12));
String s = "Version " + BuildConfig.VERSION_NAME;
canvas.drawText(s, 10, getHeight() - 10, p);
}
}
else
System.out.println("not drawing :(");
}
public void surfaceDestroyed(SurfaceHolder sh) {
loop.setRunning(false);
}
public void surfaceChanged(SurfaceHolder sh, int format, int width, int height) {
System.out.println("call");
}
}

Check if visibility has changed, if it has pause/resume loop:
public void onVisibilityChanged(View view, int visibility) {
super.onVisibilityChanged(view, visibility);
if(loop != null)
if(visibility == VISIBLE)
if(!loop.isRunning())
loop.setRunning(true);
else;
else if(visibility == INVISIBLE)
if(loop.isRunning())
loop.setRunning(false);
}

In my case I covered sh.unlockCanvasAndPost with
if(sh.getSurface().isValid()){
sh.unlockCanvasAndPost(canvas);
}
If we will check isValid() source will see:
Returns true if this object holds a valid surface.
#return True if it holds a physical surface, so lockCanvas() will succeed.Otherwise returns false.

How to display GIF file

I'm using this library as a guide to display a 'gif' file. When using the saved gif in drawableit display correctly the gif I call it like this
<pl.droidsonroids.gif.GifImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="#+id/imgView1"
android:src="#drawable/gifFile"
/>
but when removing the src and tried like initializing the GifImageView in the Activity like this
GifImageView gifFromFile = (GifImageView) findViewById(R.id.imgView1);
gifFromFile.setImageBitmap(Utils.getBitmapImagefromStorage(context, imageHome));
Where getBitmapImagefromStorage get the path and imageHome gets the filename the gif file doesn't play its only display like an image. It was said that If given drawable is not a GIF then mentioned Views work like plain ImageView and ImageButton. But the file I'm providing is a gif.I'm wondering if I'm using it correctly.
Also the file can be png or gif so I needed to support the two.

GifTextView gifImageView;
In onCreate
gifImageView = (GifTextView) findViewById(R.id.imageView);
Call this method in onCreate
public void playGif(){
Animation fadeout = new AlphaAnimation(1.f, 1.f);
fadeout.setDuration(2500); // You can modify the duration here
fadeout.setAnimationListener(new Animation.AnimationListener() {
#Override
public void onAnimationStart(Animation animation) {
gifImageView.setBackgroundResource(R.drawable.gif_image);//your gif file
}
#Override
public void onAnimationRepeat(Animation animation) {
}
#Override
public void onAnimationEnd(Animation animation) {
}
});
gifImageView.startAnimation(fadeout);
}
In your layout file
<pl.droidsonroids.gif.GifTextView
android:id="#+id/imageView"
android:layout_width="fill_parent"
android:scaleType="fitXY"
android:layout_height="fill_parent"
/>

Try this way to work with GIF in your app
public class PlayGifView extends View{
private static final int DEFAULT_MOVIEW_DURATION = 1000;
private int mMovieResourceId;
private Movie mMovie;
private long mMovieStart = 0;
private int mCurrentAnimationTime = 0;
#SuppressLint("NewApi")
public PlayGifView(Context context, AttributeSet attrs) {
super(context, attrs);
/**
* Starting from HONEYCOMB have to turn off HardWare acceleration to draw
* Movie on Canvas.
*/
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
setLayerType(View.LAYER_TYPE_SOFTWARE, null);
}
}
public void setImageResource(int mvId){
this.mMovieResourceId = mvId;
mMovie = Movie.decodeStream(getResources().openRawResource(mMovieResourceId));
requestLayout();
}
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
if(mMovie != null){
setMeasuredDimension(mMovie.width(), mMovie.height());
}else{
setMeasuredDimension(getSuggestedMinimumWidth(), getSuggestedMinimumHeight());
}
}
#Override
protected void onDraw(Canvas canvas) {
if (mMovie != null){
updateAnimtionTime();
drawGif(canvas);
invalidate();
}else{
drawGif(canvas);
}
}
private void updateAnimtionTime() {
long now = android.os.SystemClock.uptimeMillis();
if (mMovieStart == 0) {
mMovieStart = now;
}
int dur = mMovie.duration();
if (dur == 0) {
dur = DEFAULT_MOVIEW_DURATION;
}
mCurrentAnimationTime = (int) ((now - mMovieStart) % dur);
}
private void drawGif(Canvas canvas) {
mMovie.setTime(mCurrentAnimationTime);
mMovie.draw(canvas, 0, 0);
canvas.restore();
}
}
in your activity class
PlayGifView pGif = (PlayGifView) findViewById(R.id.viewGif);
pGif.setImageResource(R.drawable.yourgifimage);
then in your XML
<YourPackageName.PlayGifView
android:id="#+id/viewGif"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center" />

I tried using GifDrawable
File gifFile = new File(context.getExternalFilesDir(null)
.getAbsolutePath(), imageHome);
GifDrawable gifFromPath = new GifDrawable(gifFile);
And then instead of using setImageBitmap I use setImageDrawable
GifImageView gifImageView = (GifImageView) findViewById(R.id.textViewDealFinder);
gifImageView.setImageDrawable(gifFromPath);

Android thread wait until visible

I've made a custom pie chart view that I want to animate starting when the pie chart is visible. Currently what I have is the pie chart animating but by the time you can actually see it on the screen the animation is half over. This is what I have:
public class SinglePieChart extends SurfaceView implements SurfaceHolder.Callback {
// Chart setting variables
private int emptyCircleCol, strokeColor, number, total;
// Paint for drawing custom view
private Paint circlePaint;
private RectF rect;
private Context context;
private AnimThread animThread;
private SurfaceHolder holder;
// animation variables
private float speed;
private float current = 0.0f;
private boolean percentsCalculated = false;
private float degree;
private int viewWidth, viewHeight;
public SinglePieChart(Context ctx, AttributeSet attrs) {
super(ctx, attrs);
context = ctx;
// Paint object for drawing in doDraw
circlePaint = new Paint();
circlePaint.setStyle(Style.STROKE);
circlePaint.setStrokeWidth(3);
circlePaint.setAntiAlias(true);
circlePaint.setDither(true);
rect = new RectF();
//get the attributes specified in attrs.xml using the name we included
TypedArray a = context.getTheme().obtainStyledAttributes(attrs,
R.styleable.DashboardChartSmall, 0, 0);
try {
//get the colors specified using the names in attrs.xml
emptyCircleCol = a.getColor(R.styleable.DashboardChartSmall_smCircleColor, 0xFF65676E); // light gray is default
strokeColor = a.getColor(R.styleable.DashboardChartSmall_smColor, 0xFF39B54A); // green is default
// Default number values
total = a.getInteger(R.styleable.DashboardChartSmall_smTotal, 1);
number = a.getInteger(R.styleable.DashboardChartSmall_smNumber, 0);
} finally {
a.recycle();
}
this.setZOrderOnTop(true);
holder = getHolder();
holder.setFormat(PixelFormat.TRANSPARENT);
holder.addCallback(this);
}
protected void calculateValues() {
degree = 360 * number / total;
percentsCalculated = true;
speed = 10 * number / total;
viewWidth = this.getMeasuredWidth();
viewHeight = this.getMeasuredHeight();
float top, left, bottom, right;
if (viewWidth < viewHeight) {
left = 4;
right = viewWidth - 4;
top = ((viewHeight - viewWidth) / 2) + 4;
bottom = viewHeight - top;
} else {
top = 4;
bottom = viewHeight - 4;
left = ((viewWidth - viewHeight) / 2) + 4;
right = viewWidth - left;
}
rect.set(left, top, right, bottom);
}
protected void doDraw(Canvas canvas) {
if (total == 0) {
// Number values are not ready
animThread.setRunning(false);
return;
}
if (!percentsCalculated) {
calculateValues();
}
// set the paint color using the circle color specified
float last = current;
float start = -90;
circlePaint.setColor(strokeColor);
canvas.drawArc(rect, start, (last > degree) ? degree : last, false, circlePaint);
start += (last > number) ? number : last;
last = (last < number) ? 0 : last - number;
circlePaint.setColor(emptyCircleCol);
if (current > 360) {
current = 360;
}
canvas.drawArc(rect, start, 360 - current, false, circlePaint);
current += speed;
if (last > 0 || number == 0) {
// we're done
animThread.setRunning(false);
}
}
public void setNumbers(int num, int tot) {
number = num;
total = tot;
invalidate();
requestLayout();
}
public void setColor(int col) {
strokeColor = col;
}
public void redraw() {
calculateValues();
animThread.setRunning(true);
invalidate();
requestLayout();
}
#Override
public void surfaceChanged(SurfaceHolder arg0, int arg1, int arg2, int arg3) {
}
#Override
public void surfaceCreated(SurfaceHolder arg0) {
animThread = new AnimThread(holder, context, this);
animThread.setRunning(true);
animThread.start();
}
#Override
public void surfaceDestroyed(SurfaceHolder arg0) {
animThread.setRunning(false);
boolean retry = true;
while(retry) {
try {
animThread.join();
retry = false;
} catch(Exception e) {
Log.v("Exception Occured", e.getMessage());
}
}
}
public class AnimThread extends Thread {
boolean mRun;
Canvas mcanvas;
SurfaceHolder surfaceHolder;
Context context;
SinglePieChart msurfacePanel;
public AnimThread(SurfaceHolder sholder, Context ctx, SinglePieChart spanel) {
surfaceHolder = sholder;
context = ctx;
mRun = false;
msurfacePanel = spanel;
}
void setRunning(boolean bRun) {
mRun = bRun;
}
#Override
public void run() {
super.run();
while (mRun) {
mcanvas = surfaceHolder.lockCanvas();
if (mcanvas != null) {
msurfacePanel.doDraw(mcanvas);
surfaceHolder.unlockCanvasAndPost(mcanvas);
}
}
}
}
}
Also if you see any programming errors, memory leaks, poor performing code, please let me know. I'm new to Android.
Here is the layout that uses the SinglePieChart class:
<?xml version="1.0" encoding="utf-8"?>
<merge xmlns:android="http://schemas.android.com/apk/res/android">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1">
<com.davidscoville.vokab.views.elements.SinglePieChart
android:id="#+id/smallPieChart"
android:layout_width="match_parent"
android:layout_height="match_parent" />
<TextView
android:id="#+id/dashSmNumber"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:textSize="25sp"
android:textColor="#FFFFFF" />
</RelativeLayout>
<TextView
android:id="#+id/dashSmLabel"
android:layout_width="match_parent"
android:layout_height="20dp"
android:textSize="14sp"
android:gravity="center"
android:textColor="#FFFFFF" />
</merge>

Alright I'm going with the my pie chart won't automatically animate and it will have a new function that the Activity will trigger to start animating once it's ready. I wish there was an easier way...

Alternatively you can use the animation framework(or nine old androids if you want to support older apis). This will allow you to animate properties on your view, in your case the start and current variables.
I'd set this to happen during onAttachedToWindow.
Note if you aren't doing a lot of other things in this pie chart a surfaceview might be overkill for your needs.

Animations in Android

I'm new in Android and I want to do some animations. I'm trying to make my sprite sheet move automatically. But there is a problem with screen rendering. It leaves a trail while it is moving.Click here to see the screen shot
This is my code:
public class SampleAnimationActivity extends Activity {
/** Called when the activity is first created. */
Screen screen;
MapAnimation mapAnimation;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
screen = new Screen(this);
setContentView(screen);
}
#Override
protected void onDestroy() {
super.onDestroy();
}
#Override
protected void onPause() {
super.onPause();
}
#Override
protected void onResume() {
super.onResume();
}
public class Screen extends SurfaceView implements Callback{
private SurfaceHolder holder;
private MySurfaceViewThread mySurfaceViewThread;
private boolean isSurfaceCreated;
private Bitmap character, tiles;
public Screen(Context context) {
super(context);
initialize();
}
public void initialize(){
//Create a new SurfaceHolder and assign this class as its callback...
holder = getHolder();
holder.addCallback(this);
isSurfaceCreated = false;
character = BitmapFactory.decodeResource(getResources(),R.drawable.penguin_sprite);
tiles = BitmapFactory.decodeResource(getResources(), R.drawable.tile_sprites);
resume();
}
public void resume(){
//Create and start the graphics update thread.
if(mySurfaceViewThread == null){
mySurfaceViewThread = new MySurfaceViewThread();
if(isSurfaceCreated == true){
mySurfaceViewThread.start();
}
}
}
public void pause(){
//Kill the graphics update thread
if(mySurfaceViewThread != null){
mySurfaceViewThread.pause();
mySurfaceViewThread = null;
}
}
#Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
}
#Override
public void surfaceCreated(SurfaceHolder holder) {
isSurfaceCreated = true;
if(mySurfaceViewThread != null){
mySurfaceViewThread.start();
}
}
#Override
public void surfaceDestroyed(SurfaceHolder holder) {
isSurfaceCreated = false;
pause();
}
public class MySurfaceViewThread extends Thread{
private boolean isPaused;
private boolean characterLoaded, characterDrawn;
private SurfaceHolder surfaceHolder;
public MySurfaceViewThread(){
super();
isPaused = false;
characterLoaded = false;
surfaceHolder = holder;
characterDrawn = false;
}
public void run(){
//Repeat the drawing loop until the thread is stopped
while(!isPaused){
if(!surfaceHolder.getSurface().isValid()){
continue;
}
if(characterLoaded == false){
mapAnimation = new MapAnimation(screen, character);
characterLoaded = true;
}
Canvas canvas = surfaceHolder.lockCanvas();
mapAnimation.onDraw(canvas);
surfaceHolder.unlockCanvasAndPost(canvas);
}
}
public void pause(){
}
public void onDraw(){
}
}
}
}
public class MapAnimation {
private Screen screen;
private Bitmap character;
private int width, height, xPosition, yPosition, xSpeed, ySpeed;
public MapAnimation(Screen screen, Bitmap character) {
this.screen = screen;
this.character = character;
this.width = character.getWidth();
this.height = character.getHeight();
xPosition = 0;
yPosition = 0;
xSpeed = 5;
ySpeed = 5;
}
public void updateCharacter(){
if(xPosition > screen.getWidth() - width - xSpeed){
xSpeed = 0;
ySpeed = 5;
}
if(yPosition > screen.getHeight() - height - ySpeed){
xSpeed = -5;
ySpeed = 0;
}
if(xPosition + xSpeed < 0){
xPosition=0;
xSpeed = 0;
ySpeed = -5;
}
if(yPosition+ySpeed < 0){
yPosition = 0;
xSpeed = 5;
ySpeed = 0;
}
xPosition += xSpeed;
yPosition += ySpeed;
}
public void onDraw(Canvas canvas){
updateCharacter();
Rect src = new Rect(0, 0,135,225);
Rect dst = new Rect(xPosition, yPosition, xPosition+width, yPosition+height);
canvas.drawBitmap(character, src, dst, null);
}
}
Your help will be deeply appreciated :)

I already solved my problem, I just need to add "drawColor(color.BLACk);" before calling mapAnimation.onDraw() method.

Fast Scroll display problem with ListAdapter and SectionIndexer

I have a list of events which are seperated by month and year (Jun 2010, Jul 2010 etc.). I have enabled fast scrolling because the list is really long. I've also implemented SectionIndexer so that people can see what month and year they are currently viewing when scrolling down the list of events at speed.
I don't have any problem with the implementation, just how the information is shown. Fast scrolling with SectionIndexer seems to only really be able to support a label with a single letter. If the list was alphabetised this would be perfect, however I want it to display a bit more text.
If you look at the screenshot bellow you'll see the problem I'm having.
(source: matto1990.com)
What I want to know is: is it possible to change how the text in the centre of the screen is displayed. Can I change it somehow to make it look right (with the background covering all of the text).
Thanks in advance. If you need any clarification, or code just ask.

EDIT: Full sample code for this solution available here.
I had this same problem - I needed to display full text in the overlay rectangle rather than just a single character. I managed to solve it using the following code as an example: http://code.google.com/p/apps-for-android/source/browse/trunk/RingsExtended/src/com/example/android/rings_extended/FastScrollView.java
The author said that this was copied from the Contacts app, which apparently uses its own implementation rather than just setting fastScrollEnabled="true" on the ListView. I altered it a little bit so that you can customize the overlay rectangle width, overlay rectangle height, overlay text size, and scroll thumb width.
For the record, the final result looks like this: http://nolanwlawson.files.wordpress.com/2011/03/pokedroid_1.png
All you need to do is add these values to your res/values/attrs.xml:
<declare-styleable name="CustomFastScrollView">
<attr name="overlayWidth" format="dimension"/>
<attr name="overlayHeight" format="dimension"/>
<attr name="overlayTextSize" format="dimension"/>
<attr name="overlayScrollThumbWidth" format="dimension"/>
</declare-styleable>
And then use this CustomFastScrollView instead of the one in the link:
public class CustomFastScrollView extends FrameLayout
implements OnScrollListener, OnHierarchyChangeListener {
private Drawable mCurrentThumb;
private Drawable mOverlayDrawable;
private int mThumbH;
private int mThumbW;
private int mThumbY;
private RectF mOverlayPos;
// custom values I defined
private int mOverlayWidth;
private int mOverlayHeight;
private float mOverlayTextSize;
private int mOverlayScrollThumbWidth;
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;
public static interface SectionIndexer {
Object[] getSections();
int getPositionForSection(int section);
int getSectionForPosition(int position);
}
public CustomFastScrollView(Context context) {
super(context);
init(context, null);
}
public CustomFastScrollView(Context context, AttributeSet attrs) {
super(context, attrs);
init(context, attrs);
}
public CustomFastScrollView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init(context, attrs);
}
private void useThumbDrawable(Drawable drawable) {
mCurrentThumb = drawable;
mThumbW = mOverlayScrollThumbWidth;//mCurrentThumb.getIntrinsicWidth();
mThumbH = mCurrentThumb.getIntrinsicHeight();
mChangedBounds = true;
}
private void init(Context context, AttributeSet attrs) {
// set all attributes from xml
if (attrs != null) {
TypedArray typedArray = context.obtainStyledAttributes(attrs,
R.styleable.CustomFastScrollView);
mOverlayHeight = typedArray.getDimensionPixelSize(
R.styleable.CustomFastScrollView_overlayHeight, 0);
mOverlayWidth = typedArray.getDimensionPixelSize(
R.styleable.CustomFastScrollView_overlayWidth, 0);
mOverlayTextSize = typedArray.getDimensionPixelSize(
R.styleable.CustomFastScrollView_overlayTextSize, 0);
mOverlayScrollThumbWidth = typedArray.getDimensionPixelSize(
R.styleable.CustomFastScrollView_overlayScrollThumbWidth, 0);
}
// Get both the scrollbar states drawables
final Resources res = context.getResources();
Drawable thumbDrawable = res.getDrawable(R.drawable.scrollbar_handle_accelerated_anim2);
useThumbDrawable(thumbDrawable);
mOverlayDrawable = res.getDrawable(android.R.drawable.alert_dark_frame);
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(mOverlayTextSize);
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 CustomFastScrollView.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 + 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 - mOverlayWidth) / 2;
pos.right = pos.left + mOverlayWidth;
pos.top = h / 10; // 10% from top
pos.bottom = pos.top + mOverlayHeight;
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();
}
if (adapter instanceof SectionIndexer) {
mListAdapter = (BaseAdapter) adapter;
mSections = ((SectionIndexer) mListAdapter).getSections();
}
}
public void onChildViewAdded(View parent, View child) {
if (child instanceof ListView) {
mList = (ListView)child;
mList.setOnScrollListener(this);
getSections();
}
}
public void onChildViewRemoved(View parent, View child) {
if (child == mList) {
mList = null;
mListAdapter = null;
mSections = null;
}
}
#Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
if (mThumbVisible && ev.getAction() == MotionEvent.ACTION_DOWN) {
if (ev.getX() > getWidth() - mThumbW && ev.getY() >= mThumbY &&
ev.getY() <= mThumbY + mThumbH) {
mDragging = true;
return true;
}
}
return false;
}
private void scrollTo(float position) {
int count = mList.getCount();
mScrollCompleted = false;
final Object[] sections = mSections;
int sectionIndex;
if (sections != null && sections.length > 1) {
final int nSections = sections.length;
int section = (int) (position * nSections);
if (section >= nSections) {
section = nSections - 1;
}
sectionIndex = section;
final SectionIndexer baseAdapter = (SectionIndexer) mListAdapter;
int index = baseAdapter.getPositionForSection(section);
// Given the expected section and index, the following code will
// try to account for missing sections (no names starting with..)
// It will compute the scroll space of surrounding empty sections
// and interpolate the currently visible letter's range across the
// available space, so that there is always some list movement while
// the user moves the thumb.
int nextIndex = count;
int prevIndex = index;
int prevSection = section;
int nextSection = section + 1;
// Assume the next section is unique
if (section < nSections - 1) {
nextIndex = baseAdapter.getPositionForSection(section + 1);
}
// Find the previous index if we're slicing the previous section
if (nextIndex == index) {
// Non-existent letter
while (section > 0) {
section--;
prevIndex = baseAdapter.getPositionForSection(section);
if (prevIndex != index) {
prevSection = section;
sectionIndex = section;
break;
}
}
}
// Find the next index, in case the assumed next index is not
// unique. For instance, if there is no P, then request for P's
// position actually returns Q's. So we need to look ahead to make
// sure that there is really a Q at Q's position. If not, move
// further down...
int nextNextSection = nextSection + 1;
while (nextNextSection < nSections &&
baseAdapter.getPositionForSection(nextNextSection) == nextIndex) {
nextNextSection++;
nextSection++;
}
// Compute the beginning and ending scroll range percentage of the
// currently visible letter. This could be equal to or greater than
// (1 / nSections).
float fPrev = (float) prevSection / nSections;
float fNext = (float) nextSection / nSections;
index = prevIndex + (int) ((nextIndex - prevIndex) * (position - fPrev)
/ (fNext - fPrev));
// Don't overflow
if (index > count - 1) index = count - 1;
mList.setSelectionFromTop(index + mListOffset, 0);
} else {
int index = (int) (position * count);
mList.setSelectionFromTop(index + mListOffset, 0);
sectionIndex = -1;
}
if (sectionIndex >= 0) {
String text = mSectionText = sections[sectionIndex].toString();
mDrawOverlay = (text.length() != 1 || text.charAt(0) != ' ') &&
sectionIndex < sections.length;
} else {
mDrawOverlay = false;
}
}
private void cancelFling() {
// Cancel the list fling
MotionEvent cancelFling = MotionEvent.obtain(0, 0, MotionEvent.ACTION_CANCEL, 0, 0, 0);
mList.onTouchEvent(cancelFling);
cancelFling.recycle();
}
#Override
public boolean onTouchEvent(MotionEvent me) {
if (me.getAction() == MotionEvent.ACTION_DOWN) {
if (me.getX() > getWidth() - mThumbW
&& me.getY() >= mThumbY
&& me.getY() <= mThumbY + mThumbH) {
mDragging = true;
if (mListAdapter == null && mList != null) {
getSections();
}
cancelFling();
return true;
}
} else if (me.getAction() == MotionEvent.ACTION_UP) {
if (mDragging) {
mDragging = false;
final Handler handler = mHandler;
handler.removeCallbacks(mScrollFade);
handler.postDelayed(mScrollFade, 1000);
return true;
}
} else if (me.getAction() == MotionEvent.ACTION_MOVE) {
if (mDragging) {
final int viewHeight = getHeight();
mThumbY = (int) me.getY() - mThumbH + 10;
if (mThumbY < 0) {
mThumbY = 0;
} else if (mThumbY + mThumbH > viewHeight) {
mThumbY = viewHeight - mThumbH;
}
// If the previous scrollTo is still pending
if (mScrollCompleted) {
scrollTo((float) mThumbY / (viewHeight - mThumbH));
}
return true;
}
}
return super.onTouchEvent(me);
}
public class ScrollFade implements Runnable {
long mStartTime;
long mFadeDuration;
boolean mStarted;
static final int ALPHA_MAX = 200;
static final long FADE_DURATION = 200;
void startFade() {
mFadeDuration = FADE_DURATION;
mStartTime = SystemClock.uptimeMillis();
mStarted = true;
}
int getAlpha() {
if (!mStarted) {
return ALPHA_MAX;
}
int alpha;
long now = SystemClock.uptimeMillis();
if (now > mStartTime + mFadeDuration) {
alpha = 0;
} else {
alpha = (int) (ALPHA_MAX - ((now - mStartTime) * ALPHA_MAX) / mFadeDuration);
}
return alpha;
}
public void run() {
if (!mStarted) {
startFade();
invalidate();
}
if (getAlpha() > 0) {
final int y = mThumbY;
final int viewWidth = getWidth();
invalidate(viewWidth - mThumbW, y, viewWidth, y + mThumbH);
} else {
mStarted = false;
removeThumb();
}
}
}
}
You can also tweak the translucency of the scroll thumb using ALPHA_MAX.
Then put something like this in your layout xml file:
<com.myapp.CustomFastScrollView android:layout_width="wrap_content"
android:layout_height="fill_parent"
myapp:overlayWidth="175dp" myapp:overlayHeight="110dp" myapp:overlayTextSize="36dp"
myapp:overlayScrollThumbWidth="60dp" android:id="#+id/fast_scroll_view">
<ListView android:id="#android:id/list" android:layout_width="wrap_content"
android:layout_height="fill_parent"/>
<TextView android:id="#android:id/empty"
android:layout_width="wrap_content" android:layout_height="wrap_content"
android:text="" />
</com.myapp.CustomFastScrollView>
Don't forget to declare your attributes in that layout xml file as well:
... xmlns:myapp= "http://schemas.android.com/apk/res/com.myapp" ...
You'll also need to grab the R.drawable.scrollbar_handle_accelerated_anim2 drawables from that Android source code. The link above only contains the mdpi one.

The FastScroller widget is responsible for drawing the overlay. You should probably take a look at its source:
https://android.googlesource.com/platform/frameworks/base/+/gingerbread-release/core/java/android/widget/FastScroller.java
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// If user is dragging the scroll bar, draw the alphabet overlay