I'm writing a simple Whack a Mole clone, and I've got my UI elements declared in a GridLayout in a layout.xml, then assigned to ImageView variables in an array programmatically. I've got a startGame() method that simply takes a random int, pulls it from the array and causes it to go visible for a second, then repeats. For some reason, when I put this code in a while() loop, it causes my UI to go blank as soon as it's launched.
I know it's the while() loop because I tried taking the code out of the while() loop, and it ran correctly (once), but turns everything white when placed in a while loop.
Here's the method causing the problem:
public void startGame() {
gameStarted = true;
while(gameStarted) {
randomInt = rand.nextInt(11);
mole[randomInt].setVisibility(View.VISIBLE);
handler.postDelayed(new Runnable() {
#Override
public void run() {
mole[randomInt].setVisibility(View.INVISIBLE);
}
}, 5000);
}
}
All the other relevant code is in onCreate, it's otherwise just a skeleton Activity subclass.
public class WAM_Activity extends Activity {
private ImageView[] mole = new ImageView[11];
private int[] moleId = {R.id.mole1, R.id.mole3, R.id.mole4, R.id.mole5, R.id.mole6, R.id.mole7, R.id.mole8, R.id.mole9, R.id.mole10, R.id.mole11, R.id.mole12};
private boolean gameStarted;
private int randomInt = 0;
private Random rand = new Random();
Handler handler = new Handler();
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.wam_view_layout);
for (int i = 0; i < 11; i++) {
mole[i] = (ImageView) findViewById(moleId[i]);
mole[i].setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
//do stuff eventually
}
});
}
gameStarted = true;
startGame();
}
Any idea why this isn't working? I've been staring at it for hours and I'm quite stumped.
Android doesn't work that way, when onCreate is called, it need to be finished in order for the app to keep responding, I'm surprised you are not getting any "App not respopnding" error.
If you want to create a "game loop" you can simply by creating a new Thread and putting the while in there.
Activity's lifecycle must be executed without blocking them for the app to operate correctly, for more info check here.
Do you know about threads? if you want i can post an example of how to do that with threads but it might be long and if you don't know what a Thread is it will be too confusing for you.
Edit: Ok I'll make an example of a Thread
When I create my games I usually have only one Activity that the only thing it does is creating a custom SurfaceView and nothing else.
public class GameActivity extends Activity
{
//This is a custom class that extends SurfaceView - I will write it below
private GameSurface game;
#Override
protected void onCreate(Bundle bundle)
{
super.onCreate(bundle);
//Create a new instance of the game
game = new GameSurface(this);
//Set the View of the game to the activity
setContentView(game);
}
}
You can also add extra stuff like onSaveInstanceState to save game data and restore them later but I don't want to add them now so the code looks simple.
This class was very simple, let's move on to our SurfaceView. The reason I picked a SurfaceView to do that it's because it is made to allow custom graphics to be drawn on it - exactly what we want on a video game. I will try to make the class as simple as possible:
/*SurfaceHolder.Callback will run some functions in our class when
our surface is completed - at that point we can initialize data
that have to do with the View's width/height.
I don't know if you've noticed that on a View's onCreate()
when you call getWidth() or getHeight() you get 0, that's because
the surface is not initialized yet, this is a way to fix that.
Also we need a Runnable to run the Thread inside this class,
no need to make more classes and make it more complicated*/
public class GameSurface extends SurfaceView
implements SurfaceHolder.Callback, Runnable
{
//This is our thread - we need the "running" variable to be
//able to stop the Thread manually, this will go inside our "while" loop
private Thread thread;
private boolean running;
//Right here you can add more variables that draw graphics
//For example you can create a new class that has a function that
//takes Canvas as a parameter and draws stuff into it, I will add
//a Rect in this case which is a class already made by android
//but you can create your own class that draws images or more
//complicated stuff
private Rect myRect;
//Rect needs a paint to give it color
private Paint myPaint;
//Constructor
public GameSurface(Context context)
{
super(context);
//This is the callback to let us know when surface is completed
getHolder().addCallback(this);
}
//When a class implements SurfaceHolder.Callback you are forced to
//create three functions "surfaceCreated", "surfaceChanged" and
//"surfaceDestroyed" these are called when the surface is created,
//when some settings are changed (like the orientation) and when
//it is about to be destroyed
#Override
public void surfaceCreated(Surface holder)
{
//Let's initialize our Rect, lets assume we want it to have 40
//pixels height and fill the screen's width
myRect = new Rect(0, 0, getWidth(), 40);
//Give color to the rect
myPaint = new Paint();
myPaint.setARGB(0, 255, 0, 0);
//In case you are not familiar with the Rect class, as
//parameters it gets Rect(left, top, right, bottom)
//Time to start our Thread - nothing much to explain here if
//you know how threads work, remember this class implements
//Runnable so the Thread's constructor gets "this" as parameter
running = true;
thread = new Thread(this);
thread.start();
}
//We won't use this one for now, but we are forced to type it
//Even if we leave it empty
#Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {}
//When the surface is destroyed we just want the Thread to
//terminate - we don't want threads running when our app is not visible!
#Override
public void surfaceDestroyed(SurfaceHolder holder)
//We will type this function later
{destroyThread();}
//Time for the interesting stuff! let's start with input
#Override
public boolean onTouchEvent(MotionEvent event)
{
//The logic is as follows: when our Rect is touched, we want
//it to become smaller
if (event.getAction() == MotionEvent.ACTION_DOWN)
{
if (myRect.contains((int) event.getX(), (int) event.getY())
{
myRect.right -= 5;
//Return true - we did something with the input
return true;
}
}
return super.onTouchEvent(event);
}
//This is our update, it will run once per frame
private void update()
{
//Let's assume we want our rect to move 1 pixel downwards
//on every frame
myRect.offset(0, 1);
}
//Now for our draw function
public void draw(Canvas canvas)
{
//Here we want to draw a background and our rect
canvas.drawARGB(0, 0, 0, 255);
canvas.drawRect(myRect, myPaint);
}
//The only thing left is our run() function for the Thread
#Override
public void run()
{
//Screen
Canvas canvas;
//Our game cycle (the famous while)
while(running)
{
//Count start time so we can calculate frames
int startTime = System.currentTimeMillis();
//Update our game
update();
//Empty screen so it can obtain new instance
canvas = null;
//Try locking the canvas for pixel editing on surface
try
{
//Try getting screen
canvas = getHolder().lockCanvas();
//Succeeded
if (canvas != null) synchronized (getHolder())
{
//Actual drawing - our draw function
draw(canvas);
}
} finally
{
//Draw changes
if (canvas != null) getHolder().unlockCanvasAndPost(canvas);
}
//End Frame - 1000/30 means 30 frames per second
int frameTime = System.currentTimeMillis() -startTime;
if (frameTime < 1000/30)
try { Thread.sleep(1000/30 -frameTime); } catch (InterruptedException e){}
}
}
//Last but not least, our function for closing the thread
private void destroyThread()
{
//Stop thread's loop
running = false;
//Try to join thread with UI thread
boolean retry = true;
while (retry)
{
try {thread.join(); retry = false;}
catch (InterruptedException e) {}
}
}
}
I may have made some minor mistakes (probably with case sensitive letters) so feel free to correct these, I wrote the code at once so I didn't have time to test it, it should work flawlessly though.
If you have any more questions, need more explanation or something is not working right let me know!
Related
Yesterday I asked a question pertaining to Android graphics, and now that I have the basis up and running, I've made a rendering loop inside of my custom view class.
protected void render() {
long startTime = System.nanoTime();
long elapsedTime;
while (Main.running) {
Bitmap image = Bitmap.createBitmap(Main.WIDTH, Main.HEIGHT, null); //creates new Bitmap to draw onto
Canvas canvas = new Canvas(image); //new Canvas with the attached blank Bitmap
long newTime = System.nanoTime();
elapsedTime = newTime - startTime;
if (elapsedTime >= 1000000000/60) { //if enough time has passed for it to update
startTime = newTime;
Main.player.render(canvas); //this renders a test object, see below
}
display = Bitmap.createBitmap(image); //this writes to the display Bitmap that is drawn in onDraw, see below
invalidate(); //invoke onDraw()
}
}
Here is the code for drawing my player image (which DOES work if I draw it once rather than in a loop.)
public void render(Canvas c) {
int xp = (int) x;
int yp = (int) y;
c.drawBitmap(Images.box, xp, yp, null);
}
And inside onDraw:
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.drawBitmap(display, 0, 0, null);
}
If I just render the player and call invalidate() once, rather than looping it multiple times, it displays fine (and dandy). However, when I put it in the loop block it does not render.
According to my logging, the loop is functional and calls invalidate(), but it never actually enters the onDraw method during the loop.
If anybody could explain why this is happening that would be very grand, and if you need more information please let me know and I will provide.
EDIT:
In my main Activity class, I have a thread for game logic and then enter the render loop with the main thread after starting the logic thread.
Thread update = new Thread() { //game logic thread
public void run() {
loop(); //game logic loop
}
};
update.start(); //start logic thread
surface.render(); //start render loop (surface is the name of my custom view)
I have tried making a separate thread for rendering and entering the game loop with my main thread, however that still did not work.
I'm trying to create a simple game loop (its not really a game yet) that displays a circle, then after it ticks 100 times draws another circle. I also have a text field that should display how many times the loop has ran. Relevant code is as follows:
MainActivity
public class MainActivity extends Activity
{
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
DrawView v = new DrawView(this);
v.setBackgroundColor(Color.WHITE);
setContentView(v);
}
}
DrawView
public class DrawView extends SurfaceView implements SurfaceHolder.Callback
{
Paint p = new Paint();
MainThread thread;
private int y=0;
public DrawView(Context c)
{
super(c);
thread = new MainThread(this, getHolder());
thread.running = true;
getHolder().addCallback(this);
setFocusable(true);
}
public void draw(Canvas c)
{
if(c==null)
return;
super.onDraw(c);
p.setColor(Color.RED);
p.setTextSize(32);
p.setTypeface(Typeface.SANS_SERIF);
c.drawCircle(getWidth()/2-100,getHeight()/2, 50, p);
c.drawText("y = " + y, 50, 50, p);
if(y==100)
c.drawCircle(getWidth()/2+100,getHeight()/2, 50, p);
else
y++;
}
public void surfaceCreated(SurfaceHolder p1)
{
thread.start();
}
MainThread
public class MainThread extends Thread
{
private DrawView page;
private SurfaceHolder holder;
public boolean running;
public MainThread(DrawView p, SurfaceHolder h)
{
super();
page = p;
holder = h;
}
#Override
public void run()
{
while(running)
{
Canvas c = holder.lockCanvas();
page.draw(c);
holder.unlockCanvasAndPost(c);
}
}
}
It just displays the first circle and the text saying "y = 2." Nothing seems to update, or its doing it twice and then stopping. I am new to Android programming but not to Java. I'm sure I'm just missing something simple. Thanks for any help.
EDIT: Upon further observation, it seems the thread crashes randomly. Everytime I run the app, it dislays "y = " and then a different number each time. I'd reckon it makes it that many ticks before crashing. After I close the app, I get a message that says "Unfortunately, MyApp has stopped." I don't know enough about how Android works to know why its crashing.
EDIT 2: I've discovered its throwing an IllegalArgumentException on the line holder.unlockCanvasAndPost(c). Again, l'm not sure why. Can anyone explain what's happening and how to fix it?
EDIT 3: Logging the value of y each tick reveals that it couts up correctly and stops when it reaches 100 as intended. What happens onscreen does not reflect that for some reason.
I think what you're looking for is a combination of a Handler and a Runnable.
The handler calls the runnable, which runs once, then decides if it should call again.
something like:
private Handler renderHandler = new Handler();
private Runnable renderRunnable = new Runnable() {
#Override
public void run() {
//... do stuff here;
if(shouldRunAgain){
renderHandler.postDelayed(renderRunnable, 1000); // for 1 second
}
}
};
renderHandler.post(renderRunnable);
edit:
without seeing a log cat, I'm going to make an assumption that the UI updates are happening from a thread other than the main UI thread, causing the crash.
have a look at this, this, and this - I think these are more in line of what you're looking for.
There are multiple similar questions like mine, but these questions didn't help me.
I'm making a game. The game thread, SurfaceView and Activity is already finished and works so far. The problem is that the canvas is not redrawn. At startup, it draws the icon on the background, but at every tick, the icon doesn't move (It should move once a second). I want to mention, that I never needed to call postInvalidate. I have a working example where I never called it, but it doesn't work in my current example (I don't want to go into it deeper, since I actually don't need to call it). I copied the current code from my working example, the concept and the way of implementation is exactly the same, but my current code doesn't refresh the canvas. When I log the drawing positions in onDraw method, I see that it's coordinates are updated every second as expected, so I can be sure it's a canvas drawing problem. I have searched for hours but I didn't find what's different to my working example (except that I'm using another Android version and I don't extend thread but implement Runnable, because it's a bad style to extend thread. Nevertheless, I also extended thread to see if there is any difference, but it doesn't help). I already tried to clean the canvas by using canvas.drawColor(Color.BLACK), but that didn't help either. I already tried to use background colors instead of a background image which changes randomly every tick, but it didn't change but stays always the same.
I figured out that the canvas at the very first call has a density of (for example) 240. After the second tick, the canvas density is always 0. I know that the density will not help me here, but maybe it's an important information for someone.
Here are the important classes....
game layout, R.layout.game
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/gameContainer"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<com.mydomain.mygame.base.game.GameSurface
android:id="#+id/gameSurface"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1.0"
android:background="#drawable/background_game" >
</com.mydomain.mygame.base.game.GameSurface>
<!-- ...more definitions -->
</LinearLayout>
GameActivity (contains layout)
public class GameActivity extends Activity
{
#SuppressWarnings("unused")
private GameSurface gameSurface;
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.game);
gameSurface = (GameSurface)findViewById(R.id.gameSurface);
//TODO on button click -> execute methods
}
}
GameSurface (log in onDraw shows updated coordinates every tick)
public class GameSurface extends SurfaceView implements SurfaceHolder.Callback
{
private GameThread thread;
protected final static int TICK_FREQUENCY = 100;// ms, stays always the same. It's a technical constant which doesn't change
private static final String TAG = GameSurface.class.getSimpleName();
public GameSurface(Context context, AttributeSet attrs)
{
super(context, attrs);
ShapeManager.INSTANCE.init(context);
SurfaceHolder holder = getHolder();
holder.addCallback(this);
setFocusable(true); // make sure we get key events
thread = new GameThread(holder, this);
}
public void updateStatus()
{
GameProcessor.INSTANCE.updateShapes();
}
#Override
protected void onDraw(Canvas canvas)
{
for (Shape shape : GameProcessor.INSTANCE.getShapes())
{
Log.i(TAG, "getX()=" + shape.getX() + ", getY()=" + shape.getY());
canvas.drawBitmap(shape.getBitmap(), shape.getX(), shape.getY(), null);
}
}
#Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height)
{
//will never invoked since we only operate in landscape
}
#Override
public void surfaceCreated(SurfaceHolder holder)
{
// start the thread here so we don't busy-wait in run
thread.setRunning(true);
new Thread(thread).start();
}
#Override
public void surfaceDestroyed(SurfaceHolder holder)
{
Log.i(TAG, "executing surfaceDestroyed()...");
thread.setRunning(false);
}
}
GameThread
public class GameThread implements Runnable
{
private SurfaceHolder surfaceHolder;
private boolean running = false;
private GameSurface gameSurface;
private long lastTick;
public GameThread(SurfaceHolder surfaceHolder, GameSurface gameSurface)
{
this.surfaceHolder = surfaceHolder;
this.gameSurface = gameSurface;
lastTick = System.currentTimeMillis();
}
#Override
public void run()
{
Canvas canvas;
while (running)
{
canvas = null;
if (System.currentTimeMillis() > lastTick + GameSurface.TICK_FREQUENCY)
{
long timeDifference = System.currentTimeMillis() - (lastTick + GameSurface.TICK_FREQUENCY);
try
{
canvas = surfaceHolder.lockCanvas(null);
synchronized (surfaceHolder)
{
gameSurface.updateStatus();
gameSurface.draw(canvas);
}
}
finally
{
if (canvas != null)
{
surfaceHolder.unlockCanvasAndPost(canvas);
}
}
lastTick = System.currentTimeMillis() - timeDifference;
}
}
}
public void setRunning(boolean running)
{
this.running = running;
}
}
Any ideas why this code doesn't update my canvas? I can't explain it. I do not post ShapeManager and GameProcessor since they don't have anything to do with the problem (and they only load and control the current states and speed of the game).
[UPDATE]
I figured out that onDraw() is invoked before the game thread has started. That means that canvas is passed to this method before thread is using it. The interesting thing is that, after the thread has started, it always uses the same canvas, but it's not the canvas reference which is passed the very first time. Although canvas = surfaceHolder.lockCanvas(null); is assigned every tick, it's always the same reference, but it's not the original reference.
In a working example of mine, the reference is always the same, since I create the bitmaps at constructor initialization time. I can't do that in my current implementation, since I have to do calculations with values I get from onMeasure() which is invoked much later than the constructor.
I tried to somehow pass the original canvas to the thread, but the reference still changes. Meanwhile I think this is the problem, but I don't know how to solve it yet.
As often happens, I found the solution on my own.
Obviously it's really a problem that it draws to different canvas instances. I'm still not sure why this happens. Didn't have the problem before. Nevertheless, I can avoid drawing to canvas by setting setWillNotDraw(true); in my GameSurface constructor and I must not invoke gameSurface.draw(canvas) in my thread, but gameSurface.postInvalidate() instead.
To use a SurfaceView for drawing a 2D game in Android, I use this in the main activity's onCreate():
setContentView(new GameView(this));
Which is a reference to this class:
public class GameView extends SurfaceView implements SurfaceHolder.Callback
Additionally, I have a thread with its run() function:
public void run() {
Canvas c;
while (_run) {
c = null;
try {
c = _surfaceHolder.lockCanvas(null);
synchronized (_surfaceHolder) {
_panel.updatePhysics();
_panel.onDraw(c);
}
}
finally { // when exception is thrown above we may not leave the surface in an inconsistent state
if (c != null) {
_surfaceHolder.unlockCanvasAndPost(c);
}
}
}
}
In updatePhysics() I do some calculations. They are more complex than this simple example, of course, but work the same way:
public void updatePhysics() {
GraphicObject.Coordinates coord;
GraphicObject.Speed speed;
for (GraphicObject graphic : _allElements) {
coord = graphic.getCoordinates();
speed = graphic.getSpeed();
coord.setX(coord.getX() + speed.getX());
coord.setY(coord.getY() + speed.getY());
...
}
}
And in onDraw(), I draw everything to the canvas:
#Override
public void onDraw(Canvas canvas) {
canvas.drawBitmap(BITMAP, xPos, yPos, null);
...
}
This works fine - everything. And when I tested it on my device, it looked pretty good. But when I gave it to someone else and he did a test game, the objects were moving much faster! Why is this so? Because the thread calls updatePhysics() as often as possible which means that fast devices call this function more often?
How can I prevent this and make the game equally fast on all devices? Something like this?
private long lastRun = System.currentTimeMillis();
public void updatePhysics() {
long millisPassed = System.currentTimeMillis()-lastRun;
...
float newCoord = (coord.getX() + speed.getX()) * millisPassed / 33;
coord.setX(newCoord);
...
}
Thanks for your help!
If you can, use the time directly to calculate all your physics. That would usually work best.
If you have no way to calculate based on time because what you are doing that is just step based and you know that generating the next step does not take much time then you have another option.
You create two threads. The first one advances the state at a fixed rate (and you have to be sure that this works on slow devices at that rate too). The second one takes the current state is sees and draws that. Now the second thread can be as slow as it wants because it simply skips some states (or draws the same state several times if it is faster).
Small example below has one thread that advances some state object and replaces the reference each time so the consuming thread does not need to worry that it's state object gets modified
class GameState {
private int state = 0;
public GameState advanceState() {
GameState result = new GameState();
result.state = this.state + 1;
return result;
}
}
class SurfaceViewImplementation extends SurfaceView {
// the current state
volatile GameState mState = new GameState();
void somewhere() {
Thread fastProducer = new Thread(new Runnable() {
private static final long MAX_WAIT = 1000 / 60;
#Override
public void run() {
while (!Thread.interrupted()) {
long timeBefore = SystemClock.currentThreadTimeMillis();
GameState newState = mState.advanceState();
mState = newState;
long timeAfter = SystemClock.currentThreadTimeMillis();
long timeSpent = timeAfter - timeBefore;
SystemClock.sleep(Math.max(0, MAX_WAIT - timeSpent));
}
}
});
fastProducer.start();
Thread slowConsumer = new Thread(new Runnable() {
#Override
public void run() {
while (!Thread.interrupted()) {
GameState currentState = mState;
longRunningDraw(currentState);
}
}
});
slowConsumer.start();
}
}
That will still fail to give you a speed independant result if the producing thread can't run at the desired rate.
I would save the time when I start rendering the frame(in your case is updatePhysics()), and then next time I would got to this point, I know how much time pass, if it's to fast you can use Thread.Sleep();
I am trying to put an image on the screen and change it every five seconds. This is not in an Activity class. Sorry if is a stupid question. This is a huge learning curve for me.
public class Panel extends SurfaceView implements SurfaceHolder.Callback {
private Handler mHandler = new Handler();
//stuff
public void doDraw(Canvas canvas) {
int counter = 0;
canvas.drawColor(Color.BLACK);
dot1.doDraw(getResources(), canvas, counter);
mHandler.removeCallbacks(panelDraw);
mHandler.postDelayed(panelDraw, 5000);
}
private Runnable panelDraw = new Runnable() {
public void run() {
}
};
(Panel->)mPanel.doDraw(canvas) in another class calls the doDraw listed in Panel. This is in a loop.
As far as I can tell, the first image isn't stopping for five seconds, and due to other code the cat pic flashes all over the screen. Can I get away with putting nothing in run()? I wanted to put the dot1.doDraw(getResources(), canvas, counter) one in there, but I couldn't/didn't think I could give void run() parameters or Runnable panelDraw resources, canvas, counter parameters.
Any help is appreciated. Let me know if I need to give more code.
A little more about my game: Kitten photos should appear one at random locations on the screen. If one does not click on the current kitty image with an allotted time, the game ends. These pictures last < 1 sec in the end (right now it's more for testing purposes). If you don't click the kitty in that time span, the game ends.
I heard that if you need to do a lot of drawing, you're better off using SurfaceView like in the tutorial I followed very closely: http://www.droidnova.com/2d-tutorial-series-part-v,848.html My Activity class (Scene1) has setContentView(new Panel(this)), so I don't know how to put stuff in the Activity class when it all goes in the Panel class. Like where do I put the ImageView code if the Activity thread doesn't really do much and hands it all off to Panel? Also if I have a ViewThread (public class ViewThread extends Thread) that handles the running:
public void run() {
Canvas canvas = null;
while (mRun1) {
do {
canvas = mHolder.lockCanvas();
if (canvas != null) {
mPanel.doDraw(canvas);
mRun1 = true;
mRun1 = mPanel.get_run();
mHolder.unlockCanvasAndPost(canvas);
}
} while (mRun1 == true);
The dot class has something like:
public void firstRing(Resources res, Canvas canvas, int counter){
Random rand = new Random();
switch(counter) {
case 0: mBitmap = BitmapFactory.decodeResource(res,
R.drawable.cat1_m);
break;
case 1: mBitmap = BitmapFactory.decodeResource(res,
R.drawable.cat2_m);
break;
case 2: mBitmap = BitmapFactory.decodeResource(res,
R.drawable.cat2_m);
break;
case 3: mBitmap = BitmapFactory.decodeResource(res,
R.drawable.cat2_m);
break;
case 4: mBitmap = BitmapFactory.decodeResource(res,
R.drawable.cat2_m);
break;
case 5: mBitmap = BitmapFactory.decodeResource(res,
R.drawable.cat1_m);
break;
}
mX = rand.nextInt((int)(Panel.mWidth - mBitmap.getWidth()));
mY = rand.nextInt((int)(Panel.mHeight - mBitmap.getHeight()));
canvas.drawBitmap(mBitmap, mX, mY, null);
and
public void doDraw(Resources res, Canvas canvas, int counter) {
firstRing(res, canvas, counter);
}
Thanks for the info, Barry, although I am a little confused. Do I try ImageView or do I stick with Handler(), although I don't know how to use it and it's not working now? Do I need something in public void run()?
This code should work better than my last answer, but I haven't compiled or tested it. Even if it doesn't work it will point you in the right direction. I assume you have an Activity subclass somewhere so just copy my code into your activity. Your layout should have an <ImageView> tag in it somewhere.
The code below creates a Handler in Activity.onCreate(), which is run in the UI thread, guaranteeing all calls to the Handler will also be run in the UI thread. It then calls showNextKittyImage() to display the first image. showNextKittyImage() sets the Drawable resource id for the ImageView, and then calls Handler.sendEmptyMessageDelayed() to call the handler 5 seconds later. The Handler calls showNextKittyImage() and the cycle repeats.
An ImageView is still preferable to a SurfaceView because it is designed to display images. All you need to do is pass it the Drawable resource id instead of messing with Bitmaps. If you really want or need to do it with a SurfaceView then I cannot help you.
This code will also not make the kittens appear at random locations. Get it working in one location first, then add code to move the ImageView around the screen randomly. If you need help at that point I strongly recommend you post a new question as you've asked A LOT for one posting.
Good luck,
Barry
public class KittyActivity extends Activity {
Handler mHandler;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Inflate your view
setContentView(R.layout.YOUR_LAYOUT);
// Create a handler ON THE UI THREAD
mHandler = new Handler(Message result) {
public void handleMessage(Message result) {
showNextKittyImage();
}
};
// Show the first kitty
showNextKittyImage();
}
public void showNextKittyImage() {
int kitty = getNextKitty();
ImageView iv = findViewById(R.id.YOUR_IMAGE_VIEW_ID);
iv.setImageResource(kitty);
// OPTIONAL: Move the ImageView to a new random location
mHandler.sendEmptyMessageDelayed(0, 5000);
}
private int getNextKitty() {
// Your code to get the next kitty drawable id
}
}