Efficient way to load large image sequences for animation - android-animation

Question

I have 4 image sequences (png format) that I need to use for my animations. Each sequence is about 50 frames long and each frame is about 300x300, so I have something like 30 MB of resources to load. What's the most efficient way to load them to avoid memory leaks? Should I go for xml drawable animations or there's a better way?
I don't need to display all of them on the screen at the same time. Only one animation at time will be displayed.

Answer 1

Maybe is a bit late :) but I hope this can help other users.
At the end I've solved it with a simple loop which loads an image, draws it and destroy it.
int frames = 50;
//LOADING-REMOVING NEEDED FRAMES
//set animation range
i = currentFrame % frames;
//frame to cache
frameList.add(BitmapsLoader(i)); //custom function to load a specified frame from res
if (frameList.size() == 3) {
//frame to draw
canvas.drawBitmap(frameList.get(1), left, top, null);
//frame to remove
frameList.get(0).recycle();
frameList.remove(0);
}
This keeps the memory allocation stable, no matters how many frames your animation is. Obviously it costs more on CPU, as we're not pre-loading all resources but we keep loading them at each frame. Despite these facts, my app is running smoothly.
Tested on a Samsung Galaxy S3 and on a Galaxy Tab 4.

Answer 2

Thanks a lot.
I'm facing the same problem and after seen your answer for a while I have solved it by overriding an AnimationDrawable.
So, if the problem is you that can't load all images in array because it is too big for the memory to hold it, then load the image when you need it.
My AnimationDrawable is this:
public abstract class MyAnimationDrawable extends AnimationDrawable {
private Context context;
private int current;
private int reqWidth;
private int reqHeight;
private int totalTime;
public MyAnimationDrawable(Context context, int reqWidth, int reqHeight) {
this.context = context;
this.current = 0;
//In my case size of screen to scale Drawable
this.reqWidth = reqWidth;
this.reqHeight = reqHeight;
this.totalTime = 0;
}
#Override
public void addFrame(Drawable frame, int duration) {
super.addFrame(frame, duration);
totalTime += duration;
}
#Override
public void start() {
super.start();
new Handler().postDelayed(new Runnable() {
public void run() {
onAnimationFinish();
}
}, totalTime);
}
public int getTotalTime() {
return totalTime;
}
#Override
public void draw(Canvas canvas) {
try {
//Loading image from assets, you could make it from resources
Bitmap bmp = BitmapFactory.decodeStream(context.getAssets().open("presentation/intro_000"+(current < 10 ? "0"+current : current)+".jpg"));
//Scaling image to fitCenter
Matrix m = new Matrix();
m.setRectToRect(new RectF(0, 0, bmp.getWidth(), bmp.getHeight()), new RectF(0, 0, reqWidth, reqHeight), Matrix.ScaleToFit.CENTER);
bmp = Bitmap.createBitmap(bmp, 0, 0, bmp.getWidth(), bmp.getHeight(), m, true);
//Calculating the start 'x' and 'y' to paint the Bitmap
int x = (reqWidth - bmp.getWidth()) / 2;
int y = (reqHeight - bmp.getHeight()) / 2;
//Painting Bitmap in canvas
canvas.drawBitmap(bmp, x, y, null);
//Jump to next item
current++;
} catch (IOException e) {
e.printStackTrace();
}
}
abstract void onAnimationFinish();
}
Now to play animation you need to do what next
//Get your ImageView
View image = MainActivity.this.findViewById(R.id.presentation);
//Create AnimationDrawable
final AnimationDrawable animation = new MyAnimationDrawable(this, displayMetrics.widthPixels, displayMetrics.heightPixels) {
#Override
void onAnimationFinish() {
//Do something when finish animation
}
};
animation.setOneShot(true); //dont repeat animation
//This is just to say that my AnimationDrawable has 72 frames with 50 milliseconds interval
try {
//Always load same bitmap, anyway you load the right one in draw() method in MyAnimationDrawable
Bitmap bmp = BitmapFactory.decodeStream(MainActivity.this.getAssets().open("presentation/intro_00000.jpg"));
for (int i = 0; i < 72; i++) {
animation.addFrame(new BitmapDrawable(getResources(), bmp), 50);
}
} catch (IOException e) {
e.printStackTrace();
}
//Set AnimationDrawable to ImageView
if (Build.VERSION.SDK_INT < 16) {
image.setBackgroundDrawable(animation);
} else {
image.setBackground(animation);
}
//Start animation
image.post(new Runnable() {
#Override
public void run() {
animation.start();
}
});
That is all, and works OK form me!!!