为动画加载大型图像序列的有效方法

Question

我有 4 个图像序列（png 格式）需要用于我的动画。每个序列大约 50 帧长，每帧大约 300x300，所以我有大约 30 MB 的资源要加载。加载它们以避免内存泄漏的最有效方法是什么？我应该选择 xml 可绘制动画还是有更好的方法？

我不需要同时在屏幕上显示所有这些。一次只会显示一个动画。

Answer 1

也许有点晚了:)但我希望这可以帮助其他用户。最后，我用一个简单的循环解决了这个问题，该循环加载图像、绘制图像并销毁它。

        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);
        }

这使内存分配保持稳定，无论您的动画有多少帧。显然，它在 CPU 上的成本更高，因为我们没有预加载所有资源，而是在每一帧持续加载它们。尽管有这些事实，我的应用程序还是运行顺利。在 Samsung Galaxy S3 和 Galaxy Tab 4 上测试。

Answer 2

非常感谢。我遇到了同样的问题，在看了你的回答一段时间后，我通过重写 AnimationDrawable 解决了这个问题。因此，如果问题是您无法加载数组中的所有图像，因为它太大而内存无法容纳它，那么请在需要时加载图像。我的 AnimationDrawable 是这样的：

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();

}

现在要播放动画，您需要执行下一步操作

    //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();
        }

    });

就这些了，对我来说没问题！！！

为动画加载大型图像序列的有效方法

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