WPF Images Disappearing

Question

I'm writing a WPF Page application that on page load creates a series of CroppedBitmaps from a large source bitmap image, for the purposes of creation a 2D sprite like animation.  This creates quite a large number of images in memory.  There are three pages in the application, that transition from one to the other after a set amount of time.  Everything at first seems okay, however, I've noticed that after awhile, some of the images are no longer being displayed.  Each time the page loads, it should be reloading these images into memory, but it seems not to be the case.

Here's the code of my Animation Class

namespace MyProgram
{
    public delegate void NewCustomAnimationFinishedHandler(object sender, NewCustomAnimationEventArgs e);
    public delegate void NewCustomAnimationStartedHandler(object sender, NewCustomAnimationEventArgs e);

    public class NewCustomAnimationEventArgs : EventArgs
    {
        public string animKey;

        public NewCustomAnimationEventArgs(string key)
        {
            animKey = key;
        }
    }


    public class NewCustomAnimation : DependencyObject
    {
        #region Public / Privates Variable - Properties
        //public List<BitmapImage> Frames = new List<BitmapImage>();
        public DispatcherTimer animationTimer;
        public int totalFrames;
        public int currentFrame = 0;

        public List<Int32Rect> FrameRects;
        public List<CroppedBitmap> Frames;
        public BitmapImage source;

        #region Dependency Properties
        public static readonly DependencyProperty CurrentFrameProperty = DependencyProperty.Register("CurrentFrame", typeof(CroppedBitmap), typeof(NewCustomAnimation));
        public CroppedBitmap CurrentFrame
        {
            get { return (CroppedBitmap)GetValue(CurrentFrameProperty); }
            set { SetValue(CurrentFrameProperty, value); }
        }

        public static readonly DependencyProperty ImagePathProperty = DependencyProperty.Register("ImagePath", typeof(String), typeof(NewCustomAnimation), new PropertyMetadata("C:\\Childrens\\SteveTheSturgeon\\SwimRight"));
        public String ImagePath
        {
            get { return (String)GetValue(ImagePathProperty); }
            set { SetValue(ImagePathProperty, value); }
        }
        #endregion

        #endregion

        #region Event Declarations

        public event NewCustomAnimationFinishedHandler AnimationCompleted;
        public event NewCustomAnimationStartedHandler AnimationStarted;
        #endregion

        #region Constructor
        public NewCustomAnimation(string path)
        {
            FrameRects = new List<Int32Rect>();
            Frames = new List<CroppedBitmap>();
            ImagePath = path;
            LoadImage();
            animationTimer = new DispatcherTimer();
            animationTimer.Interval = TimeSpan.FromMilliseconds(33.33);
            animationTimer.Tick += new EventHandler(animationTimer_Tick);
            currentFrame = 0;
        }

        #endregion

        #region Public Functions

        public void StartAnimation()
        {
            animationTimer.Start();
            currentFrame = 0;
            OnAnimationStarted(new NewCustomAnimationEventArgs("beep"));
        }

        public void EndAnimation()
        {
            animationTimer.Stop();
        }

        public void FinishAnimation()
        {
            //MessageBox.Show("Killing Animation...");
            animationTimer.Stop();
            animationTimer.Tick -= animationTimer_Tick;

            cEventHelper.RemoveAllEventHandlers(this);

            Frames.Clear();
            FrameRects.Clear();
        }

        protected virtual void OnAnimationCompleted(NewCustomAnimationEventArgs e)
        {
            NewCustomAnimationFinishedHandler tmp = AnimationCompleted;
            if (tmp != null)
                AnimationCompleted(this, e);
        }

        protected virtual void OnAnimationStarted(NewCustomAnimationEventArgs e)
        {
            NewCustomAnimationStartedHandler tmp = AnimationStarted;
            if (tmp != null)
                AnimationStarted(this, e);
        }

        #endregion

        #region Private Functions

        private void LoadImage()
        {
            source = new BitmapImage(new Uri(ImagePath + "\\sprite.png"));

            XmlDocument doc = new XmlDocument();
            doc.Load(ImagePath + "\\sprite.xml");

            XmlNodeList animList = doc.GetElementsByTagName("sprite");

            foreach (XmlNode node in animList)
            {
                XmlElement animElement = (XmlElement)node;

                int x = Int32.Parse(animElement.GetAttribute("x"));
                int y = Int32.Parse(animElement.GetAttribute("y"));
                int w = Int32.Parse(animElement.GetAttribute("w"));
                int h = Int32.Parse(animElement.GetAttribute("h"));
                Int32Rect r = new Int32Rect(x, y, w, h);
                FrameRects.Add(r);

                totalFrames = FrameRects.Count;

            }

            foreach (Int32Rect r in FrameRects)
            {
                CroppedBitmap c;
                c = new CroppedBitmap(source, r);
                c.Freeze();
                Frames.Add(c);
            }

            CurrentFrame = Frames[0]; //new CroppedBitmap(source, FrameRects[0]);
            
        }

        #endregion

        #region Event Handler Methods
        void animationTimer_Tick(object sender, EventArgs e)
        {
            currentFrame++;
            if (currentFrame >= totalFrames)
            {
                currentFrame = 0;
                OnAnimationCompleted(new NewCustomAnimationEventArgs("test"));
            }

            CurrentFrame = Frames[currentFrame];// new CroppedBitmap(source, FrameRects[currentFrame]);  
        }

        #endregion
    }
}

Any help getting this sorted out would be greatly appreciated!

James Thompson

Answer 1

If you put the project somewhere we can download and debug.

---

JP Cowboy Coders Unite!

Answer 2

Hi James Thompson,

Could you share a repro sample with me, it is hard to find the root cause based on above code.

Best regards,

---

Sheldon _Xiao[MSFT]
MSDN Community Support | Feedback to us
Microsoft
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