Performance of Graphics.DrawImage

[kirkage]

I am attempting to create a program in C# which part of it consists of one image fading to another. The best way I found this to work is from an example by Bob Powell on the thread http://www.thescripts.com/forum/thread106125.html.

The issue is the performance of this code. A simple program that fades two images at 1280x1024 takes ~100% CPU. This is of course an issue. I'm hoping to see if anyone has a suggestion on how to accomplish this in a much more efficient manner. The code I am using is below,

The class:

public class FadePanel : Control
    {
 
        Image _imageA;
 
        public Image ImageA
        {
            get { return _imageA; }
            set { _imageA = value; }
        }
 
        Image _imageB;
 
        public Image ImageB
        {
            get { return _imageB; }
            set { _imageB = value; }
        }
 
        int _fade = 0;
        float _fadeTime;
 
        public float FadeTime
        {
            get { return _fadeTime; }
            set { _fadeTime = value; }
        }
 
        Timer t = new Timer();
 
        public FadePanel()
        {
 
            SetStyle(ControlStyles.AllPaintingInWmPaint | ControlStyles.UserPaint |
                ControlStyles.DoubleBuffer, true);
 
            t.Tick += new EventHandler(t_Tick);
 
        }
 
        protected override void OnPaint(PaintEventArgs e)
        {
            if (_imageA == null)
                return;
 
            e.Graphics.DrawImage(_imageA, this.ClientRectangle, 0, 0, _imageA.Width, 
                _imageA.Height, GraphicsUnit.Pixel);
 
            if (_imageB == null)
                return;
 
            ImageAttributes ia = new ImageAttributes();
 
            ColorMatrix cm = new ColorMatrix();
 
            cm.Matrix33 = 1.0f / 255 * _fade;
 
            ia.SetColorMatrix(cm);
 
            e.Graphics.DrawImage(_imageB, this.ClientRectangle, 0, 0, _imageA.Width,
                _imageA.Height, GraphicsUnit.Pixel, ia);
 
            //base.OnPaint(e);
        }
 
        public void Fade()
        {
            _fade = 1;
            this.t.Interval = (int)(1000f * _fadeTime / 32);
            this.t.Enabled = true;
        }
 
        private void t_Tick(object sender, EventArgs e)
        {
            _fade += 8;
            if (_fade >= 255)
            {
                _fade = 255;
                t.Enabled = false;
            }
            Invalidate();
        }
 
        protected override void OnPaintBackground(PaintEventArgs pevent)
        {
 
        }
    }
 

The form is of proper size for the images and this is the constructor for the form.

public Form1()
        {
            InitializeComponent();
 
            fpPictureBox.ImageA = Image.FromFile(@"images\forest01.jpg");
            fpPictureBox.ImageB = Image.FromFile(@"images\winter01.jpg");
            fpPictureBox.Fade();
        }
 

Any help is appreciated.

[kirkage]

I've worked on this some more but have not found a solution. No ideas from anyone?

[RedSon]

You can try setting the thread priority level of your processes worker thread to a lower level.