Better Way to Display new Image Document in Picturebox

Question

I'm using WinForms. In my Form i have a picturebox. This program looks in "C:\image\" directory to find a specified image document, in my case a tif file. There is always only one picture in "C:\image\" directory.

After it locates the file, the program displays the image document in the picturebox.

When i was running this i saw that the CPU usage was high. My Goal is to make performance better or find out if there is a better way of coding this.

What i have to do: I have to manually go into my C:\image\ directory and delete the current image document then place a new image document in there so my picturebox will show the new image document.

In short, i have to delete the old image document and replace it with the new one, so i can view the new image document in my picturebox.

   int picWidth, picHeight;

    private void Form1_Load(object sender, EventArgs e)
    {
        timer1_Tick(sender, e);
    }

    private void File_Length()
    {
        try
        {
            string path = @"C:\image\";
            string[] filename = Directory.GetFiles(path, "*.tif"); //gets a specific image doc.

            FileInfo fi = new FileInfo(filename[0]);
            byte[] buff = new byte[fi.Length];
            using (FileStream fs = File.OpenRead(filename[0]))
            {
                fs.Read(buff, 0, (int)fi.Length);
            }
            MemoryStream ms = new MemoryStream(buff);
            Bitmap img1 = new Bitmap(ms);
            //opened = true; // the files was opened.
            pictureBox1.Image = img1;

            pictureBox1.Width = img1.Width;
            pictureBox1.Height = img1.Height;
            picWidth = pictureBox1.Width;
            picHeight = pictureBox1.Height;
        }
        catch(Exception)
        {
            //MessageBox.Show(ex.Message);
        }
    }

    public void InitTimer()
    {
        timer1 = new Timer(); 
        timer1.Tick += new EventHandler(timer1_Tick); //calls method
        timer1.Interval = 2000; // in miliseconds (1 second = 1000 millisecond)
        timer1.Start(); //starts timer
    }

    private void timer1_Tick(object sender, EventArgs e)
    {
        File_Length(); //checking the file length every 2000 miliseconds
    }

This should probably be on codereview.stackexchange.com because its working code. But your code does have an issue, if it doesn't find a TIF file in the directory (between you deleting and copying a new one in, or if it was just deleted), you will get an index out of range exception in your `File_Length` method. You need to check that `filename.Length > 0` before proceeding. Also, what kind of `Timer` are you using? — Ron Beyer, Nov 05 '15 at 19:16
I didn't even know about the codereview.stackexchange thank you. I'm using the basic timer in the toolbox that visual studio provides. If that was what you where asking. @RonBeyer — Learning_To_Code, Nov 05 '15 at 19:20
and thank you for pointing filename.Length > 0 out :) @RonBeyer — Learning_To_Code, Nov 05 '15 at 19:25
Timer is not needed. I just didn't know how i could check for the images in the directory, so i used the timer to check every couple seconds. @capricorn — Learning_To_Code, Nov 05 '15 at 19:52
I have another application whenever you hit display on the other application it basically deletes the old image and replaces it with a new image in the directory. I need to do it more than one time. @capricorn — Learning_To_Code, Nov 05 '15 at 19:55
The other application deletes and places images into the "C:\image\" directory. My application must view the new images every time there's a new image in the directory. @capricorn — Learning_To_Code, Nov 05 '15 at 20:02
The "C:\image\" directory only has one image file named display.tif. The other application first deletes the old image named "display.tif," and places a new image and names it display.tif. — Learning_To_Code, Nov 05 '15 at 20:08

c4pricorn · Accepted Answer · 2015-11-05T21:34:24.020

1

Checking folder for new image by file date and change image - working example:

    int picWidth, picHeight;
    Timer timer1;
    DateTime oldfiledate;

    public void InitTimer()
    {
        timer1 = new Timer();
        timer1.Tick += new EventHandler(timer1_Tick); //add event
        timer1.Interval = 2000; // in miliseconds (1 second = 1000 millisecond)
        timer1.Start(); //starts timer
    }

    private void timer1_Tick(object sender, EventArgs e)
    {
        ChangeImage(); //call check&change function
    }

    private void Form1_Load(object sender, EventArgs e)
    {
        timer1_Tick(sender, e);  //raise timer event once to load image on start
        InitTimer();
    }

    private void ChangeImage()
    {
        string filename = @"c:\image\display.tif";

        DateTime filedate = File.GetLastWriteTime(filename);

        if (filedate > oldfiledate)   // change image only if the date is newer
        {
            FileInfo fi = new FileInfo(filename);
            byte[] buff = new byte[fi.Length];
            using (FileStream fs = File.OpenRead(filename))  //read-only mode
            {
                fs.Read(buff, 0, (int)fi.Length);
            }
            MemoryStream ms = new MemoryStream(buff);

            Bitmap img1 = new Bitmap(ms);
            pictureBox1.Image = img1;

            pictureBox1.Width = img1.Width;
            pictureBox1.Height = img1.Height;
            picWidth = pictureBox1.Width;
            picHeight = pictureBox1.Height;
            oldfiledate = filedate;  //remember last file date
        }
    }

Tested on C#2010Ex .NET 4 Client Profile.

edited Nov 05 '15 at 21:34

answered Nov 05 '15 at 19:48

c4pricorn

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You cant go into the folder and delete the image this way. The image is locked by the application. In my code i cloned so i could delete it. – Learning_To_Code Nov 05 '15 at 20:46
Hmm tested with image opened on other app... No errors. – c4pricorn Nov 05 '15 at 20:49
Error: File In Use The action can't be completed because the file is open in vshost32.exe – Learning_To_Code Nov 05 '15 at 20:53
Try this code: `Bitmap img1 = new Bitmap(Image.FromFile(filename));` `picturebox1.Image = img1;` – c4pricorn Nov 05 '15 at 21:00
The file is supposed to be able to delete while its open in my app. The other app is just deleting the old image and replacing them with a new image in the directory. – Learning_To_Code Nov 05 '15 at 21:02
`Bitmap img1 = new Bitmap(Image.FromFile(filename)); picturebox1.Image = img1;` It came up with the same issue :( – Learning_To_Code Nov 05 '15 at 21:04
FileStream also with the same issue? – c4pricorn Nov 05 '15 at 21:14
Tested code with filestream and no errors... I have no idea why all examples working... – c4pricorn Nov 05 '15 at 21:19
The file stream works! Thanks! can you add some comments to what you did so i can learn how you did it. – Learning_To_Code Nov 05 '15 at 21:26
Nothing,,, only copy some lines from Your code... Maybe `File.OpenRead` is better and can read locked files... But why my examples are working on my computer with no errors? – c4pricorn Nov 05 '15 at 21:29
1

Here is a good discussion about it http://stackoverflow.com/questions/6576341/open-image-from-file-then-release-lock – Learning_To_Code Nov 05 '15 at 21:38
1

Right. `Bitmap` lock file until `Dispose()`. `File.OpenRead` is better and faster than Bitmap. – c4pricorn Nov 05 '15 at 21:48

Better Way to Display new Image Document in Picturebox

1 Answers1