referencing a control from a string

Tom Wright

I have a number of PictureBox controls that show a Street Stop Light. Each Picturebox control is controled by two radio buttons for a total of 8 picturebox control and 16 radio buttons. One for Run (turns the Stop Light Green) One for Stop (turns the light red). I am storing the name of the PictureBox control in the tag of it respective radio buttons. Can I take this string and use it to reference the Picturebox control and change the image? Here is me code:

    private void OnCheckedChange(object sender, EventArgs e)
    {
        RadioButton rb = (RadioButton)sender;
        if (rb.Checked && rb.Text.Contains("Run"))
        {
            OnLoadPictureImage(rb.Tag.ToString(), radioButton1.Checked);
        }
        else
        {
            OnLoadPictureImage(rb.Tag.ToString(), radioButton1.Checked);
        }
    }

    private void OnLoadPictureImage(String picBox, Boolean ObjectStatus)
    {
        try
        {
            PictureBox pb = new PictureBox();
            pb = (PictureBox)this.Controls\[picBox\];
            if (ObjectStatus)
            {
                Stream s = File.Open("../images/traffic-light-green.jpg", FileMode.Open);
                Image temp = Image.FromStream(s);
                s.Close();
                pb.Image = temp;
            }
            else
            {
                Stream s = File.Open("../images/traffic-light-red.jpg", FileMode.Open);
                Image temp = Image.FromStream(s);
                s.Close();
                pb.Image = temp;
            }
        }
        catch (Exception err)
        {
            MessageBox.Show("Error finding image: " + err.Message);
        }
    }

Is this not possible? Thanks Tom

Tom Wright tawright915@gmail.com

Jimmanuel

why not just store a reference to the PictureBox in the Tag? [edit] I may be making assumptions based on the limited scope of the code snippet, but shouldn't this

OnLoadPictureImage(rb.Tag.ToString(), radioButton1.Checked);

instead read

OnLoadPictureImage(rb.Tag.ToString(), rb.Checked);

Why create a new PictureBox inside of OnLoadPictureImage here:

PictureBox pb = new PictureBox();

pb is immediately overwritten to another PictureBox so wouldn't it be better to set it to null and not waste the time or resources creating the throw-away object?

Last modified: 16mins after originally posted --

:Badger:

Tom Wright

I did it that way because when I reference the PictureBox.image property I received and error that the object had not been instantiated. Either way it's still null...almost like it cannot find it. Oh...and I did have it like this: OnLoadPictureImage(rb.Tag.ToString(), rb.Checked); Just doing some debugging when I thought I'd post this to the forum and I forgot to set it back like I had it. Thanks for the help. Tom

Tom Wright tawright915@gmail.com

Tom Wright

The exact error was: Object reference not set to an instance of an object. T

Tom Wright tawright915@gmail.com

Jimmanuel

where? and in response to your original question,

pb = (PictureBox)this.Controls[picBox];

should work fine just fine as long as this.Controls[picBox] actually is a PictureBox. Doing a safe cast (this.Controls[picBox] as PictureBox) and then checking for null would be a safer way to do it.

:Badger:

Tom Wright

pb.Image = temp; <----- Here....when I try and set the image.

Tom Wright tawright915@gmail.com

Jimmanuel

and pb is what's null? a safe cast (the as operator) and null check would be better than C-style cast and no null check, and as long as the object names are stored correctly in the Tags then it should work.

:Badger:

xcorporation

private void Form1_Load(object sender, EventArgs e)
{
for (int x = 0; x < this.Controls.Count; ++x)
{
for (int y = 0; y < this.Controls[x].Controls.Count; ++y)
{
if (this.Controls[x].Controls[y].GetType() == typeof(RadioButton))
{
RadioButton _rdbtn = (RadioButton)this.Controls[x].Controls[y];
_rdbtn.CheckedChanged += new EventHandler(_rdbtn_CheckedChanged);
}
}
}
}

void _rdbtn_CheckedChanged(object sender, EventArgs e)
{
for (int x = 0; x < this.Controls.Count; ++x)
{
for (int y = 0; y < this.Controls[x].Controls.Count; ++y)
{
if (this.Controls[x].Controls[y].GetType() == typeof(RadioButton))
{
// Founded the radio button
RadioButton _rdbtn = (RadioButton)this.Controls[x].Controls[y];

     if (\_rdbtn.Checked == true)
     {
       for (int z = 0; z < this.Controls\[x\].Controls.Count; ++z)
       {
        if (this.Controls\[x\].Controls\[z\].GetType() == typeof(PictureBox))
        {
          // Change to green

          PictureBox \_pic = (PictureBox)this.Controls\[x\].Controls\[z\];

          if (\_pic.Tag == "Hi")
          {
           // this is the one you want to work with...

          }
        }
       }
     }
    }
  }
 }

}

Take note... if (rb.Checked && rb.Text.Contains("Run")) { OnLoadPictureImage(rb.Tag.ToString(), radioButton1.Checked); } else { OnLoadPictureImage(rb.Tag.ToString(), radioButton1.Checked); } will always execute irrelevant true or false. i assume one is 'Unchecked' This code should help only if you have the radio / image / etc. on panels. remove the 2nd layer of loops if you not using panels... Regards, X

Yeee :cool:

modified on Tuesday, May 19, 2009 5:17 PM

Jimmanuel

modification to my previous statement: in order for this to work:

pb = (PictureBox)this.Controls[picBox];

the picture box needs to be parented by the main form. If it exists on a child panel or a tab control or something like that then it won't exist in the main forms control collection. You'll have to recursively search the this.Control objects to find it. Like I said before, why not just store the picture box itself in the tag of the radio button? Then you'd have

PictureBox pb = rb.Tag as PictureBox;

and you'd be done.

:Badger:

Tom Wright · modified on Tuesday, May 19, 2009 5:17 PM

I see. I did not know that I had to iterate through all of the controls. Currently the Radio buttons are in group fields. I have 6 sets of Run/Stop radiobuttons on my form in 6 group fields. I ran into a problem where they were not in group fields and then only one radiobutton was allowed to be selected from the rest. Thanks for the help. Tom

Tom Wright tawright915@gmail.com