InvokeRequired for child controls

Question

Hello.

When updating controls on a multi-threaded application, we check the InvokeRequired property and use a invoke a delegate to update the controls if necessary.

My question is, if a control has other controls in it, for example a StatusStrip that has a ToolStripStatusLabel and a ToolStripProgressBar, is it enough to check the InvokeRequired property on the StatusStrip, and update all the child controls, or do I need to check the InvokeRequired property for each child control individually?

Thanks.

 

Answer 1

There are controls which doesn't provide InvokeRequired  property, for such controls parent will be responsible for that . Which mean you call

control.Parent.InvokeRequired. If control provides this property you have to call that exclusively.

Answer 2

Thank you.

Answer 3

when you need to change properties across threads, you are able to use the code below, 

 

richTextBox1.Invoke(new Action(() =>

                    {

                        richTextBox1.Text += dr["ItemID"].ToString() + " - " + dr["ShortDesc"].ToString() + "\r\n";

                    }));

 

with this you don't need to check the InvokeRequired property.

---

The fastest methods aren't always the quicdkest methods

MCPD : Windows & Web Developer
Microsoft Certified Technology Specialist ( Windows & Web )

@Gordon_Nologo

Answer 4

All the Controls and the Form are necessarily created in the same thread. The simpler is to use the InvokeRequired and the Invoke method from the Form. That way, the code is shorter if it resides within the Form's code.

Answer 5

when you need to change properties across threads, you are able to use the code below,

richTextBox1.Invoke(new Action(() =>

                    {

                        richTextBox1.Text += dr["ItemID"].ToString() + " - " + dr["ShortDesc"].ToString() + "\r\n";

                    }));

 

with this you don't need to check the InvokeRequired property.

Yes, calling Invoke works even if you don't test InvokeRequired first. But it does some work that is useless if you're already working within the UI. Call Invoke only if InvokeRequired is true.

Answer 6

when you need to change properties across threads, you are able to use the code below,

richTextBox1.Invoke(new Action(() =>

                    {

                        richTextBox1.Text += dr["ItemID"].ToString() + " - " + dr["ShortDesc"].ToString() + "\r\n";

                    }));

 

with this you don't need to check the InvokeRequired property.

Yes, calling Invoke works even if you don't test InvokeRequired first. But it does some work that is useless if you're already working within the UI. Call Invoke only if InvokeRequired is true.

I normally call this from a Backgroundworker so invoke is always required.

---

The fastest methods aren't always the quicdkest methods

MCPD : Windows & Web Developer
Microsoft Certified Technology Specialist ( Windows & Web )

@Gordon_Nologo