Cannot enable a Ribbon button programmatically - vsto

Question

I developed a VSTO 4 add-in for Excel. It works perfect, however, I have a button placed in the custom tab of its Ribbon control that is initially disabled.
After clicked other ribbon button in my custom tab, I need to enable the initially disabled button.
I tried with:
btnCancelar.Visible = true;
In the Click event of a button, but button is not shown. The strange thing is that when debugging, it still does not appear, but if a MessageBox is shown, the button get visible at last.
I don't understand this behaviour. How can I enable or disable a ribbon button dynamically by code?

Answer 1

I'm not sure what your language is used in your project, but I guess you can tranform it to your own language used. I'll show the example here in C#:
First you need to implement a so called Callback function in the RibbonXML definition:
<button id="buttonSomething" label="Content" size="large" getVisible="EnableControl"/>
then the next step is to implement the Callback function:
public bool EnableControl(IRibbonControl control)
{
return true; // visible ... false = invisible
}
VSTO will trigger the getVisible Callback and depending on the return value enable or disable the visible state (don't forget to remove any Visible property from the RibbonXML, otherwise the Callback is not triggered)
In case of the Ribbon Designer you need to make sure your Click signature is correct, the easies way to do that is by double clicking the button on the ribbon designer. This will create the Click method for you, for instance:
I created a Ribbon with the Ribbon designer and added two buttons. Double clicked the first button to get an empty method like below, and added the code.
private void button1_Click(object sender, RibbonControlEventArgs e)
{
// Toggle button visibility and make sure the button is enabled
// Visible (obviously) makes it visible, while Enabled is grayed if
// false. You don't need this it is Enabled by default, so just for
// demo purposes
button2.Visible = !button2.Visible;
button2.Enabled = button2.Visible;
// Force Ribbon Invalidate ...
this.RibbonUI.Invalidate();
// Long running proces
}
This worked perfectly for me, so if it doesn't work for you please provide more details of your coding.

Answer 2

I have created a workaround to this.
It was simple. Just started the long running process in different thread. That way, cancel button is shown when it should and then hidden after the process ends.
I used this code to launch the process in the Ribbon.cs code:
btnCancelar.Visible = true;
Action action = () => {
Formatter.GenerateNewSheet(Formatter.TargetType.ImpresionEtiquetas, frm.CustomerID, workbook, btnCancelar);
};
System.Threading.Tasks.Task.Factory.StartNew(action);
And inside the process method I have this code:
public static bool GenerateNewSheet(TargetType type, string customerID, Excel.Workbook workbook, Microsoft.Office.Tools.Ribbon.RibbonButton btnCancelar)
{
try
{
_cancelled = false;
InfoLog.ClearLog();
switch (type)
{
case TargetType.ImpresionEtiquetas:
return GenerateTagPrinting(customerID, workbook);
}
return false;
}
finally
{
btnCancelar.Visible = false;
}
}
The interesting thing here I have discovered is that Excel is thread safe, so it was not necessary to add a synchronization mechanism neither when adding rows in the new sheet nor when setting Visible property to false again.
Regards
Jaime