Switch focus/activate another Application after opening it

Issue

I added an "Edit with Photoshop" button and succeeded opening Photoshop with a file using this code:

Type PhotoshopType = Type.GetTypeFromProgID("Photoshop.Application");
object PhotoshopInst = Activator.CreateInstance(PhotoshopType);                    
PhotoshopType.InvokeMember("Open", BindingFlags.InvokeMethod, null, PhotoshopInst, new object[1] { "c:\files\image.jpg" });  

But I am failing to activate (give focus to) Photoshop so the user does not have to switch manually.
Any idea on how to accomplish it?

Solution

This is typically a use-case for the UIAutomation technology. Here is a sample C# console app that does this:

dynamic instance = Activator.CreateInstance(Type.GetTypeFromProgID("Photoshop.Application"));
instance.Open(@"c:\files\image.jpg");

// add a COM reference to "UIAutomationClient"
// uncheck "Embed interop types" in the UIAutomationClient Reference properties (or redeclare the ids manually)
var uia = new UIAutomationClient.CUIAutomation();
var root = uia.GetRootElement();

// find Photoshop window (it's a top level window)
var ps = root.FindFirst(UIAutomationClient.TreeScope.TreeScope_Children,
    uia.CreateAndCondition(
            uia.CreatePropertyCondition(UIAutomationClient.UIA_PropertyIds.UIA_LocalizedControlTypePropertyId, "window"),
            uia.CreatePropertyCondition(UIAutomationClient.UIA_PropertyIds.UIA_ClassNamePropertyId, "Photoshop")
            )
    );

if (ps != null)
{
    // this is not to be confused with Win32's SetFocus API
    // it does a lot more
    ps.SetFocus();
}

To determine how to search for Photoshop, you can use the Inspect tool from Windows SDK and you will see something like this:

Where the "localized control type" is "window" and the ClassName" is "Photoshop".

Answered By – Simon Mourier

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