Re: Launched window not activating

FROM : Ken Tozier
DATE : Tue Apr 12 06:32:38 2005

On Apr 11, 2005, at 10:13 PM, Charilaos Skiadas wrote:

> Ken,
>
> Where from are the cameraNotifications posted?


They come from the ICA (image capture) interface (not my app) so I 
don't really know what's happening under the hood.

> The method handling them will be running in that same thread that they 
> were posted on, regardless of in which thread you registered for the 
> notification, so the downloader methods dealing with the notifications 
> might actually not be running in the main thread.


I just did a test in the callback handler checking to see if I was 
multithreaded but it doesn't appear that the ICA stuff is forking a new 
thread for messages it delivers. I was still single threaded inside the 
callback.

> In that case, your downloader should be using 
> performSelectorOnMainThread: for the creation of the window and 
> bringing it to front, to make sure these operations take place in the 
> main thread.


OK I tried performSelectorOnMainThread and got basically the same 
result. The window appears in unactivated form and sending it a 
"makeKeyAndOrderFront" from within performSelectorOnMainThread doesn't 
do anything. You can click on it and move it around the screen but it 
never comes to the front.

> In any case it's a good idea to give it a try this way, and ensure 
> that all the UI stuff happens in the main thread.
> This might talk a bit more about the issue:
> http://cocoa.mamasam.com/MACOSXDEV/2004/02/2/85391.php


Thanks for the link.

Ken


>
> HTH
> On Apr 11, 2005, at 8:51 PM, Ken Tozier wrote:
>

>> Sorry to keep beating this issue, but there is something 
>> fundamentally wrong somewhere in the following six steps and I'm just 
>> not experienced enough with Cocoa GUI stuff to see it. To me, the 
>> algorithm looks fine, but there is some subtle thing that Cocoa 
>> doesn't like.
>>
>> The problem is that the window generated in step 6.A and displayed in 
>> 6.B is never frontmost and can't even be forced to front by clicking 
>> on it. The only way to bring it to front is to put the window load 
>> code inside a thread (which I'm told is bad for GUI stuff) Even when 
>> it's placed in a thread, it doesn't become frontmost without manually 
>> clicking on it.
>>
>> Anyone see the error?
>>
>> Thanks
>>
>> Ken
>>
>> Sequence of events:
>> --------------------------------
>> 1. Application opens "main" nib
>>
>> 2. "AppController" instance inside "main" nib initializes it's 
>> "downloader" instance
>>
>>     - (id) init
>>     {
>>         self = [super init];
>>         if (self)
>>         {
>>             downloader        = [[ICADownloader alloc] init];
>>         }
>>         
>>         return self;
>>     }
>>
>> 3. Downloader instance registers for camera connect events in it's 
>> "init" method
>>
>>
>>     - (id) init
>>     {
>>         self    = [super init];
>>         if (self)
>>         {
>>             [self registerForCameraConnectNotifications];
>>         }
>>         
>>         return self;
>>     }
>>
>>
>> 4. Time passes
>>
>> 5. User plugs in a camera
>>
>> 6. Downloader receives camera connect notification and performs 
>> following actions:
>>
>>     A. Creates a new window by loading the "DownloadWindow" nib file 
>> using NSWindowController with an owner of "self".
>>     B. Displays the window.
>>     C. Downloads photos to a specified directory.
>>     D. Closes window.
>>
>> 7. Done/Waits for another camera connect event.
>>
>>
>> Hierarchically, the location of the window create code is
>>
>> App
>> {
>>    Main Nib
>>    {
>>      AppController
>>      {
>>          downloader
>>          {
>>            handleCameraConnect <- (callback method)
>>            {
>>                NSWindowController    *wind
>>            }
>>          }
>>      }
>>    }
>> }
>>
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> Haris
>