我如何使用Cocoa的辅助功能API来检测窗口是否被带到前面？ [英] How can I use Cocoa's Accessibility API to detect that a window is brought to front?

问题描述

我使用辅助功能API来检测特定应用程序何时打开窗口，关闭窗口，窗口移动或调整大小，或主要和/或聚焦。但是，客户端应用程序似乎将一个窗口移动到前面，而没有辅助功能API通知被
触发。

I'm using the Accessibility API to detect when a certain application opens windows, closes windows, when the windows are moved or resized, or made main and/or focused. However the client app seems to move a window to front without an Accessibility API notification being fired.

我的应用程序如何检测另一个应用程序带来了窗口

How can my application detect when another application brings a window to front, without making it key?

我希望找到一个适用于OS X 10.4和10.5的解决方案

I'm hoping to find a solution that works on OS X 10.4 and 10.5

更多信息：
我现在使用这些语句。它们工作正常，当用户手动选择一个窗口将其带到前面。但是当应用程序本身将窗口置于前端时，它不能工作。

More info: I'm using these statements at the moment. They work fine when the user manually selects a window to bring it to front. But it doens't work when the app itself is bringing the window to the front.

AXObserverAddNotification(observer, element, kAXMainWindowChangedNotification, 0);
AXObserverAddNotification(observer, element, kAXFocusedWindowChangedNotification, 0);

推荐答案

我无法订阅目前的窗口变更，但你可以问当前应用程序的可访问性API，以及当前应用程序最前景窗口。

I've been unable to subscribe to current window changes, but you can ask the accessibility API for the current application, and the current applications most foreground window.

假设您有一个名为CurrentAppData的类，其中包含以下数据：

Imagine you have a class called CurrentAppData, with the following data:

@interface CurrentAppData : NSObject {
    NSString* _title;
    AXUIElementRef _systemWide;
    AXUIElementRef _app;
    AXUIElementRef _window;
}

查找当前应用程序的代码如下：

The code to find the current application looks something like this:

-(void) updateCurrentApplication {
   // get the currently active application  
   _app = (AXUIElementRef)[CurrentAppData
                           valueOfExistingAttribute:kAXFocusedApplicationAttribute 
                                        ofUIElement:_systemWide];

   // Get the window that has focus for this application
   _window = (AXUIElementRef)[CurrentAppData 
                              valueOfExistingAttribute:kAXFocusedWindowAttribute 
                                           ofUIElement:_app];

   NSString* appName = [CurrentAppData descriptionOfValue:_window
                                             beingVerbose:TRUE];    

   [self setTitle:appName];
}

在此示例中，_systemWide变量在类init函数中初始化为：
_system = AXUIElementCreateSystemWide（）;

In this example the _systemWide variable is initialized in the classes init function as: _system = AXUIElementCreateSystemWide();

类函数valueOfExistingAttribute如下所示：

The class function valueOfExistingAttribute looks like this:

// -------------------------------------------------------------------------------
//  valueOfExistingAttribute:attribute:element
//
//  Given a uiElement and its attribute, return the value of an accessibility
//  object's attribute.
// -------------------------------------------------------------------------------
+ (id)valueOfExistingAttribute:(CFStringRef)attribute ofUIElement:(AXUIElementRef)element
{
    id result = nil;
    NSArray *attrNames;

    if (AXUIElementCopyAttributeNames(element, (CFArrayRef *)&attrNames) == kAXErrorSuccess) 
    {
        if ( [attrNames indexOfObject:(NSString *)attribute] != NSNotFound
                &&
            AXUIElementCopyAttributeValue(element, attribute, (CFTypeRef *)&result) == kAXErrorSuccess
        ) 
        {
            [result autorelease];
        }
        [attrNames release];
    }
    return result;
}

上一个函数取自Apple UIElementInspector 示例，这也是了解辅助功能API的一个很好的资源。

The previous function was taken from the Apple UIElementInspector example, which is also a great resource for learning about the Accessibility API.

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