macos - 检测 macOS Catalina 上的屏幕录制设置

Question

检测用户是否启用此 API 的可靠方法是什么？

即使禁用屏幕录制 API，

CGWindowListCreateImage 也会返回有效对象。有多种可能的组合(kCGWindowListOptionInclusionWindow、kCGWindowListOptionOnScreenBelowWindow)，并且只有某些组合会返回 NULL。

- (CGImageRef)createScreenshotImage
{
    NSWindow *window = [[self view] window];
    NSRect rect = [window frame];

    rect.origin.y = NSHeight([[window screen] frame]) - NSMaxY([window frame]);
    CGImageRef screenshot = CGWindowListCreateImage(
                                                    rect,
                                                    kCGWindowListOptionIncludingWindow,
                                                    //kCGWindowListOptionOnScreenBelowWindow,
                                                    0,//(CGWindowID)[window windowNumber],
                                                    kCGWindowImageBoundsIgnoreFraming);//kCGWindowImageDefault
    return screenshot;
}

唯一可靠的方法是通过 CGDisplayStreamCreate，这是有风险的，因为 Apple 每年都会更改隐私设置。

   - (BOOL)canRecordScreen
    {
        if (@available(macOS 10.15, *)) {
            CGDisplayStreamRef stream = CGDisplayStreamCreate(CGMainDisplayID(), 1, 1, kCVPixelFormatType_32BGRA, nil, ^(CGDisplayStreamFrameStatus status, uint64_t displayTime, IOSurfaceRef frameSurface, CGDisplayStreamUpdateRef updateRef) {
                ;
            });
            BOOL canRecord = stream != NULL;
            if (stream) { 
              CFRelease(stream); 
            }
            return canRecord;
        } else {
            return YES;
        }
    }

Answer 1

这里提出的所有解决方案都存在这样或那样的缺陷。问题的根源在于您对窗口的了解权限(通过窗口列表中的名称)与您对窗口的进程所有者(例如 WindowServer 和 Dock)的了解权限之间没有关联。您查看屏幕上像素的权限是两组稀疏信息的组合。

以下启发式涵盖了 macOS 10.15.1 起的所有情况:

BOOL canRecordScreen = YES;
if (@available(macOS 10.15, *)) {
    canRecordScreen = NO;
    NSRunningApplication *runningApplication = NSRunningApplication.currentApplication;
    NSNumber *ourProcessIdentifier = [NSNumber numberWithInteger:runningApplication.processIdentifier];

    CFArrayRef windowList = CGWindowListCopyWindowInfo(kCGWindowListOptionOnScreenOnly, kCGNullWindowID);
    NSUInteger numberOfWindows = CFArrayGetCount(windowList);
    for (int index = 0; index < numberOfWindows; index++) {
        // get information for each window
        NSDictionary *windowInfo = (NSDictionary *)CFArrayGetValueAtIndex(windowList, index);
        NSString *windowName = windowInfo[(id)kCGWindowName];
        NSNumber *processIdentifier = windowInfo[(id)kCGWindowOwnerPID];

        // don't check windows owned by this process
        if (! [processIdentifier isEqual:ourProcessIdentifier]) {
            // get process information for each window
            pid_t pid = processIdentifier.intValue;
            NSRunningApplication *windowRunningApplication = [NSRunningApplication runningApplicationWithProcessIdentifier:pid];
            if (! windowRunningApplication) {
                // ignore processes we don't have access to, such as WindowServer, which manages the windows named "Menubar" and "Backstop Menubar"
            }
            else {
                NSString *windowExecutableName = windowRunningApplication.executableURL.lastPathComponent;
                if (windowName) {
                    if ([windowExecutableName isEqual:@"Dock"]) {
                        // ignore the Dock, which provides the desktop picture
                    }
                    else {
                        canRecordScreen = YES;
                        break;
                    }
                }
            }
        }
    }
    CFRelease(windowList);
}

如果未设置canRecordScreen，则需要设置某种对话框来警告用户他们只能看到菜单栏、桌面图片和应用程序自己的图片 window 。这是how we presented it在我们的应用程序中xScope .

是的，我仍然对这些保护措施是通过 little regard to usability 引入的感到痛苦。 .