how to get windowid from applescript - applescript

Question

I am trying to get window id of of every window.
set r to {}
tell application "System Events"
repeat with t in windows of processes
set sid to id of t
set end of r to {title:title of t, id:sid}
end repeat
end tell
r
The above code returns
error "System Events got an error: Can’t get id of item 1 of every window of every process." number -1728 from id of item 1 of every window of every process
How to get the window id of every window?

Answer 1

I wrote a little Objective-C program for you that gets the window owners, window names and window ids:
////////////////////////////////////////////////////////////////////////////////
// windowlist.m
// Mark Setchell
//
// Get list of windows with their WindowOwnerNames, WindowNames and WindowNumbers
//
// Compile with:
// clang windowlist.m -o windowlist -framework coregraphics -framework cocoa
//
// Run with:
// ./windowlist
//
// You can then run "screencapture" to capture that window:
//
// screencapture -l<windowid> -x someFile.[png|jpg|tif]
////////////////////////////////////////////////////////////////////////////////
#include <Cocoa/Cocoa.h>
#include <CoreGraphics/CGWindow.h>
int main(int argc, char **argv)
{
NSArray *windows = (NSArray *)CGWindowListCopyWindowInfo(kCGWindowListExcludeDesktopElements|kCGWindowListOptionOnScreenOnly,kCGNullWindowID);
for(NSDictionary *window in windows){
int WindowNum = [[window objectForKey:(NSString *)kCGWindowNumber] intValue];
NSString* OwnerName = [window objectForKey:(NSString *)kCGWindowOwnerName];
NSString* WindowName= [window objectForKey:(NSString *)kCGWindowName];
printf("%s:%s:%d\n",[OwnerName UTF8String],[WindowName UTF8String],WindowNum);
}
}
Output
./windowlist
Preview:(null):300
Safari:(null):48
Terminal:(null):231
VirtualBox:(null):212
Mail:(null):150
Dropbox:(null):181
Finder:(null):118
Notification Center:(null):83
Google Drive:(null):73
Copy:(null):68
InkServer:(null):49
iTerm:(null):44
Google Drive::69
Copy::66
Dropbox::63
Creative Cloud::57
Spotlight::41
SystemUIServer::33
SystemUIServer:(null):36
SystemUIServer::31
Window Server:Menubar:3
Dock:Dock:23
iTerm:2. bash:190
iTerm:1. bash:336

Answer 2

This is not possible with this code.
In the processes array of System Events the property id of a window is not required to be available in AppleScript, that's the reason why you get the error.
If an application has an AppleScript dictionary and the windows element is provided then all windows have an id property, but not all applications support AppleScript and the non-document based applications don't provide the windows element by default.