I'm trying to work out what the best way to draw over the top of all other items on the screen on OS X. I don't want to impede the user's ability to interact with their applications, but want to 'annotate' them. I want to be able to draw up to 20 different annotations. The top half of this screenshot from Gizmodo happens to nicely show the kind of thing I want to do. http://gizmodo.com/assets/resources/2006/07/04%20Safari.jpg (sorry, I'm too new to post it as an image)
The questions I think I need to answer are:
Should I create a single window for
each drawing and draw to that? If
so, how do I minimise overhead?
What kind of window or other context should I use given that I don't want any window
decoration?
I don't think I want the overhead of creating 20 windows, but I also don't know that I want to create a full-screen, invisible window that contains my context (I presume a subclassed NSView), because I fear that will a) cause problems interacting with what's below and b) break the niceties of only redrawing when necessary (my actual drawing will likely only cover 10% of the screen)
I've not worked with Quartz2d before, so I just can't get my head around how to get the 'right' context to draw on from the documentation. Any help would be appreciated.
Thanks,
Who
You can only draw into a window. You can make a transparent, borderless window but it will need to be at the front.
You could set it's level to something like NSPopUpMenuWindowLevel to make it draw above other windows (this will be very annoying to users) but clicking on it will:
a) activate and bring to the front your app
b) Prevent the app underneath receiving mouse events
Is that what you want?
Related
It is possible to use the SetWindowPos API on Windows to keep a windows always on top of other windows, and there are many questions on StackOverflow dealing with this.
It is possible to keep only part of a Window always visible? I.e. specify a clipping region inside an existing window, and keep only that part visible?
A use case would be the following (on Windows):
User clicks on icon to run app.
User highlights a portion of the screen to focus on (similar to the Snipping Tool on Windows 7)
The highlighted part of the screen remains always visible, even when other windows/programs are moved over the selected region.
I know the issues that would spring up with having other applications that are also set to being topmost. Just curious if this is even possible?
Even if you change part of your window to be transparent to what's below (with a clipping region) it's still going to take all the mouse clicks, etc. that occur over the transparent part.
Your best bet is to create a new smaller window and make it top-most while hiding the main one.
Is it possible to create an invisible X window? For initialization of an OpenGL ES 2.0 context, one has to create a X window manually, but I can't find a way to make it invisible. Since I'm only doing GPGPU I don't need an output window. In fact, it is rather annoying in my case.
I'm aware of a solution from an earlier question, where it has been pointed out to use InputOnly in XCreateWindow(). This, however, leads to the X error GLXBadDrawable. Probably because EGL requires the window to respond to graphics request. Is there another way? Maybe create it minimized? But I can't find anything on that either. Also setting the window's size really small doesn't help, since it always occupies the whole screen on my device (Nokia N9).
When you create an X window, it is created unmapped, so what about creating an InputOutput window and leaving it unmapped? Another option would be (if the window must stay mapped), to move it out of the screen.
I previously asked a question about changing the cursor system-wide on OSX. I used NSCursor to change the cursor, but the effects are only as long as the application is active. When another application becomes active, the custom cursor is lost.
Here is a related, more general question. How can you write an application to have system-wife effects? For example drawing an image on-screen even when your application is not active, and something else is?
I understand I probably need to go at a lower level than the Cocoa APIs. I just cannot figure out where to start looking? Any specific Carbon APIs that I need to be looking at? Or even lower?
Any pointers would be appreciated! If you specifically know how to change the cursor system-wide or how to draw an image and move it around (no matter what application is active), that would solve my current problem as well! Can I write an application that can achieve this when its installed on the system?
Thanks!
You can achieve the effect you want, but not the way you're thinking about doing it.
You say,
I am writing a presentation aid application that shows the equivalent of the "laser pointer" on screen, programmatically. My first idea was to use the mouse cursor itself as the pointer, and change its appearance as a red circle.
Then fake that. Create an application, perhaps of type LSUIElement, perhaps not, depending on the behavior you want. Create a borderless window (type NSBorderlessWindowMask) and fill it with a clear color. Set its window level high enough so that it floats over everything (using -[NSWindow setLevel:], though I can't think of what the best level would be off-hand), and draw into it.
It's true that you cannot set the cursor when you are not the foremost app. It's true that you cannot just scribble on the screen. But you can get the same effects if you're clever.
This behaviour is not provided by any APIs on Mac OS X. You would have to modify the resource files in the OS, and that's a very dangerous operation that could brick the target computer. You have to know what you're doing.
Are you trying to implement a theming app or something like that? What's your goal? If you tell us what you are trying to do, we may be able to suggest alternate approaches.
I am trying to make a simple application in which there is a empty red rectangle and whenever the mouse is moved over the upper half border of the rectangle the cursor will become closed hand.
I started with selecting the foundation command line project.Made a transparent NSWindow and embedded a NSView in it with the rectangle, made window to accept mouse moved events(by method: -setAcceptsMouseMovedEvents). I have overridden -canBecomeKeyWindow and -canBecomeMainWindow window to return YES. But somehow none of the -mouseMoved events are being received by NSView.
When I put the same code by making a cocoa application project and creating my window in -applicationDidFinishLaunching method , my view was able to receive -mouseMoved events.
why is it not receiving mouse moved events when I use foundation command line utility project ?
I have also observed that whenever I make a window(carbon or cocoa) through foundation cmd line utility project , the window doesn't become key even on clicking the title bar.On clicking the title bar color remains light grey instead of becoming dark grey. Why is this happening?
I have overridden -canBecomeKeyWindow and -canBecomeMainWindow of NSwindow to return YES.
I would agree with what Joshua has already said. Any application that is going to show a user interface, be it a faceless background process or one which shows up in the Dock, should be in the form of an application bundle, not a plain old Mach-O executable like the Foundation tool template will create.
Also, there are reasons why views do not respond to mouseMoved: events by default:
Mouse moved events can quickly flood the event queue
There is generally little reason to use mouseMoved:, as tracking areas are
far more effective and efficient.
A while back, I wrote a little test app that demonstrates the differences between these 2 approaches:
Moving your mouse around the upper view for roughly 20 seconds results in 1000 events, while in the lower view, which uses tracking areas, less than 50.
Sample GitHub project: https://github.com/NSGod/MouseMoved-vs-TrackingAreas
Again, as Joshua mentioned, it would be helpful if you could describe what you're trying to accomplish. If your app needs to be a background app (LSUIElement == 1), and present an interface without appearing in the Dock, then there are ways to do that (as Josh mentioned, a command-line, non-bundled app is not the way).
You have no event loop to detect events and pass them to your window because your program does not start an NSApplication. See the main.m file of a typical Cocoa application.
It might be helpful to describe what you're trying to accomplish by taking this approach. My guess is you're building a daemon but want a GUI interface to manage the otherwise "headless" daemon. That or you're building a new login management system. In either case, there are specific ways to do both and this isn't it. :-)
We have a fairly complex GUI, so when certain windows are resized their Redraw() is set to false till the operation is completed. The problem with this is that if the OS "Show window content while dragging" setting is checked, when decreasing the window's size the windows behind it are not repainted. This means I have to force the repaint myself so the remains of the resized window are deleted. I have no problem getting the dimensions of the region that was uncovered. What I'm looking for is best way to cause all windows within that region to repaint their part.
Not being much of a GUI programmer, I can traverse the uncovered region and list the windows in it. Then, I can ask each one of them to repaint its part. But I'm quite certain there has to be a better way to do this...
It is worth mentioning the app is written in PowerBuilder. This means I can call whatever Win32 function I'd like, but have limited control over the GUI behavior and the message handling. If there's a better way to prevent the window's content resize from being visible, or there's a way to make a non-redrawn window clean after itself, I'd love to hear it (just have the limitations above in mind).
I'm curious what version of PowerBuilder you are working in? I do resizing all the time and never run into issues like you are describing.
Maybe you can lay out some more detail on why you need to set your redraws to false within the PowerBuilder environment.
Hope I can help.