I'a currently working on a small utility, it's my first ever X project. The utility is used to draw a small circle around your mouse pointer. I use an app called Pinpoint to do the same on my Mac, it helps me find my mouse as I'm visually impaired.
The utility creates an transparent X window and draw a circle inside, it then moves that window with the mouse pointer so that the circle follows the mouse.
It currently works, except for one detail. Mouse events are not propagated up to the underlying windows. Basically, the utility makes the mouse useless.
As far as I can tell from the Xlib docs, if not otherwise specified, new windows should propagate all events. How can I fix this?
The code can be found on GitHub: https://github.com/blubber/circle-cursor it's a bit messy currently, becaue it is just a proof of concept.
I would suggest doing via cursor image as well, there are many ways when you won't be able to receive mouse events and only possible source would be polling with XQueryPointer.
With xfixes extension you can subscribe to all cursor image changed events and get most recent shape of the cursor, and whit XRender you can set your own ( possibly animated cursor )
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What happens is that I initiate the window drag instruction with Neutralino.window.setDraggableRegion, it works but there is a very big problem in rendering.
I am on a windows system. Here is a video of the problem:
Video of the problem
As you specified, the window is dragging but the mouse doesn't move with the point you click on, instead the mouse is at a different position.
I Looked at how draggable region function works under the hood, and it's handled by the JavaScript Client File, by setting the window position to the amount of mouse has moved on x and y.
since the mouse pointer doesn't move instead the window moves relative to the position from where you started clicking.
I will raise this issue, and soon a fix for this will be out!
Issue has been raised
I have a program using glfw for window management and opengl for rendering. The program works on Windows and linux, and eventually Mac OSX so I want any solution to be portable.
glfw seems to either support a cursor, or getting full mouse input but not both. For example, with the cursor enabled (default) the glfwscroll_callback does nothing. If I disable the cursor, then scrolling the mouse is captured but then the user cannot see where the mouse pointer is. That's ok if I can draw the cursor myself when I want but I cannot find any function to drawcursor at a particular location.
How does the cursor work, ie what is the hardware basis for the cursor? Is there a sprite in hardware still? If it's all in software, I suppose we could draw a cursor at the current mouse location the last thing in render. But that's not convenient. For one thing if the scene hasn't changed, I shut down rendering completely to reduce power.
Is there any way to manually draw a cursor on top of the current screen so that we don't have to manage the buffers manually? Is my only option to change the logic and not render the scene if nothing has changed, but to manually draw a cursor on top of the current scene every frame?
I would like to draw some sort of window on top of all the other windows. For example, to display some debugging infos (like conky) or things like a timer.
The main thing is that I would like to able to continue using the other windows while using it (the events go through transparently).
I've tried doing it with pygtk, pyqt and others but can't find a way to make it a real overlay with no event capture.
Is there some low-level x11 solution?
I think the Composite-extension-approach will not work when a compositing manager is running (and thus Composite's overlay window is already used).
Since you explicitly mention "no event capture":
The SHAPE extension allows to set some different shapes for a window. Version 1.1 of this extension added the "input" shape. Just setting this to an empty region should pretty much do what you want.
Some concrete example of exactly what I think you ask for can be found in Conky's source code: http://sources.debian.net/src/conky/1.10.3-1/src/x11.cc/?hl=769#L764-L781
Edit: Since you said that you didn't find anything in Gtk (well, PyGtk), here is the function that you need in Gtk: https://developer.gnome.org/gdk3/stable/gdk3-Windows.html#gdk-window-input-shape-combine-region
You might need Composite extension + GetOverlayWindow request:
Version 0.3 of the protocol adds the Composite Overlay Window, which
provides compositing managers with a surface on which to draw without
interference. This window is always above normal windows and is always
below the screen saver window. It is an InputOutput window whose width
and height are the screen dimensions. Its visual is the root visual
and its border width is zero. Attempts to redirect it using the
composite extension are ignored. This window does not appear in the
reply of the QueryTree request. It is also an override redirect
window. These last two features make it invisible to window managers
and other X11 clients. The only way to access the XID of this window
is via the CompositeGetOverlayWindow request. Initially, the Composite
Overlay Window is unmapped.
CompositeGetOverlayWindow returns the XID of the Composite Overlay
Window. If the window has not yet been mapped, it is mapped by this
request. When all clients who have called this request have terminated
their X11 connections the window is unmapped.
Composite managers may render directly to the Composite Overlay
Window, or they may reparent other windows to be children of this
window and render to these. Multiple clients may render to the
Composite Overlay Window, create child windows of it, reshape it, and
redefine its input region, but the specific arbitration rules followed
by these clients is not defined by this specification; these policies
should be defined by the clients themselves.
C api : XCompositeGetOverlayWindow
PyGTK Solution:
I think the composite and shapes X extensions are sufficiently ubiquitous and shall assume here that they are active on your system. Here's PyGtk code for this:
# avoid title bar and standard window minimize, maximize, close buttons
win.set_decorated(False)
# make the window stick above all others (super button will still override it in the z-order, which is fine)
win.set_keep_above(True)
# make events pass through
region = cairo.Region(cairo.RectangleInt(0, 0, 0, 0))
my_window.input_shape_combine_region(region)
win.show_all()
# set the entire window to be semi-transparent, if we like
win.set_opacity(0.2)
Basically what this does is tell Gtk that other than pixel (0,0) the entire window my_window should not be considered part of itself in terms of event propagation. That in turn, according to my current understanding means that when the pointer moves and clicks, the events go to the underlying window under the pointer position, as if my_window was not there.
Caveat:
This does allow your overlay window being the focus window (due to user-solicited window switching or just because it pops up and gets the focus when your application starts). Which means that for example, keyboard events will still undesirably go to it up until the user has clicked through it to make it lose focus in favor of whatever window is under the cursor. I would likely use the approach described here to iron out this aspect.
If there's a different and proper approach for making a portion of the screen "display stuff but not receive events", without building an oddball window like above over it, I'm happy to learn about it.
I assume that one's particular desktop environment (gnome, unity, etc. on linux) may interfere with this solution depending on version and configuration, on some occasions.
The game I'm designing currently requires a first person controller and luckily Three.js offers that class as well.
However I can't stop the camera from flying around. I know that the mouse movement causes the fly because it happens as soon as I move the mouse. But reading the js code,I cant find the attribue which causes this movement. Here is how I initiate the controls:
controls = new THREE.FirstPersonControls(camera);
controls.movementSpeed = 0.1;
controls.lookSpeed = 0.001;
controls.lookVertical = true;
I do not want the view direction to change when I am not moving the mouse.
any idea ?
Keep in mind that the FPS style mouse movement in webGL is usable rather only in a full screen mode. If an application runs in a standard windowed mode, the cursor is visible, and the application can not detect cursor movements that cross the edge of the window. This makes it impossible to look around in the FPS style (look movement stops when the cursors reaches the window edge).
This is probably the main reason why a PointerLockControls demo asks you to switch to the full screen mode.
With FirstPersonControls the look movement continues when the mouse reaches the edge. Such approach works well in the windowed mode.
You might want to use the PointerLockControls instead
See an example here:
https://github.com/mrdoob/three.js/blob/master/examples/misc_controls_pointerlock.html
I'd like to write a Linux screen magnifier that's customized to my liking. Ideally, the magnified window would be a square about 150 pixels wide that follows the mouse cursor wherever it goes.
Is it possible to do this in X11? Would it be easier to have an application window that follows the mouse around, or would it be better (or possible) to forget about the window altogether and just make the mouse pointer a 150x150 square that magnifies whatever's underneath?
Look at the source to xeyes?
This actually already exists, it's called Xmag (do a Google search for additional info). You might want to check out the source code for it if you want to know how it works.
EDIT: looks like I misread your question a little bit... if you want a magnified square to follow the mouse pointer around, I suppose it should be possible, but I don't know the technical details of how you'd do it. Regardless, the place to start is probably by looking at Xmag as a starting point.
I am unsure if this can run as its own app or would have to be integrated into your window manager. Either way, you would need libx11 (might have a different name from distro to distro). Also, I would suggest taking a look at swarp. I know this is not even close to what you are talking about, but the source code is only 35 lines and it shows what can be done with libx11.
I would personally make that a frameless window that always stays atop with a 1px hole in the middle. The events that the user makes (Mouse clicks, keypresses, whatever) is passed to the window below.
And when the user moves it's cursor it is ought to be visible to your window and you just move it over a bit. For the magnifying part, well - that is left as an exercise to the reader (Because I do not know how to do that as of yet ;-).
Texworks comes with such a feature to inspect the pdf resulting from typesetting a latex source. You can also choose between a square or a circular magnifier. See https://www.tug.org/texworks/ for access to the code which can serve a launchpad.