Is it possible to resize a client from the compositor?

[xTrayambak]

Hello. I've checked the docs for LSurface and couldn't find any function to set a surface's size, only its position. Is there a way to force a surface to resize on the compositor side?

Sorry if this is an obvious question. I'm just not very well versed with the Louvre API.

[ehopperdietzel]

Hi! I noticed you started developing a compositor some time ago and now you're creating bindings for Nim. That's very cool!

A surface on its own only contains a buffer (texture) and some properties like scaling factor, transform, etc. What gives a surface additional "functionality" is a role, which is assigned by the client. Without a role, surfaces shouldn't be displayed (i.e., LSurface::mapped() returns false). When a client assigns a role to a surface, the LSurface::roleChanged() event is triggered. You can access the role with LSurface::role() or with role-specific functions. For example, LSurface::toplevel() returns a pointer to an LToplevelRole, or nullptr if the surface has another role.

There are many different roles which are listed here. The one you're probably looking for is LToplevelRole, which represents typical desktop windows. The LToplevelRole::configureXXX methods allow you to set the size of a window, change its state (maximized, fullscreen, etc.) and more. This is an asynchronous operation, to know when the client has applied your configuration, you should override the LToplevelRole::atomsChanged() event, which lets you handle many of its properties' changes atomically.

For example:

// Somewhere in your code

#include <LSurface.h>
#include <LToplevelRole.h>

if (surface->toplevel()) 
    surface->toplevel()->configureSize(800, 600); // Not applied immediately

// In your own toplevel implementation
void YourToplevelRoleImp::atomsChanged(LBitset<AtomChanges> changes, const Atoms &prevAtoms) {
    if (changes.check(WindowGeometryChanged)) {
        // Now windowGeometry().size() should be (800x600) (if the client obeyed your request)

        // And what was the previous size? : prevAtoms.windowGeometry.size()
    }
}

I understand that the documentation can be overwhelming and difficult to navigate. As a tip, I recommend always clicking on the More... link at the top of each class page. That will take you to a brief description of the core concepts of each class, making it easier to understand.

[xTrayambak]

Thank you for the quick answer! Louvre is quite the joy to write code with, I must admit. I've used wlroots before, and Louvre is leaps more friendlier than it. :^)

[ehopperdietzel]

I am glad you enjoy using it! 😄