Prevent zoom following the cursor

[vdegenne]

When using the zoom feature, the zoom's position adapts to the cursor's position on the screen. I don't see an option on the GUI, but if there is a way to prevent that please let me know!

[Could as well be a feature request.]

[ammen99]

This is a feature request for sure, we don't have support for it right now. But it shouldn't be hard to add to zoom. Maybe as a separate modifier? So we have modifier for the current behavior, another modifier option for a 'fixed' zoom or whatever name is best.

[vdegenne]

I opened an issue: #3027

Would love to see this implemented!

Maybe as a separate modifier? So we have modifier for the current behavior, another modifier option for a 'fixed' zoom or whatever name is best.

Yes that would be the way to go. A checkbox "Lock zoom" or something. The default being the current behavior.

[soreau]

@vdegenne I tried my hand at this and you were right about it not behaving correctly when locked. I just put a transformer on the views to adjust the pointer input, but it still doesn't scale the coordinates when moving or resizing but it works. You can find the patch here.

[soreau]

@vdegenne I think I got it all worked out now, complete with animated transitions when unlocking and not constantly redrawing needlessly every frame. It's still in the zoom-no-follow branch. Let me know what you think. 👍

[vdegenne]

I installed your branch and everything seems perfect (the cursor shadows are gone, and the switch transition really is a nice touch). I'll report if anything unusual comes up.

Note: Really thankful you guys looked into it and helped me. Thanks again.

[vdegenne]

@soreau What about an option to always keep the pointer in the center of the viewport (especially in free mode)? I remember trying to implement that before but it was very challenging because that means as we get closer to the edges of the actual visible space we have to trick some functions into thinking there are still renderable pixels out there to avoid crashes or glitches.
I was close to something but it was all glitchy outside (best way to describe it, it was similar to the falling cards when winning a game of solitaire on old windows systems..).
Unfortunately I removed the branch because it was all messy and seemed like a dead end.
Let me know if you want to have fun trying to figure this out..
Maybe I'll come up with another PR when the pending one gets validated.

[soreau]

You mean something like this?

diff --git a/metadata/zoom.xml b/metadata/zoom.xml
index f4a005c0..9f5cda8f 100644
--- a/metadata/zoom.xml
+++ b/metadata/zoom.xml
@@ -30,6 +30,11 @@
 			<_long>Allows the locked viewport to move when the cursor reaches its edge.</_long>
 			<default>true</default>
 		</option>
+		<option name="centered" type="bool">
+			<_short>Center cursor</_short>
+			<_long>Center cursor within zoomed area.</_long>
+			<default>true</default>
+		</option>
 		<option name="interpolation_method" type="int">
 			<_short>Interpolation method</_short>
 			<_long>Sets the pixel interpolation method to use.</_long>
diff --git a/plugins/single_plugins/zoom.cpp b/plugins/single_plugins/zoom.cpp
index 964a237a..762c050d 100644
--- a/plugins/single_plugins/zoom.cpp
+++ b/plugins/single_plugins/zoom.cpp
@@ -16,6 +16,7 @@ class wayfire_zoom_screen : public wf::per_output_plugin_instance_t
 
     wf::option_wrapper_t<wf::keybinding_t> modifier{"zoom/modifier"};
     wf::option_wrapper_t<wf::activatorbinding_t> lock{"zoom/lock"};
+    wf::option_wrapper_t<bool> centered{"zoom/centered"};
     wf::option_wrapper_t<double> speed{"zoom/speed"};
     wf::option_wrapper_t<wf::animation_description_t> smoothing_duration{"zoom/smoothing_duration"};
     wf::option_wrapper_t<bool> edge{"zoom/edge"};
@@ -224,6 +225,15 @@ class wayfire_zoom_screen : public wf::per_output_plugin_instance_t
             }
         }
 
+        if (!locked && centered)
+        {
+            wlr_box_closest_point(&b, cur_pos.x, cur_pos.y, &cur_pos.x, &cur_pos.y);
+            wf::geometry_t box = {cur_pos.x, cur_pos.y, 1, 1};
+            box = output->render->get_target_framebuffer().framebuffer_geometry_from_geometry_box(box);
+            x1 = std::min(float(box.x), b.width - tw / 2) - tw / 2;
+            y1 = std::min(float(box.y), b.height - th / 2) - th / 2;
+        }
+
         x1 = std::clamp(x1, 0.0f, w - 1.0f);
         y1 = std::clamp(y1, 0.0f, h - 1.0f);
         tw = std::clamp(tw, 0.0f, w - x1);

[soreau]

I pushed a variant that should work with animations and such.

[vdegenne]

That's so clean!

I found a situation where it would make wayfire crashes, does it happen to you too?
Try this:

• unzoom completely
• use the assigned keybind to go in locked mode
• then zoom

It should crash.

Maybe we should just prevent the keybind to even work if we are zoomed out completely, the question to ask is would some user even need to lock an area before zooming? The way it's designed I think it's more natural to just zoom and lock.

[soreau]

Yes, I fixed the crash and pushed some fixes for transformed outputs. And yes, I made it so it just doesn't lock with zoomed all the way out, which was the original intention anyway. Should work better now, thanks for testing!

[soreau]

@vdegenne I cleaned up the patches and made a pull request here #3138

There should be no difference between this and the last changes pushed to the branch. Cheers.