floating: Implement smarter clamping for window location

A small part of the window always remains on-screen regardless of the working
area changes.

Interactive move lets the user position the window anywhere; automatic actions
like toggle-window-floating and dialog opening try to put the window fully
on-screen.

The size-fraction canonical floating window position remains unclamped, and
clamping happens when recomputing the logical position.

1 files changed, 49 insertions, 0 deletions

diff --git a/src/utils/mod.rs b/src/utils/mod.rs
index b4ba1002..e7dff735 100644
--- a/src/utils/mod.rs
+++ b/src/utils/mod.rs
@@ -272,6 +272,18 @@ pub fn ensure_min_max_size(mut x: i32, min_size: i32, max_size: i32) -> i32 {
     x
 }
 
+pub fn clamp_preferring_top_left_in_area(
+    area: Rectangle<f64, Logical>,
+    rect: &mut Rectangle<f64, Logical>,
+) {
+    rect.loc.x = f64::min(rect.loc.x, area.loc.x + area.size.w - rect.size.w);
+    rect.loc.y = f64::min(rect.loc.y, area.loc.y + area.size.h - rect.size.h);
+
+    // Clamp by top and left last so it takes precedence.
+    rect.loc.x = f64::max(rect.loc.x, area.loc.x);
+    rect.loc.y = f64::max(rect.loc.y, area.loc.y);
+}
+
 #[cfg(feature = "dbus")]
 pub fn show_screenshot_notification(image_path: Option<PathBuf>) {
     let mut notification = notify_rust::Notification::new();
@@ -309,3 +321,40 @@ pub fn cause_panic() {
     let b = Duration::from_secs(2);
     let _ = a - b;
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_clamp_preferring_top_left() {
+        fn check(
+            (ax, ay, aw, ah): (i32, i32, i32, i32),
+            (rx, ry, rw, rh): (i32, i32, i32, i32),
+            (ex, ey): (i32, i32),
+        ) {
+            let area = Rectangle::from_loc_and_size((ax, ay), (aw, ah)).to_f64();
+            let mut rect = Rectangle::from_loc_and_size((rx, ry), (rw, rh)).to_f64();
+            clamp_preferring_top_left_in_area(area, &mut rect);
+            assert_eq!(rect.loc, Point::from((ex, ey)).to_f64());
+        }
+
+        check((0, 0, 10, 20), (2, 3, 4, 5), (2, 3));
+        check((0, 0, 10, 20), (-2, 3, 4, 5), (0, 3));
+        check((0, 0, 10, 20), (2, -3, 4, 5), (2, 0));
+        check((0, 0, 10, 20), (-2, -3, 4, 5), (0, 0));
+
+        check((1, 1, 10, 20), (2, 3, 4, 5), (2, 3));
+        check((1, 1, 10, 20), (-2, 3, 4, 5), (1, 3));
+        check((1, 1, 10, 20), (2, -3, 4, 5), (2, 1));
+        check((1, 1, 10, 20), (-2, -3, 4, 5), (1, 1));
+
+        check((0, 0, 10, 20), (20, 3, 4, 5), (6, 3));
+        check((0, 0, 10, 20), (2, 30, 4, 5), (2, 15));
+        check((0, 0, 10, 20), (20, 30, 4, 5), (6, 15));
+
+        check((0, 0, 10, 20), (20, 30, 40, 5), (0, 15));
+        check((0, 0, 10, 20), (20, 30, 4, 50), (6, 0));
+        check((0, 0, 10, 20), (20, 30, 40, 50), (0, 0));
+    }
+}