config/lua: add simple layout API (#14258)

Adds a simple layout lua api

1 files changed, 55 insertions, 0 deletions

diff --git a/example/layouts/spiral.lua b/example/layouts/spiral.lua
new file mode 100644
index 00000000..e97f4dbd
--- /dev/null
+++ b/example/layouts/spiral.lua
@@ -0,0 +1,55 @@
+local state = {
+    ratio = 0.58,
+    offset = 0,
+}
+
+local sides = { "left", "top", "right", "bottom" }
+local opposite = {
+    left = "right",
+    right = "left",
+    top = "bottom",
+    bottom = "top",
+}
+
+local function clamp(x, min, max)
+    return math.max(min, math.min(max, x))
+end
+
+hl.layout.register("spiral", {
+    recalculate = function(ctx)
+        local n = #ctx.targets
+        if n == 0 then
+            return
+        end
+
+        local area = ctx.area
+
+        for i, target in ipairs(ctx.targets) do
+            if i == n then
+                target:place(area)
+            else
+                local side = sides[((i - 1 + state.offset) % #sides) + 1]
+                target:place(ctx:split(area, side, state.ratio))
+                area = ctx:split(area, opposite[side], 1.0 - state.ratio)
+            end
+        end
+    end,
+
+    layout_msg = function(ctx, msg)
+        local command, arg = msg:match("^(%S+)%s*(.*)$")
+
+        if command == "ratio" then
+            state.ratio = clamp(tonumber(arg) or state.ratio, 0.1, 0.9)
+        elseif command == "grow" then
+            state.ratio = clamp(state.ratio + 0.05, 0.1, 0.9)
+        elseif command == "shrink" then
+            state.ratio = clamp(state.ratio - 0.05, 0.1, 0.9)
+        elseif command == "rotate" then
+            state.offset = (state.offset + 1) % #sides
+        else
+            return "spiral: expected ratio <0.1..0.9>, grow, shrink, or rotate"
+        end
+
+        return true
+    end,
+})