feat(Padding): user configuration for custom padding

src/layout/Padding.zig

@@ -24,13 +24,22 @@ pub fn Layout(comptime Event: type, comptime Renderer: type) type {
         size: terminal.Size = undefined,
         element: Element = undefined,
         events: Events = undefined,
-        padding: u16 = undefined,
+        config: Config = undefined,
 
-        pub fn init(allocator: std.mem.Allocator, padding: u16, element: Element) @This() {
+        // TODO: padding (for all 4 directions?)
+        const Config = struct {
+            padding: ?u16 = undefined,
+            left: u16 = 0,
+            right: u16 = 0,
+            top: u16 = 0,
+            bottom: u16 = 0,
+        };
+
+        pub fn init(allocator: std.mem.Allocator, config: Config, element: Element) @This() {
             return .{
+                .config = config,
                 .element = element,
                 .events = Events.init(allocator),
-                .padding = padding,
             };
         }
 
@@ -58,16 +67,32 @@ pub fn Layout(comptime Event: type, comptime Renderer: type) type {
                         size.cols,
                         size.rows,
                     });
-                    const sub_event: Event = .{
-                        .resize = .{
-                            .anchor = .{
-                                .col = size.anchor.col + this.padding,
-                                .row = size.anchor.row + this.padding,
+                    var sub_event: Event = undefined;
+                    if (this.config.padding) |padding| {
+                        // used overall padding
+                        sub_event = .{
+                            .resize = .{
+                                .anchor = .{
+                                    .col = size.anchor.col + padding,
+                                    .row = size.anchor.row + padding,
+                                },
+                                .cols = size.cols -| (padding * 2),
+                                .rows = size.rows -| (padding * 2),
                             },
-                            .cols = size.cols -| this.padding -| this.padding,
-                            .rows = size.rows -| this.padding -| this.padding,
-                        },
-                    };
+                        };
+                    } else {
+                        // use all for directions individually
+                        sub_event = .{
+                            .resize = .{
+                                .anchor = .{
+                                    .col = size.anchor.col + this.config.left,
+                                    .row = size.anchor.row + this.config.top,
+                                },
+                                .cols = size.cols -| this.config.left -| this.config.right,
+                                .rows = size.rows -| this.config.top -| this.config.bottom,
+                            },
+                        };
+                    }
                     // adjust size according to the containing elements
                     switch ((&this.element).*) {
                         .layout => |*layout| {