WIP layout engine

2024-10-10 12:54:53 -06:00
commit 13c8a36ba7
17 changed files with 685 additions and 0 deletions
@@ -0,0 +1,184 @@
+open Ansi
+
+type bounded_constraints = {
+  max_width: int option;
+  min_width: int option;
+  max_height: int option;
+  min_height: int option;
+}
+
+type constraints = 
+  | Unbounded
+  | Bounded of bounded_constraints
+
+type size = {
+  height: int;
+  width: int
+}
+
+type alignment =
+  | Start
+  | Center
+  | End
+  | Stretch
+  | Even
+
+type cross_alignment =
+  | Start
+  | Center
+  | End
+  | Stretch
+  | Even
+
+type box_options = {
+  alignment: alignment;
+  cross_alignment: cross_alignment;
+}
+
+type padding_options = {
+  left: int;
+  right: int;
+  bottom: int;
+  top: int;
+}
+
+type widget_options = 
+  | Box of box_options
+  | Padding of padding_options
+
+let default_padding_opts = {
+    left = 0;
+    right = 0;
+    bottom = 0;
+    top = 0;
+  }
+
+let default_column_opts = {
+    alignment = Start;
+    cross_alignment = Center;
+  }
+
+let default_row_opts = {
+    alignment = Start;
+    cross_alignment = Center;
+  }
+
+type ansi_widget = 
+  | Column of box_options * ansi_widget list
+  | Row of box_options * ansi_widget list
+  | Text of string
+  | Padding of padding_options * ansi_widget
+
+type widget_element =
+  | ElementColumn of constraints * size ref * box_options * widget_element list
+  | ElementRow of constraints * size ref * box_options * widget_element list
+  | ElementText of constraints * size ref * string
+  | ElementPadding of constraints * size ref * padding_options * widget_element
+
+let size_of_widget_element = function
+  | ElementColumn (_, s, _, _) -> !s
+  | ElementRow (_, s, _, _) -> !s
+  | ElementText (_, s, _) -> !s
+  | ElementPadding (_, s, _, _) -> !s
+
+(* let descend_widget_tree_list widget_list = *) 
+  (* let widgets = List.iter descend_widget_tree widge_list in *)
+  (* List.fold_left (^) widgets *)
+
+let rec make_spacer = function
+  | 0 -> ""
+  | n -> " " ^ make_spacer (n - 1)
+
+let rec descend_widget_tree depth widget_tree  =
+  match widget_tree with
+  | Column (c_opts, widgets) -> 
+    let _ = c_opts in
+    let deeper = depth + 1 in
+    let widget_strings = List.map (descend_widget_tree deeper) widgets in
+    let line = String.concat "" widget_strings in
+    let spacer = make_spacer depth in
+    spacer ^ "Column ->\n" ^ line
+
+  | Row (r_opts, widgets) -> 
+    let _ = r_opts in
+    let deeper = depth + 1 in
+    let widget_strings = List.map (descend_widget_tree deeper) widgets in
+    let line = String.concat "" widget_strings in
+    let spacer = make_spacer depth in
+    spacer ^ "Row ->\n" ^ line
+  | Text s -> 
+    let spacer = make_spacer depth in
+    spacer ^ Printf.sprintf "Text: \"%s\"\n" s
+  | Padding (_, widget) -> 
+    let spacer = make_spacer depth in
+    spacer ^ "Padding ->\n" ^ descend_widget_tree (depth + 1) widget
+
+let debug_string_of_widget ansi_widget =
+  (* let {x = term_x; y = term_y} = termsize in *)
+  descend_widget_tree 0 ansi_widget
+
+let max_constraints =
+  let {x = term_x; y = term_y} = termsize in 
+  Bounded {max_width = Some term_x; max_height = Some term_y; min_height = Some 0; min_width = Some 0}
+
+(**
+1. Layout - Descend tree, parent passing down constraints, child passing up size
+2. Convert ansi_widget tree to widget_element tree
+**)
+
+let layout_tree ansi_widget =
+  let filter_sizes elements =  List.map size_of_widget_element elements in
+  let sum_sizes_col = (fun {height = h; width = w} element ->
+      {height = h + element.height; width = max w element.width}
+    ) in
+  let sum_sizes_row = (fun {height = h; width = w} element ->
+      {height = max h element.height; width = w + element.width}
+    ) in
+  let subtract_bound some_x x =
+    match some_x with
+    | Some i -> Some (max (x - i) 0)
+    | None -> Some x
+      in
+  let rec layout_tree_list constraints widgets =
+    let constrained_layout = layout_tree_rec constraints in
+    let elements = List.map constrained_layout widgets in
+    elements
+  and layout_tree_rec constraints widget_tree =
+    let size = ref {height = 0; width = 0} in
+    match widget_tree with
+    | Column (c_opts, widgets) ->
+      let widget_elements = (layout_tree_list constraints widgets) in
+      let sizes = filter_sizes widget_elements in
+      size := List.fold_left sum_sizes_col {height = 0; width = 0} sizes;
+      ElementColumn( constraints, size, c_opts, widget_elements)
+    | Row (r_opts, widgets) -> 
+      let widget_elements = (layout_tree_list constraints widgets) in
+      let sizes = filter_sizes widget_elements in
+      size := List.fold_left sum_sizes_row {height = 0; width = 0} sizes;
+      ElementRow( constraints, size, r_opts, widget_elements)
+    | Text (s) -> 
+      size := {height = 1; width = String.length s};
+      ElementText (constraints, size, s)
+    | Padding (p_opts, widget) -> 
+      let vertical_padding = p_opts.top + p_opts.bottom in
+      let horizontal_padding = p_opts.left + p_opts.right in
+      let new_constraints = match constraints with
+        | Bounded cons -> Bounded {
+            max_height = (subtract_bound cons.max_height vertical_padding);
+            max_width = (subtract_bound cons.max_width horizontal_padding);
+            min_height = Some vertical_padding;
+            min_width = Some horizontal_padding; }
+        | Unbounded -> Bounded {
+            max_height = None;
+            max_width = None;
+            min_height = Some vertical_padding;
+            min_width = Some horizontal_padding;
+             }
+      in
+      let element = layout_tree_rec new_constraints widget in 
+      let element_size = size_of_widget_element element in
+      size := {width = horizontal_padding + element_size.width; height = vertical_padding + element_size.width};
+      ElementPadding (constraints, size, p_opts, element)
+  in
+  let size = ref {height = 0; width = 0} in
+  layout_tree_rec max_constraints ansi_widget