wip

src/musicplayer/musicplayer.gleam

@@ -52,7 +52,7 @@ pub fn new(
         handle_key(musicplayer, input_keys)
       })
 
-      process.spawn(fn() { update_playback_time_loop(mpv, ui, 250) })
+      process.spawn(fn() { update_playback_time_loop(mpv, ui, 1000) })
 
       Ok(pid)
     }

src/musicplayer/ui/ansi.gleam

@@ -0,0 +1,42 @@
+import gleam/list
+import gleam/string
+import gleam/string_tree
+
+import musicplayer/ui/internal
+
+pub fn text(chars: String, x: Int, y: Int) {
+  internal.chars_at(chars, x, y)
+}
+
+pub fn box(x: Int, y: Int, width: Int, height: Int) -> String {
+  let box_chars = #("┌", "┐", "└", "┘", "─", "│")
+  let #(tl, tr, bl, br, h, v) = box_chars
+
+  // Add top of box
+  let tree =
+    string_tree.new()
+    |> string_tree.append(internal.chars_at(
+      tl <> string.repeat(h, width - 2) <> tr,
+      x,
+      y,
+    ))
+
+  // Add sides of box
+  let tree_with_sides =
+    list.range(1, height - 2)
+    |> list.map(fn(row) {
+      tree
+      |> string_tree.append(internal.chars_at(v, x, y + row))
+      |> string_tree.append(internal.chars_at(v, x + width - 1, y + row))
+    })
+    |> string_tree.concat
+
+  // Add bottom of box
+  tree_with_sides
+  |> string_tree.append(internal.chars_at(
+    bl <> string.repeat(h, width - 2) <> br,
+    x,
+    y + height - 1,
+  ))
+  |> string_tree.to_string
+}

src/musicplayer/ui/control.gleam

@@ -3,7 +3,7 @@ import gleam/erlang/process.{type Subject}
 import musicplayer/ui/layout.{type Section}
 
 pub type Control {
-  UpdateDimensions(columns: Int, rows: Int)
+  UpdateDimensions(width: Int, height: Int)
   UpdateState(section: Section, content: String)
 
   Exit(reply_to: Subject(Nil))

src/musicplayer/ui/internal.gleam

@@ -3,16 +3,6 @@ import gleam/io
 
 // https://en.wikipedia.org/wiki/ANSI_escape_code#Control_Sequence_Introducer_commands
 
-pub const move_to_home = "\u{001B}[H"
-
-pub const disable_auto_wrap = "\u{001B}[?7l"
-
-pub const enable_auto_wrap = "\u{001B}[?7h"
-
-pub fn update(frame: String) -> Nil {
-  io.print(disable_auto_wrap <> move_to_home <> frame <> enable_auto_wrap)
-}
-
 pub fn clear_screen() -> Nil {
   io.print("\u{001B}[2J\u{001B}[H")
 }
@@ -22,6 +12,10 @@ pub fn chars_at(chars: String, x: Int, y: Int) -> String {
   seq <> chars
 }
 
+pub fn print(chars: String) -> Nil {
+  io.print(chars)
+}
+
 pub fn hide_cursor() -> Nil {
   io.print("\u{001B}[?25l")
 }

src/musicplayer/ui/layout.gleam

@@ -1,97 +1,89 @@
 import gleam/dict
+import gleam/float
 import gleam/int
 import gleam/list
-import gleam/pair
-import gleam/set
 import gleam/string
+import gleam/string_tree
 
 import musicplayer/logging/logging
+import musicplayer/ui/ansi
 import musicplayer/ui/internal
-import musicplayer/ui/plot.{type Buffer}
-
-pub const root_section = "reserved_root_section"
 
 pub type Section {
   Section(String)
 
+  Root
   Header
   Search
   PlaybackTime
 }
 
-pub type Dimension {
+pub type NodeType {
-  Percent(width: Int, height: Int)
+  Container
-  // TODO add Flex that flows
+  Row
-}
+  Cell
-
-pub type Style {
-  Style(dimensions: Dimension)
 }
 
+/// A Nodes width and height is in percentage (of the available width/height of its parent Node)
 pub type Node {
-  Row(content: String, style: Style, children: List(Section))
+  Node(
-  Cell(content: String, style: Style)
+    t: NodeType,
+    content: String,
+    width_percent: Int,
+    height_percent: Int,
+    children: List(Section),
+  )
 }
 
-pub type ViewIdx =
-  Int
-
-pub type View =
-  dict.Dict(Section, Node)
-
-// Layout consists of a list Views, and only one View is rendered at a time
 pub type Layout {
-  Layout(
+  Layout(width: Int, height: Int, nodes: dict.Dict(Section, Node))
-    columns: Int,
-    rows: Int,
-    current_view: ViewIdx,
-    views: dict.Dict(ViewIdx, View),
-  )
 }
 
-pub fn new(
+pub fn new() -> Layout {
-  columns: Int,
+  let nodes =
-  rows: Int,
+    dict.from_list([
-  views: List(List(#(Section, Node))),
+      #(
-) -> Layout {
+        Root,
-  let views =
+        Node(
-    list.index_map(views, fn(view_nodes, i) { #(i, view_nodes) })
+          t: Container,
-    |> list.fold(dict.new(), fn(view_acc, iv) {
+          content: "Music Player",
-      let #(i, view_nodes) = iv
+          width_percent: 100,
-
+          height_percent: 100,
-      dict.insert(view_acc, i, view_loop(i, view_nodes))
+          children: [Header, Search, PlaybackTime],
-    })
-
-  Layout(columns:, rows:, current_view: 0, views:)
-}
-
-fn view_loop(i: ViewIdx, view_nodes: List(#(Section, Node))) -> View {
-  let children =
-    view_nodes
-    |> list.flat_map(fn(node) {
-      case pair.second(node) {
-        Row(children: c, ..) -> c
-        Cell(..) -> []
-      }
-    })
-    |> set.from_list
-
-  // All sections that are not children of other nodes will be added as
-  // children to the root
-  let orphans =
-    view_nodes
-    |> list.map(pair.first)
-    |> list.filter(fn(node) { !set.contains(children, node) })
-
-  dict.from_list(view_nodes)
-  |> dict.insert(
-    Section(string.append("view_", string.inspect(i))),
-    Row(
-      content: "",
-      style: Style(dimensions: Percent(width: 100, height: 100)),
-      children: orphans,
         ),
-  )
+      ),
+      #(
+        Header,
+        Node(
+          t: Row,
+          content: "Foo (1) | Bar (2) | Baz (3)",
+          width_percent: 100,
+          height_percent: 33,
+          children: [],
+        ),
+      ),
+      #(
+        Search,
+        Node(
+          t: Row,
+          content: "",
+          width_percent: 100,
+          height_percent: 33,
+          children: [],
+        ),
+      ),
+      #(
+        PlaybackTime,
+        Node(
+          t: Row,
+          content: "00:00",
+          width_percent: 100,
+          height_percent: 33,
+          children: [],
+        ),
+      ),
+    ])
+  Layout(width: 0, height: 0, nodes: nodes)
 }
 
 pub fn update_section(
@@ -99,148 +91,141 @@ pub fn update_section(
   section: Section,
   content: String,
 ) -> Layout {
-  case dict.get(layout.views, layout.current_view) {
+  case dict.get(layout.nodes, section) {
     Error(_) -> layout
-    Ok(view) ->
+    Ok(node) ->
-      case dict.get(view, section) {
-        Error(_) -> layout
-        Ok(node) -> {
-          let updated_node = case node {
-            Cell(..) -> Cell(..node, content: content)
-            Row(..) -> Row(..node, content: content)
-          }
-
-          let updated_view = dict.insert(view, section, updated_node)
-
       Layout(
         ..layout,
-            views: dict.insert(layout.views, layout.current_view, updated_view),
+        nodes: dict.insert(
+          layout.nodes,
+          section,
+          Node(..node, content: content),
+        ),
       )
   }
 }
-  }
-}
 
-pub fn update_dimensions(layout: Layout, columns: Int, rows: Int) -> Layout {
+pub fn update_dimensions(layout: Layout, width: Int, height: Int) -> Layout {
-  Layout(..layout, columns:, rows:)
+  Layout(..layout, width:, height:)
 }
 
 pub fn render(layout: Layout) -> Nil {
-  [layout.columns, layout.rows]
+  internal.clear_screen()
+  [layout.width, layout.height]
   |> list.map(int.to_string)
   |> string.join(" ")
   |> string.append("layout - render: ", _)
   |> logging.log
 
-  let context =
+  let container_width = int.to_float(layout.width)
-    RenderContext(
+  let container_height = int.to_float(layout.height)
-      parent_width: layout.columns,
+  let container_top_left_x = 1
-      parent_height: layout.rows,
+  let container_top_left_y = 1
-      parent_top_left_x: 1,
+
-      parent_top_left_y: 1,
+  let ansi_renders =
-      position_index: 0,
+    Renders(
+      box: fn(tree, x, y, w, h) {
+        string_tree.append(tree, ansi.box(x, y, w, h))
+      },
+      text: fn(tree, chars, x, y) {
+        string_tree.append(tree, ansi.text(chars, x, y))
+      },
     )
 
-  case dict.get(layout.views, layout.current_view) {
+  string_tree.new()
-    Error(_) -> Nil
+  |> render_generic(
-    Ok(view) -> {
+    layout,
-      let buffer: Buffer = dict.new()
+    container_width,
-
+    container_height,
-      render_loop(
+    container_top_left_x,
-        view,
+    container_top_left_y,
-        context,
+    0,
-        Section(string.append("view_", string.inspect(layout.current_view))),
+    Root,
-        buffer,
+    _,
+    ansi_renders,
   )
-      |> plot.flush_buffer(layout.columns, layout.rows)
+  |> string_tree.to_string
-      |> internal.update
+  |> internal.print
-    }
-  }
 }
 
-pub type RenderContext {
+pub type Renders(into) {
-  RenderContext(
+  Renders(
-    parent_width: Int,
+    text: fn(into, String, Int, Int) -> into,
-    parent_height: Int,
+    box: fn(into, Int, Int, Int, Int) -> into,
-    parent_top_left_x: Int,
-    parent_top_left_y: Int,
-    position_index: Int,
   )
 }
 
-pub fn render_loop(
+pub fn render_generic(
-  view: View,
+  layout: Layout,
-  context: RenderContext,
+  // Dimensions
+  container_width: Float,
+  container_height: Float,
+  container_tl_x: Int,
+  container_tl_y: Int,
+  // State
+  index: Int,
   from: Section,
-  buffer: Buffer,
+  render_into: into,
-) -> Buffer {
+  renders: Renders(into),
-  case dict.get(view, from) {
+) -> into {
-    Error(_) -> buffer
+  case dict.get(layout.nodes, from) {
+    Error(_) -> render_into
     Ok(node) -> {
-      // Margin between container and the node being rendered
+      let margin = 2.0
-      let margin = 2
 
-      let #(node_width, node_height) = case node.style.dimensions {
+      let width =
-        Percent(width:, height:) -> {
+        container_width *. { int.to_float(node.width_percent) /. 100.0 }
-          let width = { context.parent_width * width } / 100
+        |> float.floor
-          let height = { context.parent_height * height } / 100
+        |> float.truncate
 
-          #(width, height)
+      let height =
-        }
+        container_height *. { int.to_float(node.height_percent) /. 100.0 }
-      }
+        |> float.floor
+        |> float.truncate
 
-      // Check if this node should be placed to the left or below the parent
+      let #(cx, cy) = case node.t {
-      let #(node_top_left_x, node_top_left_y) = case node {
+        Container -> #(container_tl_x, container_tl_y)
-        Row(..) -> #(
+        Row -> #(container_tl_x, container_tl_y + { index * height })
-          context.parent_top_left_x,
+        Cell -> #(container_tl_x + { index * width }, container_tl_y)
-          context.parent_top_left_y + { context.position_index * node_height },
-        )
-        Cell(..) -> #(
-          context.parent_top_left_x + { context.position_index * node_width },
-          context.parent_top_left_y,
-        )
       }
 
       let parent =
-        plot.box(
+        render_into
-          buffer,
+        |> renders.box(cx, cy, width, height)
-          node_top_left_x,
+        // + 2 for header margin
-          node_top_left_y,
+        |> renders.text(node.content, cx + 2, cy)
-          node_width,
-          node_height,
-        )
-        |> plot.text(node.content, node_top_left_x, node_top_left_y)
 
-      case node {
+      list.index_map(node.children, fn(child, i) { #(i, child) })
-        Cell(..) -> parent
+      |> list.fold(parent, fn(acc_into, ic) {
-        Row(children:, ..) -> {
-          list.index_map(children, fn(child, i) { #(i, child) })
-          |> list.fold(parent, fn(acc_buffer, ic) {
         let #(i, child) = ic
 
-            let #(child_width, child_height) = case node.style.dimensions {
+        let cw =
-              Percent(width:, height:) -> {
+          container_width
-                let width = { { context.parent_width * width } / 100 } - margin
+          *. { int.to_float(node.width_percent) /. 100.0 }
-                let height =
+          -. margin
-                  { { context.parent_height * height } / 100 } - margin
+          |> float.floor
 
-                #(width, height)
+        let ch =
-              }
+          container_height
-            }
+          *. { int.to_float(node.height_percent) /. 100.0 }
+          -. margin
+          |> float.floor
 
-            let context =
+        let child_origin_x = container_tl_x + 1
-              RenderContext(
+        let child_origin_y = container_tl_y + 1
-                parent_width: child_width,
+
-                parent_height: child_height,
+        render_generic(
-                parent_top_left_x: context.parent_top_left_x + 1,
+          layout,
-                parent_top_left_y: context.parent_top_left_y + 1,
+          cw,
-                position_index: i,
+          ch,
+          child_origin_x,
+          child_origin_y,
+          i,
+          child,
+          acc_into,
+          renders,
         )
-
-            render_loop(view, context, child, acc_buffer)
       })
     }
   }
 }
-  }
-}

src/musicplayer/ui/layout_examples/layout_examples.gleam

@@ -1,12 +1,14 @@
+import gleam/dict
+
 import musicplayer/ui/internal
-import musicplayer/ui/layout.{Percent, Section, Style}
+import musicplayer/ui/layout.{Container, Layout, Node, Section}
 import musicplayer/ui/layout_examples/wait_for_input.{wait_for_input}
 
 pub fn main() {
-  let assert Ok(columns) = internal.io_get_columns()
+  let assert Ok(width) = internal.io_get_columns()
-  let assert Ok(rows) = internal.io_get_rows()
+  let assert Ok(height) = internal.io_get_rows()
 
-  two_rows_with_cells(columns, rows)
+  two_rows_with_cells(width, height)
   |> layout.render
 
   wait_for_input()
@@ -15,44 +17,66 @@ pub fn main() {
 /// Two rows:
 /// First row has two cells
 /// Second row has no cells
-fn two_rows_with_cells(columns: Int, rows: Int) -> layout.Layout {
+fn two_rows_with_cells(width: Int, height: Int) -> layout.Layout {
-  let views = [
+  let nodes =
-    [
+    dict.from_list([
+      #(
+        Section("Root"),
+        Node(
+          t: Container,
+          content: "container",
+          width_percent: 100,
+          height_percent: 100,
+          children: [
+            Section("Row1"),
+            Section("Row2"),
+          ],
+        ),
+      ),
       #(
         Section("Row1"),
-        layout.Row(
+        Node(
+          t: layout.Row,
           content: "row 1",
-          style: Style(dimensions: Percent(width: 100, height: 50)),
+          width_percent: 100,
+          height_percent: 50,
           children: [
             Section("A"),
-            Section("B"),
+            Section("A"),
           ],
         ),
       ),
       #(
         Section("A"),
-        layout.Cell(
+        Node(
+          t: layout.Cell,
           content: "cell 1",
-          style: Style(dimensions: Percent(width: 50, height: 50)),
+          width_percent: 50,
+          height_percent: 100,
+          children: [],
         ),
       ),
       #(
         Section("B"),
-        layout.Cell(
+        Node(
+          t: layout.Cell,
           content: "cell 2",
-          style: Style(dimensions: Percent(width: 50, height: 50)),
+          width_percent: 50,
+          height_percent: 100,
+          children: [],
         ),
       ),
       #(
         Section("Row2"),
-        layout.Row(
+        Node(
+          t: layout.Row,
           content: "row 2",
-          style: Style(dimensions: Percent(width: 50, height: 50)),
+          width_percent: 100,
+          height_percent: 50,
           children: [],
         ),
       ),
-    ],
+    ])
-  ]
 
-  layout.new(columns, rows, views)
+  Layout(width:, height:, nodes: nodes)
 }

src/musicplayer/ui/plot.gleam

@@ -1,71 +0,0 @@
-import gleam/dict.{type Dict}
-import gleam/list
-import gleam/string
-
-pub type Buffer =
-  Dict(#(Int, Int), String)
-
-pub fn flush_buffer(buffer: Buffer, columns: Int, rows: Int) -> String {
-  list.range(1, rows)
-  |> list.map(fn(y) {
-    list.range(1, columns)
-    |> list.map(fn(x) {
-      case dict.get(buffer, #(x, y)) {
-        Ok(char) -> char
-        Error(_) -> " "
-      }
-    })
-    |> string.join("")
-  })
-  |> string.join("\r\n")
-}
-
-pub fn text(buffer: Buffer, text: String, x: Int, y: Int) -> Buffer {
-  text
-  |> string.to_graphemes
-  |> list.index_fold(buffer, fn(acc, char, i) {
-    dict.insert(acc, #(x + i, y), char)
-  })
-}
-
-pub fn box(buffer: Buffer, x: Int, y: Int, width: Int, height: Int) -> Buffer {
-  let box_chars = #("┌", "┐", "└", "┘", "─", "│")
-  let #(tl, tr, bl, br, hor, ver) = box_chars
-
-  case width < 2 || height < 2 {
-    True -> buffer
-    False -> {
-      buffer
-      |> dict.insert(#(x, y), tl)
-      |> dict.insert(#(x + width - 1, y), tr)
-      |> dict.insert(#(x, y + height - 1), bl)
-      |> dict.insert(#(x + width - 1, y + height - 1), br)
-      |> horizontal_line(x + 1, y, width - 2, hor)
-      |> horizontal_line(x + 1, y + height - 1, width - 2, hor)
-      |> vertical_line(x, y + 1, height - 2, ver)
-      |> vertical_line(x + width - 1, y + 1, height - 2, ver)
-    }
-  }
-}
-
-fn horizontal_line(
-  buffer: Buffer,
-  x: Int,
-  y: Int,
-  len: Int,
-  char: String,
-) -> Buffer {
-  list.range(0, len - 1)
-  |> list.fold(buffer, fn(acc, i) { dict.insert(acc, #(x + i, y), char) })
-}
-
-fn vertical_line(
-  buffer: Buffer,
-  x: Int,
-  y: Int,
-  len: Int,
-  char: String,
-) -> Buffer {
-  list.range(0, len - 1)
-  |> list.fold(buffer, fn(acc, i) { dict.insert(acc, #(x, y + i), char) })
-}

src/musicplayer/ui/ui.gleam

@@ -17,45 +17,7 @@ pub fn new() -> Result(Subject(Control), String) {
   let redraw_name = process.new_name("redraw")
   let redraw: Subject(Layout) = process.named_subject(redraw_name)
 
-  let layout =
+  let layout = layout.new()
-    [
-      [
-        #(
-          layout.Header,
-          layout.Row(
-            content: "Foo (1) | Bar (2) | Baz (3)",
-            style: layout.Style(dimensions: layout.Percent(
-              width: 100,
-              height: 33,
-            )),
-            children: [],
-          ),
-        ),
-        #(
-          layout.Search,
-          layout.Row(
-            content: "",
-            style: layout.Style(dimensions: layout.Percent(
-              width: 100,
-              height: 33,
-            )),
-            children: [],
-          ),
-        ),
-        #(
-          layout.PlaybackTime,
-          layout.Row(
-            content: "00:00",
-            style: layout.Style(dimensions: layout.Percent(
-              width: 100,
-              height: 33,
-            )),
-            children: [],
-          ),
-        ),
-      ],
-    ]
-    |> layout.new(0, 0, _)
 
   case
     actor.new(State(redraw, layout))
@@ -89,19 +51,19 @@ fn handle_message(
   control: Control,
 ) -> actor.Next(State(redraw, layout), Control) {
   case control {
-    control.UpdateDimensions(columns, rows) -> {
+    control.UpdateDimensions(width, height) -> {
-      let current_dimensions = #(state.layout.columns, state.layout.rows)
+      let current_dimensions = #(state.layout.width, state.layout.height)
 
-      case #(columns, rows) == current_dimensions {
+      case #(width, height) == current_dimensions {
         True -> actor.continue(state)
         False -> {
-          [columns, rows]
+          [width, height]
           |> list.map(int.to_string)
           |> string.join(" ")
           |> string.append("ui - updating dimensions: ", _)
           |> logging.log
 
-          let layout = layout.update_dimensions(state.layout, columns, rows)
+          let layout = layout.update_dimensions(state.layout, width, height)
 
           process.send(state.redraw, layout)
           actor.continue(State(..state, layout:))

test/musicplayer/ui/layout_test.gleam

@@ -3,22 +3,40 @@ import gleam/io
 import gleam/string
 import gleeunit
 import gleeunit/should
+import musicplayer/ui/virtual_ansi
 
-import musicplayer/ui/layout.{Percent, RenderContext, Section, Style}
+import musicplayer/ui/layout.{Layout, Node, Section}
-import musicplayer/ui/plot
 
 pub fn main() -> Nil {
   gleeunit.main()
 }
 
-pub fn percent_layout_test() {
+pub fn foo_test() {
-  let views = [
+  let layout =
-    [
+    Layout(
+      width: 80,
+      height: 20,
+      nodes: dict.from_list([
+        #(
+          Section("Root"),
+          Node(
+            t: layout.Container,
+            content: "container",
+            width_percent: 100,
+            height_percent: 100,
+            children: [
+              Section("Row1"),
+              Section("Row2"),
+            ],
+          ),
+        ),
         #(
           Section("Row1"),
-        layout.Row(
+          Node(
+            t: layout.Row,
             content: "row 1",
-          style: Style(dimensions: Percent(width: 100, height: 50)),
+            width_percent: 100,
+            height_percent: 50,
             children: [
               Section("A"),
               Section("B"),
@@ -27,36 +45,40 @@ pub fn percent_layout_test() {
         ),
         #(
           Section("A"),
-        layout.Cell(
+          Node(
+            t: layout.Cell,
             content: "cell 1",
-          style: Style(dimensions: Percent(width: 50, height: 100)),
+            width_percent: 50,
+            height_percent: 100,
+            children: [],
           ),
         ),
         #(
           Section("B"),
-        layout.Cell(
+          Node(
+            t: layout.Cell,
             content: "cell 2",
-          style: Style(dimensions: Percent(width: 50, height: 100)),
+            width_percent: 50,
+            height_percent: 100,
+            children: [],
           ),
         ),
         #(
           Section("Row2"),
-        layout.Row(
+          Node(
+            t: layout.Row,
             content: "row 1",
-          style: Style(dimensions: Percent(width: 100, height: 50)),
+            width_percent: 100,
+            height_percent: 50,
             children: [],
           ),
         ),
-    ],
+      ]),
-  ]
+    )
-
-  let columns = 80
-  let rows = 20
-  let layout = layout.new(columns, rows, views)
 
   let expected =
     "
-┌──────────────────────────────────────────────────────────────────────────────┐
+container──────────────────────────────────────────────────────────────────────┐
 │row 1────────────────────────────────────────────────────────────────────────┐│
 ││cell 1───────────────────────────────┐cell 2───────────────────────────────┐││
 │││                                    ││                                    │││
@@ -77,30 +99,10 @@ pub fn percent_layout_test() {
 │└────────────────────────────────────────────────────────────────────────────┘│
 └──────────────────────────────────────────────────────────────────────────────┘
 "
-    |> string.replace(each: "\n", with: "\r\n")
-    |> string.trim
 
-  let context =
+  let visual =
-    RenderContext(
+    virtual_ansi.render(layout, Section("Root"), layout.width, layout.height)
-      parent_width: layout.columns,
+  case visual == string.trim(expected) {
-      parent_height: layout.rows,
-      parent_top_left_x: 1,
-      parent_top_left_y: 1,
-      position_index: 0,
-    )
-
-  let assert Ok(view) = dict.get(layout.views, layout.current_view)
-
-  let flushed =
-    layout.render_loop(
-      view,
-      context,
-      Section(string.append("view_", string.inspect(layout.current_view))),
-      dict.new(),
-    )
-    |> plot.flush_buffer(layout.columns, layout.rows)
-
-  case flushed == expected {
     True -> Nil
     False -> {
       io.println("Test failed")
@@ -108,9 +110,9 @@ pub fn percent_layout_test() {
       io.println(string.trim(expected))
 
       io.println("Got:")
-      io.println(flushed)
+      io.println(visual)
 
-      should.equal(flushed, expected)
+      should.equal(visual, expected)
     }
   }
 }

test/musicplayer/ui/virtual_ansi.gleam

@@ -0,0 +1,113 @@
+import gleam/dict
+import gleam/int
+import gleam/list
+import gleam/string
+
+import musicplayer/ui/layout.{type Layout, type Section, Renders}
+
+pub type Screen =
+  dict.Dict(#(Int, Int), String)
+
+pub fn render(layout: Layout, root: Section, width: Int, height: Int) -> String {
+  let test_renders =
+    Renders(
+      box: fn(screen, x, y, w, h) { box(screen, x, y, w, h) },
+      text: fn(screen, chars, x, y) { text(screen, chars, x, y) },
+    )
+
+  let screen =
+    layout.render_generic(
+      layout,
+      int.to_float(width),
+      int.to_float(height),
+      1,
+      1,
+      0,
+      root,
+      dict.new(),
+      test_renders,
+    )
+
+  screen_to_string(screen)
+}
+
+pub fn screen_to_string(screen: Screen) -> String {
+  let keys = dict.keys(screen)
+
+  // Find the bounding box of the drawing
+  let max_x = list.fold(keys, 0, fn(m, k) { int.max(m, k.0) })
+  let max_y = list.fold(keys, 0, fn(m, k) { int.max(m, k.1) })
+
+  // We start from 1 because ANSI is 1-based
+  let min_y = list.fold(keys, 1000, fn(m, k) { int.min(m, k.1) })
+
+  list.range(min_y, max_y)
+  |> list.map(fn(y) {
+    list.range(1, max_x)
+    |> list.map(fn(x) {
+      case dict.get(screen, #(x, y)) {
+        Ok(char) -> char
+        Error(_) -> " "
+        // Fill gaps with space
+      }
+    })
+    |> string.join("")
+  })
+  |> string.join("\n")
+}
+
+pub fn text(screen: Screen, text: String, start_x: Int, y: Int) -> Screen {
+  // We use to_graphemes to ensure Unicode characters (like emoji or box lines)
+  // are treated as single visual units
+  text
+  |> string.to_graphemes
+  |> list.index_fold(screen, fn(acc, char, i) {
+    dict.insert(acc, #(start_x + i, y), char)
+  })
+}
+
+pub fn box(screen: Screen, x: Int, y: Int, w: Int, h: Int) -> Screen {
+  let box_chars = #("┌", "┐", "└", "┘", "─", "│")
+  let #(tl, tr, bl, br, hor, ver) = box_chars
+
+  // Don't draw impossible boxes
+  case w < 2 || h < 2 {
+    True -> screen
+    False -> {
+      screen
+      // 1. Corners
+      |> dict.insert(#(x, y), tl)
+      |> dict.insert(#(x + w - 1, y), tr)
+      |> dict.insert(#(x, y + h - 1), bl)
+      |> dict.insert(#(x + w - 1, y + h - 1), br)
+      // 2. Top and Bottom edges
+      |> horizontal_line(x + 1, y, w - 2, hor)
+      |> horizontal_line(x + 1, y + h - 1, w - 2, hor)
+      // 3. Side edges
+      |> vertical_line(x, y + 1, h - 2, ver)
+      |> vertical_line(x + w - 1, y + 1, h - 2, ver)
+    }
+  }
+}
+
+fn horizontal_line(
+  screen: Screen,
+  x: Int,
+  y: Int,
+  len: Int,
+  char: String,
+) -> Screen {
+  list.range(0, len - 1)
+  |> list.fold(screen, fn(acc, i) { dict.insert(acc, #(x + i, y), char) })
+}
+
+fn vertical_line(
+  screen: Screen,
+  x: Int,
+  y: Int,
+  len: Int,
+  char: String,
+) -> Screen {
+  list.range(0, len - 1)
+  |> list.fold(screen, fn(acc, i) { dict.insert(acc, #(x, y + i), char) })
+}