change colour of text in search bar as well

temp.txt

@@ -1 +1,172 @@
-hello wor!d again
+structure GlDraw =
+struct
+  open CML
+  open DrawMsg
+
+  (* The name doesn't make it clear, but this structure
+   * couples GLFW and OpenGL.
+   * I'm not sure if I will use native windowing systems
+   * or other graphics APIs at a later stage,
+   * but the current priority is GLFW + OpenGL. 
+   * *)
+  type t =
+    { textVertexBuffer: Word32.word
+    , textProgram: Word32.word
+    , textDrawLength: int
+    , window: MLton.Pointer.t
+    }
+
+  fun createShader (shaderType, shaderString) =
+    let
+      val shader = Gles3.createShader shaderType
+      val _ = Gles3.shaderSource (shader, shaderString)
+      val _ = Gles3.compileShader shader
+    in
+      shader
+    end
+
+  fun createProgram (vertexShader, fragmentShader) =
+    let
+      val program = Gles3.createProgram ()
+      val _ = Gles3.attachShader (program, vertexShader)
+      val _ = Gles3.attachShader (program, fragmentShader)
+      val _ = Gles3.linkProgram program
+    in
+      program
+    end
+
+  fun create window =
+    let
+      (* create vertex buffer, program, etc. for text. *)
+      val textVertexBuffer = Gles3.createBuffer ()
+      val xyzRgbVertexShader = createShader
+        (Gles3.VERTEX_SHADER, GlShaders.xyzRgbVertexShaderString)
+
+      val rgbFragmentShader = createShader
+        (Gles3.FRAGMENT_SHADER, GlShaders.rgbFragmentShaderString)
+
+      val textProgram = createProgram (xyzRgbVertexShader, rgbFragmentShader)
+
+      (* clean up shaders which are no longer needed once progran is linked. *)
+      val _ = Gles3.deleteShader xyzRgbVertexShader
+      val _ = Gles3.deleteShader rgbFragmentShader
+
+      (* because we only have a single vertex buffer, 
+       * we only need to bind and set attributes once. *)
+      val _ = Gles3.bindBuffer textVertexBuffer
+
+      (* enable xyz component from uploaded array *)
+      val _ = Gles3.vertexAttribPointer (0, 3, 6, 0)
+      val _ = Gles3.enableVertexAttribArray 0
+      (* enable rgb component from uploaded array *)
+      val _ = Gles3.vertexAttribPointer (1, 3, 6, 12)
+      val _ = Gles3.enableVertexAttribArray 1
+
+      val _ = Gles3.useProgram textProgram
+    in
+      { textVertexBuffer = textVertexBuffer
+      , textProgram = textProgram
+      , textDrawLength = 0
+      , window = window
+      }
+    end
+
+  fun uploadText (shellState: t, vec) =
+    let
+      val {textVertexBuffer, textProgram, textDrawLength = _, window} =
+        shellState
+
+      val _ = Gles3.bufferData (vec, Vector.length vec, Gles3.STATIC_DRAW)
+      val newTextDrawLength = Vector.length vec div 6
+    in
+      { textVertexBuffer = textVertexBuffer
+      , textProgram = textProgram
+      , textDrawLength = newTextDrawLength
+      , window = window
+      }
+    end
+
+  fun draw (drawObject: t) =
+    let
+      val {textVertexBuffer, textDrawLength, textProgram, window = _} =
+        drawObject
+    in
+      Gles3.drawArrays (Gles3.TRIANGLES, 0, textDrawLength)
+    end
+
+  fun yank (shellState: t, str) =
+    let
+      (* print when text is yanked *)
+      val msg = "|" ^ String.toCString str ^ "|\n"
+      val () = print msg
+      val () = Glfw.setClipboardString (#window shellState, str)
+    in
+      shellState
+    end
+
+  fun consumeDrawEvent (shellState, msg) =
+    let
+      val {textVertexBuffer, textProgram, window, textDrawLength = _, ...} =
+        shellState
+    in
+      case msg of
+        DRAW_TEXT textVec => uploadText (shellState, textVec)
+      | YANK str => yank (shellState, str)
+    end
+
+  local
+    fun loop (pos, msgVec, shellState) =
+      if pos = Vector.length msgVec then
+        shellState
+      else
+        let
+          val msg = Vector.sub (msgVec, pos)
+          val shellState = consumeDrawEvent (shellState, msg)
+        in
+          loop (pos + 1, msgVec, shellState)
+        end
+  in
+    fun consumeDrawEvents shellState =
+      loop (0, DrawMailbox.getMessagesAndClear (), shellState)
+  end
+
+  local
+    fun updateLoop (pos, msgVec, app) =
+      if pos = Vector.length msgVec then
+        app
+      else
+        let
+          val msg = Vector.sub (msgVec, pos)
+          val app = Updater.update (app, msg)
+        in
+          updateLoop (pos + 1, msgVec, app)
+        end
+  in
+    fun update app =
+      updateLoop (0, InputMailbox.getMessagesAndClear (), app)
+  end
+
+  fun helpLoop (app, shellState as {window, ...}: t) =
+    case Glfw.windowShouldClose window of
+      false =>
+        let
+          val shellState = consumeDrawEvents shellState
+
+          val _ = Gles3.clearColor (0.97, 0.95, 0.937, 1.0)
+          val _ = Gles3.clear ()
+
+          val app = update app
+          val _ = draw shellState
+
+          val _ = Glfw.swapBuffers window
+          val _ = Glfw.waitEvents ()
+        in
+          helpLoop (app, shellState)
+        end
+    | true => Glfw.terminate ()
+
+  fun loop (app, window) =
+    let val shellState = create window
+    in helpLoop (app, shellState)
+    end
+end