begin preparation for drawing cursor

fcore/app-update.sml

@@ -11,8 +11,9 @@ struct
       val {buffer, windowWidth, windowHeight, startLine} = app
 
       val newBuffer = LineGap.goToLine (startLine, buffer)
-      val textVec =
+      val cursorIdx = 0 (* TEMP *)
-        TextBuilder.build (startLine, newBuffer, newWidth, newHeight)
+      val textVec = TextBuilder.build
+        (startLine, cursorIdx, newBuffer, newWidth, newHeight)
 
       val newApp = AppWith.bufferAndSize (app, newBuffer, newWidth, newHeight)
       val msg = REDRAW_TEXT textVec

fcore/text-builder.sml

@@ -1,7 +1,7 @@
 signature TEXT_BUILDER =
 sig
   (* Prerequisite: LineGap is moved to requested line first. *)
-  val build: int * LineGap.t * int * int
+  val build: int * int * LineGap.t * int * int
              -> Real32.real vector
 end
 
@@ -144,11 +144,214 @@ struct
           )
     | [] => acc
 
+  (* same as buildTextStringAfterCursor, except this keeps track of absolute
+   * index and cursor pos too *)
+  fun buildTextStringBeforeCursor
+    ( pos, str, acc, posX, posY, startX
+    , windowWidth, windowHeight, fWindowWidth, fWindowHeight
+    , r, g, b, tl, absIdx, cursorPos
+    ) =
+    if pos < String.size str then
+      case String.sub (str, pos) of
+        #" " =>
+          buildTextStringBeforeCursor
+           ( pos + 1, str, acc, posX + xSpace, posY, startX
+           , windowWidth, windowHeight, fWindowWidth, fWindowHeight
+           , r, g, b, tl, absIdx + 1, cursorPos
+           )
+      | #"\t" =>
+          buildTextStringBeforeCursor
+           ( pos + 1, str, acc, posX + xSpace3, posY, startX
+           , windowWidth, windowHeight, fWindowWidth, fWindowHeight
+           , r, g, b, tl, absIdx + 1, cursorPos
+           )
+      | #"\n" =>
+          if posY + ySpace < windowHeight then
+            buildTextStringBeforeCursor
+              ( pos + 1, str, acc, startX, posY + ySpace, startX
+              , windowWidth, windowHeight, fWindowWidth, fWindowHeight
+              , r, g, b, tl, absIdx + 1, cursorPos
+              )
+          else
+            acc
+      | #"\r" =>
+          if posY + ySpace < windowHeight then
+            if
+              pos < String.size str - 1
+              andalso String.sub (str, pos + 1) = #"\n"
+            then 
+              buildTextStringBeforeCursor
+                ( pos + 2, str, acc, startX, posY + ySpace, startX
+                , windowWidth, windowHeight, fWindowWidth, fWindowHeight
+                , r, g, b, tl, absIdx + 1, cursorPos
+                )
+            else 
+              buildTextStringBeforeCursor
+                ( pos + 1, str, acc, startX, posY + ySpace, startX
+                , windowWidth, windowHeight, fWindowWidth, fWindowHeight
+                , r, g, b, tl, absIdx + 1, cursorPos
+                )
+          else
+            acc
+      | chr =>
+          let
+            val chrFun = Vector.sub (CozetteAscii.asciiTable, Char.ord chr)
+          in
+            if posX + xSpace < windowWidth then
+              let
+                val chrVec = chrFun
+                  (posX, posY, fontSize, fontSize, fWindowWidth, fWindowHeight, r, g, b)
+                val acc = chrVec :: acc
+              in
+                buildTextStringBeforeCursor
+                  ( pos + 1, str, acc, posX + xSpace, posY, startX
+                  , windowWidth, windowHeight, fWindowWidth, fWindowHeight
+                  , r, g, b, tl, absIdx + 1, cursorPos
+                  )
+              end
+            else if posY + ySpace < windowHeight then
+              let
+                val chrVec = chrFun
+                  ( startX, posY + ySpace, fontSize, fontSize
+                  , fWindowWidth, fWindowHeight
+                  , r, g, b
+                  )
+                val acc = chrVec :: acc
+              in
+                buildTextStringBeforeCursor
+                  ( pos + 1, str, acc, startX + xSpace, posY + ySpace, startX
+                  , windowWidth, windowHeight, fWindowWidth, fWindowHeight
+                  , r, g, b, tl, absIdx + 1, cursorPos
+                  )
+              end
+            else
+              acc
+          end
+    else
+      continueBuildTextLineGapBeforeCursor
+        ( tl, acc, posX, posY, startX
+        , windowWidth, windowHeight, fWindowWidth, fWindowHeight
+        , r, g, b, absIdx, cursorPos
+        )
+
+  and buildTextStringWithinCursor
+    ( pos, str, acc, posX, posY, startX
+    , windowWidth, windowHeight, fWindowWidth, fWindowHeight
+    , r, g, b, tl, absIdx, cursorPos
+    ) =
+    if pos < String.size str then
+      case String.sub (str, pos) of
+        #" " =>
+          buildTextStringWithinCursor
+           ( pos + 1, str, acc, posX + xSpace, posY, startX
+           , windowWidth, windowHeight, fWindowWidth, fWindowHeight
+           , r, g, b, tl, absIdx + 1, cursorPos
+           )
+      | #"\t" =>
+          buildTextStringWithinCursor
+           ( pos + 1, str, acc, posX + xSpace3, posY, startX
+           , windowWidth, windowHeight, fWindowWidth, fWindowHeight
+           , r, g, b, tl, absIdx + 1, cursorPos
+           )
+      | #"\n" =>
+          if posY + ySpace < windowHeight then
+            buildTextStringWithinCursor
+              ( pos + 1, str, acc, startX, posY + ySpace, startX
+              , windowWidth, windowHeight, fWindowWidth, fWindowHeight
+              , r, g, b, tl, absIdx + 1, cursorPos
+              )
+          else
+            acc
+      | #"\r" =>
+          if posY + ySpace < windowHeight then
+            if
+              pos < String.size str - 1
+              andalso String.sub (str, pos + 1) = #"\n"
+            then 
+              buildTextStringWithinCursor
+                ( pos + 2, str, acc, startX, posY + ySpace, startX
+                , windowWidth, windowHeight, fWindowWidth, fWindowHeight
+                , r, g, b, tl, absIdx + 1, cursorPos
+                )
+            else 
+              buildTextStringWithinCursor
+                ( pos + 1, str, acc, startX, posY + ySpace, startX
+                , windowWidth, windowHeight, fWindowWidth, fWindowHeight
+                , r, g, b, tl, absIdx + 1, cursorPos
+                )
+          else
+            acc
+      | chr =>
+          let
+            val chrFun = Vector.sub (CozetteAscii.asciiTable, Char.ord chr)
+          in
+            if posX + xSpace < windowWidth then
+              let
+                val chrVec = chrFun
+                  (posX, posY, fontSize, fontSize, fWindowWidth, fWindowHeight, r, g, b)
+                val acc = chrVec :: acc
+              in
+                buildTextStringWithinCursor
+                  ( pos + 1, str, acc, posX + xSpace, posY, startX
+                  , windowWidth, windowHeight, fWindowWidth, fWindowHeight
+                  , r, g, b, tl, absIdx + 1, cursorPos
+                  )
+              end
+            else if posY + ySpace < windowHeight then
+              let
+                val chrVec = chrFun
+                  ( startX, posY + ySpace, fontSize, fontSize
+                  , fWindowWidth, fWindowHeight
+                  , r, g, b
+                  )
+                val acc = chrVec :: acc
+              in
+                buildTextStringWithinCursor
+                  ( pos + 1, str, acc, startX + xSpace, posY + ySpace, startX
+                  , windowWidth, windowHeight, fWindowWidth, fWindowHeight
+                  , r, g, b, tl, absIdx + 1, cursorPos
+                  )
+              end
+            else
+              acc
+          end
+    else
+      (* we have built cursor now, so can call after-cursor function
+       * to build rest of text *)
+      continueBuildTextLineGapAfterCursor
+        ( tl, acc, posX, posY, startX
+        , windowWidth, windowHeight, fWindowWidth, fWindowHeight
+        , r, g, b
+        )
+
+  and continueBuildTextLineGapBeforeCursor
+    ( strList, acc, posX, posY, startX
+    , windowWidth, windowHeight, fWindowWidth, fWindowHeight
+    , r, g, b, absIdx, cursorPos
+    ) =
+    case strList of
+      hd :: tl =>
+      if cursorPos >= absIdx + cursorPos then
+        (* if end of string is before cursor *)
+        buildTextStringBeforeCursor
+          ( 0, hd, acc, posX, posY, startX
+          , windowWidth, windowHeight, fWindowWidth, fWindowHeight
+          , r, g, b, tl, absIdx, cursorPos
+          )
+      else
+        (* if within cursor *)
+        buildTextStringWithinCursor
+          ( 0, hd, acc, posX, posY, startX
+          , windowWidth, windowHeight, fWindowWidth, fWindowHeight
+          , r, g, b, tl, absIdx, cursorPos
+          )
+    | [] => acc
+
   fun build
-    (startLine, lineGap: LineGap.t, windowWidth, windowHeight) =
+    (startLine, cursorPos, lineGap: LineGap.t, windowWidth, windowHeight) =
     let
       val lineGap = LineGap.goToLine (startLine, lineGap)
-      val {rightStrings, rightLines, line = curLine, ...} = lineGap
+      val {rightStrings, rightLines, line = curLine, idx = curIdx, ...} = lineGap
 
       val acc =
         case (rightStrings, rightLines) of
@@ -172,14 +375,24 @@ struct
                   end
                 else
                   0
+
+                val absIdx = curIdx + startIdx
+
+                val f =
+                  if cursorPos < curIdx + String.size rStrHd then
+                    (* if cursor is within string *)
+                    buildTextStringWithinCursor
+                  else
+                    (* if cursor is after string *)
+                    buildTextStringBeforeCursor
             in
-              buildTextStringAfterCursor
+              f
                 ( startIdx, rStrHd, []
                 , 5, 5, 5
                 , windowWidth, windowHeight
                 , Real32.fromInt windowWidth, Real32.fromInt windowHeight
                 , 0.67, 0.51, 0.83
-                , rStrTl
+                , rStrTl, absIdx, cursorPos
                 )
             end
         | (_, _) =>