improve creation of click points, so that we can have a pixel be a perfect square, even if the canvas isn't

fcore/app-init.sml

@@ -18,8 +18,9 @@ struct
     , canvasHeight
     ) : app_type =
     let
-      val xClickPoints = ClickPoints.generate (wStart, wFinish, canvasWidth)
-      val yClickPoints = ClickPoints.generate (hStart, hFinish, canvasHeight)
+      val (xClickPoints, yClickPoints) =
+        ClickPoints.generate
+          (windowWidth, windowHeight, canvasWidth, canvasHeight)
 
       val maxPoints = Int.max (canvasWidth, canvasHeight)
       val squares = Vector.tabulate (maxPoints, fn _ =>

fcore/app-with.sml

@@ -160,9 +160,7 @@ struct
       }
     end
 
-  fun helpWindowResize
-    (app: app_type, windowWidth, windowHeight, wStart, wFinish, hStart, hFinish) :
-    app_type =
+  fun windowResize (app: app_type, windowWidth, windowHeight) : app_type =
     let
       val
         { mode
@@ -188,9 +186,9 @@ struct
         , modalNum
         } = app
 
-      val maxPoints = Int.max (canvasWidth, canvasHeight)
-      val xClickPoints = ClickPoints.generate (wStart, wFinish, maxPoints)
-      val yClickPoints = ClickPoints.generate (hStart, hFinish, maxPoints)
+      val (xClickPoints, yClickPoints) =
+        ClickPoints.generate
+          (windowWidth, windowHeight, canvasWidth, canvasHeight)
     in
       { mode = mode
       , squares = squares
@@ -216,29 +214,6 @@ struct
       }
     end
 
-  fun windowResize (app: app_type, windowWidth, windowHeight) =
-    if windowWidth = windowHeight then
-      helpWindowResize
-        (app, windowWidth, windowHeight, 0, windowWidth, 0, windowHeight)
-    else if windowWidth > windowHeight then
-      let
-        val difference = windowWidth - windowHeight
-        val wStart = difference div 2
-        val wFinish = wStart + windowHeight
-      in
-        helpWindowResize
-          (app, windowWidth, windowHeight, wStart, wFinish, 0, windowHeight)
-      end
-    else
-      let
-        val difference = windowHeight - windowWidth
-        val hStart = difference div 2
-        val hFinish = hStart + windowWidth
-      in
-        helpWindowResize
-          (app, windowWidth, windowHeight, 0, windowWidth, hStart, hFinish)
-      end
-
   fun mousePosition (app: app_type, mouseX, mouseY) =
     let
       val

fcore/click-points.sml

@@ -1,12 +1,23 @@
 structure ClickPoints =
 struct
-  fun generate (start, finish, numPoints) =
+  fun generate (windowWidth, windowHeight, canvasWidth, canvasHeight) =
     let
-      val difference = finish - start
-      val increment = Real32.fromInt difference / Real32.fromInt numPoints
+      val realWindowWidth = Real32.fromInt windowWidth
+      val realCanvasWidth = Real32.fromInt canvasWidth
+      val realWindowHeight = Real32.fromInt windowHeight
+      val realCanvasHeight = Real32.fromInt canvasHeight
+
+      val xPixelSize = realWindowWidth / realCanvasWidth
+      val yPixelSize = realWindowHeight / realCanvasHeight
+
+      val pixelSize = Real32.min (xPixelSize, yPixelSize)
+
+      val xClickPoints = Vector.tabulate (canvasWidth + 1, fn i =>
+        Real32.fromInt i * pixelSize)
+      val yClickPoints = Vector.tabulate (canvasHeight + 1, fn i =>
+        Real32.fromInt i * pixelSize)
     in
-      Vector.tabulate (numPoints + 1, fn idx =>
-        (Real32.fromInt idx * increment))
+      (xClickPoints, yClickPoints)
     end
 
   fun getClickPos (clickPoints, mousePos, idx) =