Even better

src/wells.nim

@@ -28,7 +28,14 @@ proc newWell*(width, height: int): Well =
 
 proc dimensions(well): Vec2 = vec2(float well.width, float well.height)
 
-proc margins*(well): tuple[w: int, h: int] = (well.width div 9, well.height div 9)
+proc margins(well): tuple[w: int, h: int] = (well.width div 9, well.height div 9)
+
+proc textArea(well): tuple[w: int, h: int] = (
+    well.width - ((well.width div 9) shl 1),
+    well.height - ((well.height div 9) shl 1),
+  )
+
+proc vec2(t: (int, int)): Vec2 = vec2(float t[0], float t[1])
 
 proc rect*(well): Rect =
   result.wh = well.dimensions
@@ -37,21 +44,33 @@ proc rectAt(well; i: int): Rect =
   if i < well.panes.len:
     let
       (quo, rem) = divmod(i, 3)
-      shiftOff = quo.succ
-      scaleDiv = 1 shl quo.succ
+      shiftOff = succ quo
       fullWh = well.dimensions
-    result.w = float(well.width shr shiftOff)
-    result.h = float(well.height shr shiftOff)
+      textArea = well.textArea
+      paneArea = vec2(float(well.width shr shiftOff), float(well.height shr shiftOff))
+    result.w = float(textArea.w shr shiftOff)
+    result.h = float(textArea.h shr shiftOff)
     case rem
     of 0:
-      result.xy = fullWh - (result.wh * 2.0)
+      result.xy = fullWh - (paneArea * 2.0)
     of 1:
-      result.x = fullWh.x - result.w
-      result.y = fullWh.y - (result.h * 2.0)
+      result.x = fullWh.x - paneArea.x
+      result.y = fullWh.y - (paneArea.y * 2.0)
     of 2:
-      result.x = fullWh.x - (result.w * 2.0)
-      result.y = fullWh.y - result.h
+      result.x = fullWh.x - (paneArea.x * 2.0)
+      result.y = fullWh.y - paneArea.y
     else: discard
+    result.xy = result.xy + (result.wh / 9.0)
+
+proc quadAt(well; i: int): Rect =
+  if i < well.panes.len:
+    let
+      (quo, rem) = divmod(i, 3)
+      shiftOff = succ quo
+      fullWh = well.dimensions
+    assert rem == 0
+    result.wh = vec2(float(well.width shr shiftOff), float(well.height shr shiftOff))
+    result.xy = fullWh - result.wh
 
 proc place(well; offset, width, height: int): (Pane, Rect) =
   ## Return the `Pane` at `offset` from the top of `well` or `nil` if
@@ -68,9 +87,10 @@ proc append*(well; text: string; font: Font) =
     let pane = well.panes.peekLast()
     pane.spans.add(span)
     var
-      arrangement = typeset(pane.spans, well.dimensions)
+      textArea = well.textArea.vec2
+      arrangement = typeset(pane.spans, textArea)
       bounds = layoutBounds arrangement
-    if bounds.y <= well.dimensions.y:
+    if bounds.y <= textArea.y:
       doAssert pane.spans.len > 0, "text does not find on a single pane - " & $bounds & $well.dimensions
       pane.arrangement = arrangement
       break
@@ -99,9 +119,8 @@ proc texture*(well; index: int; renderer: RendererPtr): TexturePtr =
     if pane.texture.isNil and not pane.arrangement.isNil:
       assert pane.image.isNil
       let
-        w = (well.width div 9) * 7
-        h = (well.height div 9) * 7
-      pane.image = newImage(w, h)
+        textArea = well.textArea
+      pane.image = newImage(textArea.w, textArea.h)
       pane.image.fill(rgba(255, 255, 255, 255))
       pane.image.fillText(pane.arrangement)
       var surface = createRGBSurfaceFrom(
@@ -124,17 +143,17 @@ iterator intersectingPanes*(well; view: Rect): Intersection =
     zoom = 1.0
   while intersect.index < well.panes.len:
     var paneRect = well.rectAt(intersect.index)
-    if (intersect.index mod 3) == 0:
-      let quad = rect(paneRect.xy, paneRect.wh * 2.0)
-      if not view.overlaps quad:
-        # all further panes are non-intersecting
-        break
+    let stepDown = (intersect.index mod 3) == 0
+    if stepDown:
       zoom = zoom * 2.0
-    let margin = paneRect.wh / 9.0
-    paneRect.xy = paneRect.xy + margin
-    paneRect.wh = paneRect.wh - (margin * 2.0)
     if view.overlaps paneRect:
       intersect.dst = view and paneRect
       intersect.src = rect(intersect.dst.xy - paneRect.xy, intersect.dst.wh) * zoom
       yield(intersect)
+    if stepDown:
+      let quad = well.quadAt(intersect.index)
+      if not view.overlaps quad:
+        echo "view ", view, " does not overlap quadrant ", quad
+        # all further panes are non-intersecting
+        break
     inc(intersect.index)