Section/Text: fix shape/drawing operations in text

l0/ASSFoundation/Section/Text.moon

@@ -38,10 +38,10 @@ return (ASS, ASSFInst, yutilsMissingMsg, createASSClass, Functional, LineCollect
   TextSection.getTextExtents = =>
     return aegisub.text_extents @getStyleTable!, @value
 
-  TextSection.getTextMetrics = (calculateBounds) =>
+  TextSection.getTextMetrics = (calculateBounds, text = @value) =>
     logger\assert Yutils, yutilsMissingMsg
     fontObj, tagList = @getYutilsFont!
-    extents = fontObj.text_extents @value
+    extents = fontObj.text_extents text
     metrics = fontObj.metrics!
 
     -- make sure we convert uint64 (returned from ffi) to lua numbers here
@@ -50,21 +50,70 @@ return (ASS, ASSFInst, yutilsMissingMsg, createASSClass, Functional, LineCollect
 
     local shape
     if calculateBounds
-      shape = fontObj.text_to_shape @value
+      shape = fontObj.text_to_shape text
       metrics.bounds = {Yutils.shape.bounding shape}
       metrics.bounds.w = (metrics.bounds[3] or 0) - (metrics.bounds[1] or 0)
       metrics.bounds.h = (metrics.bounds[4] or 0) - (metrics.bounds[2] or 0)
 
     return metrics, tagList, shape
 
-  TextSection.getShape = (applyRotation = false) =>
-    metrics, tagList, shape = @getTextMetrics true
-    drawing, align = ASS.Draw.DrawingBase{str: shape}
-    align =  tagList.tags.align\getSet!
-
-    with metrics -- fix position based on aligment
-      drawing\sub not align.left and (.width  - .bounds.w) / (align.centerH and 2 or 1) or 0,
-        not align.top and (.height - .bounds.h) / (align.centerV and 2 or 1) or 0
+  TextSection.getShape = (applyRotation = false, applyScale = false) =>
+    tagList = @getEffectiveTags true, true, false
+    fs = tagList.tags.fontsize\getTagParams!
+    fscy = tagList.tags.scale_y\getTagParams!
+    align = tagList.tags.align\getSet!
+
+    -- Calculate the vertical offset for each line seperated by linebreak
+    _, breakCount = @value\gsub "\\N", ""
+    breakCount += 1
+    verticalOffset = (fs * fscy) / 100
+    offsetTable = [ (i-1)*verticalOffset for i = 1, breakCount ]
+
+    shape, longestWidth, xAlignOffset,  metrics = "", 0, 0
+    sec = Functional.string.split @value, "\\N"
+    for i, text in ipairs sec
+      metrics, _, tempShape = @getTextMetrics true, text
+      drawing = ASS.Draw.DrawingBase{str: tempShape}
+
+      local xOffset, yOffset
+      -- Reconstruct the shape with proper vertical offset for each line
+      if align.bottom
+        yOffset = offsetTable[breakCount - i + 1] 
+      elseif align.top
+        yOffset = offsetTable[i] * (-1)
+      else
+        yOffset = (offsetTable[breakCount - i + 1] - offsetTable[i])/2
+
+      -- Reconstruct the shape with proper horizontal offset for each line
+      -- However, this constructed shape will be offseted by the width or half of width (depending on alignment) of the longest line
+      -- So the whole shape will later have to be offseted by that amount
+      if align.left
+        xOffset = 0
+        longestWidth = 0
+      elseif align.right
+        xOffset = metrics.width
+        if xOffset > longestWidth
+          longestWidth = xOffset
+          xAlignOffset = metrics.bounds.w
+      else
+        xOffset = (metrics.width)/2
+        if xOffset > longestWidth
+          longestWidth = xOffset
+          xAlignOffset = metrics.bounds.w/2
+      drawing\sub xOffset, yOffset
+      shape ..= "#{drawing\getTagParams!} "
+
+    drawing = ASS.Draw.DrawingBase{str: shape}
+    with metrics
+      .bounds = { Yutils.shape.bounding shape}
+      .bounds.h = (.bounds[4] or 0) - (.bounds[2] or 0)
+      drawing\sub  (-1) * xAlignOffset, not align.top and (.height - .bounds.h) / (align.centerV and 2 or 1) or 0
+
+    -- Scale the drawings based on fscx and fscy values
+    if applyScale
+      facX = 100/tagList.tags.scale_x\getTagParams!
+      facY = 100/tagList.tags.scale_y\getTagParams!
+      drawing\mul facX, facY
 
     -- rotate shape
     if applyRotation
@@ -73,8 +122,8 @@ return (ASS, ASSFInst, yutilsMissingMsg, createASSClass, Functional, LineCollect
 
     return drawing
 
-  TextSection.convertToDrawing = (applyRotation) =>
-    shape = @getShape(applyRotation)
+  TextSection.convertToDrawing = =>
+    shape = @getShape false, true
     @value, @contours, @scale = nil, shape.contours, shape.scale
     setmetatable @, ASS.Section.Drawing
     return @