* Speed up scanline order inversion

hexfont.lua

@@ -55,7 +55,15 @@ hexfont.constructor = function(self, properties)
    -- Defaults
    self.background_color = properties.background_color or { 0x00 }
    self.foreground_color = properties.foreground_color or { 0xFF }
+
+   -- scanline order “bottom-top” was chosen as the default to match
+   -- the default scanline order of tga_encoder and to require users
+   -- using another file format encoder to care about scanline order
+   -- (users who “do not care about scanline order” might find their
+   -- glyphs upside down … the fault, naturally, lies with the user)
    self.scanline_order = properties.scanline_order or "bottom-top"
+
+   -- tab size = 8 half-width spaces when using GNU Unifont
    self.tabulator_size = properties.tabulator_size or 8 * 8
    self.kerning = properties.kerning or false
 
@@ -133,16 +141,6 @@ hexfont.bitmap_to_pixels = function(self, bitmap_hex)
       "boolean" == type(self.kerning)
    )
 
-   -- scanline order “bottom-top” was chosen as the default to match
-   -- the default scanline order of tga_encoder and to require users
-   -- using another file format encoder to care about scanline order
-   -- (users who “do not care about scanline order” might find their
-   -- glyphs upside down … the fault, naturally, lies with the user)
-   assert(
-      "bottom-top" == self.scanline_order or
-      "top-bottom" == self.scanline_order
-   )
-
    local height = 16
    local width = bitmap_hex:len() * 4 / height
    assert(
@@ -171,12 +169,6 @@ hexfont.bitmap_to_pixels = function(self, bitmap_hex)
       end
    end
 
-   -- flip image upside down for ”bottom-top” scanline order
-   -- (i.e. the first encoded pixel is the bottom left pixel)
-   if "bottom-top" == self.scanline_order then
-      pixels = pixelops.flip_vertically(pixels)
-   end
-
    if self.kerning then
       -- remove rightmost column if it is empty
       local remove_rightmost_column = true
@@ -301,15 +293,8 @@ hexfont.render_text = function(self, text)
       if nil == result then
          result = pixels
       else
-         if "bottom-top" == self.scanline_order then
+         for i = 1, #pixels do
-            for i = #pixels, 1, -1 do
+            result[#result+1] = pixels[i]
-               table.insert(result, 1, pixels[i])
-            end
-         end
-         if "top-bottom" == self.scanline_order then
-            for i = 1, #pixels do
-               result[#result+1] = pixels[i]
-            end
          end
       end
       local pixels_width = #pixels[1]
@@ -328,5 +313,10 @@ hexfont.render_text = function(self, text)
          )
       end
    end
+   -- flip image upside down for ”bottom-top” scanline order
+   -- (i.e. the first encoded pixel is the bottom left pixel)
+   if "bottom-top" == self.scanline_order then
+      result = pixelops.flip_vertically(result)
+   end
    return result
 end