Added ALIGN_JUSTIFY

Fixes #53

Author: britzl

README.md

@@ -148,7 +148,7 @@ The `settings` table can contain the following values:
 * `color` (vector4) - The default color of text. Will be white if not specified.
 * `shadow` (vector4) - The default shadow color of text. Will be transparent if not specified.
 * `outline` (vector4) - The default outline color of text. Will be transparent if not specified.
-* `align` (hash) - One of `richtext.ALIGN_LEFT`, `richtext.ALIGN_CENTER` and `richtext.ALIGN_RIGHT`. Defaults to `richtext.ALIGN_LEFT`. Defines how the words of a line of text are positioned in relation the provided `position`.
+* `align` (hash) - One of `richtext.ALIGN_LEFT`, `richtext.ALIGN_CENTER`, `richtext.ALIGN_RIGHT` and `richtext.ALIGN_JUSTIFY`. Defaults to `richtext.ALIGN_LEFT`. Defines how the words of a line of text are positioned in relation the provided `position`. Width must be specified for `richtext.ALIGN_JUSTIFY`.
 * `line_spacing` (number) - Value to multiply line height with. Set to a value lower than 1.0 to reduce space between lines and a value higher than 1.0 to increase space between lines. Defaults to 1.0.
 * `image_pixel_grid_snap` (boolean) - Set to true to position image on full pixels (positions rounded to nearest integer) to avoid effects of anti-aliasing. Defaults to false.
 * `combine_words` (boolean) - Set to true to combine words with the same style on a line into a single node. This is useful for very long texts where the maximum number of nodes would exceed the limit set in the GUI. The disadvantage is that any per word operations will not work since the words have been combined.
@@ -276,6 +276,9 @@ Center text. The words of a line are centered on the specified position (see `ri
 ### richtext.ALIGN_RIGHT
 Right-align text. The words of a line ends at the specified position (see `richtext.create` settings above).
 
+### richtext.ALIGN_JUSTIFT
+Justify text. The words of a line start at the specified position and are spaced such that the last character of the last word ends at the right edge of the line bounds (see `richtext.create` settings above).
+
 
 # Credits
 * Smiley icons in example app from [Flaticons](https://www.flaticon.com/packs/smileys-3)

example/example.gui_script

@@ -64,15 +64,18 @@ end
 
 
 local function create_align_example()
+	local settings_align_justify = { position = vmath.vector3(10, 420, 0), align = richtext.ALIGN_JUSTIFY, width = 300 }
+	local justify = richtext.create("Justify this text\nDo it for both lines", "Roboto-Regular", settings_align_justify)
+
 	local settings_align_left = { position = vmath.vector3(10, 310, 0), align = richtext.ALIGN_LEFT }
-	local left = richtext.create("Left align this text\nDo it for both lines", "Roboto-Regular", settings_align_leftb)
+	local left = richtext.create("Left align this text\nDo it for both lines", "Roboto-Regular", settings_align_left)
 
 	local settings_align_right = { position = vmath.vector3(640, 200, 0), align = richtext.ALIGN_RIGHT }
 	local right = richtext.create("Right align this text\nDo it for both lines", "Roboto-Regular", settings_align_right)
 
 	local settings_align_center = { position = vmath.vector3(320, 90, 0), align = richtext.ALIGN_CENTER }
 	local center = richtext.create("Center words around the specified position\nAnd these words as well", "Roboto-Regular", settings_align_center)
-	return merge(left, right, center)
+	return merge(justify, left, right, center)
 end
 
 

richtext/richtext.lua

@@ -6,6 +6,7 @@ local M = {}
 M.ALIGN_CENTER = hash("ALIGN_CENTER")
 M.ALIGN_LEFT = hash("ALIGN_LEFT")
 M.ALIGN_RIGHT = hash("ALIGN_RIGHT")
+M.ALIGN_JUSTIFY = hash("ALIGN_JUSTIFY")
 
 
 local V4_ZERO = vmath.vector4(0)
@@ -130,6 +131,15 @@ local function position_words(words, line_width, line_height, position, settings
 		position.x = position.x - line_width / 2
 	end
 
+	local spacing = 0
+	if settings.align == M.ALIGN_JUSTIFY and #words > 1 then
+		local words_width = 0
+		for i=1,#words do
+			local word = words[i]
+			words_width = words_width + word.metrics.total_width
+		end
+		spacing = (settings.width - words_width) / (#words - 1)
+	end
 	for i=1,#words do
 		local word = words[i]
 		-- align spine animations to bottom of line since
@@ -143,7 +153,7 @@ local function position_words(words, line_width, line_height, position, settings
 		else
 			gui.set_position(word.node, position)
 		end
-		position.x = position.x + word.metrics.total_width
+		position.x = position.x + word.metrics.total_width + spacing
 		words[i] = nil
 	end
 end
@@ -315,7 +325,10 @@ function M.create(text, font, settings)
 	settings.line_spacing = settings.line_spacing or 1
 	settings.image_pixel_grid_snap = settings.image_pixel_grid_snap or false
 	settings.combine_words = settings.combine_words or false
-
+	if settings.align == M.ALIGN_JUSTIFY and not settings.width then
+		error("Width must be specified if text should be justified")
+	end
+	
 	-- default settings for a word
 	-- will be assigned to each word unless tags override the values
 	local word_settings = {