add TextBoxWidget that handles line wrapping

widget.lua

@@ -193,6 +193,101 @@ function TextWidget:free()
 	end
 end
 
+--[[
+A TextWidget that handles long text wrapping
+]]
+TextBoxWidget = Widget:new{
+	text = nil,
+	face = nil,
+	color = 15,
+	width = 400, -- in pixels
+	line_height = 0.3, -- in em
+	v_list = nil,
+	_bb = nil,
+	_length = 0,
+}
+
+function TextBoxWidget:_wrapGreedyAlg(h_list)
+	local cur_line_width = 0
+	local space_w = sizeUtf8Text(0, G_width, self.face, " ", true).x
+	local cur_line = {}
+	local v_list = {}
+
+	for k,w in ipairs(h_list) do
+		cur_line_width = cur_line_width + w.width	
+		if cur_line_width <= self.width then
+			cur_line_width = cur_line_width + space_w
+			table.insert(cur_line, w)		
+		else
+			-- wrap to next line
+			table.insert(v_list, cur_line)
+			cur_line = {}
+			cur_line_width = w.width + space_w
+			table.insert(cur_line, w)		
+		end
+	end
+	-- handle last line
+	table.insert(v_list, cur_line)
+
+	return v_list
+end
+
+function TextBoxWidget:_getVerticalList(alg)
+	-- build horizontal list
+	h_list = {}
+	for w in self.text:gmatch("%S+") do
+		word_box = {}
+		word_box.word = w
+		word_box.width = sizeUtf8Text(0, G_width, self.face, w, true).x
+		table.insert(h_list, word_box)
+	end
+
+	-- @TODO check alg here 25.04 2012 (houqp)
+	-- @TODO replace greedy algorithm with K&P algorithm  25.04 2012 (houqp)
+	return self:_wrapGreedyAlg(h_list)
+end
+
+function TextBoxWidget:_render()
+	self.v_list = self:_getVerticalList()
+	local v_list = self.v_list
+	local font_height = self.face.size
+	local line_height_px = self.line_height * font_height
+	local space_w = sizeUtf8Text(0, G_width, self.face, " ", true).x
+	local h = (font_height + line_height_px) * #v_list - line_height_px
+	self._bb = Blitbuffer.new(self.width, h)
+	local y = font_height
+
+	for _,l in ipairs(v_list) do
+		local pen_x = 0
+		for _,w in ipairs(l) do
+			renderUtf8Text(self._bb, pen_x, y, self.face, w.word, true)
+			pen_x = pen_x + w.width + space_w
+		end
+		y = y + line_height_px + font_height
+	end
+end
+
+function TextBoxWidget:getSize()
+	if not self._bb then
+		self:_render()
+	end
+	return { w = self.width, h = self._bb:getHeight() }
+end
+
+function TextBoxWidget:paintTo(bb, x, y)
+	if not self._bb then
+		self:_render()
+	end
+	bb:blitFrom(self._bb, x, y, 0, 0, self.width, self._bb:getHeight())
+end
+
+function TextBoxWidget:free()
+	if self._bb then
+		self._bb:free()
+		self._bb = nil
+	end
+end
+
 --[[
 ImageWidget shows an image from a file
 ]]