lighttroupe/luz

class FontFactory
    def character_image(font, character)
        # a canvas to draw onto, before copying to OpenGL
        @canvas ||= CairoCanvas.new(256,256)

        @images_for_characters ||= {}        # keyed first by font...
        @images_for_characters[font] ||= Hash.new { |hash, key|
            hash[key] = generate_character_image(font, key)    # ..then by character
        }

        @images_for_characters[font][character]
    end

    def generate_character_image(font, character)
        puts "generating #{font} #{character}"
        image = Image.new

        @canvas.using { |context|
            context.save
                # clear
                context.set_source_rgba(0.0, 0.0, 0.0, 0.0)        # NOTE: alpha 0.0
                context.set_operator(:source)
                context.paint

                # Default Cairo coordinates has 0,0 in the upper left, with 1 unit translating to 1 pixel
                # Scale it so that the whole canvas goes 0.0 -> 1.0 horizontally and 0.0 -> 1.0 vertically
                context.scale(@canvas.width, @canvas.height)        # NOTE: height is multiplied by -1 to flip the canvas vertically, so bigger numbers go up (cartessian plane)

                # Move cursor to center
                context.translate(0.5, 0.5)

                context.set_source_rgba(1,1,1,1)
                context.set_antialias(Cairo::ANTIALIAS_GRAY)        # or DEFAULT or GRAY or SUBPIXEL or NONE

                weight = Cairo::FONT_WEIGHT_NORMAL
                if font =~ / Bold/
                    font = font.gsub(' Bold', '')
                    weight = Cairo::FONT_WEIGHT_BOLD
                end

                slant = Cairo::FONT_SLANT_NORMAL
                if font =~ / Italic/
                    font = font.gsub(' Italic', '')
                    slant = Cairo::FONT_SLANT_ITALIC
                end

                context.select_font_face(font, slant, weight)
                context.set_font_size(0.9)

                extents = context.text_extents(character)

                context.move_to(-0.5 - extents.x_bearing + ((1.0 - extents.width)/2.0), 0.25)
                context.show_text(character)
            context.restore
        }

        image.from_bgra8(@canvas.string_data, @canvas.width, @canvas.height)
        image
    end
end

$font_factory ||= FontFactory.new

class ActorEffectTextChildren < ActorEffect
    title                "Text Children"
    description "Apply text to children, one letter per child."

    categories :color, :child_consumer

    setting :font, :font
    setting :text, :string

    def render
        character = text[child_index]
        return unless character

        image = $font_factory.character_image(font, character.chr)
        return unless image

        image.using {
            yield
        }
    end
end