Love Game Engine GUI Elements

require("class")
require("engine")

-- GUIElement class

engine.GUIElement = newClass(engine.Entity)

-- GUIElement methods

function engine.GUIElement:setHandler(handler, ...)
    self.handler = handler
    self.handleArgs = ...
end

-- Protected methods

function engine.GUIElement:handle(...)
    self:action(...)
    if self.handler then self.handler(self, self.handleArgs) end
end

-- Virtual methods

function engine.GUIElement:action(...)
end

-- Container class

engine.Container = newClass(engine.GUIElement)

-- Container methods

function engine.Container:setup(width, height)
    self:setSize(width or 100, height or 100)
    self:setBackgroundColor({200, 200, 200})
    self:setBorderColor()
    self.borderThickness = 2
    self.hasBorder = true
    self.hasBackground = true
    self.selectable = true
end

function engine.Container:setBorderColor(color)
    self.borderColor = color or {50, 50, 50}
end

function engine.Container:draw()
    if self.hasBorder then
        love.graphics.setLineWidth(self.borderThickness)
        love.graphics.setColor(self.borderColor[1], self.borderColor[2], self.borderColor[3])
        local a = self.borderThickness / 2
        love.graphics.polygon("line", a, a, self.width - a, a, self.width - a, self.height - a, a, self.height - a)
    end
end

-- Label class

engine.Label = newClass(engine.GUIElement)

-- Label methods

function engine.Label:setup(text)
    self:setSize(1, 1)
    self:setTextColor()
    self:setFont()
    self:setText(text)
    self.hasShadow = false
    self.shadowOffsetX = -2
    self.shadowOffsetY = 2
    self.shadowAlpha = 127
end

function engine.Label:setText(text)
    self.text = text
    self:updateSize()
end

function engine.Label:setTextColor(color)
    self.textColor = color or {50, 50, 50}
end

function engine.Label:setFont(font)
    self.font = font or love.graphics.newFont(12)
    if self.text then self:updateSize() end
end

function engine.Label:preDraw()
    love.graphics.setFont(self.font)
    if self.hasShadow then
        love.graphics.setColor(0, 0, 0, self.shadowAlpha)
        love.graphics.print(self.text, self.shadowOffsetX, self.shadowOffsetY)
    end
    love.graphics.setColor(self.textColor[1], self.textColor[2], self.textColor[3])
    love.graphics.print(self.text, 0, 0)
end

-- Private methods

function engine.Label:updateSize()
    self:setSize(self.font:getWidth(self.text), self.font:getHeight())
end

-- Button class

engine.Button = newClass(engine.Label)

function engine.Button:setup(text, handler, ...)
    self:setHandler(handler, ...)
    self.borderThickness = 2
    self:getSuperClass():setup(text)
    self:setBackgroundColor({200, 200, 200})
    self:setBorderColor()
    self.hasBackground = true
    self.selectable = true
end

engine.Button.setBorderColor = engine.Container.setBorderColor

function engine.Button:focus(f)
    if f then
        self:setBackgroundColor({150, 150, 255})
    else
        self:setBackgroundColor({200, 200, 200})
    end
    self:refresh()
end

function engine.Button:mousepressed(x, y, button)
    self:refresh()
end

engine.Button.mousereleased = engine.Button.mousepressed

function engine.Button:mouseclicked(x, y, button)
    self:handle()
end

function engine.Button:draw()
    love.graphics.setBlendMode("alpha")
    love.graphics.setLineWidth(self.borderThickness)
    love.graphics.setColor(self.borderColor[1], self.borderColor[2], self.borderColor[3])
    local a = self.borderThickness / 2
    love.graphics.polygon("line", a, a, self.width - a, a, self.width - a, self.height - a, a, self.height - a)
    if love.mouse.isDown("l") and self.selected then
        love.graphics.setBlendMode("multiplicative")
        love.graphics.setColor(0, 0, 0, 127)
        love.graphics.polygon("fill", 0, 0, self.width, 0, self.width, self.height, 0, self.height)
    end
end

function engine.Button:preDraw()
    love.graphics.setColor(self.textColor[1], self.textColor[2], self.textColor[3])
    love.graphics.setFont(self.font)
    love.graphics.print(self.text, self.borderThickness * 2, self.borderThickness * 2)
end

-- Private methods

function engine.Button:updateSize()
    self:setSize(self.font:getWidth(self.text) + self.borderThickness * 4, self.font:getHeight() + self.borderThickness * 4)
end

-- TextField class

engine.TextField = newClass(engine.Button)

function engine.TextField:setup(text, width, height, handler, ...)
    self:setHandler(handler, ...)
    self.borderThickness = 2
    self:getSuperClass():getClass():setup(text)
    self:setBackgroundColor({200, 200, 200})
    self:setBorderColor()
    self.hasBackground = true
    self.selectable = true
    self:setSize(width or 125, height or 25)
end

function engine.TextField:keypressed(key, unicode)
    if key == "return" then
        self:handle()
    elseif key == "backspace" then
        self:setText(string.sub(self.text, 1, #self.text - 1))
    elseif unicode > 31 and unicode < 127 then
        self:setText(self.text .. string.char(unicode))
    end
    self:refresh()
end

function engine.TextField:mouseclicked(x, y, button)
end

-- Private methods

function engine.TextField:updateSize()
end