/spacey

-- Class: Button

-- A button is a composite sprite made of two things: a label (e.g.

-- some text like "OK") and a background (e.g. a graphic or fill).

-- A button's dimensions, e.g. its clickable area, is determined by

-- its background's dimensions.

--

-- The x and y position of the label sprite is relative to the button's

-- top-left corner. The background sprite is always drawn at the button's

-- top-left corner. The label is always drawn on top of the background.

--

-- Extends:

--		<Sprite>

--

-- Event: onMouseOver

-- Called each frame the mouse is over the button.

--

-- Event: onMouseEnter

-- Called during the first frame the user moves the mouse over the button.

--

-- Event: onMouseExit

-- Called during the first frame the user moves the mouse off of the button.

--

-- Event: onMouseDown

-- Called during the first frame the user is clicking the mouse when it is over the button.

--

-- Event: onMouseUp

-- Called when the user releases the mouse over the button.

Button = Sprite:extend

{

	-- Property: background

	-- The background <Sprite> of the button.

	-- Propetrty: label

	-- The label <Sprite> of the button.

	-- Property: enabled

	-- If false, then no events will fire for this object, even just

	-- mouse enter/exit ones. It also forces the <mouseOver> property to

	-- false. This does not change the appearance of the button

	-- on its own; that's up to you.

	enabled = true,

	-- Property: mouseOver

	-- Tracks whether the user's mouse is over the button this frame.

	mouseOver = false,

	-- Property: beingClicked

	-- Tracks whether the user has the mouse button down and started

	-- clicking the mouse inside the button.

	beingClicked = false,

	draw = function (self, x, y)

		local bg = self.background

		local label = self.label

		x = x or self.x

		y = y or self.y

		if bg then bg:draw(x + bg.x, y + bg.y) end

		if label then label:draw(x + label.x, y + label.y) end

		Sprite.draw(self, x, y)

	end,

	update = function (self, elapsed)

		local bg = self.background

		local label = self.label

		-- keep dimensions in sync with background

		if bg then

			self.width = bg.width

			self.height = bg.height

		end

		-- call hooks for mouse movement events

		if self.enabled then

			local overBefore = self.mouseOver

			self.mouseOver = self:intersects(the.mouse.x, the.mouse.y)

			if self.mouseOver then self:callHook('onMouseOver') end

			if self.mouseOver and not overBefore then self:callHook('onMouseEnter') end

			if not self.mouseOver and overBefore then self:callHook('onMouseExit') end

			-- check for clicks

			if self.mouseOver and the.mouse:justPressed() then

				self.beingClicked = true

				self:callHook('onMouseDown')

			end

			if self.beingClicked and the.mouse:justReleased() then

				if self.mouseOver then

					self:callHook('onMouseUp')

				else

					if label and label.onMouseUp then label:onMouseUp() end

					if bg and bg.onMouseUp then label:onMouseUp() end

					if self.onMouseUp then self:onMouseUp() end

				end

				self.beingClicked = false

			end

		else

			self.mouseOver = false

		end

		-- let label and background update

		if bg then bg:update(elapsed) end

		if label then label:update(elapsed) end

		Sprite.update(self, elapsed)

	end,

	callHook = function (self, name)

		local label = self.label

		local bg = self.background

		if label and label[name] then label[name](label) end

		if bg and bg[name] then bg[name](bg) end

		if self[name] then self[name](self) end

	end

}