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-- 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
}
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