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Lua and JavaScript

Scripting Tutorial - Lesson 12: Intro to Mouse Controls

Play with the script in the text box below, and then click the "run your code" button above.

platform.apilevel = '1.0'

local screen = platform.window
		local w = screen:width()
		local h = screen:height()
		local TrackedObject = nil
		
		local Color = {
		red 	 = {0xFF, 0x00, 0x00},
		green	 = {0x00, 0xFF, 0x00},
		}

Square = class()

function Square:init(x, y, width, height)
			self.x	 = x
			self.y	 = y
			self.width	= width or 20
			self.height	= height or 20
			self.color = Color.green
			self.selected = false
		end

function Square:contains(x, y)
			local sw = self.width
			local sh = self.height
			return x >= self.x - sw/2 and x <= self.x + sw/2 and
				y >= self.y - sh/2 and y <= self.y + sh/2
		end

function Square:paint(gc)
			gc:setColorRGB(unpack(self.color))
			gc:fillRect(self.x - self.width / 2, self.y - self.height / 2, 
						self.width, self.height)
			if self.selected then
				gc:setPen("medium","smooth")
				gc:setColorRGB(0, 0, 0)
				gc:drawRect(self.x - self.width / 2, self.y - self.height / 2, 
							self.width, self.height)
			end
		end

Sq = Square(w/2, h/2, h/3, h/3)
				
		function on.mouseDown(x,y)
			if Sq:contains(x, y) then
				if TrackedObject ~= nil then
					TrackedObject.selected = false
				end

TrackedObject = Sq
				Sq.selected = true
			
				screen:invalidate()
			end
		end

function on.mouseUp(x,y)
		
			if not Sq:contains(x, y) then
				Sq.x = x
				Sq.y = y
			end
		
			if TrackedObject ~= nil then		
				TrackedObject.selected = false
			end

TrackedObject = nil
			screen:invalidate()
		end			
		
		function on.mouseMove(x,y)
			if TrackedObject ~= nil then
				TrackedObject.x = x
				TrackedObject.y = y

screen:invalidate()
			end
		end
		
		function on.paint(gc)
			w = screen:width()
			h = screen:height()

Sq:paint(gc)
			
			gc:setFont("sansserif", "b", 10)
			gc:setColorRGB(unpack(Sq.color))
			gc:drawString(
					"("..Sq.x..","
					..Sq.y..")",w/10,h/10)
		end

Click "run your code!" to get started.

You can copy and paste the script (or type your own) into the lower text box and then click "run your code!" After that, explore and experiment!

If you are using a tablet or smartphone for this lesson, you will find that, sadly, you will be unable to grab and drag the shape as you can if using a computer. Study the script to see how we have worked around this limitation to still give you an experience of controlling the location of the shape using mouse clicks.

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