Zalim Bashorov
111 lines
2.6 KiB
Kotlin
111 lines
2.6 KiB
Kotlin
/*
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This shows simple text floating around.
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*/
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package hello
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import js.dom.html5.*
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import js.dom.html.window
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import js.jquery.*
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val canvas: HTMLCanvasElement
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get() {
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return window.document.getElementsByTagName("canvas").item(0)!! as HTMLCanvasElement
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}
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val context: CanvasContext
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get() {
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return canvas.getContext("2d")!!
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}
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val width: Double
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get() {
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return canvas.width
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}
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val height: Double
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get() {
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return canvas.height
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}
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// class representing a floating text
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class HelloKotlin() {
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var relX = 0.2 + 0.2 * Math.random()
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var relY = 0.4 + 0.2 * Math.random()
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val absX: Double
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get() = (relX * width)
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val absY: Double
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get() = (relY * height)
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var relXVelocity = randomVelocity()
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var relYVelocity = randomVelocity()
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val message = "Hello, Kotlin!"
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val textHeightInPixels = 20
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{
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context.font = "bold ${textHeightInPixels}px Georgia, serif"
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}
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val textWidthInPixels = context.measureText(message)!!.width
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fun draw() {
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context.save()
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move()
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// if you using chrome chances are good you wont see the shadow
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context.shadowColor = "#000000"
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context.shadowBlur = 5.0
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context.shadowOffsetX = -4.0
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context.shadowOffsetY = 4.0
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context.fillStyle = "rgb(242,160,110)"
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context.fillText(message, absX.toInt(), absY.toInt())
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context.restore()
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}
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fun move() {
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val relTextWidth = textWidthInPixels / width
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if (relX > (1.0 - relTextWidth - relXVelocity.abs) || relX < relXVelocity.abs) {
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relXVelocity *= -1
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}
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val relTextHeight = textHeightInPixels / height
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if (relY > (1.0 - relYVelocity.abs) || relY < relYVelocity.abs + relTextHeight) {
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relYVelocity *= -1
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}
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relX += relXVelocity
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relY += relYVelocity
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}
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fun randomVelocity() = 0.03 * Math.random() * (if (Math.random() < 0.5) 1 else -1)
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val Double.abs: Double
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get() = if (this > 0) this else -this
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}
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fun renderBackground() {
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context.save()
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context.fillStyle = "#5C7EED"
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context.fillRect(0, 0, width, height)
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context.restore()
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}
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fun main(args: Array<String>) {
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jq {
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val interval = 50
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// we pass a literal that constructs a new HelloKotlin object
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val logos = Array(3) {
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HelloKotlin()
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}
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window.setInterval({
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renderBackground()
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for (logo in logos) {
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logo.draw()
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}
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}, interval)
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}
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}
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