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libg.js
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libg.js
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"use strict"
// **** mini scene and canvas based graphics lib ****
//depends on lib.js
//author: Onne Gorter
//license: CC0
/// This mini canvas graphics library maintains a scene graph based on `Layer`s (and `Box`es).
/// It makes it easy to load resources and build and maintain a scene graph. And to receive
/// and process events per object. The `Layer`s have `delegate`s that do the actual rendering
/// and event handing. Both graphics and images use native objects (`CanvasRenderingContext2D`
/// context and `Image`).
var _default_scene = null
// wraps native DOM events
class GEvent {
constructor(x, y, globalx, globaly, event, target, last, delta) {
this.x = x /// x coordinate relative to this.target
this.y = y /// y coordinate relative to this.target
this.globalx = globalx /// x coordinate absolute to root of scene
this.globaly = globaly /// y coordinate absolute to root of scene
this.target = target /// the target of this event
this.domevent = event /// the native DOM event
this.last = last || false /// set to true if this is the last event of a follow
this.delta = delta || null /// set to {x,y} as difference from start of follow
}
/// convert to a global point
toGlobal() {
return {x:this.globalx, y:this.globaly}
}
/// follow a `ondown` event, and call `cb` for every `onmove` event
/// last call will be from an `onup` event and `event.last` will be `true`
follow(cb) {
if (this.domevent instanceof Touch) return startFollowTouch(this.domevent, cb, this)
pushFollowHandlers(cb, this)
}
}
function runEvent(target, x, y, globalx, globaly, event, name) {
var handler = null
if (target.delegate) handler = target.delegate[name]
if (!handler) return false
var passToParent = handler.call(target.delegate, new GEvent(x, y, globalx, globaly, event, target))
return !passToParent
}
function startFollowTouch(touch, handler, event) {
_followtouch[touch.identifier] = {handler, target: event.target, start:{x:event.globalx, y:event.globaly}}
}
function followTouch(follow, touch, globalx, globaly, name) {
var handler = follow.handler
var target = follow.target
var start = follow.start
if (!handler) return
assert(target)
var l = target.toGlobal()
var x = globalx - l.x
var y = globaly - l.y
var delta = {x:globalx - start.x, y:globaly - start.y}
var last = name === "onup"
handler.call(target.delegate, new GEvent(x, y, globalx, globaly, touch, target, last, delta))
_default_scene.schedule()
}
function pushFollowHandlers(handler, event) {
_default_scene.follow = handler
_default_scene.followtarget = event.target
_default_scene.followstart = {x:event.globalx, y:event.globaly}
_default_scene.c.onmousemove = followmousemove
_default_scene.c.onmouseup = followmouseup
}
function restoreMouseHandlers() {
_default_scene.follow = null
_default_scene.followtarget = null
_default_scene.c.onmousemove = _default_scene.onmousemove
_default_scene.c.onmouseup = _default_scene.onmouseup
}
function _follow2(event, last) {
var handler = _default_scene.follow
var target = _default_scene.followtarget
var start = _default_scene.followstart
if (!handler) return
assert(target)
var globalx = event.offsetX
var globaly = event.offsetY
var l = target.toGlobal()
var x = globalx - l.x
var y = globaly - l.y
var delta = {x:globalx - start.x, y:globaly - start.y}
handler.call(target.delegate, new GEvent(x, y, globalx, globaly, event, target, last, delta))
event.preventDefault()
_default_scene.schedule()
}
function followmousemove(event) {
_follow2(event, false)
}
function followmouseup(event) {
_follow2(event, true)
restoreMouseHandlers()
}
/// scene
class GScene {
constructor(g, c, width, height) {
this.root = new Box() /// the root of the scene, `add()` other `Layer`s, set its `style`, or give it a `delegate`
this.onready = null /// handler that is called after all assets have loaded
this.onrender = null /// handler that is called before rerendering scene
// private
this.g = g
this.c = c
this.width = c.width = g.width = width
this.height = c.height = g.height = height
this.imageloader = null
if (!_default_scene) _default_scene = this
this.schedule()
}
draw(layer) {
var g = this.g
g.save()
g.translate(layer.x, layer.y)
if (!fequals(layer.rotate, 0.001)) g.rotate(layer.rotate)
layer.draw(g, this)
g.restore()
}
render() {
this.scheduled = false
if (this.imageloader && this.imageloader.loading > 0) return
if (this.onrender) this.onrender()
var root = this.root
root.x = root.y = 0
root.width = this.c.width = this.width
root.height = this.c.height = this.height
root.layout()
this.g.font = "24px Arial"
this.g.save()
this.draw(root)
this.g.restore()
}
ready() {
this.schedule()
if (this.onready) this.onready()
}
/// call if some external event should rerender scene, harmless to call multiple times
/// internal events like `ondown`, or images that load, will call this automatically
schedule() {
if (this.scheduled) return
this.scheduled = true
requestAnimationFrame(_renderContext)
}
/// load an image from `url`, returns the img immediately
/// use `onready` to wait for all assets to have loaded
image(url) {
if (!this.imageloader) this.imageloader = new ImageLoader(this)
return this.imageloader.fetch(url)
}
}
function _renderContext() {
_default_scene.render()
}
function imageCheck(img) {
if (!img.complete) return false
if (img.naturalWidth !== "undefined" && img.naturalWidth === 0) return false
return true
}
function roundedRect(g, x, y, width, height, r) {
g.beginPath()
g.moveTo(x + r, y)
g.lineTo(x + width - r, y)
g.quadraticCurveTo(x + width, y, x + width, y + r)
g.lineTo(x + width, y + height - r)
g.quadraticCurveTo(x + width, y + height, x + width - r, y + height)
g.lineTo(x + r, y + height)
g.quadraticCurveTo(x, y + height, x, y + height - r)
g.lineTo(x, y + r)
g.quadraticCurveTo(x, y, x + r, y)
g.closePath()
}
class ImageLoader {
constructor(scene) {
this.images = {}
this.loading = 0
this.scene = scene
}
fetch(url) {
var img = this.images[url]
if (img) return img
this.loading += 1
img = this.images[url] = new Image()
img.onload = ()=> {
console.log("loaded:", img.src)
this.loaded()
}
img.onerror = (event)=> {
console.warn("error loading:", img.src)
this.loaded()
}
img.src = url
return img
}
loaded() {
this.loading -= 1
assert(this.loading >= 0)
if (this.loading === 0) {
console.log("all assets loaded")
if (this.scene) this.scene.ready()
}
}
}
/// create a new scene, give it a canvas, and insert it in the dom
function createScene(width, height, parent) {
if (typeof(parent) === "string") parent = document.getElementById(parent)
parent = parent || document.body
var c = document.createElement("canvas")
c.setAttribute("style", "-webkit-user-select:none;-khtml-user-select:none;-moz-user-select:-moz-none;-o-user-select:none;user-select:none;")
parent.appendChild(c)
var g = c.getContext("2d")
return new GScene(g, c, width || 400, height || 300)
}
function ensureMouseEvents(context, eventname, name) {
if (context[eventname]) return
context[eventname] = context.c[eventname] = (event)=> {
context.schedule()
var globalx = event.offsetX
var globaly = event.offsetY
var done = context.root.fireEvent(globalx, globaly, globalx, globaly, event, name)
if (done) event.preventDefault()
}
}
var _followtouch = {}
var _multitouch = ('ontouchstart' in window) || window.DocumentTouch && document instanceof DocumentTouch
function ensureTouchEvents(context, eventname, name) {
if (!_multitouch) return
if (context[eventname]) return
context[eventname] = context.c[eventname] = (event)=> {
context.schedule()
for (var i = 0; i < event.changedTouches.length; i++) {
var touch = event.changedTouches[i]
var globalx = touch.pageX - touch.target.offsetLeft
var globaly = touch.pageY - touch.target.offsetTop
var follow = _followtouch[touch.identifier]
if (follow) {
event.preventDefault()
followTouch(follow, touch, globalx, globaly, name)
if (eventname === "ontouchend" || eventname === "ontouchcancel") delete _followtouch[touch.identifier]
assert(Object.keys(_followtouch).length < 10)
continue
}
var done = context.root.fireEvent(globalx, globaly, globalx, globaly, touch, name)
if (done) event.preventDefault()
}
}
}
// if a delegate has event handlers, make the layer interactive and ensure the handlers are set
function ensureInteractive(layer, delegate) {
layer.interactive = false
if (!delegate) return
// TODO perhaps get scene from layer? not possible at the moment
var context = _default_scene
if (!context) return
if (delegate["ondown"]) {
layer.interactive = true
ensureMouseEvents(context, "onmousedown", "ondown")
ensureTouchEvents(context, "ontouchstart", "ondown")
ensureTouchEvents(context, "ontouchend", "onup") // the rest is here for follow ...
ensureTouchEvents(context, "ontouchcancel", "onup")
ensureTouchEvents(context, "ontouchmove", "onmove")
}
if (delegate["onup"]) {
layer.interactive = true
ensureMouseEvents(context, "onmouseup", "onup")
ensureTouchEvents(context, "ontouchend", "onup")
ensureTouchEvents(context, "ontouchcancel", "onup")
}
if (delegate["onmove"]) {
layer.interactive = true
ensureMouseEvents(context, "onmousemove", "onmove")
ensureTouchEvents(context, "ontouchmove", "onmove")
ensureTouchEvents(context, "ontouchend", "onup")
ensureTouchEvents(context, "ontouchcancel", "onup")
}
}
/// a layer that can be rendered
/// set its `style` properties to render `{background:"red"}`
/// give it a `delegate` that has methods to `draw(g)` or receive events (`ondown`, `onup`, `onmove`)
/// if the `delegate` is a function, it is assumed to be the draw function
class Layer {
constructor(style, delegate) {
style = style || {}
delegate = delegate || style.delegate || null /// delegate
this.x = style.x || 0 /// x coordinate
this.y = style.y || 0 /// y coordinate
this.z = style.z || 0 /// z index, the highest z-index is drawn last
this.width = style.width || 0 /// width of layer
this.height = style.height || 0 /// height of layer
this.rotate = style.rotate || 0 /// rotation of layer, only used for rendering, events ignore rotation
this.style = style /// style of this object, can be used to set `background` color and such
this.delegate = null /// delegate, to `draw(g)` or handle events
// private
this.parent = null
this.interactive = false
this.setDelegate(delegate)
if (style.parent) style.parent.add(this)
}
setDelegate(delegate) {
this.delegate = delegate
ensureInteractive(this, delegate)
}
/// remove this layer from the scene, can re-add afterwards
remove() {
if (!this.parent) return
this.parent.removeChild(this)
assert(!this.parent)
}
toGlobalXY(x, y) {
if (!this.parent) return {x:this.x + x, y:this.y + y}
return this.parent.toGlobalXY(this.x + x, this.y + y)
}
toGlobal() {
if (!this.parent) return {x:this.x, y:this.y}
return this.parent.toGlobalXY(this.x, this.y)
}
/// from a point or event, return an object with relative coords
toLocal(point) {
if (point instanceof GEvent) {
var p = point.toGlobal()
var l = this.toGlobal()
p.x -= l.x
p.y -= l.y
return p
}
l = this.toGlobal()
l.x = point.x - l.x
l.y = point.y - l.y
return l
}
/// from a point or event, return if the point is in this layer
contains(point) {
var l = this.toLocal(point)
return l.x >= 0 && l.x <= this.width && l.y >= 0 && l.y <= this.height
}
/// return true if {x,y} in local coords are in this layer
containsLocalXY(x, y) {
return x >= 0 && x <= this.width && y >= 0 && y <= this.height
}
/// return true if {x,y} as global coords are in this layer
containsXY(x, y) {
return this.contains({x,y})
}
// private
drawBackground(g) {
if (this.style.background || this.style.border) {
if (this.style.borderRadius) {
roundedRect(g, 0, 0, this.width, this.height, this.style.borderRadius)
} else {
g.beginPath()
g.rect(0, 0, this.width, this.height)
}
if (this.style.background) {
g.fillStyle = this.style.background
g.fill()
}
if (this.style.border) {
g.strokeStyle = this.style.border
g.lineWidth = this.style.borderWidth || 1
g.stroke()
}
}
if (this.style.backgroundImage && imageCheck(this.style.backgroundImage)) {
g.drawImage(this.style.backgroundImage, 0, 0, this.width, this.height)
}
}
drawDelegate(g, scene) {
if (this.delegate) {
if (typeof(this.delegate) === "function") {
g.beginPath()
return this.delegate(g, this, scene)
}
if (this.delegate.draw) {
g.beginPath()
return this.delegate.draw(g, this, scene)
}
}
}
draw(g, scene) {
this.drawBackground(g)
this.drawDelegate(g, scene)
}
fireEvent(x, y, globalx, globaly, event, name) {
if (!this.interactive || !this.containsLocalXY(x, y)) return false
return runEvent(this, x, y, globalx, globaly, event, name)
}
layout() {
if (this.delegate && this.delegate.layout) this.delegate.layout(this)
}
minHeight() {
return this.style.minHeight || this.height
}
minWidth() {
return this.style.minWidth || this.width
}
}
function zsortfn(left, right) { return left.z - right.z }
function zsort(ls) {
var il = ls.length
if (il === 0) return ls
var z = ls[0]
var sort = false
for (var i = 1; i < il; i++) {
if (ls[i].z !== z) { sort = true; break }
}
if (!sort) return ls
return ls.slice().stablesort(zsortfn)
}
/// a container for layers, is a layer itself
class Box extends Layer {
constructor(delegate, width, height) {
super(delegate, width, height)
this.children = []
}
/// add layers, may also pass in objects that have a `layer` property
add() {
for (var i = 0, il = arguments.length; i < il; i++) {
var object = arguments[i]
var layer = (object instanceof Layer)? object : object.layer
assert(layer instanceof Layer)
assert(!layer.parent)
layer.parent = this
this.children.push(layer)
if (object !== layer && !layer.delegate) layer.setDelegate(object)
}
}
/// remove a layer, may also pass in object that has a `layer` property
removeChild(child) {
var layer = (child instanceof Layer)? child : child.layer
assert(layer.parent === this)
assert(this.children.indexOf(layer) >= 0)
layer.parent = null
this.children.remove(layer)
assert(this.children.indexOf(layer) < 0)
}
// private
draw(g, scene) {
super.draw(g, scene)
var cs = zsort(this.children)
for (var i = 0, il = cs.length; i < il; i++) {
var layer = cs[i]
assert(layer instanceof Layer)
assert(layer.parent === this)
scene.draw(layer)
}
}
fireEvent(x, y, globalx, globaly, event, name) {
// TODO should take zindex sorting into account
for (var i = 0, il = this.children.length; i < il; i++) {
var layer = this.children[il - 1 - i]
assert(layer instanceof Layer)
assert(layer.parent === this)
var done = layer.fireEvent(x - layer.x, y - layer.y, globalx, globaly, event, name)
if (done) return done
}
if (!this.interactive || !this.containsLocalXY(x, y)) return false
return runEvent(this, x, y, globalx, globaly, event, name)
}
layout() {
var cs = this.children
for (var i = 0, il = cs.length; i < il; i++) {
var layer = cs[i]
layer.layout()
}
}
}
class Column extends Box {
layout() {
if (this.delegate && this.delegate.layout) this.delegate.layout(this)
var padding = (this.style.padding || 0)
var gutter = (this.style.gutter || 0)
var grow = 0
var height = padding * 2
var cs = this.children
for (var i = 0, il = cs.length; i < il; i++) {
var layer = cs[i]
layer.layout()
if (layer.style.position === "absolute") continue
height += layer.minHeight()
grow += Math.max(0, (layer.style.grow || 0))
}
height += gutter * Math.max(0, cs.length - 1)
var y = padding
var leftover = this.height - height
if (grow === 0) {
switch (this.style.justifyContent) {
case "start": break
case "end": y += leftover; break
default: y += leftover / 2
}
} else {
grow = leftover / grow
}
var palign = (this.style.alignItems || "stretch")
for (var i = 0, il = cs.length; i < il; i++) {
var layer = cs[i]
if (layer.style.position === "absolute") continue
var align = layer.style.alignSelf || palign
switch (align) {
case "start": layer.x = 0; break
case "center": layer.x = this.width/2 / layer.width/2; break
case "end": layer.x = this.width - layer.width; break
default: layer.x = 0; layer.width = this.width
}
layer.y = Math.floor(y)
if (grow && layer.style.grow) {
layer.height = Math.floor(layer.minHeight() + layer.style.grow * grow)
}
y += layer.height + gutter
}
}
}
class Row extends Box {
layout() {
if (this.delegate && this.delegate.layout) this.delegate.layout(this)
var padding = (this.style.padding || 0)
var gutter = (this.style.gutter || 0)
var grow = 0
var width = padding * 2
var cs = this.children
for (var i = 0, il = cs.length; i < il; i++) {
var layer = cs[i]
layer.layout()
if (layer.style.position === "absolute") continue
width += layer.minWidth()
grow += Math.max(0, (layer.style.grow || 0))
}
width += gutter * Math.max(0, cs.length - 1)
var x = padding
var leftover = this.width - width
if (grow === 0) {
switch (this.style.justifyContent) {
case "start": break
case "end": x += leftover; break
default: x += leftover / 2
}
} else {
grow = leftover / grow
}
var palign = (this.style.alignItems || "stretch")
for (var i = 0, il = cs.length; i < il; i++) {
var layer = cs[i]
if (layer.style.position === "absolute") continue
var align = layer.style.alignSelf || palign
switch (align) {
case "start": layer.y = 0; break
case "center": layer.y = this.height/2 / layer.height/2; break
case "end": layer.y = this.height - layer.height; break
default: layer.y = 0; layer.height = this.height
}
layer.x = Math.floor(x)
if (grow && layer.style.grow) {
layer.width = Math.floor(layer.minWidth() + layer.style.grow * grow)
}
x += layer.width + gutter
}
}
}
function col() {
var box = new Column()
for (var i = 0, il = arguments.length; i < il; i++) {
var child = arguments[i]
if (child) box.add(child)
}
return box
}
function row() {
var box = new Row()
for (var i = 0, il = arguments.length; i < il; i++) {
var child = arguments[i]
if (child) box.add(child)
}
return box
}
class TextLayer extends Layer {
constructor(text, style, delegate) {
super(style, delegate)
this.text = text
this._text = null
}
draw(g) {
this.drawBackground(g)
this.setFont(g)
this.layout()
var x = 0
var y = this.height * 0.76
switch (this.style.align) {
case "left": x = 0; break
case "right": x = this.width - this.width; break
default: x = this.width/2 - this.width / 2
}
if (this.style.shadowColor) {
g.fillStyle = this.style.shadowColor
g.fillText(this._text, x - 1, y - 1)
}
g.fillStyle = this.style.color || "black"
g.fillText(this._text, x, y)
this.drawDelegate(g)
}
setFont(g) {
if (g.font === this._font) return
this._font = this.style.font || "24px Arial"
g.font = this._font
}
layout() {
if (this._text === this.text) return
this._text = this.text
var g = _default_scene.g
this.setFont(g)
this.width = g.measureText(this.text).width
this.height = 2 + g.measureText("W").width // no way to get font metrics, so approx
}
minWidth() {
return this.width
}
minHeight() {
return this.height
}
}