Famo.us - How to add content to a CanvasSurface - famo.us

I've just moved to Famo.us and think it has some amazing potential. I am trying to build a new App using Famo.us and will be having 'layered' Views, one of which has a CanvasSurface inside.
My question is about how I would populate the CanvasSurface? I have checked the Docs and while they talk about some of the parameter options they do not tell you how.
I have a View within which I add a Layout and then a Surface to that Layout. Other Views that have ImageSurfaces work fine - but I do not know if I am on the right track with CanvasSurface.
So far I have: (part of inside a BackgroundView.js file)
function BackgroundView() {
View.apply(this, arguments);
_createLayout.call(this);
_createBody.call(this);
_setListeners.call(this);
}
function _createBody() {
this.bodySurface = new CanvasSurface({
canvasSize : [undefined, undefined]
});
var bodyContext= this.bodySurface.getContext('2d');
bodyContext.fillText("Text on Canvas", 100, 100);
this.layout.content.add(this.bodySurface);
}
It runs with no errors, but shows nothing. The CanvasSurface is rendered...
Are there any examples using CanvasSurface or does anyone have any thoughts?
Thanks again for your help in advance.
:)

There are a couple of things I added to your code.. Defining the prototype and prototype.constructor, as well as adding the CanvasSurface to the BackgroundView. I found that canvasSize does not currently support the undefined size attribute like Surface does. You need to be explicit and use pixel size.
Check out what I did to your code.. Hope this helps..
var Engine = require('famous/core/Engine');
var Surface = require('famous/core/Surface');
var View = require('famous/core/View');
var CanvasSurface = require('famous/surfaces/CanvasSurface');
var context = Engine.createContext();
function BackgroundView() {
View.apply(this, arguments);
// _createLayout.call(this);
_createBody.call(this);
// _setListeners.call(this);
}
BackgroundView.prototype = Object.create(View.prototype);
BackgroundView.prototype.constructor = BackgroundView;
function _createBody() {
this.bodySurface = new CanvasSurface({
size:[400,200]
});
var bodyContext= this.bodySurface.getContext('2d');
bodyContext.font="20px Georgia";
bodyContext.fillText("Hello World!",50,50);
this.add(this.bodySurface);
}
var bg = new BackgroundView();
context.add(bg);

Related

Scrollview Pull to Refresh Famo.us

I'm trying to implement a pull to reload/refresh type effect, that you see in lots of apps, with scrollview. I've got multiple pain points on this.
Just stopping a scrollview past where it wants to sit is a pain. Setting velocity or speed limit doesn't work, just setting the position just makes it bounce because it wants to continue back.
Then setting up an event call that doesn't just fire when they scroll too hard up while doing their normal browsing.
If anyone has thoughts on how to accomplish this I'd appreciate it. If I don't get any responses in a day I'll start posting my specific attempts and where they fell short. I can't believe I'm the only one trying to implement this pretty common feature.
You could use the FlexScrollView which supports this feature out of the box (it is nearly impossible to do it right with the stock famo.us scrollview..):
var FlexScrollView = require('famous-flex/FlexScrollView');
var RefreshLoader = require('famous-refresh-loader/RefreshLoader');
var scrollView = new FlexScrollView({
autoPipeEvents: true,
pullToRefreshHeader: new RefreshLoader({
size: [undefined, 60],
pullToRefresh: true,
color: 'green',
backgroundColor: 'white',
particleCount: 8,
particleSize: 7
})
});
Demo: https://rawgit.com/IjzerenHein/famous-flex-chat/master/dist/index.html
Repo: https://github.com/IjzerenHein/famous-flex
RefreshLoader: https://github.com/IjzerenHein/famous-refresh-loader
Tutorial: https://github.com/IjzerenHein/famous-flex/blob/master/tutorials/FlexScrollView.md
I finally have a solution for you. It relies only on start, and end events of the scrollview sync. To start you will see the scrollview.reset function. This function is taken for scrollviews internals to return _scroller to its default behavior.
We will use a transitionable and scrollview._scroller.positionFrom to control the behavior of the scrollview when it should not be default. Essentially everything is normalized on scrollview.sync.on 'start' and the update is carried out on scrollview.sync.on 'end' if the position of the scrollview has reached the refresh offset.
Much of the functionality is tied to the fact that I am using a timeout to simulate the load time of the refresh. It may be more appropriate to have a variable that is keeping track of whether a request is still being made.
Anyway, I hope this gives you some ideas.. Here is the full example.
var Engine = require('famous/core/Engine');
var Surface = require('famous/core/Surface');
var Transform = require('famous/core/Transform');
var Scrollview = require('famous/views/Scrollview');
var Transitionable = require('famous/transitions/Transitionable');
var SnapTransition = require('famous/transitions/SnapTransition');
Transitionable.registerMethod('snap',SnapTransition);
var snap = { method:'snap', period:200, dampingRatio:0.4 }
var context = Engine.createContext();
var scrollview = new Scrollview();
var surfaces = [];
scrollview.sequenceFrom(surfaces);
for (var i = 0; i < 20; i++) {
var surface = new Surface({
size: [undefined, 200],
properties: {
backgroundColor: "hsl(" + (i * 360 / 20) + ", 100%, 50%)",
}
});
surface.pipe(scrollview);
surfaces.push(surface);
}
scrollview.trans = new Transitionable(0);
// Timeout that will simulate loading time
scrollview.timer = null;
// Total simulated load time
scrollview.timeout = 500;
// Vertical offset scrollview will start load at
scrollview.refreshOffset = 100;
// Reset scroller to default behavior
scrollview.reset = function(){
scrollview._scroller.positionFrom(scrollview.getPosition.bind(scrollview));
}
scrollview.sync.on('start',function(){
clearTimeout(scrollview.timer);
scrollview.trans.halt();
var pos = scrollview.trans.get()
if (pos != 0) scrollview.setPosition(pos);
scrollview.reset()
});
scrollview.sync.on('end',function(){
var pos = scrollview.getPosition();
if (pos < (-scrollview.refreshOffset)) {
scrollview.trans.halt();
scrollview.trans.set(pos);
scrollview._scroller.positionFrom(function(){
return scrollview.trans.get();
});
scrollview.trans.set(-scrollview.refreshOffset,snap,function(){
scrollview.timer = setTimeout(function(){
scrollview.trans.halt();
scrollview.trans.set(0,snap,function(){
scrollview.reset()
});
}, scrollview.timeout );
});
} else {
scrollview.trans.halt();
scrollview.trans.set(0);
}
});
context.add(scrollview);

How to reset an app in Famo.us?

If I create a context and add some layout and surfaces, but later want to restart the entire app is there a way to do this?
Is there a method on the Engine?
Basically I am asking if there is something that is the opposite of Engine.createContext ?
You can use a RenderController to add/remove content from the render-tree:
// import dependencies
var Engine = require('famous/core/Engine');
var RenderNode = require('famous/core/RenderNode');
var RenderController = require('famous/views/RenderController');
// create context & render-controller
var context = Engine.createContext();
var renderController = new RenderController();
context.add(renderController);
function restart() {
// create content you want to show
var content = new AppView();
// Show content
var renderNode = new RenderNode(content);
renderController.show(renderNode, {duration: 0});
}
restart();

code like Lightbox example

I'm searching for an code example of the Lightbox demo from famo.us. Unfortunately, the interesting part of the app in the codepen is uglified in the pens version of the famous.lib.js.
It's not the whole gallery thing I'm interested in, its "just" a scollable view with multiple elements in one row, depending on their size and the screen size.
Has anyone experiences in developing a View/Layout like this?
Thanks in advance
I have been doing some work with Scrollview and GridLayout. You can calculate grid dimensions based on contextSize and target/min cell size.
Here is an example to get you started. I am essentially adding a gridLayout as the sole view in Scrollview. I know this may work against scrollviews efficient rendering in that scrollview will always be rendering the entire grid, but I am doing it for the examples sake. I use Modifier around the gridLayout to ensure the size of the view is always calculated and scrollview always scrolls the right amount. So anyway, here is what I did..
var Engine = require('famous/core/Engine');
var Surface = require('famous/core/Surface');
var RenderNode = require('famous/core/RenderNode');
var Modifier = require('famous/core/Modifier'); // edited
var Scrollview = require('famous/views/Scrollview');
var GridLayout = require('famous/views/GridLayout');
var context = Engine.createContext();
var scrollViews = [];
var scrollview = new Scrollview();
scrollview.sequenceFrom(scrollViews);
var gridCells = [];
var grid = new GridLayout();
grid.sequenceFrom(gridCells);
grid.mod = new Modifier();
var cellCount = 24;
var cellMinWidth = 200.0;
grid.mod.sizeFrom(function(){
var size = context.getSize();
var cellsX = Math.floor(size[0] / cellMinWidth);
var cellsY = Math.ceil(cellCount * 1.0 / cellsX);
var cellHeight = size[0] * 1.0 / cellsX;
grid.setOptions({dimensions:[cellsX,cellsY]});
return [undefined,cellsY*cellHeight];
});
grid.node = new RenderNode();
grid.node.add(grid.mod).add(grid);
for (var i = 0; i < cellCount; i++) {
var surface = new Surface({
size:[undefined,undefined],
properties: {
backgroundColor:'hsl('+(i*360/12)+',75%,50%)'
}
});
gridCells.push(surface);
surface.pipe(scrollview);
};
scrollViews.push(grid.node);
context.add(scrollview);
FWIW To really maximize the efficiency of scrollview, you need to have a list of views that are rendered sequentially. Since we are only rendering one view in scrollview, we are always rendering everything, all the time. I have thought of a couple ways to get around this though, that both extend beyond the scope is this example.
You could do the visibility check yourself and render nodes based on the position of the scrollview.
You could create a gridLayout for each row, then manage the cells within each grid using list manipulation techniques.
BONUS:
If you just want to use GridLayout just for the modifiers, I found using _modifiers property rather helpful (Note: only available after deploy!). I was able to create a rearrangeable layout using this technique. The surfaces are all floating outside the gridlayout and only being positioned via their draggable modifier based on the gridlayouts modifiers. Here is that working demo of that..
http://higherorderhuman.com/examples/rearrangeable.html
Hope this helps!

How to build an endless animation with famo.us?

I'm willing to build an endless animation using famous (for example an endless rolling gear or a randomly shaken surface). Should I write a custom Transitionable with an infinite duration or there is something smarter to achieve this ?
I would recommend using Modifiers transformFrom method to define a position or rotation based on time. This allows you to set a transform that will be updated on every tick of the engine, but will be controlled via actual time.
Here is an example of that..
Hope it helps!
var Engine = require('famous/core/Engine');
var Surface = require('famous/core/Surface');
var Transform = require('famous/core/Transform');
var Modifier = require('famous/core/Modifier');
var context = Engine.createContext();
var surface = new Surface({
size:[200,200],
content: "Hello",
properties: {
lineHeight:"200px",
color:"white",
textAlign:"center",
backgroundColor:'green'
}
})
surface.mod = new Modifier({
origin: [0.5,0.5],
align:[0.5,0.5]
});
var startTime = (new Date).getTime();
surface.mod.transformFrom(function(){
var currentTime = (new Date).getTime();
var rotation = (currentTime - startTime) / 360.0;
return Transform.rotate(0,0,rotation);
});
context.add(surface.mod).add(surface);
The answer is to use Transitionables
First you use use Transitionable.set(destination, {duration: VALUE})
Each Engine 'prerender' (every frame), you use Transitionable.get() to update a Modifier Transform
At the end of the Transitionable, it will run a callback to update the new destination
this.transit = new Transitionable(0);
// ------- when i say twerk, you twerk ----->
var _createWheelMod = function() {
var _setWheelModRotation = function() {
Engine.on("prerender", function() {
this.wheelMod.setTransform(Transform.rotate(0, 0, this.transit.get()));
}.bind(this));
};
// ------------ charge lasers ------->
var _setDestination = function() {
this.transit.set(100 + this.transit.get(), {duration: 2e5},
_setDestination.bind(this)); // callback when the transition has finished
};
_setWheelModRotation.call(this);
_setDestination.call(this);
};

Get reference to paper via dom element

Is there a way to get the paper for an element by referencing the element?
I'm creating elements in a loop and with each element i'm creating a new Raphael(...). See sample below.
Basically I want to stop the animation on click, but paper is undefined and calling stop() on the element itself doesn't work either.
$.each(el,function(key,value)
{
var li = $("<li>",{id:"item"+key).appendTo("#myUl");
var ppr = new Raphael($("item"+key),get(0),48,48);
//... do stuff like animate ...
li.click(function()
{
console.log($(this).paper); //undefined
})
})
I was wondering about a closure like below to capture the paper, so when the anonymous func runs, it has the variable captured.
Note, I'm not sure this is the best method overall, something feels a bit clunky about creating a new paper each time, but just trying to address the specific issue.
Untested code, but if you can get it on a fiddle, I think it should be possible to sort.
$.each(el,function(key,value)
{
var li = $("<li>",{id:"item"+key).appendTo("#myUl");
var ppr = new Raphael($("item"+key),get(0),48,48);
(function() {
var myPaper = ppr;
li.click(function()
{
console.log(myPaper);
})
})();
})
You can also attach the paper to the element's "data" using https://api.jquery.com/data/
$.each(el,function(key,value)
{
var li = $("<li>",{id:"item"+key).appendTo("#myUl");
var ppr = new Raphael($("item"+key),get(0),48,48);
li.data("paper", ppr ); // SAVE
li.click(function()
{
console.log($(this).data("paper")); // LOAD
})
})