I'm planning to write a diagram editor-style application, where you organize objects on a canvas. This application will need to support setting viewport, zooming, cropping and a lot of other standard features of such a graph style application. I'm looking for toolkits or frameworks which could supports drawing in a standard mathematical coordinate space (0,0 as center point, extendable in all directions), and will scale, crop and zoom this according to (user) commands. Language doesn't really matter, but the more geared it is towards standard GUI applications the better. I would namely like to be able to reuse standard controls and buttons on the canvas if possible.
I think Qt is your friend here. Offers what you need, is multiplatform, quite well-designed and there are bindings for several languages.
From my experience, anything mid-level like C++ with toolboxes - QT, GTK, Windows API etc is horrible for such a work. Not that they can't do it, just that there's 15 lines of obscure code per each simple operation - they are simply not very efficient and more geared towards creating fixed GUI than arbitrary graphics.
This sounds like a good work for Flash, optionally something on top of SVG, maybe even a web app in Javascript.
Related
I have a grid based coordinate system where the distance between each grid center is a set number of pixels. Doing this in OpenGL I made a camera using view/projection matrices. Changing view center and scale for the whole scene could be made by setting matrix elements.
This is from a prototype using OpenGL that I made before going full Tcl/Tk. The node positions are {[1..5], [1..3]} (text at fractional y-offset):
How would I accomplish this in Tcl/Tk? I'm reading about canvas zooming however was hoping for a smaller example; create line between 1..2, 3..4, pan, zoom, pan again, zoom again.
The Tk canvas widget supports panning (it's following the Tk scrollable window protocol) but doesn't allow zooming of the viewport. (It has a scale method, but that just changes the coordinates of the objects, which is not the same thing; in particular, it doesn't change things like font sizes, embedded window/image sizes, line thicknesses, etc.) You can control the panning via the xview and yview methods, as with any scrollable Tk widget.
However, there's an alternative that might be more suitable for you.
Paul Obermeier's Tcl3D, which allows you to use OpenGL together with Tcl/Tk, would let you keep a lot of what you've done so far with writing OpenGL code, and yet it still provides the benefits of being able to use Tcl/Tk. Basically, the core of it is that it includes Togl, a package for presenting an OpenGL drawing surface as a Tk widget, together with bindings to the OpenGL API. I know of quite a few people who use Tcl3D to power their (both commercial and open-source) applications, and you'd end up with a hybrid that should provide the best of both worlds. (Also, it's considered entirely reasonable to include some custom C code in a Tcl application that needs a bit more performance in a critical spot; it's outright good style to do this. Complex GUIs sometimes need that sort of thing.)
I am trying to choose the right technology to use for updating a project that basically renders thousands of points in a zoomable, pannable graph. The current implementation, using Protovis, is underperformant. Check it out here:
http://www.planethunters.org/classify
There are about 2000 points when fully zoomed out. Try using the handles on the bottom to zoom in a bit, and drag it to pan around. You will see that it is quite choppy and your CPU usage probably goes up to 100% on one core unless you have a really fast computer. Each change to the focus area calls a redraw to protovis which is pretty darn slow and is worse with more points drawn.
I would like to make some updates to the interface as well as change the underlying visualization technology to be more responsive with animation and interaction. From the following article, it seems like the choice is between another SVG-based library, or a canvas-based one:
http://www.sitepoint.com/how-to-choose-between-canvas-and-svg/
d3.js, which grew out of Protovis, is SVG-based and is supposed to be better at rendering animations. However, I'm dubious as to how much better and what its performance ceiling is. For that reason, I'm also considering a more complete overhaul using a canvas-based library like KineticJS. However, before I get too far into using one approach or another, I'd like to hear from someone who has done a similar web application with this much data and get their opinion.
The most important thing is performance, with a secondary focus on ease of adding other interaction features and programming the animation. There will probably be no more than 2000 points at once, with those small error bars on each one. Zooming in, out, and panning around need to be smooth. If the most recent SVG libraries are decent at this, then perhaps the ease of using d3 will outweigh the increased setup for KineticJS, etc. But if there is a huge performance advantage to using a canvas, especially for people with slower computers, then I would definitely prefer to go that way.
Example of app made by the NYTimes that uses SVG, but still animates acceptably smoothly:
http://www.nytimes.com/interactive/2012/05/17/business/dealbook/how-the-facebook-offering-compares.html . If I can get that performance and not have to write my own canvas drawing code, I would probably go for SVG.
I noticed that some users have used a hybrid of d3.js manipulation combined with canvas rendering. However, I can't find much documentation about this online or get in contact with the OP of that post. If anyone has any experience doing this kind of DOM-to-Canvas (demo, code) implementation, I would like to hear from you as well. It seems to be a good hybrid of being able to manipulate data and having custom control over how to render it (and therefore performance), but I'm wondering if having to load everything into the DOM is still going to slow things down.
I know that there are some existing questions that are similar to this one, but none of them exactly ask the same thing. Thanks for your help.
Follow-up: the implementation I ended up using is at https://github.com/zooniverse/LightCurves
Fortunately, drawing 2000 circles is a pretty easy example to test. So here are four possible implementations, two each of Canvas and SVG:
Canvas geometric zooming
Canvas semantic zooming
SVG geometric zooming
SVG semantic zooming
These examples use D3's zoom behavior to implement zooming and panning. Aside from whether the circles are rendered in Canvas or SVG, the other major distinction is whether you use geometric or semantic zooming.
Geometric zooming means you apply a single transform to the entire viewport: when you zoom in, circles become bigger. Semantic zooming in contrast means you apply transforms to each circle individually: when you zoom in, the circles remain the same size but they spread out. Planethunters.org currently uses semantic zooming, but it might be useful to consider other cases.
Geometric zooming simplifies the implementation: you apply a translate and scale once, and then all the circles are re-rendered. The SVG implementation is particularly simple, updating a single "transform" attribute. The performance of both geometric zooming examples feels more than adequate. For semantic zooming, you'll notice that D3 is significantly faster than Protovis. This is because it's doing a lot less work for each zoom event. (The Protovis version has to recalculate all attributes on all elements.) The Canvas-based semantic zooming is a bit more zippy than SVG, but SVG semantic zooming still feels responsive.
Yet there is no magic bullet for performance, and these four possible approaches don't begin to cover the full space of possibilities. For example, you could combine geometric and semantic zooming, using the geometric approach for panning (updating the "transform" attribute) and only redrawing individual circles while zooming. You could probably even combine one or more of these techniques with CSS3 transforms to add some hardware acceleration (as in the hierarchical edge bundling example), although that can be tricky to implement and may introduce visual artifacts.
Still, my personal preference is to keep as much in SVG as possible, and use Canvas only for the "inner loop" when rendering is the bottleneck. SVG has so many conveniences for development—such as CSS, data-joins and the element inspector—that it is often premature optimization to start with Canvas. Combining Canvas with SVG, as in the Facebook IPO visualization you linked, is a flexible way to retain most of these conveniences while still eking out the best performance. I also used this technique in Cubism.js, where the special case of time-series visualization lends itself well to bitmap caching.
As these examples show, you can use D3 with Canvas, even though parts of D3 are SVG-specific. See also this force-directed graph and this collision detection example.
I think that in your case the decision between canvas and svg is not like a decision between »riding a Horse« or driving a »Porsche«. For me it is more like the decision about the cars color.
Let me explain:
Assuming that, based on the framework the operations
draw a star,
add a star and
remove a star
take linear time. So, if your decision of the framework was good it is a bit faster, otherwise a bit slower.
If you go on assuming that the framework is just fast, than it becomes totally obvious that the lack of performance is caused be the high amount of stars and handling them is something none of the frameworks can do for you, at least I do not know about this.
What I want to say is that the base of the problem leads to a basic problem of computational geometry, namely: range searching and another one of computer graphics: level of detail.
To solve your performance problem you need to implement a good preprocessor which is able to find very fast which stars to display and is perhaps able to cluster stars which are close together, depending on the zoom. The only thing that keeps your view vivid and fast is keeping the number of stars to draw as low possible.
As you stated, that the most important thing is performance, than I would tend to use canvas, because it works without DOM operations. It also offers the opportunity to use webGL, what increases graphic performance a lot.
BTW: did you check paper.js? It uses canvas, but emulates vector graphics.
PS: In this Book you can find a very detailed discussion about graphics on the web, the technologies, pros and cons of canvas, SVG and DHTML.
I recently worked on a near-realtime dashboard (refresh every 5 seconds) and chose to use charts that render using canvas.
We tried Highcharts(SVG based JavaScript Charting library) and CanvasJS(Canvas based JavaScript Charting library). Although Highcharts is a fantastic charting API and offers way more features we decided to use CanvasJS.
We needed to display at least 15 minutes of data per chart (with option to pick range of max two hours).
So for 15 minutes: 900 points(data point per second) x2(line and bar combination chart) x4 charts = 7200 points total.
Using chrome profiler, with CanvasJS the memory never went above 30MB while with Highcharts memory usage exceeded 600MB.
Also with refresh time of 5 seconds CanvasJS rendering was allot more responsive then Highcharts.
We used one timer (setInterval 5 seconds) to make 4 REST API calls to pull the data from back end server which connected to Elasticsearch. Each chart updated as data is received by JQuery.post().
That said for offline reports I would go with Highcharts since its more flexible API.
There's also Zing charts which claims to use either SVG or Canvas but haven't looked at them.
Canvas should be considered when performance is really critical. SVG for flexibility. Not that canvas frameworks aren't flexible, but it takes allot more work for canvas framework to get the same functionality as an svg framework.
Might also look into Meteor Charts, which is built on top of the uber fast KineticJS framework: http://meteorcharts.com/
I also found when we print to PDF a page with SVG graphics, the resulting PDF still contains a vector-based image, while if you print a page with Canvas graphics, the image in the resulting PDF file is rasterized.
paper.js
EaselJS
fabric.js
KineticJS
Hello guys I am new in html5 canvas development and I am lost in choosing canvas frameworks. There are so many of them that I can't find out what to use. So here I am! I want your help to choose which one is better for my needs. There are my needs
1) I want the framework used Vector graphics, I know canvas is not DOM, I realy don't care about it but what I mean is I want to manipulate with objects after its creation, PaperJS has this feature I don't know about others. If advanced mouse events will be available it would be better.
2) I want to use the framework for images, I will load image and animate them with canvas, move, animate some colors...
3) I want the framework to be fast because of my needs (image animation should be smooth)
4) I want the framework to have good community because I know I will need some help.
So what do you think which one is better for me? and please if you can write down from my list which are the strength and weakness for each framework?
HTML5 canvas is still very fresh environment. You can get impression there is a lot of tools already available, they are often quite immature though.
My answer will cover only part of your question because I used only KineticJS and EaselJS.
You can start from reading opinions at this page (mine is the last one at the bottom).
Speaking shortly KineticJS has lower entry barrier. It's simple drawing library and has some support for mouse events too. At the time I was trying to use it it was barely extendable. I found it really hard to customize for my needs.
EaselJS is a bit harder to start with, but it's more advanced too. Now it's part of other libs set known all together as CreateJS. It seems that lot of development going around there.
Both Kinetic and Easel supports mouse event. I don't remember
well the Kinetic, sensing 'onMouseOver' is costy with Easel though.
Also both mentioned libs allows objects manipulation. You can find
here TweenJS also useful as addition.
Again both Kinetic and Easel allows this. Easel also has support for
sprites - 'animated images' well known for web game developers.
I'm not sure about Kinetic as I haven't reached animation part of my
project before I dropped it (the lib, not the project). With Easel
speed is tricky. It has some optimization methods implemented like
for example objects cache or snapToPixel flag. Examples seems to run
really well. However for my project using Easel smoothness still is
an issue despite quite a lot of effort put in optimization. Maybe I
misused the API or there is still place for more optimalization I
haven't noticed.
Both libs are quite young but seems to be actively developed.
Authors are rather responsive. Community still isn't big, but I
guess CreateJS as more complete set of tools for creating games will
grow faster.
If you want to check here is the project I mentioned. It's a web page made with usage of EaselJS + TweenJS. Still needs some minor tweaking though.
I'm building a business application which mostly involves tables and other typical form elements. Due to the nature of my application however, I need to place groups of these elements together in a dynamic tree structure which will take up all of the available screen real estate. If real estate is low, there will be some form of smart scrolling allowing users to focus on certain areas of the tree. It could be called an advanced data visualization web form.
Historically, I would have accomplished this by simply using divs and javascript. The canvas element however seems like a more logical way to build my structure. Most uses of the canvas element that I can find are however geared towards graphics and animations (mostly games). Is canvas overkill for this? Will I benefit from using it? Are there alternatives?
Yes, canvas is overkill. It is very much a drawing board and not much more. It is certainly not something that I would expect to create user controls in. Games etc. are more suited as they aren't really standard user controls and wouldn't be expected to behave as such.
A tree structure could easily be implemented with a series of nested uls. Using some JavaScript to expand collapse them by adding and removing classes.
Here is a nice jQuery plugin for you to use or get some ideas of how you could use it.
Edit:
I would stay away from canvas just because of the overhead of the drawing. If you can extend a standard JavaScript treeview to add more functionality this would seem like the best option ot me. Creating controls from scratch in canvas is no small feat.
Edit2 (Post mockup):
This just looks like a multi-part form to me, with hidden forms/areas which are displayed as apropriately. This is far too common to require creating this with canvas.
Canvas is not fully supported in all browsers yet. I recommend using either Jquery or another framework.
I'm trying to make some web-based board games, and I want the interface to be pannable and zoomable. Much like how in Google Maps, you can pan and zoom the map, I want the game board to be moved and zoomed. Unlike Google Maps of course, I do not want to work with image tiles.
Can anyone give me recommendations as to what technology to use? Would this be a good fit for plain HTML? HTML 5 Canvas? or SVG? Any particular JS libraries to recommend or something else entirely?
I'd like to avoid flash and Java. And browser compatibility is plus, but not the most important factor. For example, I think it would probably be OK to require Chrome Frame for older IEs.
Any ideas/advice would be appreciated.
A few thoughts:
Use the OpenLayers UI with a "fixed" strategy to load vector graphics for your board all at once. (This is overly heavy-weight, probably, but comes with pan-zoom and IE compatibility.)
Use Raphael to build your board in SVG, using RaphaelZPD for pan-zoom. RaphaelZPD isn't cross-browser (even though Raphael is), so you'd need Chrome Frame for IE compatibility. This would be pretty lightweight, I think.
Use pure SVG for your board, use SVGpan for pan-zoom. Chrome Frame required here too, though you could use SVGweb if you wanted. You could draw your boards right in Inkscape, clean up the SVG's and add whatever ID's you need in the XML (SVG is XML under the hood), and interact with the board with jQuerySVG if you like, or script interaction by hand. Did I mention that CSS works with SVG? I think this is your best bet.
I can't think of an advantage to using Canvas here, unless you had lots of animation or bitmaps. SVG is far more transparent in how it works - it's XML under the hood, and when rendered in a page, becomes DOM nodes you can easily manipulate in modern browsers.
Plain HTML would probably be hard to handle scaling with. I've seen plenty of image scalers, but haven't seen complex HTML structures, and complexity would be compounded by needing to pan at a zoomed level.
If you want total control of your development environment you could create your own web rendering plataform. I think you can use HTML canvas 5 as your interface with the browser.
You can easily implement drag, pan and zoom using HTML canvas. This approach is very similar with game development in many plataforms. Here an example of using HTML canvas 5 for an interface that supports pan, drag, and zoom.
Having the control of your environment you will have a wide range of possibilities.
If you don't mind tiles, I'd suggest checking out Polymaps "A JavaScript library for image- and vector-tiled maps using SVG". It's probably possible to borrow some parts from there for panning and zooming.