A Proposal to Add 2D Graphics Rendering and Display to C++ [pdf]

http://isocpp.org/files/papers/N3888.pdf

by adamnemecek • 13 years ago

28 53 13 years ago

isocpp.org

angersock• 13 years ago

It's not quite the Java 2D API, but damned it's close.

Why not just knock off a good API, like that for <canvas>?

adamnemecek5• 13 years ago

AFAIK, Cairo is said to be the bee's knees. As in, I've heard multiple people refer to it as a yardstick of good library design.

TheZenPsycho2• 13 years ago

It's covered in the linked document. To paraphrase:

1. It includes some extraneous things such as some CSS stuff. 2. There is some evidence that some of the canvas api may be covered by patents.

robin_reala2• 13 years ago

Regarding (1), the mention of CSS refers specifically to SVG, not canvas.

fyolnish• 13 years ago

Cairo & <canvas>'s drawing models are rather similar iirc.

ygra• 13 years ago

As are pretty much all immediate-mode 2D graphics APIs, except maybe OpenGL (when used as such).

thristian• 13 years ago

The <canvas> drawing model is a very thin layer over the Mac OS X Cocoa drawing model (because it was originally developed by Apple as a proprietary extension to Webkit). The Cocoa drawing model is based on the "Display PDF" model, which is a descendant of the "Display Postscript" system used by the original NeXT OS, which of course was derived from the PostScript page layout language.

I think Cairo just borrowed the PostScript drawing model from the start.

rwbt• 13 years ago

I'm not sure about Cairo, but IMHO AGG is probably one of the best C++ libraries out there. Great use of C++ capabilities like templates. Too bad, development isn't active anymore.

AGG - http://antigrain.com

adamnemecek5• 13 years ago

Oh shit, apparently the guy behind AGG, Maxim Shemanarev, died 2 months ago.

http://beta.slashdot.org/submission/3154635/rip-maxim-sheman...

shurcooL2• 13 years ago

Oh man, that is so unfortunate.

ezolotko• 13 years ago

Very sad.

yeureka• 13 years ago

What a sad loss...

AGG is amazing and I always thought Maxim was a little bit of a genius.

sigmaml• 13 years ago

I came across AGG very recently. Yes, several parts of the code are designed and implemented very well. Unfortunate that Maxim died.

Someone• 13 years ago

Earlier discussion: https://news.ycombinator.com/item?id=7012329

copx• 13 years ago

In the past the argument against putting things like this in the standard library was always that it is non-portable. C and C++ are meant to run on systems which do not even have a monitor, much less a GPU (think embedded). The logic was that standard library functions should work on all systems. That is also the reason why the "file system" API of ISO C/C++ is so severely limited. It is designed for the lowest common denominator. There are no functions for handling directories because of the assumption that some platforms do not even have directories. In fact the file system API does not even assume a hard disk but can be implemented by returning handles to RAM.

Now that this principle seems to be abandoned why not go all the way and give us a full GUI toolkit? That would be so much more versatile than just a 2D drawing API.

I do not see much use for this except maybe making ISO C++ tutorials more exciting because your programs can show something else than console output.

And I mean Cairo is not a simple framebuffer, it is quite complex so why not make another step and give us a full GUI?

I read that the C++ guys want a standard library comparable to those of modern languages like Java, C#, Python etc. and they all come with GUI support.

Oh, and before they even think about adding graphics they should beef up the file system API. That is an actual issue. Right now every piece of crossplatform C/C++ includes a wrapper around platform specific APIs just to handle something as basic as getting a list of all files in a directory. They want to give us vector graphics rendering before that?

adamnemecek5• 13 years ago

> Oh, and before they even think about adding graphics they should beef up the file system API.

It's being worked on. http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2012/n333... and I think that it should be part of C++14 or C++17 http://isocpp.org/std/status.

rat87• 13 years ago

Why not a full gui? I think I can give a simple reason. Desktop Gui libraries are large and complicated. Assuming you want a full featured cross-platform the choice would probably be qt. But Qt suffers from a lot of api version churn(much faster then c++ standards), includes language extensions(moc) and does a lot of things in a non standard way for c++(including using its own collections and strings). The alternative I can see would be to write a very minimal functionality cross-platfrom gui library or use something other library that might not as cross platform(lacking mobile platforms(recent initial qt support but likely to improve in the future), not as easy to port, not as good looking on some platforms)

pjmlp6• 13 years ago

If you check the working groups there are lots of APIs being worked on, including file system ones.

http://isocpp.org/std/the-committee

- SG1, Concurrency

- SG2, Modules

- SG3, File System

- SG4, Networking

- SG5, Transactional Memory

- SG6, Numerics

- SG7, Reflection

- SG8, Concepts

- SG9, Ranges

- SG10, Feature Test

- SG11, Databases

- SG12, Undefined and Unspecified Behavior

- SG13, Graphics

Any modern language should have a "batteries included" set of libraries, even when targeted for systems programming.

the_mitsuhiko• 13 years ago

Any modern language should have a "batteries included" set of libraries, even when targeted for systems programming.

I would argue the inverse: modern languages should have a lean standard library but a strong package ecosystem.

midas0073• 13 years ago

Third-party libraries are third-party for a reason.

Adding every conceivable library as standard doesn't make sense, unless you're Java, in which case no one cares how much crap you bring along.

zurn• 13 years ago

Other platforms doing this include Python, Erlang, Perl, and C#.

"Batteries included" works very well in many cases. Having a single de-facto dominant implementation helps.

Daishiman5• 13 years ago

None of those languages are meant for systems programming.

nhaehnle• 13 years ago

At least in the case of Python, "batteries included" decidedly works badly when it comes to graphics. The really usable and used GUI and graphics libraries for Python are all third-party.

It is indeed helpful in other areas, though.

JasuM2• 13 years ago

Cairo is dual-licensed under the LGPL and MPL. Both of these are restrictive enough to make them incompatible with, eg., App Store terms. Yet the proposal does not seem to even mention the license (or maybe I just missed it).

The standards committee is conserned about portability, at least on a technical level. I wonder what their take is on portability issues caused by license terms.

pmelendez3• 13 years ago

They wouldn't be using the library code. They would just specify what have to be implemented based on the library. They have been doing this with all the libraries that they include in the standard (such as part of boost) and most of the time the resulted specification is way simpler and limited than the original inspiration. Also this is a design for implementation, once done each implementer have to decide how to make it real.

JasuM2• 13 years ago

Boost has a very liberal license, unlike Cairo. C++ libraries, at least the GNU C++ library, have directly based some of their implementations on Boost.

This might lead to C++ library vendors not implementing the standard and requiring using a third party library, perhaps later integrating them into their own libraries.

Thinking about it, it is not probably a bad thing, it will just take longer than with other parts of the standard. Of course, this is just pure speculation and things might turn out very differently.

rcfox2• 13 years ago

The motivation reads exactly like the xkcd comic on standards. http://xkcd.com/927/

The rest of the document reads like someone just discovered the Cairo library and wouldn't it be cool if we jammed this into our already overly-bloated standards document?

There is no all-purpose graphics library. What's good for games isn't necessarily good for rendering PDFs and vice versa.

adamnemecek5• 13 years ago

That comic is starting to be used in situation where it's pretty irrelevant, such as here. How many cross-platform 2D graphics libraries are there?

Also, the purpose is pretty obvious if you look at the use cases of Cairo and it's obviously not meant for (serious) game making, but there already is an open standard for that.

rcfox2• 13 years ago

I'd say it's very relevant. The "Motivation and Scope" section bemoans the over-abundance of library choices and then declares that there should be one standard library for all developers to use. That's literally the situation in the comic.

How many cross-platform 2D graphics libraries are there?

The document itself points out 4 cross-platform libraries. A simple Google search for "cross-platform 2d library" yields at least a dozen more.

Also, the purpose is pretty obvious if you look at the use cases of Cairo and it's obviously not meant for (serious) game making ...

They explicitly state that they want to serve rendering of any type, including games.

frankzinger2• 13 years ago

...wouldn't it be cool if we jammed this into our already overly-bloated standards document?"

I think C++ gets the most flack for being too complex and bloated. But when you compare it to Java and C#, C++11, the language (based on language specification word/page count), is smaller than Java and only a little bigger than C#. The C++11 standard library is much smaller than both the Java 7 SE and the .Net (FX only) libraries.

Source: http://media.ch9.ms/ch9/5c51/d30749f7-09d7-4266-bd57-d1d4461..., just after 15 minutes in. Or http://view.officeapps.live.com/op/view.aspx?src=http%3a%2f%..., slide 14 and 15 (see the top-right corner of slide 14 for the metrics used for the comparison (page/word count of the language specs). EDIT, for context: the speaker/author referenced is Herb Sutter, member of the C++ standisation committee, and one of the authors of the graphics proposal in question.

Daishiman5• 13 years ago

Yeah, but you can actually understand what is going on in Java pretty quickly and get the weird corners cases on Stack Overflow.

By contrast, C++ requires that the user understand most of the minutiae, details, corner cases, and weird things that the language describes just to get a rather low level of competence.

The length of a language spec has little to do with its usability.

edmccard• 13 years ago

But when you compare it to Java and C#, C++11, the language (based on language specification word/page count), is smaller than Java

I watched the presentation where Herb Sutter said that, and I think that claim is disingenuous, because the Java Language Specification is much wordier than the C++ spec.

For example, the section on integer literals in the JLS is 1.5 times longer (measured by word count) than the same section in the latest C++ draft. Is it because Java's literals are more complex than C++? No, it's because of things like explicitly listing the minumum and maximum numeric values of int and long literals (in each of decimal, hex, octal and binary)

In general, I think that the terseness of the C++ spec is not a good measure of the relative simplicity of C++.

a-nikolaev• 13 years ago

Absolutely agree. OpenGL, SDL, Cairo, all are great and useful for their own purposes, with rather small overlap between then. A single uniform API for graphics is practically impossible, so why bother? To attract beginners?

Graphics has very limited usage without full GUI. I can think of only games and chart-rendering applications (or similar) that don't really need GUI. But games require some means for windows-handling (like GLUT in OpenGL). And "chart-rendering" require output routines to produce PDF/PS/SVG/PNG.. In any case, you need quite a lot of auxiliary IO functions to really do anything useful. So, how much of thes auxiliary stuff will be included in the standard library?

Also, if they plan to implement output with both DirectX and OpenGL, there is quite a lot of work to ensure that everything works on computers with GPU, without GPU, with ancient GPU, on Windows, Linux, OSX and actually looks roughly the same. This is not easy, if you want to do it efficiently.

For game development, beginners choose Flash game engines, or GameMaker, or something like that. I doubt that C++ can work better for them, even with Cairo built in.

The standard library will always have limitations, so you will need to use external libraries at some point anyway. And a transition to an external library can be difficult, if the standard library is already used extensively.

Yes, probably, humongous standard library is good for cross-platform development, but it must be implemented first. And again, external libraries are sometimes necessary anyway. Also some UI libraries are already cross-platform, like Qt, btw.

jbb555• 13 years ago

C++ needs something.

It's a bit embarrassing when someone used to the standard library from most other languages asks "How do I draw this picture of a cat" or "how do I print 'Hello World!' in red in a welcoming font" and you have to say, erm, well.. there is nothing in c++ for that. Maybe you can find a platform dependent library that will work for you.

It doesn't need a library to do everything, but something that lets you draw and write text to a window seems like something that should be available on every platform that can support it.

ahomescu1• 13 years ago

"Most other languages" seems like an exaggeration. I don't think you can do any of the things you list easily in Python, PHP (you wouldn't even want to in PHP), JavaScript or Haskell.

hendzen• 13 years ago

Python includes Tkinter for GUI programming. That said, Tkinter is pretty crappy compared to PyQt.

shurcooL2• 13 years ago

It is available in the form of cross platform libraries like GLFW.

pmelendez3• 13 years ago

I know it is irrelevant but still is interesting that one of the authors is Herb Sutter from Microsoft and that he chooses to propose an open source library from C instead of something coming from Microsoft.

A Proposal to Add 2D Graphics Rendering and Display to C++ [pdf]

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