Planning Inkface v0.2

With v0.1.X of Inkface libraries feasibility of SVG based GUI framework is proven. With different experiments, the following structure seems to be evolving.

The inkface library provides canvas objects to draw on. These canvas objects can be implemented using different backends. Currently only X is used as backend. Clutter seems possible, it will be there in v0.2.X. Inkface library loads the SVG elements with the help of altsvg library. altsvg library is responsible for parsing the SVG document and rendering its component elements.

I spent past few weeks investigating the SVG rendering solutions that are out there. There are two major efforts in open source to the best of my knowledge: librsvg (Gnome library, which is the base of current libaltsvg) and Qt’s couple of libraries (QtSVG and other being a KHTML component).

They are good libraries with their own advantages and pitfalls. But they are made with a simple purpose in mind - Parse the SVG document and render it as an image. They do not handle the individual elements of the SVG DOM tree in a dynamic way. This is the reason, none of them fully supports animation extension of SVG specs.

In the inkface framework, following two things are expected from the altsvg library:
1. Separate rendering of different elements of an SVG document.
2. Programmatic access to the SVG attributes of these individual elements.

I have spent very long time trying to understand librsvg. It was very painful to get it working the way it works right now. I am not satisfied with the patches I applied on top of librsvg to accomplish the 1st requirement above. (2nd requirement is not available in v0.1.X). I have faced great difficulty to understand the highly recursive logic of librsvg. It will take much larger effort to tweak it elegantly so that both the above requirements are fulfilled.

I also looked into Qt SVG libraries. Qt’s code is elegant and easy to understand. But I am afraid, it is tightly embedded inside Qt framework (at least it will take long to tear it and take away what’s needed, not sure if that’s worth it).

After exploring above two options, I have also considered implementing altsvg from scratch. And that sounds like a better option after all. I have started experimenting with that option. Here are some details.

As the altsvg block shows, there are two distinct components in these libraries:
a) SVG parsing - nothing but a standard XML parsing
b) SVG rendering - librsvg uses cairo and QtSVG uses their PaintEngine for this logic.

I plan to reimplement the SVG parsing part. The rendering will be done by cairo or Qt’s PaintEngine. Cairo and Qt’s rendering library are mature libraries and their role is orthogonal to the above two requirements of the inkface framework.

Furthermore I figure that the SVG parsing part is not as performance critical as rendering part. But it will have to go through lot of iterations of design and implementation. So I will be implementing it in python. Python’s excellent support for XML parsing will speed up the prototyping.

So far I see following advantages of implementing altsvg from scratch and that too in python:

1. It will save energy and time in trying to understand existing librsvg/QtSVG libraries and try to redesign them for the purpose that they might not have been designed for in the first place.
2. Some initial work on this front has proved that, I can totally eliminate the need for a designer to change in XML nodes in Inkscape. They will also not need to explicitly mention the order as an attribute of the element. The order in which the elements are shown in the Inkscape will be recognized by the inkface framework. Also the name of the element can be defined using Inkscape’s “Object Properties” option in the context menu.
3. Most of the developers who have inquired about this project, have asked about the portability. The choice of python will help address that issue.
4. It certainly would be a daunting task to aim for a full SVG compliance with my own implementation. But in retrospect, I think that’s not the goal. It’s not necessary initially to implement all of SVG spec. Some basic features like paths (lines, bezier curves, rectangles, ellipses) and gradients should be available soon enough. They are the most widely used elements. Further features like filters can be implemented incrementally. I suspect, that will be a translation of librsvg’s cairo calls to PyCairo calls.
5. I am not sure how can I do this, but a progressive rendering of SVG elements seems possible. It will need more interaction between inkface and altsvg. It will improve load time of the GUI.

There are other two topics as well. But I may address them in some later post. Implementation of inkface (its role in the big picture, the clutter backend) and benefits of using OpenGL for rasterization (Qt has a proven advantage over cairo in this regard. I know glitz can solve this problem for cairo, but I didn’t find any numbers to support that)


Home


Archive

2018

Why gamers like pixelated games

2017

Collecting Vs Hoarding Netflix

Game Design tip for Programmers - Less Automation

Review Ghost In The Shell - The blinds scene

Why Electron is the best development platform?

Project Dialog

2016

Don't Panic

The Entanglement Pattern

The flying cars analogy

Road Trip of Atlantic Canada

Having done attitude

2015

Before fixing performance issues

No Exams, Yes Video games

Podcasts Français

2014

Quotable Quotes

Conned?!

2013

Uruguay's President

New rules for Formula 1

Software Engineering Code of Ethics and Professional Practice

Something's missing

2012

Coffeescript: To switch or not to switch

Water from air

The single most reason that keeps me using Vim

Time travel fiction

When your git branch diverges from your remote

Something like Olivia - John Mayer

Online courses - New technology, Old rules

Kelsey Grammer is spectacular

Why Patriotism doesn't make sense

Why sea steading is important to pursue?

Prometheus

Rolling back latest git commit

Google Lunar X Prize

iTunes Download stopped (err =9006)

Good essay on user centric software design

Why we need to explore Seasteading?

2011

Master pieces from screen

How to write interactive CLI utility in node.js

The Gods Themselves by Isaac Asimov

Why OpenGL ES is so hard?

How to print stack trace anywhere in Javascript

It's not fair to compare Android with Internet Explorer

How to debug WebWorker threads?

Why can't I criticize Government if I don't vote? I sure can.

Elon Musk quote

Don't label yourself

Why the hi-tech minds are writing Social apps?

Truce with exercise

JavaScript is the next C

Ever growing todo list is a good sign for creative projects

Lesser women in tech... So what?

HTML5 offline cache - use swapCache carefully

How Wikipedia and Flattr can together change the World

2010

Discovering LastPass

Functional programming in Javascipt using Underscore.js

Youtube ETA - Chrome extension

Why secure airports when it's planes that fly?

Mac book red light audio jack problem on Linux

How to save HTML5 canvas image to Google App Engine

Why don't they publish eBooks for free but with embedded ads?

Silicon Valley and Hi-tech

Reality distortion field around

Indirect experiments

Music sharing

ReaderScope 2.0.6 - Find Comments

ReaderScope 2.0

predictably irrational

ReaderScope upcoming changes

Tuxmac

Why "Open" is not the first concern of user?

Mutt, Gmail, gdata, notify-send: A Perfect Email solution

Are you the Matt Damon of your game?

ReaderScope 1.9 - OAuth

New app "Find Comments"

@font-face-lift

ReaderScope 1.8.{2,3} - new authentication and global share

Portable apps for iPhone, Android, Pre, n900 - Can Processing.js help?

ReaderScope 1.8.1 - rethinking features

ReaderScope 1.8 - Random

Android fragmentation : How big a deal is it?

on Dropbox

iLikeIt

ReaderScope v1.7 - Widget, new Icons and .... Ads

on Git: tips for SVN users and Git in Dropbox cloud

How to do an online IDE for Android app development

Anti Asserts

Bono's top ten list

Make Android speak your Twits with "TwitSpeak"

2009

Reality of colors

Talking Twitter client

ReaderScope 1.5 - quicker, better, prettier

Preview android.R.drawable.* images

Is definition of "Evil" changing?

on Music: Battle Studies

ReaderScope 1.4 (with a Theme Pack)

On Chrome OS

Black on White

Android AsyncTask template

The AND-OR problem of laptop and mobile phone

ReaderScope v1.3.3 - offline podcasts

ReaderScope v1.3.2 - Social Channels

ReaderScope v1.3 - Beyond Google Reader

Frets on Fire for Maemo - Update

ReaderScope 1.2.7 - Podcasts, Expanded View

Sprint HTC Hero problems with ReaderScope

ReaderScope 1.2.3 - Search

ReaderScope 1.2.1 - Auto Login

ReaderScope v1.2

ReaderScope 1.1.3 - SDCard storage

Crash report for Android App

Wifi and Battery

ReaderScope 1.1.2

ReaderScope 1.1.1 quick-n-easy features

ReaderScope 1.1 - Social Beacons

ReaderScope 1.0.2 - making deep cache simple

ReaderScope 1.0.1

ReaderScope 1.0

Detecting HTC magic on Fedora

ReaderScope beta4 - offline fun

ReaderScope beta3 - Tweet the news

ReaderScope Beta2

ReaderScope beta1 is out

Intercepting Up/Down keys from bash script

Makeshift XML beautifier in python

HTC Magic (Indian version) - expectations and facts

using android AsyncTask

Android development with Vim + Eclim

Cutewit (preview)

Einstein's Dreams

Preprocessing the GUI

Evas + Inkface in v0.2.5

easy source

FoF - PyOpenGL = miniFoF (possibly for n810)

FoF update

Twitter client with inkface-pygame v0.2.2

Frets on Fire on Maemo 5 (Fremantle)

Static IP configuration on Fedora 10

Inkface+pygame v0.2.0

Smooth scrolling with Inkface+pygame

Inkface v0.2 update and automated GUI testing

Testing Android (Koolu Beta 3) on Openmoko Freerunner

Clutter animation paths with Inkscape+Inkface (v0.1.3)

Turning a page

Planning Inkface v0.2

Debian repository on Google App Engine

Inkface + Clutter

Inkface v0.1.2, Twitter-inkface client

2008

Inkface update

Debugging python reference counts

Paul Graham nails it again!

Fedora 10 on MacBook 2,1

A great essay

Thanksgiving at Crater Lake

Digital SLR buyer's guide

more fun with notify-send

(k)ubuntu 8.10 - not ready for my home yet

Migrating to Google App Engine

Android opened - first looks inside

Has it started?

Inkface v0.1

Musical discovery of the week

Die Berlin-Affäre

aus Berlin

Inkface - SVG based GUI design

Script fun

Visualizing source code

OpenMoko photo tour

New connection with the past

George Carlin - favorite clip

temperature

80-20 rule

Python fun

OSiM'08 Berlin, Germany

Of games

"Wine" tasting

Today's slashdot and open source

Cost of Open Source

Lions for Lambs

Ubuntu reviewed

Flickr uploads from n810

Cringely and Paul Graham

Accelerometer brainstorming

Clutter Webkit

OSiM USA 2008 - Day 2

OSiM USA 2008 - Day 1

Google code

Gr8 commercial

OSiM USA 2008, see you there

OpenMoko, Android and a great hacking post

two great videos

Blog from nokia tablets

2007

cool n770 hack

Picasso

Colbie Caillat

Firefox 3 is brilliant!!!

XML RPC server inside apache mod_python

best effort technologies

coding Monalisa

formula of a horror movie

next desktop jump

The "Screen"

Nice review article on virtualization technologies

Once again... a quote from 'Troy'

Story of a random number

quotes from George Carlin

"from time import sleep"

Sea surfing under the Golden Gate

Trip videos

2006

across two hours

What I read...

How do I backup to Amazon S3 storage service

Stranger than fiction

Gas prices... seems like big scam

Another nice quote

Hilarious nerd comment

Programming & Painting

Why do we like fiction?

Troy

If Harry Potter were a computer hacker ...

Gentoo, XGL, HGG

Henry Ford

VI - A capable IDE

New blog

Safari Bookshelf

2005

Back to the L4

Quotes

GCC 2.95 rpms

repeat (ps | grep) = filtered top

Halo fixed on ATI Mobility Radeon 9000

DirectX Installation Problem

Warning: const is a keyword in ANSI C

Not much on L4 front

Last two weeks

GRUBing

Stumbled on HURD

Installed HURD console

Make problem solved

2004

Handy way to create stack trace