@bytesnz
Jack Farley, Computer Engineer

  • home
  • about

  • Minimal Accessible Tooltip

    12/1/2022

    Doing a lot of accessibility (a11y) fixes, I wondered what would be the minimum amount of code to create a WCAG 2.1 compliant custom tooltip. Unfortunately, it had to include Javascript. Here is what I can up with.
    • software
    • web
    • a11y
  • 11/28/2022

    If you are wanting to apply accessibility labels onto an image, here are the label (alt, title, aria-description, aria-label) priorities (highest first): aria-description (with aria-label, alt or title); aria-label; alt. Note aria description does not get read out if there is no other label attributes. (Tested on Windows, NVDA, and Firefox and Edge).

    • software
    • web
    • a11y

  • Email dates in Javascript

    11/24/2022

    Javscript is missing functions to format dates in some common formats, such datetime-local inputs and RFC 5322 (email dates) in a non-obsolete way. While Date.toUTCString() is close, the timezone is now obsolete (though it is handy for HTTP Date and other such headers). Here's the basic functions to get the right formats
    • software
    • javascript

  • Visibility and CSS Accordians

    11/24/2022

    When changing a reworked menu to have accordian animations, I came to the realisation that I have been missing a big issue when using max-height transition animations — accessibility. I detail a simple fix in this article.
    • software
    • web
    • a11y
    • css
    • javacsript

  • Can't touch list

    11/24/2022

    Turns out screen readers really don't like you playing with the display CSS property on lists, for example to change it to an inline list — it will cause lists items to be read like a paragraph. Here's how to do without upsetting the screen readers.
    • a11y
    • software
    • css

  • New Zealand Low Power Networks (LTE-M & NB-IoT)

    10/14/2022

    I have started experimenting with low power wide area networks (LP-WAN) in New Zealand using a u-blox SARA-R410-02B. Here is what I have experimented with so far.
    • electronics
    • software

  • JS Binary Decoder

    10/11/2022

    I have recently been dealing with parsing binary data packets from various sources, and have published two NPM libraries from it: binary-decoder and sbd-direct-ip. Here's how they came to be.
    • software
    • javascript

  • Starting with ESP32

    2/7/2022

    I started developing my trap-watch project on an ESP32-CAM using the ESP IDF. Here is the newbie difficulties I ran into.
    • esp32
    • electronics
    • software
    • trap-watch

  • VIM Window Rabbit Hole

    2/4/2022

    Developing ESP-IDF components I thought it would be great if I could make a command to open all the files for a component at once. What a rabbit hole it was. Here is how I did it.
    • linux

  • Parsing Arguments in Bash

    1/28/2022

    Making a script parse arugments in Bash took me way too long last time I did it, so here is a nice full example of how to do it using getopt
    • linux

  • Where's my bait gone?

    1/8/2022

    I have recently started trapping some introduced predators around my local area and have had baits and pre-feed disappear with nothing to show for it, so I decided to get sparky and see if I could catch the culprit in the act.
    • electronics
    • conservation
    • trap-watch

  • Bathymetric Contours

    3/26/2021

    Finally got around to creating a SLD style for GeoServer to display bathymetric contour lines using the GEBCO gridded bathymetric data. Here's how.

    Getting slightly distracted, I noticed bathymetric contour layer we are using for our app doesn't cover one of the areas we are working in.

    I had already downloaded the GEBCO gridded bathymetric data data for creating terrain tiles to use with CesiumJS and imported the TIFF into GeoServer, so I just needed to create the Style to display contours.

    I started off with the very helpful GeoSever docs() on Rendering Transformations, namely the Contour extraction example. After adjusting the Transformation level values to more useful values for us, I tried previewing the map. Lots of lines!

    Style preview showing all the contour lines

    I needed to cut down the data shown on the map for the lower (more zoomed out) levels, so looked into rules and filters and added up two additional <Rule> sections with various levels of.

    The rules produces the following previews

    Style preview showing the very high-level contours on the globe

    Style preview showing medium level contours around Oceania

    Style preview showing full detail contours along the bottom of the North Island and New Zealand

    Below is the style XML. I still need to figure out how to remove the lines produced from the edge of the TIFF image.

    
<?xml version="1.0" encoding="ISO-8859-1"?>
<StyledLayerDescriptor version="1.0.0"
  xsi:schemaLocation="http://www.opengis.net/sld StyledLayerDescriptor.xsd"
  xmlns="http://www.opengis.net/sld"
  xmlns:ogc="http://www.opengis.net/ogc"
  xmlns:xlink="http://www.w3.org/1999/xlink"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <NamedLayer>
    <Name>contour_dem</Name>
    <UserStyle>
      <Title>Bathymetry Contours</Title>
      <Abstract>Bathymetry contours produced from the GEBCO 15 arc-second gridded bathymetry</Abstract>
      <FeatureTypeStyle>
        <Transformation>
          <ogc:Function name="ras:Contour">
            <ogc:Function name="parameter">
              <ogc:Literal>data</ogc:Literal>
            </ogc:Function>
            <ogc:Function name="parameter">
              <ogc:Literal>levels</ogc:Literal>
              <ogc:Literal>0</ogc:Literal>
              <ogc:Literal>-100</ogc:Literal>
              <ogc:Literal>-200</ogc:Literal>
              <ogc:Literal>-300</ogc:Literal>
              <ogc:Literal>-400</ogc:Literal>
              <ogc:Literal>-500</ogc:Literal>
              <ogc:Literal>-600</ogc:Literal>
              <ogc:Literal>-700</ogc:Literal>
              <ogc:Literal>-800</ogc:Literal>
              <ogc:Literal>-900</ogc:Literal>
              <ogc:Literal>-1000</ogc:Literal>
              <ogc:Literal>-1100</ogc:Literal>
              <ogc:Literal>-1200</ogc:Literal>
              <ogc:Literal>-1300</ogc:Literal>
              <ogc:Literal>-1400</ogc:Literal>
              <ogc:Literal>-1500</ogc:Literal>
              <ogc:Literal>-1600</ogc:Literal>
              <ogc:Literal>-1700</ogc:Literal>
              <ogc:Literal>-1800</ogc:Literal>
              <ogc:Literal>-1900</ogc:Literal>
              <ogc:Literal>-2000</ogc:Literal>
              <ogc:Literal>-3000</ogc:Literal>
              <ogc:Literal>-4000</ogc:Literal>
              <ogc:Literal>-5000</ogc:Literal>
              <ogc:Literal>-6000</ogc:Literal>
              <ogc:Literal>-7000</ogc:Literal>
              <ogc:Literal>-8000</ogc:Literal>
              <ogc:Literal>-9000</ogc:Literal>
              <ogc:Literal>-10000</ogc:Literal>
              <ogc:Literal>-11000</ogc:Literal>
              <ogc:Literal>-12000</ogc:Literal>
            </ogc:Function>
          </ogc:Function>
        </Transformation>
        <Rule>
          <Name>deep_water</Name>
          <Title>Deep Water Contours</Title>
          <MaxScaleDenominator>800000</MaxScaleDenominator>
          <LineSymbolizer>
            <Stroke>
              <CssParameter name="stroke">#000000</CssParameter>
              <CssParameter name="stroke-width">1</CssParameter>
            </Stroke>
          </LineSymbolizer>
          <TextSymbolizer>
            <Label>
              <ogc:PropertyName>value</ogc:PropertyName>
            </Label>
            <Font>
              <CssParameter name="font-family">Arial</CssParameter>
              <CssParameter name="font-style">Normal</CssParameter>
              <CssParameter name="font-size">10</CssParameter>
            </Font>
            <LabelPlacement>
              <LinePlacement/>
            </LabelPlacement>
            <Halo>
              <Radius>
                <ogc:Literal>2</ogc:Literal>
              </Radius>
              <Fill>
                <CssParameter name="fill">#FFFFFF</CssParameter>
                <CssParameter name="fill-opacity">0.6</CssParameter>
              </Fill>
            </Halo>
            <Fill>
              <CssParameter name="fill">#000000</CssParameter>
            </Fill>
            <Priority>2000</Priority>
            <VendorOption name="followLine">true</VendorOption>
            <VendorOption name="repeat">100</VendorOption>
            <VendorOption name="maxDisplacement">50</VendorOption>
            <VendorOption name="maxAngleDelta">30</VendorOption>
          </TextSymbolizer>
        </Rule>
        <Rule>
          <Name>platform_limits</Name>
          <Title>Platform Limit Contours</Title>
          <MaxScaleDenominator>20000000</MaxScaleDenominator>
          <ogc:Filter>
            <ogc:Or>
              <ogc:PropertyIsEqualTo>
                <ogc:PropertyName>value</ogc:PropertyName>
                <ogc:Literal>-100</ogc:Literal>
              </ogc:PropertyIsEqualTo>
              <ogc:PropertyIsEqualTo>
                <ogc:PropertyName>value</ogc:PropertyName>
                <ogc:Literal>-500</ogc:Literal>
              </ogc:PropertyIsEqualTo>
              <ogc:PropertyIsEqualTo>
                <ogc:PropertyName>value</ogc:PropertyName>
                <ogc:Literal>-1000</ogc:Literal>
              </ogc:PropertyIsEqualTo>
              <ogc:PropertyIsEqualTo>
                <ogc:PropertyName>value</ogc:PropertyName>
                <ogc:Literal>-1500</ogc:Literal>
              </ogc:PropertyIsEqualTo>
              <ogc:PropertyIsEqualTo>
                <ogc:PropertyName>value</ogc:PropertyName>
                <ogc:Literal>-6000</ogc:Literal>
              </ogc:PropertyIsEqualTo>
            </ogc:Or>
          </ogc:Filter>
          <LineSymbolizer>
            <Stroke>
              <CssParameter name="stroke">#000000</CssParameter>
              <CssParameter name="stroke-width">1</CssParameter>
            </Stroke>
          </LineSymbolizer>
          <TextSymbolizer>
            <Label>
              <ogc:PropertyName>value</ogc:PropertyName>
            </Label>
            <Font>
              <CssParameter name="font-family">Arial</CssParameter>
              <CssParameter name="font-style">Normal</CssParameter>
              <CssParameter name="font-size">10</CssParameter>
            </Font>
            <LabelPlacement>
              <LinePlacement/>
            </LabelPlacement>
            <Halo>
              <Radius>
                <ogc:Literal>2</ogc:Literal>
              </Radius>
              <Fill>
                <CssParameter name="fill">#FFFFFF</CssParameter>
                <CssParameter name="fill-opacity">0.6</CssParameter>
              </Fill>
            </Halo>
            <Fill>
              <CssParameter name="fill">#000000</CssParameter>
            </Fill>
            <Priority>2000</Priority>
            <VendorOption name="followLine">true</VendorOption>
            <VendorOption name="repeat">100</VendorOption>
            <VendorOption name="maxDisplacement">50</VendorOption>
            <VendorOption name="maxAngleDelta">30</VendorOption>
          </TextSymbolizer>
        </Rule>
        <Rule>
          <Name>full</Name>
          <Title>Full Detail Contours</Title>
          <ogc:Filter>
            <ogc:Or>
              <ogc:PropertyIsEqualTo>
                <ogc:PropertyName>value</ogc:PropertyName>
                <ogc:Literal>-1000</ogc:Literal>
              </ogc:PropertyIsEqualTo>
              <ogc:PropertyIsEqualTo>
                <ogc:PropertyName>value</ogc:PropertyName>
                <ogc:Literal>-6000</ogc:Literal>
              </ogc:PropertyIsEqualTo>
            </ogc:Or>
          </ogc:Filter>
          <LineSymbolizer>
            <Stroke>
              <CssParameter name="stroke">#000000</CssParameter>
              <CssParameter name="stroke-width">1</CssParameter>
            </Stroke>
          </LineSymbolizer>
          <TextSymbolizer>
            <Label>
              <ogc:PropertyName>value</ogc:PropertyName>
            </Label>
            <Font>
              <CssParameter name="font-family">Arial</CssParameter>
              <CssParameter name="font-style">Normal</CssParameter>
              <CssParameter name="font-size">10</CssParameter>
            </Font>
            <LabelPlacement>
              <LinePlacement/>
            </LabelPlacement>
            <Halo>
              <Radius>
                <ogc:Literal>2</ogc:Literal>
              </Radius>
              <Fill>
                <CssParameter name="fill">#FFFFFF</CssParameter>
                <CssParameter name="fill-opacity">0.6</CssParameter>
              </Fill>
            </Halo>
            <Fill>
              <CssParameter name="fill">#000000</CssParameter>
            </Fill>
            <Priority>2000</Priority>
            <VendorOption name="followLine">true</VendorOption>
            <VendorOption name="repeat">100</VendorOption>
            <VendorOption name="maxDisplacement">50</VendorOption>
            <VendorOption name="maxAngleDelta">30</VendorOption>
          </TextSymbolizer>
        </Rule>
      </FeatureTypeStyle>
    </UserStyle>
  </NamedLayer>
</StyledLayerDescriptor>
    • gis
    • geoserver
    • oceans

  • shm That Cache

    2/25/2021

    I am often trying to find more space on my hard drives and found today my own docker containers wasting space thanks to ! Here's how I fixed it.
    • yarn
    • docker
    • development

  • Blob blob blob blob Stayin' Alive Stayin' Alive

    2/2/2021

    Upon recently trying Deezer again, I found their web app ate all my memory when running in Firefox, so I decided to see if I could find out why. I got as far as memory-file-data/string and Blobs. Here's how.
    • software
    • javascript
    • debugging
    • memory

  • A new Litter Survey

    12/25/2020

    In a culmination of litter surveys and litter picks, linked data and data exploration, and remoteStorage and ActivityPub, I have created a web-based litter pick/survey app that I hope will allow federated citizen science.
    • software
    • litter
    • litter-survey

  • Hoe Stream Trash

    12/14/2020

    My latest litter pick target was Hoe Stream and the White Rose Lane Local Nature Reserve. Here's how it went.
    • litter
    • pi-trash-cam
    • litter-pick
    • environment

  • Release the Beast

    11/24/2020

    I just created a Gitlab CI job to create a release with information from a CHANGELOG.md file for some of my projects. Here's how I did it.
    • software
    • gitlab
    • ci
    • release

  • Gitlab CI Caching

    9/30/2020

    I noticed something strange happening during build process during a multi-tasking bug fix. Turns out I was using Gitlab CI's caching incorrectly. I should have been using artifacts. Here's what I saw.
    • gitlab
    • continuous integration

  • Birthday Trash

    9/22/2020

    As a birthday treat, I took the day off work to try out my electronerised litter picker. Here's how it went.
    • litter
    • pi-trash-cam
    • environment

  • Pi Trash Cam

    9/13/2020

    In preparation for a day of litter picking, I finally got round to a project idea - attaching a camera to a litter picker to record it all. Here's what I did.
    • raspberry pi
    • electronics
    • litter
    • pi-trash-cam
    • environment

  • yarn add --dev webdriverio

    8/25/2020

    I finally started implementing UI testing on first-draft using WebdriverIO. While writing tests was easy, getting the tests running was a little more difficult. Here is how I did it.
    • first-draft
    • software
    • testing
    • gitlab
  • 8/16/2020

    Hooray! My new blog is live! Based on Sapper, using MongoDB and eventually ActivityPub and ActivityStreams, it will be my federated posting hub to the world.

    • software
    • blog

  • Removing EXIF Data from Photos

    8/9/2020

    Creating this new blog, I wanted to make sure there was no metadata data leaking personal information. Here's how I removed all the metadata tags except the ones I wanted from my photos.
    • exif
    • photos

  • tmux List and Reattach

    8/9/2020

    Using tmux for your terminal multiplexer but want an easy to reattach to a session? Here's a small bash script to do it.
    • tmux
    • bash
    • software

  • Selectable Shell Examples

    8/8/2020

    Here's how to help your readers save time by making your post's shell commands easy to select and copy - with a simple CSS property.
    • markdown
    • syntax
    • css

  • Be Dates You

    8/5/2020

    Making my new blog, I didn't initially set the published dates to be native dates in the database. Here what I did to change them …and do all the upgrades I needed.
    • mongodb
    • docker

  • Testing vue components

    7/8/2020

    I recently needed to test that some Vue components were creating the correct HTML. To do this, I decided to create snapshots of Object representations of the rendered HTML.
    • software
    • vue
    • testing
    • javascript

  • No More Numbers

    2/20/2019

    HTML5 number inputs aren't useful, but tel inputs, have all the power
    • javascript
    • html5
    • software

  • A Hacker "Hacked" Me

    12/21/2018

    I decided to look into the extortion emails I have been getting and wrote a small script to extract the bitcoin addresses that have been used.
    • security
    • email
    • grep

  • Mouse Surgery

    12/7/2018

    As part of my pledge not to upgrade, I decided to repair two of my failing mice instead of replacing them with a brand new model (as tempting as it was). Here's what I did.
    • pledge to not upgrade
    • electronics

  • Danger Danger, Highly Reactive

    10/29/2018
    • vue
    • reactive
    • graphing
    • data

  • Switching to SSR

    9/11/2018
    • react
    • ssr
    • react-loader

  • Clean Docker Registry

    8/10/2018
    • node
    • docker
    • console
    • javascript

  • Testing on the Filesystem

    2/1/2018
    • testing
    • javascript

  • Tag You Are

    1/26/2018
    • javascript
    • tags

  • NaN Got Me

    1/25/2018
    • rubber duck save
    • javascript
    • nodejs
    • json

  • All our app's tabs are belong to us

    4/28/2017
    • angular
    • javascript
    • localstorage
    • rxjs
    • sessionstorage

  • Developing NPM modules

    2/20/2016
    • nodejs
    • npm

  • Nfa + Nfb or N(f+fa+fb)

    2/20/2016
    • array
    • function
    • javascript
    • jsperf

  • Photo Layout

    10/31/2015
    • arranger
    • css
    • gallery hierarchy
    • html
    • javascript
    • photos
    • tinymce
    • wordpress
    • software

  • Browning Pass HideAway Web Site

    10/31/2015
    • css
    • gallery hierarchy
    • html
    • wordpress

  • Think Mobile

    10/17/2015
    • mobile
    • web

  • Pledge to Refuse and Not Buy Bottled Water

    10/13/2015
    • environment
    • pledges

  • Run PHP run!

    2/25/2015
    • maximum execution time
    • php
    • trial and error

  • Gallery Hierarchy

    11/26/2014
    • gallery
    • hierarchy
    • photos

  • Vim and functions

    10/3/2014
    • function
    • navigation
    • tags
    • vim

  • I'm making hierarchies

    9/26/2014
    • hierarchical data
    • hierarchy
    • php

  • Google Sheets fun

    9/4/2014
    • google
    • google script
    • google sheets
    • javascript
    • sheets

  • Travel Photos

    8/13/2014
    • photo management
    • photos
    • travel photos

  • Image managment scripts

    8/13/2014
    • photo management
    • photos

  • MeldCE logo

    7/31/2014
    • css
    • html5
    • javascript
    • svg

  • MoltenDB

    4/26/2014
    • database
    • moltendb
    • mongodb
    • nodejs

  • The Expensive Side

    10/29/2013
    • house

  • abcde

    9/22/2013
    • music

  • Energizer Power Plus Rechargeable Batteries

    7/16/2013
    • gadgets

  • USAR FOGTeX

    3/4/2013
    • fogtex

  • Personal Gear Bag

    2/21/2013
    • rescue
    • gear

  • Geocaching Stamp

    2/18/2013
    • stamp
    • geocaching

  • Call Record Presenter

    4/2/2007
    • parser
    • python
    • sqlite
    • web

  • Kimi Ora School

    9/25/2004
    • css
    • html

  • All About Catering Web Site

    6/25/2004
    • css
    • html

  • Quantum Accounting Web Site

    7/26/2003
    • css
    • html
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