retro - Dave's Blog


Tweet from David Risney

2016 Oct 23, 4:24
Didn't know retrospective realization of "that was a date" is common to super-smart-afraid-of-conflict narcissist’s club. Thx to @hodgman

Retweet of codinghorror

2015 Mar 26, 9:13
How Punch-Out save game passwords work, including bugs â€¦

Debugging anecdote - the color transparent black breaks accessibility

2014 May 22, 10:36

Some time back while I was working on getting the Javascript Windows Store app platform running on Windows Phone (now available on the last Windows Phone release!) I had an interesting bug that in retrospect is amusing.

I had just finished a work item to get accessibility working for JS WinPhone apps when I got a new bug: With some set of JS apps, accessibility appeared to be totally broken. At that time in development the only mechanism we had to test accessibility was a test tool that runs on the PC, connects to the phone, and dumps out the accessibility tree of whatever app is running on the phone. In this bug, the tool would spin for a while and then timeout with an error and no accessibility information.

My first thought was this was an issue in my new accessibility code. However, debugging with breakpoints on my code I could see none of my code was run nor the code that should call it. The code that called that code was a more generic messaging system that hit my breakpoints constantly.

Rather than trying to work backward from the failure point, I decided to try and narrow down the repro and work forwards from there. One thing all the apps with the bug had in common was their usage of WinJS, but not all WinJS apps demonstrated the issue. Using a binary search approach on one such app I removed unrelated app code until all that was left was the app's usage of the WinJS AppBar and the bug still occurred. I replaced the WinJS AppBar usage with direct usage of the underlying AppBar WinRT APIs and continued.

Only some calls to the AppBar WinRT object produced the issue:

        var appBar = Windows.UI.WebUI.Core.WebUICommandBar.getForCurrentView(); 
// appBar.opacity = 1;
// appBar.closeDisplayMode = Windows.UI.WebUI.Core.WebUICommandBarClosedDisplayMode.default;
appBar.backgroundColor = Windows.UI.Colors.white; // Bug!
Just setting the background color appeared to cause the issue and I didn't even have to display the AppBar. Through additional trial and error I was blown away to discover that some colors I would set caused the issue and other colors did not. Black wouldn't cause the issue but transparent black would. So would aqua but not white.

I eventually realized that predefined WinRT color values like Windows.UI.Colors.aqua would cause the issue while JS literal based colors didn't cause the issue (Windows.UI.Color is a WinRT struct which projects in JS as a JS literal object with the struct members as JS object properties so its easy to write something like {r: 0, g: 0, b: 0, a: 0} to make a color) and I had been mixing both in my tests without realizing there would be a difference. I debugged into the backgroundColor property setter that consumed the WinRT color struct to see what was different between and {a: 1, r: 0, g: 0, b: 0} and found the two structs to be byte wise exactly the same.

On a hunch I tried my test app with only a reference to the color and otherwise no interaction with the AppBar and not doing anything with the actual reference to the color:;. This too caused the issue. I knew that the implementation for these WinRT const values live in a DLL and guessed that something in the code to create these predefined colors was causing the issue. I debugged in and no luck. Now I also have experienced crusty code that would do exciting things in its DllMain, the function that's called when a DLL is loaded into the process so I tried modifying my C++ code to simply LoadLibrary the DLL containing the WinRT color definition, windows.ui.xaml.dll and found the bug still occurred! A short lived moment of relief as the world seemed to make sense again.

Debugging into DllMain nothing interesting happened. There were interesting calls in there to be sure, but all of them behind conditions that were false. I was again stumped. On another hunch I tried renaming the DLL and only LoadLibrary'ing it and the bug went away. I took a different DLL renamed it windows.ui.xaml.dll and tried LoadLibrary'ing that and the bug came back. Just the name of the DLL was causing the issue.

I searched for the DLL name in our source code index and found hits in the accessibility tool. Grinning I opened the source to find that the accessibility tool's phone side service was trying to determine if a process belonged to a XAML app or not because XAML apps had a different accessibility contract. It did this by checking to see if windows.ui.xaml.dll was loaded in the target process.

At this point I got to fix my main issue and open several new bugs for the variety of problems I had just run into. This is a how to on writing software that is difficult to debug.

PermalinkCommentsbug debug javascript JS technical windows winrt

@youtube - How DNA Changed the World of Forensics | Retro Report...

2014 May 20, 2:14

@youtube - How DNA Changed the World of Forensics | Retro Report | The New York Times


Play Fez

2012 May 7, 3:30

I'm done playing Fez. The style is atmospheric retro nastalgia and on the surface the gameplay is standard 2D platformer with one interesting Flatland style game mechanic but dig deeper to find Myst style puzzles. Despite the following I thoroughly enjoyed the game and would recommend it to anyone intrigued by the previous. Five eighths through the game I ran into one of the game's infamous Fez save game breaking issues, but I enjoyed the game enough that I started over before any patches were released and had no further issues.

While playing the game I created some tools to help keep track of my Fez notes (spoilers) including a Pixelated Image Creator that makes it easy to generate data URIs for large, black and white pixelated images, and (spoilers) a Fez Transliteration Tool to help me translate the in-game writing system.

PermalinkCommentsvideo-game fez game xbox

(via Where Can You Watch More Retro Game Master? [Video])

2012 Jan 18, 4:29

(via Where Can You Watch More Retro Game Master? [Video])

PermalinkCommentsgame video-game video

Soviet Arcade Game Posters - a set on Flickr

2010 Sep 4, 8:45
PermalinkCommentsretro poster videogame

Super Mario Crossover

2010 Apr 29, 11:47Play Super Mario Bros. as Link from Zelda, the Contra guy, Mega Man and more.
PermalinkCommentsmario smb nintendo flash web game videogame humor retro mashup zelda mega-man contra

GameSetWatch - Special: The Best Of The 2009 Demoscene, Part 1 - Demos

2010 Jan 19, 2:21"In the latest of an occasional series of demoscene-related posts on GameSetWatch before, AteBit's Paul 'EvilPaul' Grenfell presents a multi-part retrospective on 2009's best demos - starting out with the top ten real-time PC demos of the year."
PermalinkCommentsdemo demoscene graphic game videogame video programming

Public Domain Day

2010 Jan 6, 3:41Public Domain Day sounds neat. Not just celebrating the public domain but celebrating new works now available in the public domain every Jan 1st. But we'll have to wait at least nine years to celebrate in the US. We need to get the copyright lifetime to match up with retro things regaining popularity -- like when big band music was briefly popular again.PermalinkCommentscopyright ip public-domain law legal

The "blueprints" of Monsieur Eiffel

2009 Dec 23, 10:02"These designs are reproductions of Eiffel's original designs included in his book "The 300 Meter Tower", Lemercier publications, Paris 1900."PermalinkCommentsdesign architecture blueprints france eiffel eiffel-tower retro visualization illustration

Lessons Learned From Paintball

2009 Dec 16, 2:47

Dressed for Paintball.I played paintball for the first time at Eric's bachelor party a couple months ago. With the worst of my bruises fading I'm examining what I've learned:

PermalinkCommentspaintball lessons

It's 1975 And This Man Is About To Show You The Future

2009 Nov 9, 11:26Awesome tital and design.PermalinkCommentsart design technology ibm future typography retro vintage internet via:ethan_t_hein presentation


2009 Feb 5, 7:31Excellent retro intro! Be sure to watch the other two high-five videos too.PermalinkCommentshumor video obama awesome high-five funnyordie

Paul Robertson pumps pixels for energy drink - Offworld

2008 Dec 30, 3:07I was not previously aware of Paul Robertson's videos which are done in old school video game style. His two non-commercial videos are pretty crazy. All available for viewing online...PermalinkCommentsvideo videogame paul-robertson music retro ad soda

Earplug Alarm Clock

2008 Jul 9, 1:37

Dirt PileIn my previous home, just after I moved in, my neighbor which was the city of Redmond's various city government buildings, decided to build a parking structure. This was maybe 30 feet from my window, lasted for at least a year and would regularly wake me up at seven or eight in the morning. Determined to not be so punctual for work, I got earplugs which meant in addition to not hearing the construction outside, I couldn't hear my alarm. I had an idea for a combination ear plug, headphone, alarm clock that I never did anything with, except to write down the phrase "earplug / headphone / alarm clock" on a list that I just now found. In retrospect, I think this problem might be too specific to result in my earplug alarm clock selling well.

PermalinkCommentsidea earplug headphone alarm clock random nontechnical

URI Fragment Info Roundup

2008 Apr 21, 11:53

['Neverending story' by Alexandre Duret-Lutz. A framed photo of books with the droste effect applied. Licensed under creative commons.]Information about URI Fragments, the portion of URIs that follow the '#' at the end and that are used to navigate within a document, is scattered throughout various documents which I usually have to hunt down. Instead I'll link to them all here.

Definitions. Fragments are defined in the URI RFC which states that they're used to identify a secondary resource that is related to the primary resource identified by the URI as a subset of the primary, a view of the primary, or some other resource described by the primary. The interpretation of a fragment is based on the mime type of the primary resource. Tim Berners-Lee notes that determining fragment meaning from mime type is a problem because a single URI may contain a single fragment, however over HTTP a single URI can result in the same logical resource represented in different mime types. So there's one fragment but multiple mime types and so multiple interpretations of the one fragment. The URI RFC says that if an author has a single resource available in multiple mime types then the author must ensure that the various representations of a single resource must all resolve fragments to the same logical secondary resource. Depending on which mime types you're dealing with this is either not easy or not possible.

HTTP. In HTTP when URIs are used, the fragment is not included. The General Syntax section of the HTTP standard says it uses the definitions of 'URI-reference' (which includes the fragment), 'absoluteURI', and 'relativeURI' (which don't include the fragment) from the URI RFC. However, the 'URI-reference' term doesn't actually appear in the BNF for the protocol. Accordingly the headers like 'Request-URI', 'Content-Location', 'Location', and 'Referer' which include URIs are defined with 'absoluteURI' or 'relativeURI' and don't include the fragment. This is in keeping with the original fragment definition which says that the fragment is used as a view of the original resource and consequently only needed for resolution on the client. Additionally, the URI RFC explicitly notes that not including the fragment is a privacy feature such that page authors won't be able to stop clients from viewing whatever fragments the client chooses. This seems like an odd claim given that if the author wanted to selectively restrict access to portions of documents there are other options for them like breaking out the parts of a single resource to which the author wishes to restrict access into separate resources.

HTML. In HTML, the HTML mime type RFC defines HTML's fragment use which consists of fragments referring to elements with a corresponding 'id' attribute or one of a particular set of elements with a corresponding 'name' attribute. The HTML spec discusses fragment use additionally noting that the names and ids must be unique in the document and that they must consist of only US-ASCII characters. The ID and NAME attributes are further restricted in section 6 to only consist of alphanumerics, the hyphen, period, colon, and underscore. This is a subset of the characters allowed in the URI fragment so no encoding is discussed since technically its not needed. However, practically speaking, browsers like FireFox and Internet Explorer allow for names and ids containing characters outside of the defined set including characters that must be percent-encoded to appear in a URI fragment. The interpretation of percent-encoded characters in fragments for HTML documents is not consistent across browsers (or in some cases within the same browser) especially for the percent-encoded percent.

Text. Text/plain recently got a fragment definition that allows fragments to refer to particular lines or characters within a text document. The scheme no longer includes regular expressions, which disappointed me at first, but in retrospect is probably good idea for increasing the adoption of this fragment scheme and for avoiding the potential for ubiquitous DoS via regex. One of the authors also notes this on his blog. I look forward to the day when this scheme is widely implemented.

XML. XML has the XPointer framework to define its fragment structure as noted by the XML mime type definition. XPointer consists of a general scheme that contains subschemes that identify a subset of an XML document. Its too bad such a thing wasn't adopted for URI fragments in general to solve the problem of a single resource with multiple mime type representations. I wrote more about XPointer when I worked on hacking XPointer into IE.

SVG and MPEG. Through the Media Fragments Working Group I found a couple more fragment scheme definitions. SVG's fragment scheme is defined in the SVG documentation and looks similar to XML's. MPEG has one defined but I could only find it as an ISO document "Text of ISO/IEC FCD 21000-17 MPEG-12 FID" and not as an RFC which is a little disturbing.

AJAX. AJAX websites have used fragments as an escape hatch for two issues that I've seen. The first is getting a unique URL for versions of a page that are produced on the client by script. The fragment may be changed by script without forcing the page to reload. This goes outside the rules of the standards by using HTML fragments in a fashion not called out by the HTML spec. but it does seem to be inline with the spirit of the fragment in that it is a subview of the original resource and interpretted client side. The other hack-ier use of the fragment in AJAX is for cross domain communication. The basic idea is that different frames or windows may not communicate in normal fashions if they have different domains but they can view each other's URLs and accordingly can change their own fragments in order to send a message out to those who know where to look. IMO this is not inline with the spirit of the fragment but is rather a cool hack.

PermalinkCommentsxml text ajax technical url boring uri fragment rfc

Retro Sabotage: Highwaymen On Memory Lane - Flash Games [ver.9.0 req.]

2008 Mar 23, 3:26Flash versions of retro games with humorous differences.PermalinkCommentsgame humor retro games flash web internet pacman space-invaders tetris via:boingboing

ThinkGeek Bluetooth Retro Handset Review

2008 Mar 23, 1:25

I ordered a ThinkGeek Bluetooth Retro Handset to use at home. When I come home I plug my phone in to charge in my room, but then I can't hear it ring elsewhere in the hosue. The idea was to take this handset which wirelessly connects to cellphones via bluetooth and place it in another part of the house so that I can tell I'm getting an incoming call. The only issue I have with that setup is that it ringing isn't any louder than conversations held over the phone, that is, the ringing is a little quiet.

The handset pairs with cellphones in the same manner as any other handset over bluetooth. It has an internal rechargeable battery which is charged via a standard USB port built into the base of the handset and it comes with a USB cable. Next to the USB port is the only button on the phone which is pressed to answer a call, hang up a call, or begin voice dial, held down to turn the handset on and off, and held down longer to begin pairing with a cellphone. There's a blue LED in one of the holes in the microphone portion of the phone which blinks to indicate if its on or trying to pair. Transitioning between on, off, and pairing produces a cute sound and a change to the LED.

Overal I'm pleased with its simplicity and use of common parts although I wish there was a way to adjust the volume of the ring.

PermalinkCommentsthinkgeek bluetooth cellphone phone product handset

ThinkGeek :: ThinkGeek Bluetooth Retro Handset

2007 Dec 11, 11:13A bluetooth handset that's like a retro headset.PermalinkCommentsshopping retro headset bluetooth phone cellphone
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