Tag Archives: solution

Fixing problem with Yahoo geolocation service

Recently two Pebble watchfaces I’ve developed based on Paul Joel designes: Clean&Smart and Cobblestyle began to experience weather update issues – as in “weather was not updated at all”. Looking into the issue I found a weird thing: If you set your location manually – weather worked. But automatic weather based on phone location did not.

The way automatic location works is pretty straighforward. First this function is called to determine location:

function getLocation() {
  navigator.geolocation.getCurrentPosition(
    locationSuccess,
    locationError,
    {timeout: 15000, maximumAge: 60000}
  );
}

It uses phone location services (GPS, if its available, otherwise network-based location). In case of success it calls locationSuccess function. And in my tests it always called it, so location was determined successfully. Continue reading →

Solved: Issue with Pebble framebuffer after notification is dismissed

Effect Layer Issue I’ve encountered a weird issue while working with EffectLayer Library (a visual effect library for Pebble smartwatch). In this particular watchface called Clean & Smart I used “invert” effect which inverts colors of the watchface should the user choose that option in settings. It was working fine when option changed when watchface was loaded/unload and behaved weirdly only in one particular scenario: when you would receive a notification (email, text etc.) and then dismiss it. Upon coming back from notification to watchface invert effect would only partially cover the watchface (as seen on the screenshot).
I don’t know exactly what was happening, but had a theory. Continue reading →

Detect IFRAME click from parent page

If you need to detect a click on a Web Page, that’s trivial: just catch Document or Body onclick event and any element on the page you click will bubble the event to your handler.

But if one of those elements is an IFRAME – that won’t work. IFRAMEs contain other pages and their events a contained within their content and don’t bubble up. Luckily there’s a way. Take a look this snippet of jQuery code:

$('IFRAME').on('load', function () {
   $(this).contents().on('click', function () {
      alert('Click Detected!');
   })
})

It attaches handler to IFRAME’s content’s onclick event, but only after IFRAME has already been loaded. Place this code in parent page that contains IFRAMEs and it will work universally across all browsers to detect when IFRAME was clicked.

NOTE: As usual in these scenarios, this works only if parent page and children pages comply with Same Origin Policy.

Restore bricked HTC One M8

Today my trusty HTC One M8 informed me that OTA (over the air) update of system software is available. Android security updates. Naturally I let the system download and install the update. Unfortunately after install phone refused to boot – it was getting stuck on HTC logo on white screen. Bummer.

Now I researched “stuck on logo” topic in depth and tried different methods to unstick it. No dice. Moreover, after chat with HTC Support and following their advice phone would simple go to blank screen. Double bummer. Continue reading →

Solution: Windows 10: Unable to start Appstore apps

Ok, I went ahead and upgraded to Windows 10. everything went smoothly, all my settings and installed apps preserved and work without a hitch. I am loving the interface and getting along with Cortana pretty good.

But after a while I encountered a weird issue: Appstore installed apps – e.g. Calendar, Mail etc. even Windows AppStore itself wouldn’t launch. I’d either get a cryptic error message, something along the lines “Application did not start, please contact system administrator” or very briefly a window would appear and immediately closed.

Looking into Event log was a bit more explanatory, but not too much: “Microsoft.WindowsStore_8wekyb3d8bbwe!App failed with error: Access is denied. See the Microsoft-Windows-TWinUI/Operational log for additional information.”

If you google it – you will find many possible explanations of the problem and many possible ways to solve it offered, but none of those worked for me. Finally I figured it out (and Event Log entry gave me a clue): C:\Program Files\WindowsApps folder was missing necessary permissions:

WindowsApps

Namely, “ALL APPLICATION PACKAGES” was missing read & execute permissions on that folder (had to to uncheck “Hide protected operating system files” in Control Panel, File Explorer options to be able to see it). Once I added correct permissions – appstore apps started launching with no problems.

Cancel long running SQL Command in ASP.NET WebForm application

It’s an all too common scenario when your ASP.NET page takes too long to load and the culprit is slow, long running SQL query. It shouldn’t come to this, you should optimize your DB stuff to minimize delays, but if you’re trying to decode feline genome or find alien live in the neighboring galaxies – that’s unavoidable. So the page is running and at some point you decide enough is enough and decide you need to cancel it. But you want to do it gracefully, for example slow page is in an IFRAME and you want to remain in the parent page and you don’t want to close/reload the whole thing.

There’s a way. The idea is, every time you create an SqlCommand – you add it to static (shared in VB.NET) list. If command runs successfully – you remove it from the list. But if it takes too long – you can issue an AJAX call from client page to cancel the command stored in that list.

Thanks Arsalan Tamiz for posting this solution to my question on StackOverflow. His demo project was in C# (you can download it from the above link). but since most of my projects are in VB.NET – I did a conversion with some adjustments.
Continue reading →

Solution: Live Writer Error “Invalid Response Document” while connecting to WordPress

If you’re trying to connect to your WordPress blog from Windows Live Writer desktop client, you may get this dreaded error message:

Invalid Server Response – The response to the blogger.getUsersBlogs method received from the blog server was invalid: Invalid response document returned from XmlRpc Server

Invalid Response

This means that instead of expected XML response your blog sent back plain html or text message which is most likely some kind of error message. To see actual message you can either trace request response in an HTTP sniffer like Fiddler or simple enter endpoint url for your blog remote access (e.g. http://your.site.com/wordpress/xmlrpc.php) into your browser address bar.
Continue reading →

ASP.NET WebForms: Safe refresh after postback

It’s all too commons scenario in a Web Application, you initiate a postback by clicking a button (basically submitting a form), some action is performed, perhaps database is written to, all fine and good. And then you refresh the page. Or even page is refreshed for some purpose by a client-side JavaScript code. And the dreaded “resubmit” message appears, it differs from browser to browser, e.g. Firefox would say

“To display this page, Firefox must send information that will repeat any action (such as a search or order confirmation) that was performed earlier”

And if you agree – the form is resubmitted again along with all the actions performed – not good.

This issue happens because the page is submitted via POST request and in order to refresh the page – POST request has to be resubmitted along with form action. And the solution is Post/Redirect/Get pattern. The idea is to take the page submitted via POST request and convert it into GET. In ASP.NET this can be achieved via simple Response.Redirect. You can redirect to another page or you can reload your current one:

Response.Redirect(Request.RawUrl)

This code redirects to original page URL, essentially reloading the from page server side. But now it’s a GET page, safe to refresh

WriteEndObject of JSON.NET ouptuts NULL literal

JSON.NET is a very popular framework to process JSON data in .NET. We recently upgraded from v4 to v6 and noticed strange thing it started to output null to JSON strings created by JsonTextWriter object.

For example if JSON produced by v4 would look like this:

{"param1":"value1", "param2":"value2",
"someArray":[{"arrParam1": "arrValue1"}, {"arrParam2": "arrValue2"}]}

Same code, using v6, would prodcuce

{"param1":"value1", "param2":"value2",
"someArray":[{"arrParam1": "arrValue1"}, {"arrParam2": "arrValue2"}]null}

that extra “null” makes it invalid and unusable JSON.

The .NET function to create JSON writes it into a StringBuilder and is pretty straighforward.

  1. It starts with call to WriteStartObject method of JsonTextWriter
  2. Then it creates parameter name via WritePropertyName
  3. Depending on whether primitive value or raw string needs to be written WriteValue or WriteRaw methods are used respectfully
  4. Repeat steps 2 and 3 as needed
  5. Call to WriteEndObjectto finish writing.

This worked perfectly well when version 4 of Newtonsoft.Json.dll was used. After upgrading to version 6 last method – “WriteEndObject” began to output “null” to resulting JSON.

The solution is to use WriteRawValue method instead of WriteRaw – it still outputs raw string, but at the end WriteEndObject doesn’t output “null” anymore.

Solution: Lenovo Thinkpad w540 black LCD screen (only external monitor works)

I spend ungodly amount of time trying to solve this issue, there were many similar issues reported on Lenovo forums, but no solutions and contacting Lenovo support is akin jumping thru hoops of fire.

The problem began after I plugged my brand new Thinkpad w540 into external monitor and set it to mode “Extended display (monitor + built-in screen). For a while everything worked fine, but then laptop own screen went black – and nothing could revive it. The external monitor worked fine and the maddening part was – when laptop booted – Lenovo logo appeared bright and shiny on laptop own screen, so I knew graphics card was OK. I ran full Lenovo System update, I updated NVidia drivers from Nvida site – nothing helped.

Then I tried to update Intel drivers for laptop’s HD Graphics 4600 card. Intel installer refused to install them because “The driver being installed is not validated for this computer“. To bypass that I

1. Unzipped the installer package into it’s own folder (you can use WinRar to unpack actual EXE or you can download Zip version of the package).
2. Went to Device Manager, right clicked on “HD Graphics 4600 card” driver and selected Update.
3. When prompted I selected “Browse my computer for driver software”
4. Selected “Let me pick from list of Device Drivers”
5. Clicked “Have disk” and browsed for an INF file inside of GRAPHICS folder of the unpacked driver files from Step 1

Installation commenced and lo and behold – laptop’s display sprang to life.

These instructions are specific to this laptop model and videocard, but I imagine they might be helpful in other similar situations. And hopefully Lenovo will take notice and finally update their drivers.