Posts Tagged ‘Warning’

Background info on libpng warning: iCCP: known incorrect sRGB profile

I was just checking some log file saved from Buildbox and seems Qt framework was logging the error:

libpng warning: iCCP: known incorrect sRGB profile

Did some quick research on Google (sorry dear Bing) and added the following background info to the respective question on StackOverflow:

Some changes in libpng version 1.6+ cause it to issue a warning or even not work correctly with the original HP/MS sRGB profile, leading to the following stderr: libpng warning: iCCP: known incorrect sRGB profile The old profile uses a D50 whitepoint, where D65 is standard. This profile is not uncommon, being used by Adobe Photoshop, although it was not embedded into images by default.


Error detection in some chunks has improved; in particular the iCCP chunk reader now does pretty complete validation of the basic format. Some bad profiles that were previously accepted are now rejected, in particular the very old broken Microsoft/HP sRGB profile. The PNG spec requirement that only grayscale profiles may appear in images with color type 0 or 4 and that even if the image only contains gray pixels, only RGB profiles may appear in images with color type 2, 3, or 6, is now enforced. The sRGB chunk is allowed to appear in images with any color type.


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Gotcha: var x = x() in Javascript gives “Object Expected” error

At ClipFlair Studio (a Silverlight app), I had some time ago implemented a confirmation warning upon user trying to close the webpage (when it was running inside the web browser), which then had stopped functioning. It seems at some refactoring I had added code like the following:

var activityView = activityView();

and it was failing with error “Object Expected” (and even worse this was done silently – had to use browser’s debugging tools to catch it – because the respective code was running at onbeforeunload browser window event).

Such code would be fine in C#, but in Javascript it seems that a local variable with name x hides a function named x (with any number of parameters in its definition). This is obviously because functions are first-class objects in Javascript and can be treated like variables themselves too.

All started working again fine after changing that code to:

var a = activityView();

Below is the respective block of Javascript code included in a script tag at the webpage that hosts the Silverlight control. Note the “control.content.activityWindow”, where “activityWindow”  is accessed via the Silverlight HTMLBridge (that object – that has to be marked with ScriptableType class attribute – is registered using that key via HtmlPage.RegisterScriptableObject at the Silverlight app side).

function silverlightControl() {
  return document.getElementById("silverlightControl");

function onSilverlightLoad(sender, args) {
  var control = silverlightControl();
  if (control != null)

function activityWindow() {
  var control = silverlightControl();
  if ( (control != null) && (control.content != null) )
    return control.content.activityWindow;
    return null; //need this so that it doesn't return undefined

function activityView() {
  var a = activityWindow();
  if (a != null)
    return a.GetView();
    return null; //need this so that it doesn't return undefined

function onClosing() {
  var a = activityView();
  if ( (a != null) && (a.WarnOnClosing) )
    return "Do you want to exit ClipFlair Studio?";
//else return undefined is implied (no onClosing message that is) } function onClosed() { var a = activityView(); if (a != null) a.WarnOnClosing = false; } function installEventHandlers() { window.onbeforeunload = onClosing; window.onunload = onClosed; } installEventHandlers();
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