Useful javascript Snippets

Just a collection of javascript code that I find useful.
As I don't know much javascript code yet, I hope to add more to this list as i find more useful stuff.

alert() : alert('string or '+variable);
Alert can be pretty useful when debugging your code. Throw one in to see a variable's value or into a function and if/else statements to see if the code is executing. Alert has lots of good uses. One note here though; if there are a lot of things you need to debug, you should use document.write to a text area in your project instead.

I hope to add more soon and feel free to contribute some of your own.

Silverlight Experiment: movement

This took me longer to do partly because I don't know trigonometry and because silverlight/blend doesn't really have a concept of fps (frames per second) or enterframe like flash does. Flash movies are like merry go rounds, they just keep going around and around until you stop them. You use this fact to tell flash to do "stuff" every time a certain horse comes around again. "Stuff" usually involves moving, fading, scaling, etc. Say you wanted an object to move horizontally across the screen by 1 pixel every time your movie looped.

In flash it might look like this:

item.onEnterFrame = function(){
"bob" every time i see you, i want you to:
---> this._x += 1;
---> advance a step from the last place you were.
}

Blend doesn't really have an onEnterFrame ability built into it. Flash is timeline based at its very core (like a movie) but Blend is static (like a webpage). So you can either use javascript's setTimeout() function or you can employ a storyboard timer workaround, via Stegman & Andy. I did some brief tests and it seems that the storyboard timer is faster. I will post some examples of this in action when I get some time. Until then, here is the basic setup and javascript:

the xaml:

{Canvas xmlns="http://schemas.microsoft.com/client/2007"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Width="350" Height="150" x:Name="Page" Loaded="onLoaded">
{Canvas.Resources>
{Storyboard Completed="timerCompleted"
x:Name="timer" Duration="00:00:0.02" />
{/Canvas.Resources>
{/Canvas>

the Javascript:

function onLoaded(sLight)
{
 root= sLight.findName("Page"); 
 plugin = sLight.getHost();
 var timer = sLight.findName("timer");
 timer.begin();
}

function timerCompleted(sender, args)
{
///// DO STUFF HERE. Like take a step. 
var ball = sender.findName("ball");
ball["Canvas.Left"] = ball["Canvas.Left"] + 1;

// restart the timer
sender.begin();
}

You can use this approach for creating your casual game or just to move stuff around.

silverlight experiment: fading 2

I posted a partial solution to fading yesterday. Today, I think i have figured out how to efficiently fade almost anything. The big challenge for me was removing storyboards that I was no longer going to use. The solution was to use and event listener that would remove the storyboard after it had completed. I wasn't sure if the event listener would work (if mouseEnter storyboard fades target to end value, wouldn't that trigger a complete?). Surprisingly though, it actually works quite well.



XAML

<>Canvas xmlns="http://schemas.microsoft.com/client/2007"  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Width="200" Height="150"
 Background="#FF666666" x:Name="Page" Loaded="onLoaded" <>
 <>Path Width="63" Height="52" Fill="#FFFF8B00" Stretch="Fill" Canvas.Left="20.794" Canvas.Top="29.663" Data="M56.487645,98 L74.805883,83.663793 92.204852,97.5 89,97.5 89,113.2481 60.029416,113.2481 60.029416,98 z" x:Name="home" Cursor="Hand"
MouseLeave="fadeMeIn" MouseEnter="fadeMeOut"/<>
 <>Path Width="63" Height="52" Fill="#FFFF8B00" Stretch="Fill" Canvas.Left="112.794" Canvas.Top="29.663" Data="M56.487645,98 L74.805883,83.663793 92.204852,97.5 89,97.5 89,113.2481 60.029416,113.2481 60.029416,98 z" x:Name="home2" Cursor="Hand"
  MouseLeave="fadeMeIn" MouseEnter="fadeMeOut"/<>
<>/Canvas<>

Javascript

function onLoaded(s) 
{
 root=s.findName("Page"); 
 plugin = s.getHost();
}
function fadeMeOut(sender, mouseEventArgs)
{
 var sName = makeName(sender);
 var sTo = "0.3";
 var sFrom = "1.0";
 var sTarget = sender.Name;
 var fader = makeStoryBoard(sName, sFrom, sTo, sTarget);
 sender.findName('rCount').Text = 'Number of Storyboards: '+root.Resources.Count.toString();
 fader.begin();
 fader.AddEventListener("Completed", "removeStoryBoard")
}
function fadeMeIn(sender, mouseEventArgs)
{
 var sName = makeName(sender);
 var sTo = 1;
 var sFrom = sender.opacity;
 var sTarget = sender.Name;
 var fader = makeStoryBoard(sName, sFrom, sTo, sTarget);
 fader.begin();
 fader.AddEventListener("Completed", "removeStoryBoard")
}
function makeName(sender)
{
 var sBi= 1;
 do
 {
  var tempName = (sender.Name+'_sb_'+sBi);
  var sBtrue = sender.findName(tempName);
  sBi++;
 }
 while (sender.findName(tempName) != null)
 return tempName;
}
function removeStoryBoard(targetBoard)
{
 root.Resources.remove(targetBoard);
}

function makeStoryBoard(sName, sFrom, sTo, sTarget)
{
 var xamlFragment = '<>Storyboard xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" x:Name="'+sName+'"<>' +
 '<>DoubleAnimation Storyboard.TargetName="'+sTarget+'" ' +
 'Storyboard.TargetProperty="(Opacity)" ' +
 'From="'+sFrom+'" To="'+sTo+'" Duration="0:00:00.3" AutoReverse="False" /<>' +
 '<>/Storyboard<>';
 
 var myStoryBoard = plugin.content.createFromXaml(xamlFragment);
    root.Resources.Add(myStoryBoard);
 
 return myStoryBoard;
}

Does anyone have a better way to achieve this result?

silverlight experiment: fading

I recently posted something about my attempts to fade an object in Microsoft Silverlight. I have succeeded, sort of. It's not quite complete yet because i have the storyboard names hard coded. Ideally, these would be unique each time, so that they don't conflict. That will have to wait for the next post though.


FYI, don't rollover/rolloff too quickly or you will receive an error and have to reload the page =(. This is one of the problems with hard coding the Storyboard name.

The xaml

<<>Canvas
xmlns="http://schemas.microsoft.com/client/2007"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Width="200" Height="200"
Background="#FF949494"
x:Name="Page" Loaded="onLoaded"
<>>
<<>Rectangle
Width="56"
Height="49"
Stroke="#FF9B9B9B"
Canvas.Left="71"
Canvas.Top="82"
x:Name="YellowSquare"
Cursor="Hand"
MouseLeave="fadeMeIn"
MouseEnter="fadeMeOut"
Fill="#FFE0D709"
StrokeThickness="6"/<>>

<<>/Canvas<>>
<<>/pre<>>


The Javascript
function onLoaded(s)
{
root=s.findName("Page");
plugin = s.getHost();
}
function fadeMeOut(sender, mouseEventArgs)
{
var sName = "fader4";
var sTo = "0.3";
var sFrom = "1.0";
var sTarget = sender.Name;
var fader = makeStoryBoard(sName, sFrom, sTo, sTarget);

fader.begin();
}
function fadeMeIn(sender, mouseEventArgs)
{
var storBor = sender.findName("fader4");
storBor.pause();

var sName = "fader3";
var sTo = 1;
var sFrom = sender.opacity;
var sTarget = sender.Name;
var fader = makeStoryBoard(sName, sFrom, sTo, sTarget);

removeStoryBoard(storBor)
fader.begin();
fader.AddEventListener("Completed", "removeStoryBoard")
}

function removeStoryBoard(targetBoard)
{
root.Resources.remove(targetBoard);
}

function makeStoryBoard(sName, sFrom, sTo, sTarget)
{
var xamlFragment = '<>storyboard x="http://schemas.microsoft.com/winfx/2006/xaml" name="'+sName+'"<>' +
'<>doubleanimation targetname="'+sTarget+'" targetproperty="(Opacity)" from="'+sFrom+'" to="'+sTo+'" duration="0:00:00.3" autoreverse="False"<>' +
'<>/doubleanimation<>';

var myStoryBoard = plugin.content.createFromXaml(xamlFragment);
 root.Resources.Add(myStoryBoard);

return myStoryBoard;
}