Marauderz Stuff!!

Resizing Images In Silverlight

2010-03-19T00:24:20.1704806+08:00

I needed to resize an image in Silverlight and then save it out as a JPEG. I could have just used a transform on it then rendered it to a WriteableBitmap but the transforms were optimized for realtime performance and doesn't work too well when you need to maintain quality.

I stumbled upon a Bicubic Resize code in a library called AForge.Net and it was in C#, so it was simple enough for me to convert it to VB for me to use it in Silverlight. And since I DIDN'T find a lot of Bicubic Interpolation .Net resize code on the net, I'm gonna just put this copy up here.

As a bonus I kept on my comments in so you guys can see what was going through my head as I was working my way through the code.

Bicubic
Interpolation

              ''' 
              
              

              ''' Bicubically resize the src bitmap to the
dest bitmap
              

              ''' 
              
              

              ''' 
              
              

              ''' 
              
              Destination Bitmap, should
be initialized to the requested size.
              
              

              ''' 
              
              Original
Source For This Function - http://www.codeproject.com/KB/recipes/aforge.aspx
              
              
              
              

              Sub Resize(ByVal src As Imaging.WriteableBitmap, ByVal dest As Imaging.WriteableBitmap)

Dim startTime As DateTime
= Now


Dim srcwidth AsInteger =
src.PixelWidth
Dim srcHeight AsInteger =
src.PixelHeight

Dim destWidth AsInteger =
dest.PixelWidth
Dim destHeight AsInteger =
dest.PixelHeight

Dim xFactor AsDouble =
srcwidth / destWidth
Dim yFactor AsDouble =
srcHeight / destHeight

'Coordinates of src points and coefficients.. WTF?
Dim ox, oy, dx, dy, k1, k2 AsDouble
Dim ox1, oy1, ox2, oy2 AsInteger

'new color values
Dim r, g, b AsDouble

Dim xmax AsInteger =
srcwidth - 1
Dim ymax AsInteger =
srcHeight - 1

For y AsInteger =
0 To destHeight - 1
'this is getting the original Y pixel if I'm not
mistaken

oy = y * yFactor - 0.5F
'WHY is this necessary?

oy1 = oy
'WTF? It's getting the FRACTIONAL difference between
'oy and oy1?

dy = oy - oy1


For x AsInteger =
0 To destWidth - 1
'same WTF as with the Y values,
'maybe will make more sense later?

ox = x * xFactor - 0.5F

ox1 = ox

dx = ox - ox1


r = 0

g = 0

b = 0


'this loop is to gather the interpolated
'values of 2 pixels surrounding the current one
For n AsInteger =
-1 To 2
'this gets the Y coefficient


k1 = BicubicKernel(dy - n)

'this seems to be getting the new
'Y pixel where the interpolated
'value comes from

oy2 = oy1 + n

'this is to ensure we're in the right spot
If oy2 < 0 Then

oy2 = 0
ElseIf oy2 > ymax Then

oy2 = ymax
EndIf

For m AsInteger =
-1 To 2
'for X coefficient

k2 = k1 * BicubicKernel(m - dx)


ox2 = ox1 + m

If ox2 < 0 Then

ox2 = 0
ElseIf ox2 > xmax Then

ox2 = xmax
EndIf

'get original pixel color
' Dim origColor As Color = source.GetPixel(ox2, oy2)

'writablebitmap pixel is AARRGGBB
Dim srcColor AsInteger =
src.Pixels(ox2 + (srcwidth * oy2))


'set interpolated values

r += k2 * ((srcColor >> 16) And &HFF)

g += k2 * ((srcColor >> 8) And &HFF)

b += k2 * (srcColor And &HFF)
Next
Next

'after calculating coefficients we have our new color 

dest.Pixels(x + (destWidth * y)) = &HFF000000 Or (r
<< 16) Or (g << 8) Or b


Next
Next

dest.Invalidate()
Dim endTime As DateTime
= Now

Diagnostics.Debug.WriteLine(String.Format("Time
taken to squish {0}x{1} to {2}x{3} : {4} seconds", srcwidth, srcHeight,
destWidth, destHeight, endTime.Subtract(startTime).TotalSeconds))

EndSub

SharedFunction BicubicKernel(ByVal x AsDouble) AsDouble

If x > 2.0 Then
Return 0.0
EndIf

Dim a, b, c, d AsDouble
Dim xm1 AsDouble =
x - 1.0
Dim xp1 AsDouble =
x + 1.0
Dim xp2 AsDouble =
x + 2.0



If xp2 <= 0 Then

a = 0
Else

a = xp2 * xp2 * xp2
EndIf

If xp1 <= 0 Then

b = 0
Else

b = xp1 * xp1 * xp1
EndIf

If x <= 0 Then

c = 0
Else

c = x * x * x
EndIf

If xm1 <= 0 Then

d = 0
Else

d = xm1 * xm1 * xm1
EndIf

Return (0.16666666666666666 * (a - (4.0 * b) +
(6.0 * c) - (4.0 * d)))

EndFunction

There's one caveat though, I didn't do any Alpha premultiplication with this code, which basically means if your images have a non FULLY opaque region, the results won't be pretty. Here's your homework assignment if you want to have that functionality.

I learnt 2 things while porting this code.

Don't use Math.Pow() if your code is time sensitive, ie. it needs to work REALLY REALLY fast. Like in a game render loop. Takes a bit longer to run math.pow(x,3) instead of x*x*x. Not saying you shouldn't use it, just don't use it when MILISECONDS matter.
Visual Basic's IIF statement isn't good for performance as well since BOTH true and false statements seem to be evaluated and does execution time is wasted when execution time matters. Better to use the usual IF..ELSE..ENDIF construct.

After my little exercise in dabbling with this, THEN I find a WriteBitmapEx library which pretty much seems to be a very useful class for raw manipulation of images in Silverlight, check it out!

Maybe I've Been Trying Too Hard.

2010-03-14T19:52:38.6460913+08:00

Now that I've made my mobile hotspot belt, and then having everyone say... it's a terrorist's suicide belt. My aim was now to make the thing NOT look like I want to blow myself up with it. So again I head down to Daiso to see what kind of weird shit I can find and use.

Why do I love going to Daiso? Because for a crazy person like me, it's a supermarket filled with things I can use for my ideas and all going for a single price of RM5 so I don't have to think too much about how expensive the item I'm cutting up. And also, when I buy something I can think of it's FUNCTION and not of it's PRICE. So.. from today's shopping.

First of is a open ended measuring tape on belt carrying case.

Which I turn into my mobile router carrying case

COMPLETE with easy access holes for the power and USB ports.

A closed version of the measuring tape carrying case.

Is used to house the smaller 6V battery.

An old MiniDisc belt case.

Due to it's stretchable nature, can be used to carry the bigger 6V SLAB.

This is what the belt now looks like when multiple components are attached to it.

More like some dumb ass wearing way too much on his belt, less like some house made explosives. Some wiring is still exposed but most people wouldn't notice it unless they stare at it for too long.

The back of the belt where the power wires run along is covered by some felt and held in place with some velcro strips.

So, less exposed wiring means less people freaking out. :P While the belt works and looks proper now, I found a problem with the construction. The power jack that connects to the mobile router is too loose, it's easily jostled and causes the router to loose power long enough to cause a reset. I'll need to way of securing the power plug to the mobile router if I want to use it this way.

Then I took a quick look back at my little insect cage layout.

And I realized that it's actually a pretty good configuration. First of all, as the components are more or less secured in the cage, they don't jostle around that much and thus the power jack stays put. The reason the router stays put is because of this.

The USB modem almost touches the edge of the cage, so it acts as a support and stops the router from slipping around in the cage.

While the larger 6V battery does slip around if there's too much movement, it's cushioned from the router by the strap securing the router. Unfortunately during my latest testing I noticed that when the router get's uncomfortably hot, heat is transferred to the top of the battery. Not very cool since there's a "Do not overheat above 60 degrees Celsius" warning on the battery. Must see if I can do anything about that.

The cage design also allows for me to reach the power switch to turn the whole system on or off.

I guess I should stop trying so hard to make a wearable mobile router solution, and work more on how to make a proper transportation case for the whole setup so I can just throw it into a bag. :P

Project Belt Is Complete

2010-03-13T21:51:42.1607908+08:00

Today I went to pick up some parts to complete my Mobile Hotspot Project, first of all I decided to get a smaller sized battery since the one I had original, is big and bulky. So I wanted to get something that's smaller and easier to carry around.

So I got this, 6V 1.2AH battery. My first surprise was that while the battery capacity was about 1/4 of the big battery, it costs TWICE as much! While I was soldering the connection wire I learnt something new. I should solder the connector first, before soldering the wires to the battery. Because I soldered the wires to the battery first while I was soldering the connector... I shorted the connection with my soldering iron, sparks flew! Good lesson...

So after the smaller battery was completed and tested to be working I created the other component which I wanted to make.

A 4AA battery holder, with normal alkaline batteries these would theoretically give out 6V of power which should be more than enough to power the router. I measured the current with a multimeter and got a nice reading of 6.6V, So I went ahead and plugged it to the router. And I was happily surfing the net with AA batteries.... for about 10 minutes. Then the router started flickering on and off, a good indication of low power scenario. I unplugged the batteries and measured the power output and I got... 5.5V!?!?!?

I figured it's because that when an alkaline battery is used out the voltage gradually decreases on a slope. Unlike a rechargeable battery which is at the same voltage for most of it's usable lifespan and then drops. I guess the way is to introduce more power into the loop.

Luckily I was prepared for this scenario. While I was thinking of using AA batteries to power the setup, I was planning to use rechargeable batteries. But.. a rechargeable AA battery only has a voltage capacity of 1.25V, 4x1.25V = 5V. Cutting it a bit close so I thought of an idea, which is to make a power booster to bump up the voltage.

This battery case will be linked in series to the power source it's connected to, boosting the voltage of whatever it's connected to by 3V. Once I plugged this in I can again power the router... for a while, once again I could see a very drastic drop of power in the alkalines once hooked up to the router. It's obvious that alkalines aren't the best source of power to be used in this scenario.

I then decided to work on a power switch so I can turn power on and off when I wanted to without having to disconnect the power source to the component.

You might have noticed that each piece is more or less interchangable. This allows me to have some form of extendable system, for example I can have the router powered by 4AA batteries, as well as controlled by the power switch.

Then if needed to, I can plug in the booster pack.

Depending on the situation, I can plug in an extension wire, and then the lightweight 6V battery.

The reason I needed this extensibility was because I had a crazy idea, and it involves this thing.

A belt strap... cause I want to try and do this.

Hook everything up to it and really carry it around in a portable manner, the problem of course is that if people saw a SLAB strapped to someone, they probably would think that I'm a suicide bomber or something!

Anyone have a good idea to make a belt like this look less like a suicide belt?

I should have more training

2010-03-12T22:26:41.3095669+08:00

There are times when I wish I had more training and understanding about how to build electronic hacks. Especially at times when it involves AC current.

Here I've taken an AC/DC adapter, replaced it's head with a composite jack.

Just so I can charge the SLAB I gotten for my portable hotspot project.

And I don't think I chose a safe spot to do it too!

Well, power should flow from the higher 7.5V of the adapter to recharge the lower 6V of the battery.. I THINK! The charging method matches what Adrian used in his battery extender project. But heck, I'm not sure if I done everything right!

Also, the power adapter is FICKLE!! Sometimes when I turn it on it pumps out 3.5V, sometimes.. it pumps out 7.5V.. it's weird! And... how do I know if the battery is being charged? Well... the adapter was hot for a while. And I think at charge the battery has a 6.5V rating.

Maybe I should abandon project Mobile Belt?

One More To Go.

2010-03-12T09:50:27.1566084+08:00

Just one more!

So, you wanted your internet connection everywhere?

2010-03-07T21:27:32.5161069+08:00

Got a new toy recently. This here is the Sapido GR1102

It's basically a compact internet router.

So you can use this to share a hotel internet connection and what not, just like a normal router. But of course if it was just another compact router, I wouldn't have gotten it. :P

Along with a couple of other features which you can find out about on the product website, the 1st reason that I got the Sapido is that you can do this.

You can plug in a supported USB 3G modem which can then be shared wirelessly. This is especially handy when you got to meetings in other people's offices and you'd rather not (or are not allowed to) connect to their office network to get internet connectivity. You might argue that you could just connect the modem to your notebook and do the same thing, but what if you had multiple people from your office attending the meeting? Even though you can use internet connection sharing in Windows to share the connection, a dedicate device offers better performance... and your machine doesn't wait cycles trying to act as a router.

All this is fine, WHEN you have a power plug to connect to though. That's why here's the other reason I got this nifty little thing.

The GR1102 is able to be powered by 5V delivered via a USB mini cable. Or if you swap out the AC plug with the supplied connector.

You can then power it with DC current ranging from 5V ~ 12V. It sounds GREAT in theory, all I have to do is bundle this along with any one of my USB power supplies and I can be a mobile hotspot wherever I go. But what you can't see is the current requirements. Let me adjust the image so you can see the writing on the power socket more clearly.

It says "5-12V Min 10W". Now how would you go about getting 10W from 5V? It would mean that the power supply would need to be able to deliver 5V 2Amps(!)Checking with the Sapido website I found out that you don't actually need 2A, but rather just 1.5A. This is still a VERY high current requirement. As I mentioned in my car charger article previously. Sometimes it's not just a matter of volts but also amps in order to power your devices. Let me give you some examples of 5V power sources you have access to. Your computer's USB port is rated for 5V 1A, so the Sapido can NOT be powered by just ONE USB port, so you'll need to use a Y cable to power it. A typical USB battery source like what I have, outputs 5V but in varying current ranges from 500MiliAmps (apologies to people who actually know how to write the proper current notation, cause I CLEARLY DON'T!) to 1A. This is because they typically use some form of a 3.7V LiIon battery in them and then boost the voltage to 5V lowering it's current capability as a result.

So after futilely trying out a few other external batteries in the market, I figured I needed to build my own power source, a battery that clearly delivers the required voltage without passing through any voltage converters. I did the math and decided that I could build a battery pack out of EIGHT AA BATTERIES (8 x 1.2V = 9.6V, y 1.2? Rechargable batteries mar!) But I decided to try this first.

This is what we call a SLAB (Sealed Lead Acid Battery), You don't usually see one on it's own like this but it's used in thing's like UPS's, Motorcycles, and other equipment. It's a good choice for powering the Sapido because SLABs have (AFAIK) high current capacity, It's NOT a good choice for portability because SLABs are HEAVY! This one weighs errr.... more than 500 grams less than a kilo.

While SLABs are rechargeable batteries, I don't have any experience in building whatever that will recharge the battery so I referred to Adrian's old battery extender guide since he used a SLAB before. So half an hour later and again reminding myself I have no idea how to solder connector plugs properly I ended up with this.

And it works perfectly!! The battery supplies enough power to the router and I have my mobile hotspot. Or do I? I realized that not many people have actually seen a SLAB before, in fact I'd think that most people would have seen SLABs being used as bomb triggers in movies or TV shows. So I told myself carrying a SLAB with wires and tape all over it might not be such a good idea right now. I head on over to my favorite place for finding weird shit nowadays – Daiso. And I ended up with this.

For those of you who are thinking WTF? This is an INSECT CAGE, I decided to get this one instead of other normal cases because the router can get QUITE hot when in use, so the open ventilation should be sufficient to cold it off. I used the straps from my previous attempt at a car pc to secure the devices.

The 2 things just barely fit into the case itself, I haven't really done a proper test run yet cause I haven't been able to obtain a proper adapter to charge the SLAB and thus I don't know how long the power will last (Unless someone tells me that it's ok to pump 9V into the SLAB to charge it even though it says it's charging voltage is 7.2V) I'm really interested in seeing if the router will melt the cage after prolonged use!

One Step Closer

2010-03-07T00:26:10.6536129+08:00

I still remember taking this picture.

This was in 2008, WZ was just slightly over a year old then but he wanted to try and drive. And now...

Soon... soon...

Don't Call It A Q&A When You Can't Answer Anything!

2010-03-05T11:24:36.3132129+08:00

Just wasted my time paying attention to the #WP7Dev hashtag on Twitter just now, I (as well as other developers I think) thought it was to coincide with the announcement of the available frameworks on Windows Phone 7 Series done here. Another interesting thing to find out was that MS is still gonna push WM6.5 hmmmm, most likely WM6.5 is gonna become the preferred Enterprise App developement platform for writing company specific applications and the like, and WP7 for end users. That'll make for an interesting split... we'll see what happens.

So I was right about my predictions on XNA support in Windows Phone 7, I wouldn't call my prediction that Silverlight 4 support is right until they announce it at MIX, this is because from my point of view. The SL4 beta that we have access to is not fully suitable/capable of being an actual client framework yet. Hopefully something will change at MIX '10

Which was my main peeve about the Q&A session just now. They called it a Q&A session, but when most questions could not be answered, or had to be answered with a WFM (Wait for MIX) remark. WHY DID THEY EVEN BOTHER TO CALL IT A Q&A!!!

Just make the announcement on Twitter about the frameworks and leave it at that then, then people won't be pissed when they can't actually get any answers out of you since you never said you'd answer questions!

This is how you make a toy

2010-03-04T23:32:34.9176129+08:00

Kids around my part of the world most likely would know about Masked Rider, basically it's a super hero that fights monsters on a weekly basis, and it has been around for a long long time. The main thing that made it cool for us kids was the transformation belts which the heroes wore, or drivers as they are called. So anyway here's a video of the latest Kamen Rider Double's transformation sequence.

And now... this is how the TOY works.

It pretty much works EXACTLY THE SAME!!! I was really surprised as to how similar it was compared to the one depicted in the show. And then there's the detail of the thing.

It looks almost exactly the same to me. Even the memory modules in the show also look just like the toy. Down to the visible speaker at the top of the unit.

Such good design and detail leads me to one question.

Which came first? The toy or the prop? Cause I think it's sure possible that they designed the toy, ensured how it works. Then made use of the thing in the show. What an impressive way to make a toy which every Kamen Rider watching kid would want!

It's not like I can wear the thing!

The darn glowing trees

2010-02-25T01:30:55.8405714+08:00

So I went to look at some lights in the shape of trees in Shah Alam I-City, I wouldn't exactly say it was a fun experience. First of all when we got there we had the choice to park in 2 places, illegally on the road shoulder of a 4 lane highway opposite the park where said trees are, or in a large deep car park where you need to walk a bit before you can get back topside to where the fun is.

Walking isn't usually a problem but when kids and old people are involved, you could see those kind of people just worn out and sitting on the streets. This was definitely NOT meant to be a tourist spot. There were some parking near the park area.

But if you tried to park in these parking, someone resembling these guys will descend upon you.

And tell you that you can't park in the parking. I wonder why since no one is using the spots at night anyway not like we're taking spots away from the tenants. Then one of them reminded me that "This is private property, you come into my house, you abide by my rules" Well said I-City, I'll remember that.

So what can you see over at I-City? You're going there to see stuff like this.

LED Lights. Tons and tons of LED lights.

Some will be drapped over wireframes to form some interesting shapes.

Then there are some that are just hung around.

Hmmm.. maybe that's why they wanted to keep the parking empty? But then again there're many spots outside of this scenic shot.

And of course you get to see these.

These darn LED trees.

While they might look like real trees decorated with lights

They're not. So we're not looking at some meticulously decorated tree here. These are essentially glorified LAMP POSTS. But I guess it's ok that they are fake trees cause I felt a lot of heat coming from such a huge concentration of lights. (Then again it could have just been the weather.)

Nothing particularly outstanding, but I guess since they don't charge any entrance fee other than having you walk around a lot. And it is closer than FGS from PJ. So... if you have the time... why not?

The shot you see above contains about 1/3 of what there is to see over there.

Oh.. point to note for all you budding photographers going to all these light shows and trying to take shots of the lights. While a slow shutter speed will help you get nice pictures of lights, if you need to take pictures of people standing in front of lights like this.

Read your manual and figure out how to turn on rear sync flash, or night scene mode. So that you don't end up killing the effect of the lights with your flash and having your significant other go "DEE SLR also cannot take nice light picture one geh?"

Of course, if your camera can manage a high ISO shot. You can retain the multi color lit ambience of the trees.

I'm not teaching you how to take photos here, I'm just letting you know you should familiarize yourself with your gear for tricky shots like this. Lest your partner keep reminding you that your expensive camera can't take nice pictures.

OK.... I think I'm ready to go to FGS Dong Zen on Friday night then.

One Hell Of A Night

2010-02-23T00:17:43.0401076+08:00

I had one hell of a night yesterday, first of all at around 1AM I saw a very pissed off wife run outside the house. For those unfamiliar with Chinese customs 22nd Feb was the night where some special prayers would be done by some chinese.

And someone in our neighbourhood were launching thunderclaps NON STOP from 12AM to 1AM, and everytime one of those thing’s screeched through the sky, it’d wake up the dog behind my house, and more importantly it’d woke up my wife. So instead of letting her go postal on the people I decided to take it upon myself to find the source of the disturbance and take care of it.

I found the source which was a house a couple of blocks away from mine, there were 2 kids constantly setting off the things while their parents looked on. I appealed to their community spirit and asked them to stop. Luckily they complied, and I went back home to sleep.

Until I heard the dogs barking and someone banging on the window of the side room where my maid used to sleep in. Through the tinted kitchen window I saw a man walking around the back of the house. My father scared him off by screaming at him from behind the window, at which point I ran outside to see if he dropped anything and I found this in the drain.

At first I thought this was a condom wrapper from afar, but it turns out to be chewing tobacco according to friends who can read the words. Now I’m just afraid if the person will return and try to take any action against our house since we pissed him off..

sigh…