Blog redesign

Ok, I am working on the blog to make it more accessible. I've replaced the template, I made all changes in the template from javascript and CSS, not by editing it and I've removed many of the things clogging the site. Not the cats and flies, though :) The light (low band) version of the site is not working anymore. If you want just the content, you can open the RSS feed.

I would like to know what you are thinking about the new look and I hope I will find the time to write interesting posts.

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A Song of Ice and Fire by George R. R. Martin

I almost expected the guy to be Canadian. :) This series of fantasy books is a masterpiece of writing. Not only it is complex of plot and emotion, but the characters are many, diverse and (most of all) different.

So far, the A Song of Ice and Fire saga, written by American author George R. R. Martin, consists of four books, the first published in 1996 and the last in 2005. At least three other books are planned in this series. The plot is a historical fantasy, but one unlike the books I've read recently. The aspects of magic and otherworldiness are rare, the bulk of the writing being about the feudal world, with kings, knights, low borns, maidens and whores, thieves, rapists and murderers, plotters and honorable men. No wonder that, lacking a lot of special effects, the story has been selected as the basis for a TV series.

But what is more important than anything is that the writing is really good. The characters are all human, with needs, desires, qualities and faults. You can't help but empathise with them, only to suffer at the cruel fate the writer bestows upon them. Not one escapes unscathed from the malice and pettiness of other people or from shere bad luck. You get to like the characters, then Martin fucks them up. I really wanted to use a more elevated language here, but it's the truth: the world he depicts seems horribly real, not a fairy tale of valiant white knights and pure maidens, but of ridiculous people grabbing lustfully whatever life offers them as it is unlikely their fortune is going to last long.

For the bad part, though, I think the author went too deep, got himself responsible for a lot of characters that he must now move forward, in gruesome detail. The fourth book became so large that he had to split it. He did so by character and geography, rather than by time, so a lot of the characters were missing from the fourth book, A Feast for Crows, and left for the fifth, but acting in the same timeline. At the end of A Feast for Crows the author explains his decision to not just split the book in the middle with a "To Be Continued" ending, and hopes for a publication of the second half in a year. That was in 2005. Ahem.

A lot of people are a bit confused by the long wait for the fifth book. Martin keeps making promises that he doesn't keep and, in July this year, he announced that A Dance with Dragons is already 1400 pages long and 5 chapters close to completion. I hope he does finish it quickly enough, although that would only prolong my suffering anyway. I am sure the fifth book will be as brilliant as the others, but then I will have to wait another 5 years for the sixth. I know TV series usually have no plot, but at least they come weekly ;)

Bottom line: The books are great, I recommend them to any lover of fantasy or even historical novels. I can hardly wait for the TV series, A Game of Thrones, as well.

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Prince of Nothing by R. Scott Bakker

While waiting for the tenth book in the Malazan Book of the Fallen saga, I went and read Prince of Nothing, by another Canadian author, R. Scott Bakker. This is a three book story, first published in 2004, about what I can only describe as a psychopath, member of a rationalizing sect, going out into the world to protect the secret of said sect.

The book is well written, although not nearly as brilliant as the Malazan series. However the subject of it is very interesting, at least from my standpoint. It concerns a human that is trained in the ways of mental manipulation, rationale and causality, something akin to the Vulcans from StarTrek, but with a very human side to it, the one that pushes one to amass power and use their knowledge to manipulate.

No wonder that the "prince of nothing" is the central character in the books, but not the main character, the role being left to a sorcerer, a man that is at the same time keeper of arcane knowledge and the scorn of ordinary humans. I can't help but empathize with the guy: basically a geek in love with a whore, while a psychopath destroys his world with insidious manipulation. ;)

There is another central character to the story, an insane barbarian, like a tortured Conan, who is both terrifyingly strong and ridiculously fragile, both a mindless warrior and a brilliant strategist. He is also, like Achamian the sorcerer, an exponent of humanity.

Prince of Nothing is a very smart book, one that can only get better as the writing skills of Scott Bakker improve. Its assets are both a scientific approach to the human psyche and a veritable intrigue of arcane powers in conflict with each other on the background of huge masses of clueless people. The plot itself is similar to the story in the Berserk manga, at least its start, where the strong warrior chooses to follow the charismatic and ambitious leader only to his doom. The moral, as I saw it, is that while we choose to live our lives with eyes closed, we cannot in good conscience pretend to deserve control over what happens to us.

I hope the series, known as "The Second Apocalypse", continues, since Prince of Nothing raised more questions than gave answers and the plot really caught my attention. A nice book that I warmly recommend.

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Collaboration page closing

I haven't been the most present of hosts, but then again, I haven't seen much interest for the collaboration page, with its open chat and whiteboard. Therefore I replaced the link to it with the Plugoo chat. The blog desperately needs some refactoring, but not likely that it will happend soon.

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Converting WPF UserControls to Controls with a theme

I was working on this application and so I found it easy to create some controls as UserControl classes. However, I realised that if I wish to centralize the styling of the application or even move some of the controls in their own control library with a Themes folder, I would need to transform them into Control classes.

I found that there are two major problems that must be overcome:

1. the named controls in a user control can be accessed as fields in the code behind; a theme style does not allow such direct access to the elements in the control template.
2. the controls that expose an event may not expose an associated command. In a user control a simple code behind handler method can be attached to a child control event, but in a theme a command must be available in order to be bound.

Granted, when the first problem is solved, it is easy to attach events in the code of the control to the child elements, but this presents two very ugly problems: the template of the control will need to contain the child elements in question and the event will not be declared in the theme, so the behaviour would be fixed as well.

I will solve the handling of events as commands by using a solution from Samuel Jack. The article is pretty detailed, but to make the story short, one creates an attached property for each of the handled events by using a helper class:

public static class TextBoxBehaviour
{
    public static readonly DependencyProperty TextChangedCommand = 
         EventBehaviourFactory.CreateCommandExecutionEventBehaviour(
         TextBox.TextChangedEvent, "TextChangedCommand", typeof (TextBoxBehaviour));
     
    public static void SetTextChangedCommand(DependencyObject o, ICommand value)
    {
        o.SetValue(TextChangedCommand, value);
    }

    public static ICommand GetTextChangedCommand(DependencyObject o)
    {
        return o.GetValue(TextChangedCommand) as ICommand;
    }
}

then by using a very simple syntax on the control that fires the event:

<TextBox ff:TextBoxBehaviour.TextChangedCommand="{Binding TextChanged}"/>

The problem regarding access to the elements in the template is solved by reading the elements by name from the template. In some situations, like when one uses a control as a source for a data control (like using a TreeView as the first item in a ComboBox), the approach will have to be more complicated, but considering the element is stored in the template of the control, something like this replaces the work that InitializeComponent does inside a UserControl:

[TemplatePart(Name = "PART_textbox", Type = typeof (TextBox))]
public class MyThemedControl : Control, ITextControl
{
  private TextBox textbox;

  public override void OnApplyTemplate()
  {
    base.OnApplyTemplate();
    textbox = Template.FindName("PART_textbox", this) as TextBox;
  }
  ...

The code is pretty straight forward: use the FrameworkTemplate.FindName method to find the elements in the OnApplyTemplate override and remember them as fields that you can access. The only weird part is the use of the TemplatePartAttribute, which is not mandatory for this to work, but is part of a pattern recommended by Microsoft. Possibly in the future tools will check for the existence of named elements in the templates and compare them against the ones declared in the control source.

The code of a demo project can be downloaded here.

Some other technologies I have used in the project:

• the RelayCommand class, to make it easier to defined ICommand objects from code without declaring a type for each.
• the AccessKeyScoper class that allows an IsDefault button to act locally in a panel.

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Replacing BitmapEffect in WPF 4 as they are now obsolete

If you google the net for using visual effects in WPF you are very likely to hit BitmapEffects. Well, bad news, BitmapEffect is obsolete and broken in WPF4. Instead you have Effect. The idea is to write (or download) a custom Effect for the things one would normally do using the slow (but easy to use) BitmapEffects. Also, the BitmapEffectGroup doesn't work anymore and has no alternative in WPF4. Bummer! According to Dr. WPF, the framework will try to automatically translate the older BitmapEffects to the new ones. That applies for BlurBitmapEffect and for DropShadowBitmapEffect with a Noise level of 0, for the others... you are on your own.

There were 5 default BitmapEffect classes in WPF3:

1. BlurBitmapEffect - the WPF4 alternative is BlurEffect
2. OuterGlowBitmapEffect - the WPF4 alternative in the Microsoft article is BlurEffect, but I have found that it can be replaced by DropShadowEffect with ShadowDepth set to 0
3. DropShadowBitmapEffect - the WPF4 alternative is DropShadowEffect
4. BevelBitmapEffect - the WPF4 alternative is a custom class inheriting from Effect.
5. EmbossBitmapEffect - the WPF4 alternative is a custom class inheriting from Effect.

I found this project when googling to a simpler way of building ShaderEffects: WPF ShaderEffect Generator. Also, a discussion about a Bevel ShaderEffect here led me to this WPF shader library, but it's last release date is somewhere in March 2009.

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Tab order navigation in WPF

I am using this WPF control that looks like a headered panel. On the header there is a menu, a button and then, underneath, some content that could be anything. I had this request that, when using the Tab key to navigate, the focus should first come to the button, which is not the first control in the header, then jump to the controls in the content and then jump back to the menu. In other words, to make the menu the last controls that can be reached via the Tab key inside this WPF control.

Well, in WPF there is this class called KeyboardNavigation which has some very useful attached properties: TabIndex (which defaults to int.MaxValue) and TabNavigation (which defaults to Continue). As in Windows Forms, one needs to set the TabIndex to control the navigation order, but the TabNavigation property makes it a lot more versatile and clear as well. In my case, I had to do the following:

1. Set the entire panel control to KeyboardNavigation.TabNavigation=Local. That allowed me to control the tab index inside the control, otherwise the TabIndex value would have been global to the window
2. Set the TabIndex of the button to 1. That made the button the first thing to be selected in case I use Tab to navigate in the panel
3. Set the TabIndex of the content to 2. This set the controls in the content as the next controls to be accessed via the Tab key
4. Set the TabNavigation value of the content to Local. Without this, the TabIndex value would have made no sense. First of all the content panel has IsTabStop to false and, second, any control inside it would have int.MaxValue set as TabIndex which would work globally in the main control.

This example should make it clear how to use the KeyboardNavigation properties. There is one more, called ControlTabNavigation, which has a misleading name and an ambiguous description. It is not related to a control, the Control in the name comes from the Ctrl key. In WPF one can use Ctrl-Tab to navigate an alternative order thus allowing, in this case, to go directly to the menu, then the button and then the controls in the content area.

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