This ia bit of a tangent from the content I normally post, but worth checking out. Looking for a low cost way to enter the fast paced, high energy world of print collection? Interested in very small prints? Tiny Showcase has some really beautiful pieces and, though small, they sell for $10-$12/piece.
You may have noticed another long unexplained absence of movement on notstatic.com. Woops. I’ve recently acquired the prestigious role of Mr. Mom around our house. My expecting wife has been consigned to bed rest so I’m left in charge of our 18 mo. old son (George). This is fun / time consuming / boy am I tired. With that in mind, though, I’ll try to be a little more active on the blog.
Sorry that I’ve been pretty silent for the last couple of weeks. I was at PDC for a week and then took a week and a half off to visit my wife’s family in Ithaca. Well, as you can imagine, this meant a lot of flying and I used my time on the plane to build some control styles. The two I’ve made so far turned out pretty nicely, so I’ve posted them for your styling pleasure. So far, I’ve only created two styles: one for Button and one for TabControl, but more should be coming. These work with the September CTP bits (which are the same bits handed out at the PDC).
One issue that is somewhat germane to control styling is the issue of transparency and hit testing. Generally WPF just does the right thing for you. If, for example, you created a template for a Button that contained only an ellipse, the Button would only respond to a mouse click on the ellipse itself and not on the “corners” around the ellipse.
This works because the Button only gets mouse events on pixels where it has drawn something. This is usually what you want and what you would expect. There is a snag though.
The snag is characterized by the experience of a commenter on this site who was trying to get hit testing on a Canvas. He found that he couldn’t get a mouse event to fire unless he set a background on the Canvas. In the context of the model I just described, this makes sense but can be frustrating.
We also hit similiar issues in control styles where we want hit testing on a region of the control that appears transparent. This might be the case in MenuItem or a ListBoxItem, where the item spans the width of some container but only has visible content in a portion of it.
The work around is the magic system brush called Transparent. This actually maps to the color “#00000000″ and the two can be used interchangably. In fact, the only important thing here is that the value is non-null and the alpha value (the first two digits in the hex representation) is zero. By making it non-null, we enable hit testing. By making the alpha zero, we prevent it from actually drawing anything.
You can see this work in a simple example by creating two buttons and setting the background of one to null and the other to Transparent. They will look the same but behave differently.
