Archive for the 'Flex' Category

Actionscript 3 vector speedups

Thursday, September 25th, 2008

Mike Chambers has posted a comparison between the performance of AS3 arrays and the new Vectors available in Flash Player 10. The results look good: he managed a 60% speedup. This is very exciting for us at CleVR, because of the potential impact it has on the Stitcher in particular. This uses massive Arrays and lots of nested loops which seem to be just the kind of thing that would benefit from this. I haven’t had a chance to do any benchmarking of my own (hard at work on CleVR Pro) but when I do I’ll post another entry.

Hiding Flex DataGrid columns using a context menu in AIR

Thursday, August 28th, 2008

A Flex/AIR project I’m working on at the moment uses a DataGrid to display a lot of data. There needs to be lots of columns, but this means that the view can be a bit cluttered. What I wanted was an easy for the user to show or hide columns as they prefer. In Cocoa on Mac OS X you can right-click (or ctrl-click) to show a context menu to do this, which seems to be a good way. I thought there may be a way of doing this in Flex, but there didn’t appear to be. It was quite simple to implement and could be useful in lots of cases, so I thought I’d share the code. I put this in a creationComplete handler.

I’ve attached it as a context menu on the DataGrid, but you could also attach it to the header or to a button. I hope it helpful to someone.

var context:NativeMenu = new NativeMenu();
for each (var col:DataGridColumn in myDataGrid.columns){
	var menuI:NativeMenuItem = new NativeMenuItem(col.headerText);
	menuI.checked = col.visible;
	menuI.data = col;
	context.addItem(menuI);
}
context.addEventListener(Event.SELECT, function(e:Event):void {
	var t:NativeMenuItem = e.target as NativeMenuItem;
	t.checked = !t.checked;
	t.data.visible = t.checked;
});
 
myDataGrid.contextMenu = context;

State change bug in Flex

Sunday, August 17th, 2008

I’ve been trying to track down the source of a bug in the Stitcher. The issue was in the welcome screen, which has states for logging-in, creating a new account etc. The problem was that whenever the login state had been active, moving to another state would throw an error, The supplied DisplayObject must be a child of the caller. After much trial and error I worked out that it was down to the ControlBar that held the login buttons. It seems that the issue is that when Flex adds a controlbar, it doesn’t actually add it as a child of the container in which you place it. This means that when you then try to remove it, it’s in the wrong place. It seems to be related to this bug, which was apparently fixed last year. I’m going to have to produce a minimal version and see if I need to submit a bug report and/or patch.

Anyway, after changing it to use an HBox it’s working. I’ve uploaded a new version of the CleVR Stitcher with that fix and a few others. You can install it from that box in the sidebar (unless you’re reading this via the feed).

Resizing Actionscript images with bicubic or bilinear interpolation

Thursday, July 10th, 2008

I’ve had a few people contact me to ask about how to use clevrlib to resize images with bicubic or bilinear interpolation in Flash or Flex, so I’ll give an overview of how to do this.

The InterpolatedBitmapData class adds the methods getPixelBicubic and getPixelBilinear to the BitmapData class, which allows you to fetch the colour of a point that’s not on a pixel boundary. We use this when reprojecting the source images in the CleVR Stitcher, but it can work just as well for resizing an image. Bear in mind that bicubic is a lot slower than bilinear, and the quality improvement isn’t usually worthwhile. However, you’re welcome to switch to getPixelBicubic if you need to.

The basic method I’m using here for resizing is to loop through the pixels of the output image, getting the equivalent pixels in the source image. As these are found by multiplying by the ratio between the source and output sizes, the coordinates probably won’t be integers. Using regular getPixel would require rounding, and therefore give a jagged (aliased) output. The getPixelXxx methods let you pass them a Number, which needn’t be an integer, giving a much smoother result.

The sample code below shows a way of resizing an image using this method. The InterpolatedBitmapData should be created in the same way as a BitmapData, such as by draw()ing a loader onto it. The example I’ve shown below is an Event.COMPLETE handler for a Loader. Code below the cut.
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Tucows on how to use CleVR

Tuesday, June 3rd, 2008

There’s a great article over on Tucows about how to use CleVR to create and share panoramas. In fact, I’d go as far to say that it’s better than our own documentation! Go and take a look, and if you like it then Digg the article.

Important CleVR Stitcher update

Saturday, May 17th, 2008

It’s been a while since the CleVR Stitcher was updated as I’ve been working on some other important projects. I also had a much needed holiday! Today I have released a new version that fixes lots of bugs which have been reported over the past month or so. It also makes some hopefully significant improvements to the stitching algorithms. If you had problems with poor stitches in the past, then give it another try as it should do better. The improvements are mostly related to common problems in panoramas that have been shot by hand without a tripod.

Thank you everyone who submitted bug reports. They have bee very helpful. This release should fix all of the most commonly reported problems. See below for a list of updates, and important information on installing the update.
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New Stitcher, new AIR

Sunday, March 2nd, 2008

On Monday, Adobe AIR was officially launched. Of course, we’ve been using the beta version of AIR for the CleVR Stitcher for over six months now, but it’s good to see it go 1.0. This means that we’ve also released a new version of the Stitcher, which uses the latest version of AIR. You can install it below, using the shiny new installer badge. It will update or install AIR for you if needed.

New version of CleVR panoramic image Stitcher

Tuesday, January 15th, 2008

We’ve just released a new version of the CleVR Stitcher. This uses the new version of Adobe AIR, and also adds several features and fixes lots of bugs. If you download it, please do let me know what you think and if you have any problems with it.

New CleVR hotspot editor

Sunday, September 9th, 2007

The hotspot editor on CleVR.com has now been updated so it’s the same as the one in the new Stitcher. It looks quite similar to the old one, but it’s a rewrite done in Flex instead of Flash (if you don’t know what that means, don’t worry). It is however pretty much bug-free now: the old one could be a bit unstable at times. Now that it’s running off the same codebase as the Stitcher, any remaining bugs should be fixed quickly. As ever, comments and bug reports are appreciated.

If you haven’t tried adding hotspots to your panorama, give it a try. If you’re logged-in, you’ll find a button on the panorama page to edit them. Hotspots let you add another level of interactivity to your panoramas. You can create areas within the panorama that can be clicked to give more information or to move to another location. You can display text, images or even Flash files such as Youtube movies. Links to other locations lets you move around an area – for example, you could click on a doorway to move to a panorama inside a building or in a different room.

CleVR Actionscript libraries now on RIAForge

Thursday, September 6th, 2007

I’ve put up the CleVR AS3 libraries on RIAForge, where you can download them as a zip file, or use the svn repository.

The library includes a number of classes that we developed as part of the CleVR Stitcher. They include a set of matrix algebra classes, ported from the Java JAMA library. These let you do standard matrix algebra stuff, and includes support for singular value decomposition and QR decomposition.

There’s also some graphics classes. One is a subclass of BitmapData that adds bicubic and bilinear interpolation. Another is a class for calculating the histogram of an image, with methods to do histogram stretching. This gives results similar to “Auto levels” in Photoshop, or “Enhance” in iPhoto.

You will find them here. They’re released under the Creative Commons attribution licence, which basically lets you do anything with them, so long as you give credit somewhere. A link to clevr.com would usually suffice. Let me know if you have any comments, patches, or if you’re using it.