Latest posts from Codename One.
Blog
Insights, release updates, tutorials, and engineering notes from the Codename One team.
Photo Cropping Wizard
A month ago Francesco asked how to implement the common image cropping UI we see in many applications where the user can pan and zoom to decide the cropping area. We implemented that feature by effectively enhancing the ImageViewer class with two new methods: public Image getCroppedImage(int backgroundColor); public Image getCroppedImage(int width, int height, int backgroundColor); But that’s just the first step, implementing the whole UI is still not trivial. We’d like to add a more general purpose component that does that but doing this with an approach that’s sufficiently generic is hard… ...
Asynchronous Media
There are a lot of fixes and new features that I don’t get to cover enough as I’ve been busy on several fronts. One of the new features is support for asynchronous media API’s. These let us create a media object without waiting for it to complete. This is very useful if you have a complex UI and want to play a media file while doing other things. ...
TIP: Reordering Tabs
The Tabs class is pretty powerful and flexible as I mentioned before. One thing it doesn’t support is drag and drop to re-order the tabs. Here the flexibility of Codename One takes over and allows us to accomplish it. We can use the builtin drag and drop support for components within the tabs container. This is exactly how the code below works. In the drop listener we block the the default processing of drop behavior so we can move the tab manually to the new location: ...
Lightweight Text Selection
Text editing is implemented natively in Codename One. This provides a huge benefit as it allows us to ignore a lot of complex topics such as virtual keyboard localization etc. If we had to implement all that logic the overhead of Codename One would have been huge… One free benefit is seamless support for copy & paste. It “just works” thanks to the usage of the native widget we don’t need to worry about that UI. However, this breaks down when we want to provide the ability to select & copy without the ability to edit. E.g. in a web app we can usually select any bit of text and copy it… That’s convenient for some cases. ...
Camera Kit Rewrite
The native low level camera API on Android is a disaster. It’s often cited as one of the worst API’s on Android. To make matters worse there are two separate API’s Camera and Camera2 (yes really). You need to use Camera2 where it’s available but that means no support for older devices. To solve this we picked the Android Camera Kit library when we started building our low level camera support. This proved to be a mistake. ...
TIP: Rich View Revisited
A couple of years ago I posted a tip about rich text view which worked out reasonably well. But it’s a bit outdated by now and it’s worth revisiting. During these two years we published the Facebook Clone which used this component. In the facebook clone I did a lot of work for the rich text. This work added support for alignment and clickable hyperlinks as well as a couple of bug fixes. Following is the code I used in the Facebook Clone for the rich text. ...
Better Error Logging
A common pain point in most GUI frameworks is the hidden stack traces. When we have an app in production we get occasional emails from crash protection which are cryptic and hard to figure out. They usually start with the EDT loop and make no sense. The reason for that is callSerially(). When we have code that invokes callSerially we essentially lose the previous stack trace. So your stack trace would look roughly like this: ...
Zulu Desktop Builds
Sometimes you pick up a task and know in advance it’s going to be hell to implement it. Sometimes, the hell you were expecting turns out to be WAY worse than you anticipated. This is the case for modern Java desktop deployment. Amazingly, Java was able to take one of the worse deployment processes possible and make it MUCH worse than before. If you haven’t used the Codename One desktop port I’ll sum it up to you. We use javapackager (formerly javafxpackager) to essentially wrap the jar file as a DMG/pkg on Mac OS and as an EXE/MSI on Windows. This “worked” in the broad sense of the word. It had a lot of issues and we had to create a lot of workarounds. ...
The Native Version of Build isn't Coming to iOS
When we released Codename One 6.0 we mentioned that Codename One build is going through the approval process on iOS. We didn’t mention that this was a process where Apple repeatedly rejected us and we had to appeal over and over again. We wanted to have a native app because they look/feel slightly better. We also wanted native in-app-purchase as an alternative to PayPal. But it seems Apple won’t allow a native app to do basic things that a web app can easily pull off on its platform. ...
Introduction to UIFragment
I recently became frustrated by the amount of work I had to put into recreating a Component hierarchy programmatically. For a test case, I needed to create a Form with a text field in the bottom, and a button just above it on the right. I ended up with code that looked like: Form f = new Form("Test Form", new BorderLayout()); Container south = new Container(new BorderLayout()); south.add(BorderLayout.SOUTH, new TextField()); south.add(BorderLayout.NORTH, FlowLayout.encloseRight(new Button("Submit"))); f.add(BorderLayout.SOUTH, south); f.show(); The result looks something like: ...
Video Capture Constraints
The new video capture constraints API allows you to specify “constraints” when capturing videos. Constraints include: Video Quality (High or Low) Maximum duration Maximum file size Video Resolution (i.e. width and height). Support for these constraints vary by platform and device, but the API allows you to check if your constraints are supported at runtime. Essentially, you set your “preferred” constraints, and the API will give you its best attempt at meeting those constraints. This is similar to setting a visual Component’s preferred width and height. The layout manager takes these preferred dimensions under advisement, but ultimately sets the size on its own. ...
TIP: Adapting to Tablets
A while back someone asked on stackoverflow how to adapt a Codename One app to tablets. I provided quite a few references in the answer and following discussion but I think a better approach is to explain what we did with the recent Codename One Build app because that’s what I’ve been doing in all recent apps I worked on. I call this approach the “phone first” approach for universal app development. It starts by forgetting about the tablet and focusing on building a good looking phone app. In this app I usually subclass Form for all the classes which instantly creates an app that’s very suitable for phones. ...