The only built-in gesture for undo on iOS at the moment is to shake the device. This is not very intuitive to me and I’ve certainly done it by accident many times. The makers of Procreate chose a two-finger tap and have found that their users adapted to it nicely. This gesture is being adopted by more and more iOS developers. Here’s all the code you need to implement the two-finger tap for undo in your Xojo iOS apps.
Comments closedCategory: Learning
This tutorial will show you how easy it is to create animations on components of Xojo web apps, thanks to the use of the Style Editor and the WebAnimator class. Learn how to do a fade effect between two images that you can expand and adapt to your web apps.
In order to recreate this fade effect we’ll mainly use a couple of styles (WebStyle class) to set the initial status for each one of our images (instances from the WebImageView class). These will be overlaped in the web page, sharing the same position. Then we’ll add a button to the web page so it will fire the animation every time it is clicked.
Comments closedWhen I ask “What kind of variable are you?” I don’t mean “Are you an Integer, a String, a Variant, an Object?”. I am asking “are you a value type or a reference type?”. What’s the difference between the two?
Comments closedPrior to Xojo 2018r3 Window and Canvas both had a Graphics property that you could access and draw to. This was deprecated in 2011 because it had significant performance issues on all platforms. The preferred way to draw your graphics since 2011 has been to use the Window.Paint or Canvas.Paint event handlers and the supplied parameter g As Graphics.
Starting with Xojo 2018r3, this Graphics property was removed from Window and Canvas so if you had code that was still relying on it, that code will no longer compile. Here are some tips on how you can migrate your code to use the Paint event handlers and tell the Canvas to update with a call to Invalidate.
Comments closedDecember 3rd kicks off Computer Science Education Week 2018! Computer Science Education Week is held in early December every year in recognition of the birthday of computing pioneer Admiral Grace Hopper. Alongside this is the Hour of Code promotion where schools throughout the world get students to try at least 1 hour of programming at some point during the week.
Each year for Hour of Code, I volunteer at the local Middle School to talk to the students about what it is like to be a programmer and do a little bit of programming. This year I plan to demonstrate Xojo Dojo with a Raspberry Pi and show the kids how much fun coding and Xojo programming can be.
Comments closedWhile at the Xojo Developer Conference in Denver last spring*, we got a lot of great feedback about the features that people needed most from the iOS framework. We managed to sneak a few into recent releases of Xojo; here are three of my favorites!
Comments closedIn a previous entry we started to dig into web services with Xojo. The first post focused on the backend (server side), creating the Xojo app acting as middleware between the clients and the database that holds your data. We are using SQLite as the backend engine but it would not be difficult to change to other supported database engines like PostgreSQL, MySQL (MariaDB), Oracle or SQL Server, and even ODBC; all of these are supported by Xojo!
Comments closedI started learning how to code as a teenager. Back then there weren’t very many programming languages. I remember BASIC, Pascal, Fortran, COBOL, C and a handful of others that were highly specialized. Why so few? Because in the 1970’s, computers just couldn’t do very much compared to today. The available languages were sufficient for the limited tasks computers had been assigned to manage.
Over the last several decades, computer technology has exploded. The smartphone I carry around in my pocket is far more powerful than the fastest computers of my youth. As a teenager, I rarely encountered anything where a computer had played a part. Today the rare encounter would be with things where computers had played no part. Computers handle so many tasks now that, as a natural consequence, there are thousands of programming languages with more appearing every year.
With so many languages, it can be difficult to choose one. What is important in a programming language?
Comments closedThe Canvas control is a great way to draw pretty much anything to a window. With a Canvas, do all your drawing in its Paint event handler for the best quality and performance.
I’ve had many people ask for an example for how to create a Canvas that allows you to:
- Draw pictures within it (as objects)
- Move these objects
- Remove them
- Add labels to them
- Programmatically select one
This example demonstrates how to do all these things. It has a large Canvas on the window with several buttons that let you add and manage the objects on the Canvas.
Comments closed

