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Category: Learning

Recursion: Emptying a Folder

Do you need code to delete the files and folders from the selected folder? In that case, there is a technique I propose to you and that is based on recursion. That is, the ability of a function to call itself repeatedly until the task is complete; in this case, the function will call itself every time it detects a new folder/directory inside the designated original folder/directory.

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Web: Create Sliding-Animated Menus

Sometime ago a Xojo user asked if it is possible to use Xojo Web to create the kind of animated menus seen in several regular websites. After some investigation (and the invaluable help of Greg O’Lone), the answer is: yes, you can do that! If you are interested in seeing how to achieve this, continue reading!

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Animating the Web: Fading Images in-out

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.

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Hour of Code: Xojo Dojo

December 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.

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Web Services Part II: Xojo Web, at your service

In 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!

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What’s important in a programming language?

I 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?

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Drawing Objects in a Canvas with the Paint Event

The 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.

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Tutorial: Saving WebCanvas Images to Disk

The WebCanvas control is used for drawing graphics in web apps. It takes advantage of the HTML5 Canvas making it fast and powerful. Sometimes is can be useful to be able to save the graphics drawn in the WebCanvas to an image file, but unfortunately there is no built-in Xojo method to do this.

However, by using a little JavaScript you can easily add this capability to Xojo.

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Web Services: Xojo Web, at your service

Using Xojo Web to create complete web apps and solutions means not having to learn a bunch of interpreted languages and dozens of ever-changing frameworks. I’m looking at you: HTML, CSS (is that even a language?), JavaScript, PHP, et al. Of course, Xojo Web not only makes it possible to create your own web apps, but it also acts as the perfect middleware that your desktop and iOS apps can communicate with. Learn about APIs and web services with Xojo in the tutorial blog post.

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