Creating components from templates: Numeric Keyboard

With this template you can add a new Numeric Keyboard component to your project. Numeric Keyboard component provides a grid with keys the user can touch. Activating a key feeds the corresponding event to the application as if the user had pressed the key on a real keyboard.

Components created with this template are intended to be adapted to your particular design expectations. After adding the new Numeric Keyboard you should edit the component, change its appearance and if desired also its behavior. Once you have adapted the component, you can embed instances of this Numeric Keyboard wherever you need in your GUI project. Because it serves as template, it is intentionally kept very simple. Nevertheless, Numeric Keyboards created by the template are working widgets. If desired, they can already be used as they are. The following figure demonstrates the default appearance of the Numeric Keyboard created by using the here described component template:

The approach with component templates has two functions. Primarily the templates should simplify the development of new components. Instead of creating the Numeric Keyboard from scratch you can use the available template. The second function is more educative. The template implements fully working Numeric Keyboard component you can investigate and learn about the corresponding programming aspects. The template is well documented. It contains annotations and inline comments with instructions helping you to understand how the component works and how it can be adapted to your particular needs.

This chapter provides an overview how the Numeric Keyboard component template is used within your own application and how you adapt this component according to your particular needs. You will find here also further details concerning the internal implementation of the Numeric Keyboard component.

Add new Numeric Keyboard component

To create a new Numeric Keyboard component from a template you simply Drag & Drop it between the Templates window and the Composer with an opened unit. This is important in that by using the component templates you add in fact a new class to your project. Classes, in turn, can exist within units only. The following are the typical steps to create a new Numeric Keyboard component from a template:

First switch to the Composer page for the respective unit, where you want to add the new Numeric Keyboard component.

Then ensure that the Templates window is visible.

In Templates window switch to the folder Component Templates.

In the folder locate the Numeric Keyboard template.

Drag & Drop the template into the Composer window:

Eventually name the new added component.

The new created Numeric Keyboard component appears accompanied by annotation providing helpful tips how to proceed. If undesired, you can select and delete the annotation.

Use the Numeric Keyboard component

Once you have created the Numeric Keyboard component, you can use it to assemble more complex components. Technically seen, you embed an instance of the Numeric Keyboard class in-place within some superior GUI component. At the runtime, the superior GUI component takes care of the correct initialization and the displaying of all embedded components, so they appear similarly as you have composed them at the design time. Usually, the superior component where you embed the keyboard instance will be the Application component.

Step 1. Add new Numeric Keyboard instance

The following are the typical steps to create a new instance of an already existing Numeric Keyboard component:

First switch to the Composer page for the respective GUI component, where you want to add the new Numeric Keyboard. This is usually the Application component.

Then ensure that the Browser window is visible.

Within the Browser locate the class of the previously created Numeric Keyboard. This can be done easily with Browser's own filter function.

Select the found class in the Browser window.

Drag & Drop the selected class into the Composer area.

Eventually name the new instance according to its function within the application.

Component templates are intended to create widgets which can be modified and adapted to your particular design expectations. In the following sections you will learn how to do this. Originally, if not yet modified, the Numeric Keyboard appears as a white rectangle surrounded by a border and filled with text and images to represent the keys. Our intention is to keep the component templates as minimalistic as possible so they don't distract you with less important design details.

Step 2. Inspect the Numeric Keyboard instance

As long as the Numeric Keyboard is selected you can inspect and modify its properties conveniently in the Inspector window as demonstrated with the property Bounds in the screenshot below. This is in so far worth mentioning as diverse features of the Numeric Keyboard are controlled by the corresponding properties. If you are not familiar with the concept of a property and the usage of Inspector window, please read first the preceding chapter Compositing component appearance.

The Numeric Keyboard component descends from the Mosaic class Core::Group. Consequently, all of the properties listed in the above screenshot are inherited from this base class. The Numeric Keyboard itself does not add any new property.

Step 3. Arrange the Numeric Keyboard within the superior component

Once added to the component, you can freely move the Numeric Keyboard instance, or you simply grab one of its corners and resize it in this way. You can control the position and the size of the component also by directly modifying its property Bounds. If you want the Numeric Keyboard to appear behind other views you can reorder it explicitly.

IMPORTANT

Please note, this document is actually UNDER CONSTRUCTION. It is incomplete. We are working on it ...