Button

A Button in TouchGFX is a widget that is aware of touch events and can send a callback when the Button is released. Each state, pressed and released, is associated with an image.

The Button can be replicated with the FlexButton. A FlexButton is a more configurable button that takes up a bit more RAM in exchange for flexibility.

Button running in the simulator (pressed state)

Widget Group

The Button can be found in the Buttons widget group in TouchGFX Designer.

Button in TouchGFX Designer

Properties

The properties for a Button in TouchGFX Designer.

Property Group	Property Descriptions
Name	Name of the widget. Name is the unique identifier used in TouchGFX Designer and code.
Location	X and Y specify the top left corner of the widget relative to its parent. W and H specify the width and height of the widget. The size of a Button is determined by the size of the selected images. Visible specifies the visibility of the widget. Making the widget invisible also disables interacting with the widget through the screen.
Style	Style specifies a predefined setup of the widget, that sets select properties to predefined values. These styles contain images that are free to use.
Image	Released Image and Pressed Image specify the images assigned to the pressed and released states from the Designer skin library or the Project folder.
Appearance	Alpha specifies the transparency of the widget. The alpha value ranges between 0 and 255 for the widget. 0 is fully transparent and 255 is solid.
Mixins	Draggable specifies if the widget is draggable at runtime. ClickListener specifies if the widget emits a callback when clicked. FadeAnimator specifies if the widget can animate changes to its Alpha value. MoveAnimator specifies if the widget can animate changes to X and Y values.

Interactions

The actions and triggers supported by a Button are described in the following sections.

Actions

Standard widget action	Description
Move widget	Move a widget to a new position over time.
Fade widget	Modify alpha value of widget over time.
Hide widget	Hides a widget (sets visibility to false).
Show widget	Make a hidden widget visible (sets visibility to true).

Triggers

Trigger	Description
Button is clicked	A button has been clicked.

Performance

A Button is composed of two images and is dependent on image drawing. Therefore, a Button is considered a fast performing widget on most platforms.

For more details on image drawing performance, read the General UI Component Performance section.

Examples

Generated Code

In the generated code for the View base class we can see how TouchGFX Designer sets up a Button.

Screen1ViewBase.cpp

#include <gui_generated/screen1_screen/Screen1ViewBase.hpp>
#include "BitmapDatabase.hpp"

Screen1ViewBase::Screen1ViewBase()
{
    buttonName.setXY(155, 106);
    buttonName.setBitmaps(touchgfx::Bitmap(BITMAP_BLUE_BUTTONS_ROUND_EDGE_SMALL_ID), touchgfx::Bitmap(BITMAP_BLUE_BUTTONS_ROUND_EDGE_SMALL_PRESSED_ID));

    add(buttonName);
}

void Screen1ViewBase::buttonCallbackHandler(const touchgfx::AbstractButton& src)
{
    if (&src == &buttonName)
    {
        //Interaction name
        //When buttonName clicked calls the new virtual function "functionName()" set by the user
        functionName();
    }
}

Tip

You can use these functions and the others available in the Button class in user code. Remember to force a redraw by calling buttonName.invalidate() if you change the appearance of the widget.

TouchGFX Designer Examples

To further explore the Button, try creating a new application within TouchGFX Designer with the following UI template:

Button Example UI template in TouchGFX Designer

To further explore the callback handler, most of the TouchGFX Designer examples use the Button for its trigger ability "button is clicked".

API Reference

Further reading

API reference for the Button class