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Version: 4.16

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 GroupProperty Descriptions
NameName of the widget. Name is the unique identifier used in TouchGFX Designer and code.
LocationX 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.

Lock specifies if the widget should be locked in its current X, Y, W and H.
Locking the widget also disables interacting with the widget through the screen.

Visible specifies the visibility of the widget.
Making the widget invisible also disables interacting with the widget through the screen.
StyleStyle specifies a predefined setup of the widget, that sets select properties to predefined values.
These styles contain images that are free to use.
ImageReleased Image and Pressed Image specify the images assigned to the pressed and released states from the Designer skin library or the Project folder.
AppearanceAlpha 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.
MixinsDraggable 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 actionDescription
Move widgetMove a widget to a new position over time.
Fade widgetModify alpha value of widget over time.
Hide widgetHides a widget (sets visibility to false).
Show widgetMake a hidden widget visible (sets visibility to true).

Triggers#

TriggerDescription
Button is clickedA 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#