Button

Buttons are an essential way to interact with and navigate through an app, and should clearly communicate what action will occur after the user taps them

Examples

To adapt the component to the style of the application it is often necessary to change its colors.

package com.totalcross;
import totalcross.ui.gfx.Color;
import totalcross.sys.Settings;
import totalcross.ui.Button;
import totalcross.ui.MainWindow;
public class HelloWorld extends MainWindow {
private Button btnRed;
private Button btnGreen;
private Button btnBlue;
public HelloWorld(){
setUIStyle(Settings.MATERIAL_UI);
}
@Override
public void initUI(){
btnRed = new Button("Red");
btnRed.setBackForeColors(Color.RED, Color.WHITE);
add(btnRed, CENTER,CENTER );
btnGreen = new Button("Green");
btnGreen.setBackForeColors(Color.GREEN, Color.WHITE);
add(btnGreen, CENTER, AFTER );
btnBlue = new Button("Blue");
btnBlue.setBackForeColors(Color.BLUE, Color.WHITE);
add(btnBlue, CENTER,AFTER);
}
}

Full Button

Make the button the width of the screen.

package com.totalcross;
import totalcross.ui.gfx.Color;
import totalcross.sys.Settings;
import totalcross.ui.Button;
import totalcross.ui.MainWindow;
public class HelloWorld extends MainWindow {
private Button btnFull;
public HelloWorld(){
setUIStyle(Settings.MATERIAL_UI);
}
@Override
public void initUI() {
btnFull = new Button("Full Button");
btnFull.setBackForeColors(Color.BLUE, Color.WHITE);
add(btnFull, CENTER, CENTER, PARENTSIZE, PREFERRED);
}
}

Button shapes

Modify the button edges.

package com.totalcross;
import totalcross.ui.gfx.Color;
import totalcross.sys.Settings;
import totalcross.ui.Button;
import totalcross.ui.MainWindow;
public class HelloWorld extends MainWindow{
private Button btnRounded;
private Button btnBorderless;
private Button btnOutlined;
public HelloWorld(){
setUIStyle(Settings.MATERIAL_UI);
}
@Override
public void initUI(){
btnRounded = new Button("Rounded Corners Button", Button.BORDER_ROUND);
btnRounded.setBackForeColors(Color.BLUE, Color.WHITE);
add(btnRounded, CENTER, CENTER );
btnBorderless = new Button("Borderless Button", Button.BORDER_NONE);
btnBorderless.setBackForeColors(Color.BLUE, Color.WHITE);
add(btnBorderless, CENTER, AFTER+5);
btnOutlined = new Button("Outlined Button", Button.BORDER_OUTLINED);
btnOutlined.setBackForeColors(Color.BLUE, Color.WHITE);
add(btnOutlined, CENTER, AFTER+5);
}
}

Sizes

Change the buttons sizes.

package com.totalcross;
import totalcross.ui.gfx.Color;
import totalcross.sys.Settings;
import totalcross.ui.Button;
import totalcross.ui.MainWindow;
public class HelloWorld extends MainWindow {
private Button btnLarge;
private Button btnDefaultSize;
private Button btnSmall;
public HelloWorld() {
setUIStyle(Settings.MATERIAL_UI);
}
@Override
public void initUI() {
btnLarge = new Button("Large",Button.BORDER_ROUND);
btnLarge.setBackForeColors(Color.BLUE, Color.WHITE);
add(btnLarge, LEFT+20, CENTER,btnLarge.getPreferredWidth() <= 48 ? DP + 96: btnLarge.getPreferredWidth(),DP + 54);
btnDefaultSize = new Button("Default",Button.BORDER_ROUND);
btnDefaultSize.setBackForeColors(Color.BLUE, Color.WHITE);
add(btnDefaultSize, AFTER+5, CENTER_OF);
btnSmall = new Button("Small",Button.BORDER_ROUND);
btnSmall.setBackForeColors(Color.BLUE, Color.WHITE);
add(btnSmall, AFTER+5, CENTER_OF, btnSmall.getPreferredWidth() <= 24? DP + 48 : btnSmall.getPreferredWidth(), DP + 27,btnDefaultSize);
}
}

Button image

Add an image to the button.

package com.totalcross;
import totalcross.ui.gfx.Color;
import totalcross.ui.image.Image;
import totalcross.sys.Settings;
import totalcross.ui.Button;
import totalcross.ui.MainWindow;
public class HelloWorld extends MainWindow {
private Button btnLeftImage;
public HelloWorld() {
setUIStyle(Settings.MATERIAL_UI);
}
@Override
public void initUI() {
try {
Image img = new Image("images/bt_info.png");
btnLeftImage = new Button("Left Image", img.scaledBy(0.2,0.2), RIGHT,10);
btnLeftImage.setBackForeColors(Color.BLUE, Color.WHITE);
add(btnLeftImage, CENTER, AFTER+25);
} catch (Exception exception) {
exception.printStackTrace();
}
}
}

Do not forget to create a folder called "images" inside /src/main/resources and save the bt_info.png image inside it [images].

Events

Handling events with addPressListener() :

package com.totalcross;
import totalcross.ui.gfx.Color;
import totalcross.sys.Settings;
import totalcross.ui.Button;
import totalcross.ui.MainWindow;
public class HelloWorld extends MainWindow {
private Button btnRed;
private Button btnGreen;
private Button btnBlue;
public HelloWorld(){
setUIStyle(Settings.MATERIAL_UI);
}
@Override
public void initUI(){
btn = new Button("Do something");
btn.setBackForeColors(Color.RED, Color.WHITE);
btn.addPressListener((event) -> {
// DO SOMETHING
})
add(btn, CENTER,CENTER );
}
}

Behind the Class

Attributes

Type

Name

Description

boolean

Button.CENTRALIZE

Center image and text on the button.

Methods

Type

Name

Description

Constructor

Button( )

Creates a simple button

Constructor

Button(Image img)

Creates a simple button with the referred image

Constructor

Button(Image img, byte border)

Creates a button with the referreds image and border

Constructor

Button(String text)

Creates a button with the referred text

Constructor

Button(String text, byte border)

Creates a button with the referreds text and border

Constructor

Button(String text, Image img, int textPosition, int gap)

Creates a button with the referred text and image

Image

getImage( )

Return the button image

String

getText( )

Return the button text

Boolean

isPressed( )

Return true if button is pressed

void

press(boolean pressed)

If true, press the button

void

setBorder(byte border)

Set the button border style

void

setImage(Image img)

Set the button image

void

setPressedColor(int newColor)

Return the button text

void

setText(String text)

Set the button text

void

simulatePress( )

Press and depress the button

References