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

Methods

References

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