paintComponent（）TextField导致无限循环（自身+父级）

Question

After several days of research, I beg to ask your help. The following code works but generates significant CPU consumption. It seems that this simple text field executes "paintComponent" in a loop, not only its own, but also its parent (JPanel). Could you give me a way to correct that?

Thank you :)

package view;

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.GradientPaint;
import java.awt.Graphics;
import java.awt.Graphics2D;

import javax.swing.BorderFactory;
import javax.swing.JTextField;
import javax.swing.border.CompoundBorder;
import javax.swing.border.EmptyBorder;

import constants.Colors;
import constants.Polices;
import constants.Spacing;

public class FieldText extends JTextField 
{
    private static final long serialVersionUID = 4526307090633268880L;
    private int xheight = 96;
    public Boolean hinted = false;                      // Définit si le     contenu == au hint ou si le contenu a été entré par l'utilisateur.
    protected Color bgColor = Colors.INPUT;             // Background normal.
    protected Color textColor = Colors.TEXT_INPUT;      // Couleur du texte normal.
    protected Color bgHinted = Colors.INPUT;            // Background lors que le placeholder est actif.
    protected Color textHinted = Colors.TEXT_INPUT;     // Couleur du texte placeholder.
    protected Font textFont = Polices.INPUTS;           // Police texte utilisateur.
    protected Font textHintFont = Polices.INPUTS_HINT;  // Police     placeholder.

    public FieldText()
    {   
        super();
        init(null, null);
    }


    /**
     * @param text String Texte du champ (valeur) 
     * @param text String PlaceHoler
     */
        public FieldText( String text, String hint )
        {   
            super();
            init(text, hint);
        }

    /**
     * @param hint Sting Texte du champ (valeur).
     */
        public FieldText( String hint )
        {   
            super();
            init(null, hint);
        }


    private void init( String text, String hint )
    {
        setOpaque(false);
        setBackground(bgColor);
        setForeground(textColor);
        setMinimumSize( new Dimension( 200, 64 ) );
        setBorder( new CompoundBorder (
                                                BorderFactory.createMatteBorder(0, 5, 0, 0, Colors.GREEN), 
                                            new EmptyBorder(     Spacing.PADDING_INPUTS )   
                                       ) 
        );
        setFont( Polices.INPUTS );

        if ( text != null && text.length() > 0 )
        {
            setText(text);  
        }

        setHeight(-1);          // Height by default.
    }


    /**
     * Définit la hauteur de l'élément. 
     * @param height int Hauteur à attribuer à l'élément. -1 pour utiliser la hauteur par défaut (xheight).
     */
        public void setHeight( int height )
        {
            setPreferredSize( new Dimension(this.getWidth(), (height>-1)     ? height : xheight) );
        }


    @Override
    protected void paintComponent(Graphics g) 
    {       
        Graphics2D g2d = (Graphics2D)g;

        GradientPaint gp = new GradientPaint (
            0, 0, new Color( 255, 255, 255, 50 ),
            0, 20, new Color( 179, 179, 179, 50 ) 
        );

        g2d.setPaint( gp );
        g2d.fillRoundRect(0, 0, getWidth()-1, getHeight()-1, 10, 10);

        super.paintComponent(g2d);

        System.out.println("======> inside FieldText.paintComponent() ");
    }
}`

JTextField is in JPanel in JFrame.

Sorry for my bad english ...

Here a little example who causes the loop.

EDIT : Exemple integration in src/views/GuestLoginView

Here is the full src

Answer 1

Running your program doesn't cause high CPU consumption for me.

Also the TextField probably needs constant repainting to animate the blinking cursor. One repaint every second is a reasonable expectation and it is what I see on my console.

Answer 2

I rewrote your code more concisely to put it (mostly) in one file to simplify this. First, the constant repainting is caused by the blinking of insertion carat. But to do what you want you with the gradientPaint it is best to use JLayer . A couple other things to facilitate your code.

1. Don't extend JFrame. Its methods are rarely overridden so there is no need to do so. Just use an instance.
2. Instead of using init() called by the constructor, simply have multiple constructors call the main constructor using this . Like this(null, null)

JLayer allows Swing components to draw on their children. This is exactly what you want to do in your program. I have included this link so you can see the tutorial and the accompanying video. I used the names of the field that were in the video to help follow the explanation in your own code. And finally, when I ran this I did not see but a 2% CPU utilization over all of my processes on Windows 10 with a quad core i7 processor .

    package view;

    import java.awt.Color;
    import java.awt.Dimension;
    import java.awt.Font;
    import java.awt.GradientPaint;
    import java.awt.Graphics;
    import java.awt.Graphics2D;
    import java.awt.GridLayout;

    import javax.swing.BorderFactory;
    import javax.swing.JComponent;
    import javax.swing.JFrame;
    import javax.swing.JLayer;
    import javax.swing.JPanel;
    import javax.swing.JTextField;
    import javax.swing.border.CompoundBorder;
    import javax.swing.border.EmptyBorder;
    import javax.swing.plaf.LayerUI;

    import constants.Colors;
    import constants.Polices;
    import constants.Spacing;

    public class TestFrame {
       private static final long serialVersionUID = 818148271075948079L;
       private TestPanel         panelContent;
       private FieldText         field1, field2;

       JFrame                    frame            = new JFrame();

       public TestFrame() {

          frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          field1 = new FieldText("your text 1", null);
          field2 = new FieldText("your text 2", null);
          panelContent = new TestPanel();
          panelContent.add(field1);
          panelContent.add(field2);
          LayerUI<JComponent> layerUI = new MyLayerUISubClass();
          JLayer<JComponent> jlayer = new JLayer<>(panelContent, layerUI);

          panelContent.setPreferredSize(new Dimension(500, 256));
          frame.add(jlayer);
          frame.pack();
          frame.setLocationRelativeTo(null);
          frame.setVisible(true);
       }

       public static void main(String[] args) {
          new TestFrame();
       }

    }

    class MyLayerUISubClass extends LayerUI<JComponent> {
       @Override
       public void paint(Graphics g, JComponent c) {
          super.paint(g, c);
          Graphics2D g2d = (Graphics2D) g.create();

          GradientPaint gp = new GradientPaint(0, 0, new Color(255, 255, 255, 50),
                0, 20, new Color(179, 179, 179, 50));

          g2d.setPaint(gp);
          // g2d.fillRect(0, 0, c.getWidth() - 1, c.getHeight() - 1);
          g2d.fillRoundRect(0, 0, c.getWidth() - 1, c.getHeight() - 1, 10, 10);

          System.out.println("======> inside FieldText.paintComponent() ");
          g2d.dispose();
       }

    }

    class TestPanel extends JPanel {
       private static final long serialVersionUID = -4236642932453746731L;

       public TestPanel() {
          setLayout(new GridLayout(2, 1));
          setBackground(Color.black);

       }

       @Override
       protected void paintComponent(Graphics g) {
          // TODO Auto-generated method stub
          super.paintComponent(g);

          System.out.println("======> inside TestPanel.paintComponent() ");
       }
    }

    class FieldText extends JTextField {
       private static final long serialVersionUID = 4526307090633268880L;
       private int               xheight          = 96;
       public Boolean            hinted           = false;               // Définit si le contenu == au hint ou si le contenu a été entré par
                                                                         // l'utilisateur.
       protected Color           bgColor          = Colors.INPUT;        // Background normal.
       protected Color           textColor        = Colors.TEXT_INPUT;   // Couleur du texte normal.
       protected Color           bgHinted         = Colors.INPUT;        // Background lors que le placeholder est actif.
       protected Color           textHinted       = Colors.TEXT_INPUT;   // Couleur du texte placeholder.
       protected Font            textFont         = Polices.INPUTS;      // Police texte utilisateur.
       protected Font            textHintFont     = Polices.INPUTS_HINT; // Police placeholder.

       public FieldText(String text, String hint) {
          setOpaque(true);
          setBackground(bgColor);
          setForeground(textColor);
          setMinimumSize(new Dimension(200, 64));
          setBorder(new CompoundBorder(
                BorderFactory.createMatteBorder(0, 5, 0, 0, Colors.GREEN),
                new EmptyBorder(Spacing.PADDING_INPUTS)));
          setFont(Polices.INPUTS);

          if (text != null && text.length() > 0) {
             setText(text);
          }
          setHeight(-1); // Height by default.
       }

       public FieldText() {
          this(null, null);
       }

       public FieldText(String hint) {
          this(null, hint);
       }

       /**
        * Définit la hauteur de l'élément.
        * 
        * @param height
        *        int Hauteur à attribuer à l'élément. -1 pour utiliser la hauteur par
        *        défaut (xheight).
        */
       public void setHeight(int height) {
          setPreferredSize(new Dimension(this.getWidth(), (height > -1) ? height
                : xheight));
       }
    }

Answer 3

I found the problem.

It was not in the field, but in the paintComponent() of my custom button.

I had

  ImageIcon bicon = ( mouseHover ) ? new ImageIcon( iconHover ) : new ImageIcon( icon );
        setIcon(bicon);
        getIcon().paintIcon( this, g2, getIconX(), getIconY() ); 

==> setIcon in the paintComponent was not a good idea , it caused the loop and CPU usage.

Thank you for your useful advices.