La frontière avec les coins arrondis & la transparence

N. B. Il y a une coupure de bug dans ce code, qui est fixé dans la accepté de répondre à paintComponent() est de tirer sur les autres composants. Cela ne devrait être considéré comme une solution si le "clipping bug fix" est constituée.

//Paint the BG color of the parent, everywhere outside the clip
//of the text bubble.

Voir ce point dans le code de la source qui indique correctement que:

import java.awt.*;
import java.awt.image.*;
import java.awt.geom.*;
import javax.swing.*;
import javax.swing.border.*;
public class BorderTest {
public static void main(String[] args) {
Runnable r = new Runnable() {
@Override
public void run() {
JPanel gui = new JPanel(new GridLayout(2,0,5,5));
gui.setBorder(new EmptyBorder(10,10,10,10));
gui.setBackground(Color.RED);
AbstractBorder brdrLeft = new TextBubbleBorder(Color.BLACK,2,16,16);
AbstractBorder brdrRight = new TextBubbleBorder(Color.BLACK,2,16,16,false);
JLabel l1 = new JLabel("Label 1");
l1.setBorder(brdrRight);
gui.add(l1);
JLabel l2 = new JLabel("Label 2");
l2.setBorder(brdrLeft);
l2.setBackground(Color.YELLOW);
l2.setOpaque(true);
gui.add(l2);
JPanel p1 = new JPanel();
p1.add(new JLabel("Panel 1"));
p1.setBorder(brdrRight);
p1.setOpaque(false);
gui.add(p1);
JPanel p2 = new JPanel();
p2.add(new JLabel("Panel 2"));
p2.setBorder(brdrLeft);
gui.add(p2);
JOptionPane.showMessageDialog(null, gui);
}
};
//Swing GUIs should be created and updated on the EDT
//http://docs.oracle.com/javase/tutorial/uiswing/concurrency/initial.html
SwingUtilities.invokeLater(r);
}
}
class TextBubbleBorder extends AbstractBorder {
private Color color;
private int thickness = 4;
private int radii = 8;
private int pointerSize = 7;
private Insets insets = null;
private BasicStroke stroke = null;
private int strokePad;
private int pointerPad = 4;
private boolean left = true;
RenderingHints hints;
TextBubbleBorder(
Color color) {
this(color, 4, 8, 7);
}
TextBubbleBorder(
Color color, int thickness, int radii, int pointerSize) {
this.thickness = thickness;
this.radii = radii;
this.pointerSize = pointerSize;
this.color = color;
stroke = new BasicStroke(thickness);
strokePad = thickness / 2;
hints = new RenderingHints(
RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
int pad = radii + strokePad;
int bottomPad = pad + pointerSize + strokePad;
insets = new Insets(pad, pad, bottomPad, pad);
}
TextBubbleBorder(
Color color, int thickness, int radii, int pointerSize, boolean left) {
this(color, thickness, radii, pointerSize);
this.left = left;
}
@Override
public Insets getBorderInsets(Component c) {
return insets;
}
@Override
public Insets getBorderInsets(Component c, Insets insets) {
return getBorderInsets(c);
}
@Override
public void paintBorder(
Component c,
Graphics g,
int x, int y,
int width, int height) {
Graphics2D g2 = (Graphics2D) g;
int bottomLineY = height - thickness - pointerSize;
RoundRectangle2D.Double bubble = new RoundRectangle2D.Double(
0 + strokePad,
0 + strokePad,
width - thickness,
bottomLineY,
radii,
radii);
Polygon pointer = new Polygon();
if (left) {
//left point
pointer.addPoint(
strokePad + radii + pointerPad,
bottomLineY);
//right point
pointer.addPoint(
strokePad + radii + pointerPad + pointerSize,
bottomLineY);
//bottom point
pointer.addPoint(
strokePad + radii + pointerPad + (pointerSize / 2),
height - strokePad);
} else {
//left point
pointer.addPoint(
width - (strokePad + radii + pointerPad),
bottomLineY);
//right point
pointer.addPoint(
width - (strokePad + radii + pointerPad + pointerSize),
bottomLineY);
//bottom point
pointer.addPoint(
width - (strokePad + radii + pointerPad + (pointerSize / 2)),
height - strokePad);
}
Area area = new Area(bubble);
area.add(new Area(pointer));
g2.setRenderingHints(hints);
//Paint the BG color of the parent, everywhere outside the clip
//of the text bubble.
Component parent  = c.getParent();
if (parent!=null) {
Color bg = parent.getBackground();
Rectangle rect = new Rectangle(0,0,width, height);
Area borderRegion = new Area(rect);
borderRegion.subtract(area);
g2.setClip(borderRegion);
g2.setColor(bg);
g2.fillRect(0, 0, width, height);
g2.setClip(null);
}
g2.setColor(color);
g2.setStroke(stroke);
g2.draw(area);
}
}

Merci @barre Oblique inverse, simple et sympathique. J'ai agrandi cette sorte qu'il est plus réutilisable. Cela permet également à la définition d'une couleur de fond dans le constructeur. Et je montre comment vous pouvez faire un panneau circulaire pour le plaisir.

import java.awt.*;
import javax.swing.*;
public class RoundedPanelExample extends JFrame
{
public RoundedPanelExample()
{
setDefaultCloseOperation(EXIT_ON_CLOSE);
setTitle("Rounded Panel Example");
setResizable(true);
setDefaultLookAndFeelDecorated(true);
setSize(500, 500);
Container pane = getContentPane();
pane.setLayout(null);
pane.setBackground(Color.LIGHT_GRAY);
JPanel p1 = new RoundedPanel(10, Color.CYAN);
p1.setBounds(10,10,100,60);
p1.setOpaque(false);
pane.add(p1);
JPanel p2 = new RoundedPanel(15, Color.RED);
p2.setBounds(150,10,50,50);
p2.setOpaque(false);
pane.add(p2);
JPanel p3 = new RoundedPanel(30);
p3.setBounds(230,10,100,150);
p3.setOpaque(false);
pane.add(p3);
JPanel p4 = new RoundedPanel(20);
p4.setBounds(10,200,100,100);
p4.setBackground(Color.GREEN);
p4.setOpaque(false);
pane.add(p4);
JPanel p5 = new RoundedPanel(200);
p5.setBounds(150,200,200,200);
p5.setBackground(Color.BLUE);
p5.setOpaque(false);
pane.add(p5);
}
public static void main(String[] args) 
{
RoundedPanelExample gui = new RoundedPanelExample();
gui.setVisible(true);
}
class RoundedPanel extends JPanel
{
private Color backgroundColor;
private int cornerRadius = 15;
public RoundedPanel(LayoutManager layout, int radius) {
super(layout);
cornerRadius = radius;
}
public RoundedPanel(LayoutManager layout, int radius, Color bgColor) {
super(layout);
cornerRadius = radius;
backgroundColor = bgColor;
}
public RoundedPanel(int radius) {
super();
cornerRadius = radius;
}
public RoundedPanel(int radius, Color bgColor) {
super();
cornerRadius = radius;
backgroundColor = bgColor;
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Dimension arcs = new Dimension(cornerRadius, cornerRadius);
int width = getWidth();
int height = getHeight();
Graphics2D graphics = (Graphics2D) g;
graphics.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
//Draws the rounded panel with borders.
if (backgroundColor != null) {
graphics.setColor(backgroundColor);
} else {
graphics.setColor(getBackground());
}
graphics.fillRoundRect(0, 0, width-1, height-1, arcs.width, arcs.height); //paint background
graphics.setColor(getForeground());
graphics.drawRoundRect(0, 0, width-1, height-1, arcs.width, arcs.height); //paint border
}
}
}