Java圆角和透明的边框
以下屏幕截图显示了TextBubbleBorder1的测试。我想使矩形外部的组件的角完全透明并显示其下方的任何组件。我找到了一种方法，可以通过Clip在Graphics2D实例上设置a （代表圆角之外的区域）并调用来将标签的BG颜色限制在“边界内” clearRect()。可以在中看到Label 1。
但是，当父面板上有红色BG（或任何非标准颜色）时，你会看到此方法的缺点。角默认为默认面板颜色（最容易在中看到Panel 2）。
最终，我希望它能在父容器中用于非标准颜色，但是它的部分灵感来自于我需要做些什么来用渐变涂料复制该组件？
有人知道使这些角落透明的方法吗？
import java.awt.*;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(1,0,5,5));
gui.setBorder(new EmptyBorder(10,10,10,10));
gui.setBackground(Color.RED);
AbstractBorder brdr = new TextBubbleBorder(Color.BLACK,2,16,0);
JLabel l1 = new JLabel("Label 1");
l1.setBorder(brdr);
gui.add(l1);
JLabel l2 = new JLabel("Label 2");
l2.setBorder(brdr);
l2.setBackground(Color.YELLOW);
l2.setOpaque(true);
gui.add(l2);
JPanel p1 = new JPanel();
p1.add(new JLabel("Panel 1"));
p1.setBorder(brdr);
p1.setOpaque(false);
gui.add(p1);
JPanel p2 = new JPanel();
p2.add(new JLabel("Panel 2"));
p2.setBorder(brdr);
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;
RenderingHints hints;
TextBubbleBorder(
Color color) {
new TextBubbleBorder(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);
}
@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();
// 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);
Area area = new Area(bubble);
area.add(new Area(pointer));
g2.setRenderingHints(hints);
Area spareSpace = new Area(new Rectangle(0, 0, width, height));
spareSpace.subtract(area);
g2.setClip(spareSpace);
g2.clearRect(0, 0, width, height);
g2.setClip(null);
g2.setColor(color);
g2.setStroke(stroke);
g2.draw(area);
}
}
尽管sTextBubbleBorder是为带有背景图像的JTextArea的内部填充而设计的（JLabel由于上述原因，由于文本区域是一团糟，所以最终使用了a ），但通过指定a pointerSize为0，我们最终得到了一个“圆角矩形”。
回答：
// Paint the BG color of the parent, everywhere outside the clip// of the text bubble.
请参阅源代码中的这一点，该源正确显示为：
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);
}
}
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