在圆形 JLabel 图像周围创建一个可点击区域
Create a clickable area around round JLabel image
我正在尝试创建一个带有椭圆形图像的 JLabel，如下所示。
我的代码如下：
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Image;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.image.BufferedImage;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.BorderFactory;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.SwingUtilities;
public final class RoundedButtonDemo {
private static Image bi;
public static void main(String[] args) {
try {
loadImage();
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
createAndShowGUI();
}
});
} catch (IOException e) {
// handle exception
}
}
private static void loadImage() throws IOException {
int newWidth = 80;
int newHeight = 40;
bi = ImageIO.read(RoundedButtonDemo.class.getResource("/resources/login.png"));
bi = bi.getScaledInstance(newWidth, newHeight, Image.SCALE_DEFAULT);
}
private static void createAndShowGUI() {
final JFrame frame = new JFrame();
frame.setSize(400, 400);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
final JLabel label = new JLabel();
label.setSize(new Dimension(5, 5));
label.setIcon(new ImageIcon(bi));
label.setText("Hello World");
label.setHorizontalTextPosition(JLabel.CENTER);
// label.setBorder(BorderFactory.createLineBorder(Color.BLACK));
label.addMouseListener(new MouseListener() {
private int count = 0;
@Override
public void mouseClicked(MouseEvent e) {
if (e.getSource() == label) {
if (count % 2 == 0) {
label.setText("Bye");
} else {
label.setText("Hello World");
}
count++;
}
}
@Override
public void mouseEntered(MouseEvent e) {
// TODO Auto-generated method stub
}
@Override
public void mouseExited(MouseEvent e) {
// TODO Auto-generated method stub
}
@Override
public void mousePressed(MouseEvent e) {
// TODO Auto-generated method stub
}
@Override
public void mouseReleased(MouseEvent e) {
// TODO Auto-generated method stub
}
});
frame.add(label);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
}
此代码创建一个包含上述图像的 JLabel。每次单击按钮时，JLabel 的文本应根据添加到 JLabel 的 MouseListener 交替显示。
我面临的问题是，即使我在图像外部（也在 JLabel 外部）单击，也会触发 MouseListener，并且文本会交替出现。
我想要实现的目标是：
一个圆形按钮，只要在其表面的任何地方单击它就会响应 MouseListener。
我试过你的代码。你得到这种行为是因为你的 JLabel 实际上填满了整个框架。您需要为框架设置布局；像这样：
// ...
frame.setSize(400, 400);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new FlowLayout()); // <-- you need this
final JLabel label = new JLabel();
label.setPreferredSize(new Dimension(80, 40)); // <-- also this
label.setIcon(new ImageIcon(bi));
label.setText("Hello World");
// ...
FlowLayout 是最简单的布局管理器之一，其中有很多。您可以在这里阅读它们：https://docs.oracle.com/javase/tutorial/uiswing/layout/visual.html
希望这对您有所帮助。
PS：你想调试这个问题是个好主意，添加这样的边框：
// label.setBorder(BorderFactory.createLineBorder(Color.BLACK));
不确定您为什么将其注释掉。也许你没有注意到整个框架区域周围有一个黑色边框。尝试将颜色设置为 Color.RED 或更明显的颜色。
由于 pointed out, the JLabel 填满了整个内容窗格，因此单击内容窗格中的任意位置会导致标签发生鼠标事件。
一些话：
1) 您也可以使用 GridBagLayout, instead of FlowLayout, in case you want the JLabel centered in its parent component (both vertically and horizontally). This solution is here。
像这样：
final JPanel singleCenteredComponentJPanel = new JPanel(new GridBagLayout());
singleCenteredComponentJPanel.add(label);
frame.add(singleCenteredComponentJPanel);
2) 此外，如果您想忽略鼠标点击标签图标的任何透明像素（如果有），您可以执行以下操作：
使用 BufferedImage.getRGB(int x, int y), BufferedImage.getColorModel() and ColorModel.getAlpha(int pixel) 方法确定每个鼠标事件的单击像素的 alpha 值。如果 alpha 值等于 0，则像素是完全透明的，否则 alpha 值介于 1 和 255（包括两者）之间，这反过来意味着像素不是完全透明的。示例代码如下。
而不是 Image.getScaledInstance(...) to scale the image (which returns Image, but we need BufferedImage), use the solution provided here。
像这样：
private static void loadImage() throws IOException {
int newWidth = 80;
int newHeight = 40;
bi = ImageIO.read(RoundedButtonDemo.class.getResource("/resources/login.png"));
bi = getScaledBufferedImage(bi, newWidth, newHeight);
}
public static BufferedImage getScaledBufferedImage(final Image img,
final int newWidth,
final int newHeight) {
final GraphicsEnvironment genv = GraphicsEnvironment.getLocalGraphicsEnvironment();
final GraphicsDevice gdev = genv.getDefaultScreenDevice();
final GraphicsConfiguration gcnf = gdev.getDefaultConfiguration();
final BufferedImage simg = gcnf.createCompatibleImage(newWidth, newHeight, Transparency.TRANSLUCENT);
//Painting input image to output image:
final Graphics2D g2d = simg.createGraphics();
g2d.drawImage(img, 0, 0, newWidth, newHeight, null); //@Docs "...is scaled if necessary.".
g2d.dispose();
return simg;
}
同时将引用 bi 从 Image to BufferedImage 更改。
然后是标签的MouseListener：
private int count = 0;
@Override
public void mouseClicked(MouseEvent e) {
if (e.getSource() == label) {
//Get the mouse click position (in pixels),
//relative to the top-left corner of label:
final Point relativeClickPoint = e.getPoint();
//Obtain alpha value from the TYPE_INT_ARGB pixel:
final int pixel = bi.getRGB(relativeClickPoint.x, relativeClickPoint.y);
final int alpha = bi.getColorModel().getAlpha(pixel);
if (alpha > 0) { //Check if the pixel is not transparent.
if (count % 2 == 0) {
label.setText("Bye");
} else {
label.setText("Hello World");
}
count++;
}
}
}
请注意 上述实现：图像的所有透明像素都将被忽略（包括透明像素 "inside" 形状，如果有的话）。这意味着用户可以点击图像的中心，如果点击的像素是完全透明的，则什么也不会发生。所以我假设你这里的图片不是这种情况。
3) 对于 Image 的缩放，您可以使用方法 collapseInside(...) 确定新的大小：
/**
* @param resultDim Output dimension (same aspect ratio as the original dimension, and inside containerDim).
* @param originalDim Original dimension.
* @param containerDim Dimension with the maximum width and maximum height.
*/
public static void collapseInside(final Dimension resultDim,
final Dimension originalDim,
final Dimension containerDim) {
resultDim.setSize(originalDim);
if (resultDim.width > containerDim.width) {
//Adjusting height for max width:
resultDim.height = ( resultDim.height * containerDim.width ) / resultDim.width;
resultDim.width = containerDim.width;
}
if (resultDim.height > containerDim.height) {
//Adjusting width for max height:
resultDim.width = ( resultDim.width * containerDim.height ) / resultDim.height;
resultDim.height = containerDim.height;
}
}
用这个方法：
a) 缩放后 Image 的宽度将小于或等于容器的尺寸宽度 (resultDim.width <= containerDim.width)。
b) 高度相同 (resultDim.height <= containerDim.height).
c) 原始 Image 尺寸的宽高比将保留在新的 Image 尺寸中 (resultDim.width / resultDim.height == originalDim.width / originalDim.height ).
使用 Image.getScaledInstance(...) 和之前的 getScaledBufferedImage(...)，Image 的纵横比可能会改变。
所以我编辑 getScaledBufferedImage(...) 以使用 collapseInside(...)：
public static BufferedImage getScaledBufferedImage(final Image img,
final int newWidth,
final int newHeight) {
final Dimension originalDim = new Dimension(img.getWidth(null), img.getHeight(null)),
containerDim = new Dimension(newWidth, newHeight),
resultDim = new Dimension();
collapseInside(resultDim, originalDim, containerDim);
final GraphicsEnvironment genv = GraphicsEnvironment.getLocalGraphicsEnvironment();
final GraphicsDevice gdev = genv.getDefaultScreenDevice();
final GraphicsConfiguration gcnf = gdev.getDefaultConfiguration();
final BufferedImage simg = gcnf.createCompatibleImage(resultDim.width, resultDim.height, Transparency.TRANSLUCENT);
//Painting input image to output image:
final Graphics2D g2d = simg.createGraphics();
g2d.drawImage(img, 0, 0, resultDim.width, resultDim.height, null); //@Docs "...is scaled if necessary.".
g2d.dispose();
return simg;
}
以上所有三个的完整代码：
import java.awt.Dimension;
import java.awt.Graphics2D;
import java.awt.GraphicsConfiguration;
import java.awt.GraphicsDevice;
import java.awt.GraphicsEnvironment;
import java.awt.GridBagLayout;
import java.awt.Image;
import java.awt.Point;
import java.awt.Transparency;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.image.BufferedImage;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public final class RoundedButtonDemo {
private static BufferedImage bi;
public static void main(String[] args) {
try {
loadImage();
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
createAndShowGUI();
}
});
} catch (IOException e) {
// handle exception
}
}
private static void loadImage() throws IOException {
int newWidth = 80;
int newHeight = 40;
bi = ImageIO.read(RoundedButtonDemo.class.getResource("/resources/login.png"));
bi = getScaledBufferedImage(bi, newWidth, newHeight);
}
public static BufferedImage getScaledBufferedImage(final Image img,
final int newWidth,
final int newHeight) {
final Dimension originalDim = new Dimension(img.getWidth(null), img.getHeight(null)),
containerDim = new Dimension(newWidth, newHeight),
resultDim = new Dimension();
collapseInside(resultDim, originalDim, containerDim);
final GraphicsEnvironment genv = GraphicsEnvironment.getLocalGraphicsEnvironment();
final GraphicsDevice gdev = genv.getDefaultScreenDevice();
final GraphicsConfiguration gcnf = gdev.getDefaultConfiguration();
final BufferedImage simg = gcnf.createCompatibleImage(resultDim.width, resultDim.height, Transparency.TRANSLUCENT);
//Painting input image to output image:
final Graphics2D g2d = simg.createGraphics();
g2d.drawImage(img, 0, 0, resultDim.width, resultDim.height, null); //@Docs "...is scaled if necessary.".
g2d.dispose();
return simg;
}
/**
* @param resultDim Output dimension (same aspect ratio as the original dimension, and inside containerDim).
* @param originalDim Original dimension.
* @param containerDim Dimension with the maximum width and maximum height.
*/
public static void collapseInside(final Dimension resultDim,
final Dimension originalDim,
final Dimension containerDim) {
resultDim.setSize(originalDim);
if (resultDim.width > containerDim.width) {
//Adjusting height for max width:
resultDim.height = ( resultDim.height * containerDim.width ) / resultDim.width;
resultDim.width = containerDim.width;
}
if (resultDim.height > containerDim.height) {
//Adjusting width for max height:
resultDim.width = ( resultDim.width * containerDim.height ) / resultDim.height;
resultDim.height = containerDim.height;
}
}
private static void createAndShowGUI() {
final JFrame frame = new JFrame();
frame.setSize(400, 400);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
final JLabel label = new JLabel();
label.setSize(new Dimension(5, 5));
label.setIcon(new ImageIcon(bi));
label.setText("Hello World");
label.setHorizontalTextPosition(JLabel.CENTER);
// label.setBorder(BorderFactory.createLineBorder(Color.BLACK));
label.addMouseListener(new MouseListener() {
private int count = 0;
@Override
public void mouseClicked(MouseEvent e) {
if (e.getSource() == label) {
//Get the mouse click position (in pixels),
//relative to the top-left corner of label:
final Point relativeClickPoint = e.getPoint();
//Obtain alpha value from the TYPE_INT_ARGB pixel:
final int pixel = bi.getRGB(relativeClickPoint.x, relativeClickPoint.y);
final int alpha = bi.getColorModel().getAlpha(pixel);
if (alpha > 0) { //Check if the pixel is not transparent.
if (count % 2 == 0) {
label.setText("Bye");
} else {
label.setText("Hello World");
}
count++;
}
}
}
@Override
public void mouseEntered(MouseEvent e) {
// TODO Auto-generated method stub
}
@Override
public void mouseExited(MouseEvent e) {
// TODO Auto-generated method stub
}
@Override
public void mousePressed(MouseEvent e) {
// TODO Auto-generated method stub
}
@Override
public void mouseReleased(MouseEvent e) {
// TODO Auto-generated method stub
}
});
final JPanel singleCenteredComponentJPanel = new JPanel(new GridBagLayout());
singleCenteredComponentJPanel.add(label);
frame.add(singleCenteredComponentJPanel);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
}
或者，您也可以覆盖 JPanel 的 paintComponent(...) 并使用 Graphics.drawImage(...) 将 Image bi 绘制到 JPanel 像这样：
@Override
protected void paintComponent(final Graphics g) {
super.paintComponent(g);
//Drawing the image:
g.drawImage(img, 0, 0, null);
//Drawing the text:
//For centering the text, I used code from:
//
final FontMetrics metrics = g.getFontMetrics(g.getFont());
final int x = (img.getWidth(null) - metrics.stringWidth(text)) / 2;
final int y = (img.getHeight(null) - metrics.getHeight()) / 2 + metrics.getAscent();
g.drawString(text, x, y);
}
其中 img 是 bi，text 是按钮的文本（即 "Hello World" 和 "Bye"）。
然后按原样将 MouseListener 添加到 JPanel。
完整代码（如“RoundedButtonDemo1”class，在同一个包中）：
import java.awt.Dimension;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GraphicsConfiguration;
import java.awt.GraphicsDevice;
import java.awt.GraphicsEnvironment;
import java.awt.GridBagLayout;
import java.awt.Image;
import java.awt.Point;
import java.awt.Transparency;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.image.BufferedImage;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public final class RoundedButtonDemo1 {
private static BufferedImage bi;
public static void main(String[] args) {
try {
loadImage();
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
createAndShowGUI();
}
});
} catch (IOException e) {
// handle exception
}
}
private static void loadImage() throws IOException {
int newWidth = 80;
int newHeight = 40;
bi = ImageIO.read(RoundedButtonDemo1.class.getResource("/resources/login.png"));
bi = getScaledBufferedImage(bi, newWidth, newHeight);
}
public static BufferedImage getScaledBufferedImage(final Image img,
final int newWidth,
final int newHeight) {
final Dimension originalDim = new Dimension(img.getWidth(null), img.getHeight(null)),
containerDim = new Dimension(newWidth, newHeight),
resultDim = new Dimension();
collapseInside(resultDim, originalDim, containerDim);
final GraphicsEnvironment genv = GraphicsEnvironment.getLocalGraphicsEnvironment();
final GraphicsDevice gdev = genv.getDefaultScreenDevice();
final GraphicsConfiguration gcnf = gdev.getDefaultConfiguration();
final BufferedImage simg = gcnf.createCompatibleImage(resultDim.width, resultDim.height, Transparency.TRANSLUCENT);
//Painting input image to output image:
final Graphics2D g2d = simg.createGraphics();
g2d.drawImage(img, 0, 0, resultDim.width, resultDim.height, null); //@Docs "...is scaled if necessary.".
g2d.dispose();
return simg;
}
/**
* @param resultDim Output dimension (same aspect ratio as the original dimension, and inside containerDim).
* @param originalDim Original dimension.
* @param containerDim Dimension with the maximum width and maximum height.
*/
public static void collapseInside(final Dimension resultDim,
final Dimension originalDim,
final Dimension containerDim) {
resultDim.setSize(originalDim);
if (resultDim.width > containerDim.width) {
//Adjusting height for max width:
resultDim.height = ( resultDim.height * containerDim.width ) / resultDim.width;
resultDim.width = containerDim.width;
}
if (resultDim.height > containerDim.height) {
//Adjusting width for max height:
resultDim.width = ( resultDim.width * containerDim.height ) / resultDim.height;
resultDim.height = containerDim.height;
}
}
private static class CustomButton extends JPanel {
private Image img;
private String text;
public void setImage(final Image img) {
this.img = img;
final Dimension imgDim = new Dimension(img.getWidth(null), img.getHeight(null));
setMinimumSize(imgDim);
setPreferredSize(imgDim);
repaint();
}
public Image getImage() {
return img;
}
public void setText(final String text) {
this.text = text;
repaint();
}
public String getText() {
return text;
}
@Override
protected void paintComponent(final Graphics g) {
super.paintComponent(g);
//Drawing the image:
g.drawImage(img, 0, 0, null);
//Drawing the text:
//For centering the text, I used code from:
//
final FontMetrics metrics = g.getFontMetrics(g.getFont());
final int x = (img.getWidth(null) - metrics.stringWidth(text)) / 2;
final int y = (img.getHeight(null) - metrics.getHeight()) / 2 + metrics.getAscent();
g.drawString(text, x, y);
}
}
private static void createAndShowGUI() {
final JFrame frame = new JFrame();
frame.setSize(400, 400);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
final CustomButton button = new CustomButton();
button.setSize(new Dimension(5, 5));
button.setImage(bi);
button.setText("Hello World");
//button.setHorizontalTextPosition(SwingConstants.CENTER);
//button.setOpaque(false);
//button.setBorder(BorderFactory.createLineBorder(Color.BLACK));
button.addMouseListener(new MouseListener() {
private int count = 0;
@Override
public void mouseClicked(MouseEvent e) {
if (e.getSource() == button) {
//Get the mouse click position (in pixels),
//relative to the top-left corner of label:
final Point relativeClickPoint = e.getPoint();
//Obtain alpha value from the TYPE_INT_ARGB pixel:
final int pixel = bi.getRGB(relativeClickPoint.x, relativeClickPoint.y);
final int alpha = bi.getColorModel().getAlpha(pixel);
if (alpha > 0) { //Check if the pixel is not transparent.
if (count % 2 == 0) {
button.setText("Bye");
} else {
button.setText("Hello World");
}
count++;
}
}
}
@Override
public void mouseEntered(MouseEvent e) {
// TODO Auto-generated method stub
}
@Override
public void mouseExited(MouseEvent e) {
// TODO Auto-generated method stub
}
@Override
public void mousePressed(MouseEvent e) {
// TODO Auto-generated method stub
}
@Override
public void mouseReleased(MouseEvent e) {
// TODO Auto-generated method stub
}
});
final JPanel singleCenteredComponentJPanel = new JPanel(new GridBagLayout());
singleCenteredComponentJPanel.add(button);
frame.add(singleCenteredComponentJPanel);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
}
或者，如果您想要普通按钮而不是标签，看来 here 您也可以重塑按钮 !
除此之外，我还尝试了以下方法：
1) 使用 JLayeredPanes. There is a tutorial explaining them, and I guessed they could probably have a method to obtain the order of the visible pane for a given Point 或类似的东西，但他们没有。
2) 在 MouseListener 中使用 Container.getComponentAt(Point) 和 Container.findComponentAt(Point)，但是（正如我在测试后发现的) 这些方法不会 "see through" 非不透明（+透明）像素。
3) 在 JPanels (inspired by How to Create Translucent and Shaped Windows) 中搜索重塑或半透明，但没有找到。
4) How to Decorate Components with the JLayer Class 第一行说：
... enables you to draw on components and respond to component events without modifying the underlying component directly.
看起来很有希望，但我已经完成了。
我现在就到此为止。再见。
我正在尝试创建一个带有椭圆形图像的 JLabel，如下所示。
我的代码如下：
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Image;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.image.BufferedImage;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.BorderFactory;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.SwingUtilities;
public final class RoundedButtonDemo {
private static Image bi;
public static void main(String[] args) {
try {
loadImage();
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
createAndShowGUI();
}
});
} catch (IOException e) {
// handle exception
}
}
private static void loadImage() throws IOException {
int newWidth = 80;
int newHeight = 40;
bi = ImageIO.read(RoundedButtonDemo.class.getResource("/resources/login.png"));
bi = bi.getScaledInstance(newWidth, newHeight, Image.SCALE_DEFAULT);
}
private static void createAndShowGUI() {
final JFrame frame = new JFrame();
frame.setSize(400, 400);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
final JLabel label = new JLabel();
label.setSize(new Dimension(5, 5));
label.setIcon(new ImageIcon(bi));
label.setText("Hello World");
label.setHorizontalTextPosition(JLabel.CENTER);
// label.setBorder(BorderFactory.createLineBorder(Color.BLACK));
label.addMouseListener(new MouseListener() {
private int count = 0;
@Override
public void mouseClicked(MouseEvent e) {
if (e.getSource() == label) {
if (count % 2 == 0) {
label.setText("Bye");
} else {
label.setText("Hello World");
}
count++;
}
}
@Override
public void mouseEntered(MouseEvent e) {
// TODO Auto-generated method stub
}
@Override
public void mouseExited(MouseEvent e) {
// TODO Auto-generated method stub
}
@Override
public void mousePressed(MouseEvent e) {
// TODO Auto-generated method stub
}
@Override
public void mouseReleased(MouseEvent e) {
// TODO Auto-generated method stub
}
});
frame.add(label);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
}
此代码创建一个包含上述图像的 JLabel。每次单击按钮时，JLabel 的文本应根据添加到 JLabel 的 MouseListener 交替显示。
我面临的问题是，即使我在图像外部（也在 JLabel 外部）单击，也会触发 MouseListener，并且文本会交替出现。
我想要实现的目标是：
一个圆形按钮，只要在其表面的任何地方单击它就会响应 MouseListener。
我试过你的代码。你得到这种行为是因为你的 JLabel 实际上填满了整个框架。您需要为框架设置布局；像这样：
// ...
frame.setSize(400, 400);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new FlowLayout()); // <-- you need this
final JLabel label = new JLabel();
label.setPreferredSize(new Dimension(80, 40)); // <-- also this
label.setIcon(new ImageIcon(bi));
label.setText("Hello World");
// ...
FlowLayout 是最简单的布局管理器之一，其中有很多。您可以在这里阅读它们：https://docs.oracle.com/javase/tutorial/uiswing/layout/visual.html
希望这对您有所帮助。
PS：你想调试这个问题是个好主意，添加这样的边框：
// label.setBorder(BorderFactory.createLineBorder(Color.BLACK));
不确定您为什么将其注释掉。也许你没有注意到整个框架区域周围有一个黑色边框。尝试将颜色设置为 Color.RED 或更明显的颜色。
由于 JLabel 填满了整个内容窗格，因此单击内容窗格中的任意位置会导致标签发生鼠标事件。
一些话：
1) 您也可以使用 GridBagLayout, instead of FlowLayout, in case you want the JLabel centered in its parent component (both vertically and horizontally). This solution is here。
像这样：
final JPanel singleCenteredComponentJPanel = new JPanel(new GridBagLayout());
singleCenteredComponentJPanel.add(label);
frame.add(singleCenteredComponentJPanel);
2) 此外，如果您想忽略鼠标点击标签图标的任何透明像素（如果有），您可以执行以下操作：
使用 BufferedImage.getRGB(int x, int y), BufferedImage.getColorModel() and ColorModel.getAlpha(int pixel) 方法确定每个鼠标事件的单击像素的 alpha 值。如果 alpha 值等于 0，则像素是完全透明的，否则 alpha 值介于 1 和 255（包括两者）之间，这反过来意味着像素不是完全透明的。示例代码如下。
而不是 Image.getScaledInstance(...) to scale the image (which returns Image, but we need BufferedImage), use the solution provided here。
像这样：
private static void loadImage() throws IOException {
int newWidth = 80;
int newHeight = 40;
bi = ImageIO.read(RoundedButtonDemo.class.getResource("/resources/login.png"));
bi = getScaledBufferedImage(bi, newWidth, newHeight);
}
public static BufferedImage getScaledBufferedImage(final Image img,
final int newWidth,
final int newHeight) {
final GraphicsEnvironment genv = GraphicsEnvironment.getLocalGraphicsEnvironment();
final GraphicsDevice gdev = genv.getDefaultScreenDevice();
final GraphicsConfiguration gcnf = gdev.getDefaultConfiguration();
final BufferedImage simg = gcnf.createCompatibleImage(newWidth, newHeight, Transparency.TRANSLUCENT);
//Painting input image to output image:
final Graphics2D g2d = simg.createGraphics();
g2d.drawImage(img, 0, 0, newWidth, newHeight, null); //@Docs "...is scaled if necessary.".
g2d.dispose();
return simg;
}
同时将引用 bi 从 Image to BufferedImage 更改。
然后是标签的MouseListener：
private int count = 0;
@Override
public void mouseClicked(MouseEvent e) {
if (e.getSource() == label) {
//Get the mouse click position (in pixels),
//relative to the top-left corner of label:
final Point relativeClickPoint = e.getPoint();
//Obtain alpha value from the TYPE_INT_ARGB pixel:
final int pixel = bi.getRGB(relativeClickPoint.x, relativeClickPoint.y);
final int alpha = bi.getColorModel().getAlpha(pixel);
if (alpha > 0) { //Check if the pixel is not transparent.
if (count % 2 == 0) {
label.setText("Bye");
} else {
label.setText("Hello World");
}
count++;
}
}
}
请注意 上述实现：图像的所有透明像素都将被忽略（包括透明像素 "inside" 形状，如果有的话）。这意味着用户可以点击图像的中心，如果点击的像素是完全透明的，则什么也不会发生。所以我假设你这里的图片不是这种情况。
3) 对于 Image 的缩放，您可以使用方法 collapseInside(...) 确定新的大小：
/**
* @param resultDim Output dimension (same aspect ratio as the original dimension, and inside containerDim).
* @param originalDim Original dimension.
* @param containerDim Dimension with the maximum width and maximum height.
*/
public static void collapseInside(final Dimension resultDim,
final Dimension originalDim,
final Dimension containerDim) {
resultDim.setSize(originalDim);
if (resultDim.width > containerDim.width) {
//Adjusting height for max width:
resultDim.height = ( resultDim.height * containerDim.width ) / resultDim.width;
resultDim.width = containerDim.width;
}
if (resultDim.height > containerDim.height) {
//Adjusting width for max height:
resultDim.width = ( resultDim.width * containerDim.height ) / resultDim.height;
resultDim.height = containerDim.height;
}
}
用这个方法：
a) 缩放后 Image 的宽度将小于或等于容器的尺寸宽度 (resultDim.width <= containerDim.width)。
b) 高度相同 (resultDim.height <= containerDim.height).
c) 原始 Image 尺寸的宽高比将保留在新的 Image 尺寸中 (resultDim.width / resultDim.height == originalDim.width / originalDim.height ).
使用 Image.getScaledInstance(...) 和之前的 getScaledBufferedImage(...)，Image 的纵横比可能会改变。
所以我编辑 getScaledBufferedImage(...) 以使用 collapseInside(...)：
public static BufferedImage getScaledBufferedImage(final Image img,
final int newWidth,
final int newHeight) {
final Dimension originalDim = new Dimension(img.getWidth(null), img.getHeight(null)),
containerDim = new Dimension(newWidth, newHeight),
resultDim = new Dimension();
collapseInside(resultDim, originalDim, containerDim);
final GraphicsEnvironment genv = GraphicsEnvironment.getLocalGraphicsEnvironment();
final GraphicsDevice gdev = genv.getDefaultScreenDevice();
final GraphicsConfiguration gcnf = gdev.getDefaultConfiguration();
final BufferedImage simg = gcnf.createCompatibleImage(resultDim.width, resultDim.height, Transparency.TRANSLUCENT);
//Painting input image to output image:
final Graphics2D g2d = simg.createGraphics();
g2d.drawImage(img, 0, 0, resultDim.width, resultDim.height, null); //@Docs "...is scaled if necessary.".
g2d.dispose();
return simg;
}
以上所有三个的完整代码：
import java.awt.Dimension;
import java.awt.Graphics2D;
import java.awt.GraphicsConfiguration;
import java.awt.GraphicsDevice;
import java.awt.GraphicsEnvironment;
import java.awt.GridBagLayout;
import java.awt.Image;
import java.awt.Point;
import java.awt.Transparency;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.image.BufferedImage;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public final class RoundedButtonDemo {
private static BufferedImage bi;
public static void main(String[] args) {
try {
loadImage();
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
createAndShowGUI();
}
});
} catch (IOException e) {
// handle exception
}
}
private static void loadImage() throws IOException {
int newWidth = 80;
int newHeight = 40;
bi = ImageIO.read(RoundedButtonDemo.class.getResource("/resources/login.png"));
bi = getScaledBufferedImage(bi, newWidth, newHeight);
}
public static BufferedImage getScaledBufferedImage(final Image img,
final int newWidth,
final int newHeight) {
final Dimension originalDim = new Dimension(img.getWidth(null), img.getHeight(null)),
containerDim = new Dimension(newWidth, newHeight),
resultDim = new Dimension();
collapseInside(resultDim, originalDim, containerDim);
final GraphicsEnvironment genv = GraphicsEnvironment.getLocalGraphicsEnvironment();
final GraphicsDevice gdev = genv.getDefaultScreenDevice();
final GraphicsConfiguration gcnf = gdev.getDefaultConfiguration();
final BufferedImage simg = gcnf.createCompatibleImage(resultDim.width, resultDim.height, Transparency.TRANSLUCENT);
//Painting input image to output image:
final Graphics2D g2d = simg.createGraphics();
g2d.drawImage(img, 0, 0, resultDim.width, resultDim.height, null); //@Docs "...is scaled if necessary.".
g2d.dispose();
return simg;
}
/**
* @param resultDim Output dimension (same aspect ratio as the original dimension, and inside containerDim).
* @param originalDim Original dimension.
* @param containerDim Dimension with the maximum width and maximum height.
*/
public static void collapseInside(final Dimension resultDim,
final Dimension originalDim,
final Dimension containerDim) {
resultDim.setSize(originalDim);
if (resultDim.width > containerDim.width) {
//Adjusting height for max width:
resultDim.height = ( resultDim.height * containerDim.width ) / resultDim.width;
resultDim.width = containerDim.width;
}
if (resultDim.height > containerDim.height) {
//Adjusting width for max height:
resultDim.width = ( resultDim.width * containerDim.height ) / resultDim.height;
resultDim.height = containerDim.height;
}
}
private static void createAndShowGUI() {
final JFrame frame = new JFrame();
frame.setSize(400, 400);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
final JLabel label = new JLabel();
label.setSize(new Dimension(5, 5));
label.setIcon(new ImageIcon(bi));
label.setText("Hello World");
label.setHorizontalTextPosition(JLabel.CENTER);
// label.setBorder(BorderFactory.createLineBorder(Color.BLACK));
label.addMouseListener(new MouseListener() {
private int count = 0;
@Override
public void mouseClicked(MouseEvent e) {
if (e.getSource() == label) {
//Get the mouse click position (in pixels),
//relative to the top-left corner of label:
final Point relativeClickPoint = e.getPoint();
//Obtain alpha value from the TYPE_INT_ARGB pixel:
final int pixel = bi.getRGB(relativeClickPoint.x, relativeClickPoint.y);
final int alpha = bi.getColorModel().getAlpha(pixel);
if (alpha > 0) { //Check if the pixel is not transparent.
if (count % 2 == 0) {
label.setText("Bye");
} else {
label.setText("Hello World");
}
count++;
}
}
}
@Override
public void mouseEntered(MouseEvent e) {
// TODO Auto-generated method stub
}
@Override
public void mouseExited(MouseEvent e) {
// TODO Auto-generated method stub
}
@Override
public void mousePressed(MouseEvent e) {
// TODO Auto-generated method stub
}
@Override
public void mouseReleased(MouseEvent e) {
// TODO Auto-generated method stub
}
});
final JPanel singleCenteredComponentJPanel = new JPanel(new GridBagLayout());
singleCenteredComponentJPanel.add(label);
frame.add(singleCenteredComponentJPanel);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
}
或者，您也可以覆盖 JPanel 的 paintComponent(...) 并使用 Graphics.drawImage(...) 将 Image bi 绘制到 JPanel 像这样：
@Override
protected void paintComponent(final Graphics g) {
super.paintComponent(g);
//Drawing the image:
g.drawImage(img, 0, 0, null);
//Drawing the text:
//For centering the text, I used code from:
//
final FontMetrics metrics = g.getFontMetrics(g.getFont());
final int x = (img.getWidth(null) - metrics.stringWidth(text)) / 2;
final int y = (img.getHeight(null) - metrics.getHeight()) / 2 + metrics.getAscent();
g.drawString(text, x, y);
}
其中 img 是 bi，text 是按钮的文本（即 "Hello World" 和 "Bye"）。
然后按原样将 MouseListener 添加到 JPanel。
完整代码（如“RoundedButtonDemo1”class，在同一个包中）：
import java.awt.Dimension;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GraphicsConfiguration;
import java.awt.GraphicsDevice;
import java.awt.GraphicsEnvironment;
import java.awt.GridBagLayout;
import java.awt.Image;
import java.awt.Point;
import java.awt.Transparency;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.image.BufferedImage;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public final class RoundedButtonDemo1 {
private static BufferedImage bi;
public static void main(String[] args) {
try {
loadImage();
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
createAndShowGUI();
}
});
} catch (IOException e) {
// handle exception
}
}
private static void loadImage() throws IOException {
int newWidth = 80;
int newHeight = 40;
bi = ImageIO.read(RoundedButtonDemo1.class.getResource("/resources/login.png"));
bi = getScaledBufferedImage(bi, newWidth, newHeight);
}
public static BufferedImage getScaledBufferedImage(final Image img,
final int newWidth,
final int newHeight) {
final Dimension originalDim = new Dimension(img.getWidth(null), img.getHeight(null)),
containerDim = new Dimension(newWidth, newHeight),
resultDim = new Dimension();
collapseInside(resultDim, originalDim, containerDim);
final GraphicsEnvironment genv = GraphicsEnvironment.getLocalGraphicsEnvironment();
final GraphicsDevice gdev = genv.getDefaultScreenDevice();
final GraphicsConfiguration gcnf = gdev.getDefaultConfiguration();
final BufferedImage simg = gcnf.createCompatibleImage(resultDim.width, resultDim.height, Transparency.TRANSLUCENT);
//Painting input image to output image:
final Graphics2D g2d = simg.createGraphics();
g2d.drawImage(img, 0, 0, resultDim.width, resultDim.height, null); //@Docs "...is scaled if necessary.".
g2d.dispose();
return simg;
}
/**
* @param resultDim Output dimension (same aspect ratio as the original dimension, and inside containerDim).
* @param originalDim Original dimension.
* @param containerDim Dimension with the maximum width and maximum height.
*/
public static void collapseInside(final Dimension resultDim,
final Dimension originalDim,
final Dimension containerDim) {
resultDim.setSize(originalDim);
if (resultDim.width > containerDim.width) {
//Adjusting height for max width:
resultDim.height = ( resultDim.height * containerDim.width ) / resultDim.width;
resultDim.width = containerDim.width;
}
if (resultDim.height > containerDim.height) {
//Adjusting width for max height:
resultDim.width = ( resultDim.width * containerDim.height ) / resultDim.height;
resultDim.height = containerDim.height;
}
}
private static class CustomButton extends JPanel {
private Image img;
private String text;
public void setImage(final Image img) {
this.img = img;
final Dimension imgDim = new Dimension(img.getWidth(null), img.getHeight(null));
setMinimumSize(imgDim);
setPreferredSize(imgDim);
repaint();
}
public Image getImage() {
return img;
}
public void setText(final String text) {
this.text = text;
repaint();
}
public String getText() {
return text;
}
@Override
protected void paintComponent(final Graphics g) {
super.paintComponent(g);
//Drawing the image:
g.drawImage(img, 0, 0, null);
//Drawing the text:
//For centering the text, I used code from:
//
final FontMetrics metrics = g.getFontMetrics(g.getFont());
final int x = (img.getWidth(null) - metrics.stringWidth(text)) / 2;
final int y = (img.getHeight(null) - metrics.getHeight()) / 2 + metrics.getAscent();
g.drawString(text, x, y);
}
}
private static void createAndShowGUI() {
final JFrame frame = new JFrame();
frame.setSize(400, 400);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
final CustomButton button = new CustomButton();
button.setSize(new Dimension(5, 5));
button.setImage(bi);
button.setText("Hello World");
//button.setHorizontalTextPosition(SwingConstants.CENTER);
//button.setOpaque(false);
//button.setBorder(BorderFactory.createLineBorder(Color.BLACK));
button.addMouseListener(new MouseListener() {
private int count = 0;
@Override
public void mouseClicked(MouseEvent e) {
if (e.getSource() == button) {
//Get the mouse click position (in pixels),
//relative to the top-left corner of label:
final Point relativeClickPoint = e.getPoint();
//Obtain alpha value from the TYPE_INT_ARGB pixel:
final int pixel = bi.getRGB(relativeClickPoint.x, relativeClickPoint.y);
final int alpha = bi.getColorModel().getAlpha(pixel);
if (alpha > 0) { //Check if the pixel is not transparent.
if (count % 2 == 0) {
button.setText("Bye");
} else {
button.setText("Hello World");
}
count++;
}
}
}
@Override
public void mouseEntered(MouseEvent e) {
// TODO Auto-generated method stub
}
@Override
public void mouseExited(MouseEvent e) {
// TODO Auto-generated method stub
}
@Override
public void mousePressed(MouseEvent e) {
// TODO Auto-generated method stub
}
@Override
public void mouseReleased(MouseEvent e) {
// TODO Auto-generated method stub
}
});
final JPanel singleCenteredComponentJPanel = new JPanel(new GridBagLayout());
singleCenteredComponentJPanel.add(button);
frame.add(singleCenteredComponentJPanel);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
}
或者，如果您想要普通按钮而不是标签，看来 here 您也可以重塑按钮 !
除此之外，我还尝试了以下方法：
1) 使用 JLayeredPanes. There is a tutorial explaining them, and I guessed they could probably have a method to obtain the order of the visible pane for a given Point 或类似的东西，但他们没有。
2) 在 MouseListener 中使用 Container.getComponentAt(Point) 和 Container.findComponentAt(Point)，但是（正如我在测试后发现的) 这些方法不会 "see through" 非不透明（+透明）像素。
3) 在 JPanels (inspired by How to Create Translucent and Shaped Windows) 中搜索重塑或半透明，但没有找到。
4) How to Decorate Components with the JLayer Class 第一行说：
... enables you to draw on components and respond to component events without modifying the underlying component directly.
看起来很有希望，但我已经完成了。
我现在就到此为止。再见。