Java 在JPanel上添加.GIF时显示的黑色方块
我的问题是,当向JPanel添加.GIF时,它会显示.GIF的黑色方形背景 在JPanel上添加时的结果:Java 在JPanel上添加.GIF时显示的黑色方块,java,swing,jframe,jpanel,imageicon,Java,Swing,Jframe,Jpanel,Imageicon,我的问题是,当向JPanel添加.GIF时,它会显示.GIF的黑色方形背景 在JPanel上添加时的结果: String loadLink = "http://i.imgur.com/mHm6LYH.gif"; URL ajaxLoad = null; try { ajaxLoad = new URL(loadLink); } catch (MalformedURLException e3) { //
String loadLink = "http://i.imgur.com/mHm6LYH.gif";
URL ajaxLoad = null;
try {
ajaxLoad = new URL(loadLink);
} catch (MalformedURLException e3) {
// TODO Auto-generated catch block
e3.printStackTrace();
}
ImageIcon loading = new ImageIcon(ajaxLoad);
JLabel loadBar = new JLabel(loading);
loadBar.setBounds(70, 60, 54, 55);
loadBar.setOpaque(false);
//jf.add(loadBar);
p2.add(loadBar);
// Creates the Initialization Panel
p2 = new JPanel();
// Sets the background, black with 125 as alpha value
// This is less transparent
p2.setLayout(null);
p2.setBackground(new Color(0,0,0,150));
// Sets a border to the JPanel
p2.setBorder(new LineBorder(Color.WHITE));
// Sets some size to the panels
p2.setBounds(20, 20, 200, 150);
// Adds the loading gif
String loadLink = "http://i.imgur.com/mHm6LYH.gif";
URL ajaxLoad = null;
try {
ajaxLoad = new URL(loadLink);
} catch (MalformedURLException e3) {
// TODO Auto-generated catch block
e3.printStackTrace();
}
ImageIcon loading = new ImageIcon(ajaxLoad);
JLabel loadBar = new JLabel(loading);
loadBar.setBounds(70, 60, 54, 55);
loadBar.setOpaque(false);
p2.add(loadBar);
当我使用这一行时会发生:
p2.add(loadBar); // where p2 = new JPanel();
然而,当我在JFrame上添加相同的.GIF文件时,黑色的方块就不再存在了。像这样:
jf.add(loadBar); // where jf = new JFrame();
在JFrame上添加时的结果:
String loadLink = "http://i.imgur.com/mHm6LYH.gif";
URL ajaxLoad = null;
try {
ajaxLoad = new URL(loadLink);
} catch (MalformedURLException e3) {
// TODO Auto-generated catch block
e3.printStackTrace();
}
ImageIcon loading = new ImageIcon(ajaxLoad);
JLabel loadBar = new JLabel(loading);
loadBar.setBounds(70, 60, 54, 55);
loadBar.setOpaque(false);
//jf.add(loadBar);
p2.add(loadBar);
// Creates the Initialization Panel
p2 = new JPanel();
// Sets the background, black with 125 as alpha value
// This is less transparent
p2.setLayout(null);
p2.setBackground(new Color(0,0,0,150));
// Sets a border to the JPanel
p2.setBorder(new LineBorder(Color.WHITE));
// Sets some size to the panels
p2.setBounds(20, 20, 200, 150);
// Adds the loading gif
String loadLink = "http://i.imgur.com/mHm6LYH.gif";
URL ajaxLoad = null;
try {
ajaxLoad = new URL(loadLink);
} catch (MalformedURLException e3) {
// TODO Auto-generated catch block
e3.printStackTrace();
}
ImageIcon loading = new ImageIcon(ajaxLoad);
JLabel loadBar = new JLabel(loading);
loadBar.setBounds(70, 60, 54, 55);
loadBar.setOpaque(false);
p2.add(loadBar);
类代码的一部分:
String loadLink = "http://i.imgur.com/mHm6LYH.gif";
URL ajaxLoad = null;
try {
ajaxLoad = new URL(loadLink);
} catch (MalformedURLException e3) {
// TODO Auto-generated catch block
e3.printStackTrace();
}
ImageIcon loading = new ImageIcon(ajaxLoad);
JLabel loadBar = new JLabel(loading);
loadBar.setBounds(70, 60, 54, 55);
loadBar.setOpaque(false);
//jf.add(loadBar);
p2.add(loadBar);
// Creates the Initialization Panel
p2 = new JPanel();
// Sets the background, black with 125 as alpha value
// This is less transparent
p2.setLayout(null);
p2.setBackground(new Color(0,0,0,150));
// Sets a border to the JPanel
p2.setBorder(new LineBorder(Color.WHITE));
// Sets some size to the panels
p2.setBounds(20, 20, 200, 150);
// Adds the loading gif
String loadLink = "http://i.imgur.com/mHm6LYH.gif";
URL ajaxLoad = null;
try {
ajaxLoad = new URL(loadLink);
} catch (MalformedURLException e3) {
// TODO Auto-generated catch block
e3.printStackTrace();
}
ImageIcon loading = new ImageIcon(ajaxLoad);
JLabel loadBar = new JLabel(loading);
loadBar.setBounds(70, 60, 54, 55);
loadBar.setOpaque(false);
p2.add(loadBar);
有人能解释一下为什么会这样吗?谢谢你的时间和阅读
编辑:
String loadLink = "http://i.imgur.com/mHm6LYH.gif";
URL ajaxLoad = null;
try {
ajaxLoad = new URL(loadLink);
} catch (MalformedURLException e3) {
// TODO Auto-generated catch block
e3.printStackTrace();
}
ImageIcon loading = new ImageIcon(ajaxLoad);
JLabel loadBar = new JLabel(loading);
loadBar.setBounds(70, 60, 54, 55);
loadBar.setOpaque(false);
//jf.add(loadBar);
p2.add(loadBar);
// Creates the Initialization Panel
p2 = new JPanel();
// Sets the background, black with 125 as alpha value
// This is less transparent
p2.setLayout(null);
p2.setBackground(new Color(0,0,0,150));
// Sets a border to the JPanel
p2.setBorder(new LineBorder(Color.WHITE));
// Sets some size to the panels
p2.setBounds(20, 20, 200, 150);
// Adds the loading gif
String loadLink = "http://i.imgur.com/mHm6LYH.gif";
URL ajaxLoad = null;
try {
ajaxLoad = new URL(loadLink);
} catch (MalformedURLException e3) {
// TODO Auto-generated catch block
e3.printStackTrace();
}
ImageIcon loading = new ImageIcon(ajaxLoad);
JLabel loadBar = new JLabel(loading);
loadBar.setBounds(70, 60, 54, 55);
loadBar.setOpaque(false);
p2.add(loadBar);
这就是JPanel,它显示在第一张没有JLabel的图像中。我无法在代码中真正显示JFrame部分,因为它分布在整个类中。但是我不认为JFrame有问题,所以可能是这个JPanel://根据您的第一个快照加载图像需要时间 请查看以检查图像的状态 当图像完全加载时,在
JPanel
中添加图像
示例代码:
new Thread(new Runnable() {
@Override
public void run() {
int width = loading.getIconWidth();
if (width >= 0) {
isImageLoaded = true;
p2.add(loadBar);
return;
}
// Wait if the image is not loaded yet
while (!isImageLoaded) {
try {
Thread.sleep(500);
} catch (InterruptedException ie) {
}
}
}
}).start();
你的问题在这里
p2.setBackground(new Color(0,0,0,150));
Swing不支持基于alpha的backgounds,或者组件是透明的,或者组件不是透明的
这样做意味着组件“尝试”使用alpha值作为背景填充颜色,但绘制管理器不知道它应该在组件下方绘制,从而导致各种问题
现在,这有点棘手。您需要使用setOpaque(false)
使容器透明,但这意味着不会绘制背景
您需要做的是创建一个自定义组件,将它的不透明
属性设置为假
并覆盖它的paintComponent
方法,并用基于alpha的颜色填充背景。我通常喜欢使用字母组合,但这也适用于
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.GridBagLayout;
import java.awt.HeadlessException;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.border.EmptyBorder;
public class TranslucentPanelExample {
public static void main(String[] args) {
new TranslucentPanelExample();
}
public TranslucentPanelExample() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
try {
JLabel background = new JLabel(
new ImageIcon(ImageIO.read(
getClass().getResource("/background.jpg"))));
background.setLayout(new GridBagLayout());
background.add(new WaitPane());
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(background);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
} catch (IOException exp) {
exp.printStackTrace();
}
}
});
}
public class WaitPane extends JPanel {
public WaitPane() {
setLayout(new GridBagLayout());
setBorder(new EmptyBorder(12, 12, 12, 12));
// This is very important
setOpaque(false);
setBackground(new Color(0, 0, 0, 150));
String loadLink = "http://i.imgur.com/mHm6LYH.gif";
URL ajaxLoad = null;
try {
ajaxLoad = new URL(loadLink);
} catch (MalformedURLException e3) {
// TODO Auto-generated catch block
e3.printStackTrace();
}
ImageIcon loading = new ImageIcon(ajaxLoad);
JLabel loadBar = new JLabel(loading);
loadBar.setHorizontalAlignment(JLabel.CENTER);
loadBar.setVerticalAlignment(JLabel.CENTER);
add(loadBar);
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(getBackground());
g.fillRect(0, 0, getWidth(), getHeight());
}
}
}
布局管理器,布局管理器,布局管理器
布局经理的重要性我怎么强调都不过分。您所依赖的“神奇”数字可能并不总是符合现实…根据您的代码,它对我来说非常有效。你能试试这个没有背景图片的代码吗?类似的代码对我来说也不错:你们能试试我在原始帖子中发布的编辑代码吗?谢谢当您注释p2.setBackground(新颜色(0,0,0150))时;它又好了,所以问题一定在某个地方…
p2.setLayout(null)
这是您的问题之一,不幸的是,它没有工作。它仍然和以前一样,但是请检查当你使用我在原始帖子中发布的JPanel代码时,你是否遇到了和我一样的问题。谢谢。现在您的新代码已经清楚了,@MadProgrammer已经回答了。@MadProgammer,非常感谢您!我将开始使用布局管理器。