Java JComponent';验证()、重新验证()或绘制()正在调用s绘制(图形g)方法?
我已经有一段时间(2年多)没有开发JavaSwing应用程序了,所以请原谅我犯了一些愚蠢的错误 我想上传一些艺术品,这将显示为全屏图像 我遇到的问题是,我已经扩展用于表示图像对象的JComponent,没有调用它的paint()方法,也没有在现有的JPanel上绘制自己。 下面是通过扩展JComponent的“art”类上载图像和实例化的相关片段和事件 类JFrameMainArt的actionPerformed()方法(仅适用于相关部分),当打开操作结束时,图像对象应绘制在fullscreenJPanel上Java JComponent';验证()、重新验证()或绘制()正在调用s绘制(图形g)方法?,java,swing,java-2d,Java,Swing,Java 2d,我已经有一段时间(2年多)没有开发JavaSwing应用程序了,所以请原谅我犯了一些愚蠢的错误 我想上传一些艺术品,这将显示为全屏图像 我遇到的问题是,我已经扩展用于表示图像对象的JComponent,没有调用它的paint()方法,也没有在现有的JPanel上绘制自己。 下面是通过扩展JComponent的“art”类上载图像和实例化的相关片段和事件 类JFrameMainArt的actionPerformed()方法(仅适用于相关部分),当打开操作结束时,图像对象应绘制在fullscreen
@Override
public void actionPerformed(ActionEvent arg0) {
if (arg0.getActionCommand().equalsIgnoreCase("Fullscreen Mode")) {
isScreenFullscreen = true;
// full screen mode settings
fullscreenFrame.invalidate();
fullscreenFrame = null;
// create new fullscreen frame
fullscreenFrame = new JFrame();
fullscreenFrame
.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
fullscreenFrame.setUndecorated(true);
fullscreenFrame.setResizable(false);
// add label to Panel
fullscreenPanel.add(new JLabel("ALT + F4 to exit .",
SwingConstants.CENTER), BorderLayout.CENTER);
fullscreenFrame.invalidate();
GraphicsEnvironment.getLocalGraphicsEnvironment()
.getDefaultScreenDevice()
.setFullScreenWindow(fullscreenFrame);
} else if (arg0.getActionCommand().equalsIgnoreCase("Upload")) {
System.out.println("Upload Pictures");
fileChooser = new JFileChooser();
fileChooser
.setDialogTitle("Choose Your Image File (PNG or JPEG only)");
// below codes for select the file
int returnval = fileChooser.showOpenDialog(null);
File file = fileChooser.getSelectedFile();
System.out.println("Upload Pictures, selected file path: "
+ file.getAbsolutePath());
// if OPEN
if (returnval == JFileChooser.APPROVE_OPTION) {
String name = file.getName();
if (name != null) {
int i = name.indexOf('.');
// get the extension such as jpeg, or png
String extension = name.substring(i + 1);
System.out.println("extension: " + extension);
if (extension.equalsIgnoreCase("jpeg")
|| extension.equalsIgnoreCase("jpg")
|| extension.equalsIgnoreCase("png")) {
Art newArt = new Art(file, fullscreenPanel.getSize());
//test dimension
System.out.println("Dimension of image "+name+"- Dimensions "+newArt.scaleImageToJPanelDimensions(newArt.getImageFromFile()));
//add Art Jcomponent to existing JPanel
fullscreenPanel.add(newArt);
//revalidate & paint
fullscreenPanel.revalidate();
fullscreenPanel.repaint();
//pack & revalidate the Jframe
fullscreenFrame.revalidate();
} else {
System.out
.println("Error file/image type is not supported: "
+ extension);
}
}// end name not null
else {
System.out.println("Error file name: " + name);
}
} else if (returnval == JFileChooser.ERROR_OPTION) {
System.out.println("Error selecting file");
} else {
System.out.println("returnval: " + returnval);
}
}// end else if upload
else if (arg0.getActionCommand().equalsIgnoreCase("Choose Effect")) {
} else {
}
}//end method actionPerformed()
Art.java扩展了JComponent,并负责加载图像、缩放图像、绘制图像对象
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.beans.Transient;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JComponent;
public class Art extends JComponent {
private File file = null;
private BufferedImage image = null;
private Dimension dimensionToScale = null;
public Art(File file, Dimension dimensionToScale) {
super();
this.file = file;
this.dimensionToScale = dimensionToScale;
this.setVisible(true);
}
@Override
@Transient
public Dimension getPreferredSize() {
// TODO Auto-generated method stub
return this.dimensionToScale;
}
public Art(File file) {
super();
this.file = file;
this.setVisible(true);
}
public BufferedImage getImageFromFile() {
BufferedImage image = null;
if (this.file != null) {
try {
image = ImageIO.read(file);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
return image;
}
public Dimension scaleImageToJPanelDimensions(BufferedImage image) {
Dimension dimension = null;
// scaling factors
int imageWidth = image.getWidth();
int imageHeight = image.getHeight();
// scale based on largest side
int largestImageSide = Math.min(imageWidth, imageHeight);
double scaledHeight = this.dimensionToScale.getHeight()
/ largestImageSide;
double scaledWidth = this.dimensionToScale.getWidth()
/ largestImageSide;
// compute new image dimensions
imageWidth = (int) (imageWidth * scaledWidth);
imageHeight = (int) (imageHeight * scaledHeight);
dimension = new Dimension(imageWidth, imageHeight);
return dimension;
}
@Override
public void paintComponent(Graphics g) {
System.out.println("paintComponent(Graphics g) ");
super.paintComponent (g);
// repaint background
g.setColor(getBackground());
g.fillRect(0, 0, getWidth(), getHeight());
g.setColor(getForeground());
image = getImageFromFile();
if (image != null) {
// compute dimensions of image to draw
Dimension imageDimension = scaleImageToJPanelDimensions(image);
/*public abstract boolean drawImage(Image img,
int x,
int y,
int width,
int height,
ImageObserver observer)*/
g.drawImage(image, 0,0, (int) imageDimension.getWidth() ,(int)imageDimension.getHeight(),this);
} else {
System.out.println("paintComponent(Graphics g) image:"+image);
}
}
}/end Art class
任何帮助都将不胜感激
谢谢
实际工作方法,现在已绘制图像,问题已解决
public void loadArtToScreen(Art art)
{
//add Art JComponent to existing JPanel
JPanelGroupLayout.setHorizontalGroup(JPanelGroupLayout.createParallelGroup(
Alignment.LEADING).addGroup(
JPanelGroupLayout.createSequentialGroup().addGap(0)
.addComponent(art )
.addContainerGap((int)mainJFrameSize.getWidth(), Short.MAX_VALUE)));
JPanelGroupLayout.setVerticalGroup(JPanelGroupLayout.createParallelGroup(
Alignment.LEADING).addGroup(
JPanelGroupLayout.createSequentialGroup().addGap(0)
.addComponent(art )
.addContainerGap((int)mainJFrameSize.getHeight(), Short.MAX_VALUE)));
//revalidate & paint
fullscreenPanel.revalidate();
fullscreenPanel.repaint();
//pack & revalidate the Jframe
mainJFrame.revalidate();
}//end loadArtToScreen(Art art)
图像
,因此您的绘制
方法将抛出NullPointerException
Graphics#drawImage(Image,int,int,ImageObserver)
指的是图像应该绘制的位置,而不是它的大小(奇怪的是,您的缩放算法是return0x0
,但我没有花太多时间研究它)this
传递到Graphics#drawImage
paintComponent
方法而不是paint
方法的上下文中进行自定义绘制。有关更多详细信息,请参阅NullPointerException
之后,我甚至在帧变为可见和添加窗格之间引入了一个小延迟,并使其工作
在测试时尝试删除全屏要求…调用
fullscreenFrame.pack()代码>在全屏窗口上没有意义…为了更快地获得更好的帮助,请发布。我更新了上述代码,修复了您提出的错误1)我现在正在加载图像,2)我正在绘制图像从顶部开始,左0,0图像尺寸不再为零3)JComponent引用在paintComponent()中传递4)我正在使用paintComponent(),没有错误或异常,但是,图像仍然没有绘制,paintComponent()从未调用。因此,我可以让您的艺术类。paintComponent不会被调用的唯一原因是组件t不可显示(已添加到屏幕上显示的容器中)或组件没有合适的大小。这一切都不可能确定。你的片段。用一个可运行的例子,我们只能猜测@MadProgrammer,谢谢你的努力,我实际上已经发布了整个艺术课程,请参见上面。在我的程序中,我将艺术(JComponent)添加到一个具有GroupLayout的JPanel中,而JPanel(将与JFrame相同)本身被添加到我的主JFrame(也是GroupLayout)中,现在将发布整个主JFrame。@Aryanaim是的,我使用了你的艺术类,这就是为什么我可以找到错误的原因。我会避免使用GroupLayout,它不是特别动态的。尝试使用BorderLayout之类的东西作为测试,我实际上将图像加载封装在一个方法中,并发现我必须通过指定水平和垂直组件将我的艺术类(JComponent)添加到主JPanel is groupLayout中。这幅画现在已经画出来了,但是它很小,实际上画出了图片的1/4,尽管尺寸是正确的。我会接受你的回答,因为你指出了重要的错误。我将在上面发布我的工作方法,基于loadArtToScreen(艺术)方法为什么只绘制图像的1/4???谢谢