我正在绘制模拟生成的信息的图形表示。我有图表显示，但我遇到的问题是能够将其保存为.png。当它保存png时，文件全部为黑色，因此它不保存我的图形，而是创建一些空白的png文件。问题是我很难弄清楚如何在eclipse throw错误中转换为BufferedImage或RenderedImage所有的尝试，当我得到它编译时，它就像我上面描述的那样工作。有什么想法或建议吗？我已经坚持了几个星期，这或者是一个明显的解决方案，或者我无法将其保存为png。但是从我进行的研究中，可以将java 2d图形img保存为png文件，我不知道我缺少什么？一双新鲜的眼睛会受到极大的赞赏！提前感谢您，我感谢任何有关此事的建议或意见。
public class GraphDisplay extends JPanel implements RenderedImage {
final int PAD = 20;
Primate p;
public GraphDisplay(){
}
public GraphDisplay(Primate p){
this.p = p;
}
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D)g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
// now we can get x1,y1,x2,y2
double tlx= p.getMap().getX1();
double tly= p.getMap().getY1();
double brx= p.getMap().getX2();
double bry= p.getMap().getY2();
int w = getWidth();
int h= getHeight();
ArrayList <Tree> t= p.getMap().getTrees();
ArrayList<Double> xHist = p.getXHist();
ArrayList<Double> yHist = p.getYHist();
ArrayList<Double> testxHist = new ArrayList();
ArrayList<Double> testyHist = new ArrayList();
for(double i=34;i<1000;i+=5)
{
testxHist.add(i);
}
for(double i=34;i<1000;i+=5)
{
testyHist.add(i);
}
// Draw lines.
double scale=.45;
g2.setBackground(Color.WHITE);
g2.setPaint(Color.green.darker());
for(int i = 0; i < xHist.size()-1; i++) {
double x1 = PAD + (xHist.get(i)-tlx)*scale;
double y1 = (tly-yHist.get(i))*scale-PAD;
double x2 = PAD + (xHist.get(i+1)-tlx)*scale;
double y2 = (tly-yHist.get(i+1))*scale-PAD;
g2.draw(new Line2D.Double(x1, y1, x2, y2));
}
// Mark path points
if(p.getRoute()!=null)
{
ArrayList<Double> routeX= p.getRoute().getX();
ArrayList<Double> routeY= p.getRoute().getY();
g2.setPaint(Color.pink);
for(int i = 0; i < routeX.size()-1; i++) {
double x1 = PAD + (routeX.get(i)-tlx)*scale;
double y1 = (tly-routeY.get(i))*scale-PAD;
double x2 = PAD + (routeX.get(i+1)-tlx)*scale;
double y2 = (tly-routeY.get(i+1))*scale-PAD;
g2.draw(new Line2D.Double(x1, y1, x2, y2));
}
}
g2.setPaint(Color.red);
for(int i = 0; i < xHist.size(); i++) {
double x = PAD + (xHist.get(i)-tlx)*scale;
double y = (tly-yHist.get(i))*scale-PAD;
g2.fill(new Ellipse2D.Double(x-.75, y-.75, 1.5, 1.5));
}
//testing purposes
g2.setPaint(Color.BLACK);
for(int i=0;i<t.size();i++)
{
double x= PAD+(t.get(i).getX()-tlx)*scale;
double y= (tly-t.get(i).getY())*scale-PAD;
g2.fill(new Ellipse2D.Double(x-1,y-1,2,2));
}
}
public class GraphListener implements ActionListener
{
public void actionPerformed(ActionEvent event)
{
saveGraph(p);
}
}
public void saveGraph(Primate p)
{
ImageIcon saveIcon = new ImageIcon("save.png");
GraphDisplay graphImg = new GraphDisplay(p);
Object graph = new GraphDisplay(p);
BufferedImage buffGraph = new BufferedImage(500,500, BufferedImage.TYPE_INT_RGB);
graph = buffGraph.createGraphics();
RenderedImage rendGraph = (RenderedImage) graphImg;
String graphFileName = JOptionPane.showInputDialog("Please enter a name for the S1Mian graphical output file: ");
File f;
f = new File(graphFileName + ".png");
//every run is unique so do not allow the user to overwrite previously saved files...
if(!f.exists())
{
try{
ImageIO.write(buffGraph, "png", f);
JOptionPane.showMessageDialog(null, graphFileName + ".png has been created and saved to your directory...", "File Saved", JOptionPane.INFORMATION_MESSAGE, saveIcon);
}
catch (IOException e)
{
e.printStackTrace();
}
}
else{
JOptionPane.showMessageDialog(null, graphFileName +".png already exists please use a different file name...", "File Exists", JOptionPane.INFORMATION_MESSAGE, saveIcon);
}
}
public void createGraph(Primate p)
{
JFrame frame = new JFrame("S1Mian Graphical Output");
//frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //disabled now that graphical output is integrated into GUI as when clicked shut down entire program...
JPanel savePanel = new JPanel();
ImageIcon saveIcon = new ImageIcon("saveIcon.png");
JButton save = new JButton("Save");
save.setToolTipText("Saves the S1Mian graphical output to a .png file");
save.setIcon(saveIcon);
GraphListener gl = new GraphListener();
save.addActionListener(gl);
GraphDisplay graph = new GraphDisplay(p);
graph.setPreferredSize(new Dimension(950, 900));
JScrollPane graphScrollPane = new JScrollPane();
graphScrollPane.setViewportView(graph);
graphScrollPane.setViewportBorder(BorderFactory.createLineBorder(Color.black));
frame.getContentPane().add(graphScrollPane, BorderLayout.CENTER);
savePanel.add(save);
frame.getContentPane().add(savePanel, BorderLayout.NORTH);
frame.setSize(900,850);
frame.setLocation(200,200);
frame.setVisible(true);
}
答案 0 :(得分：20)
JPanel dPanel;
...
public void save()
{
BufferedImage bImg = new BufferedImage(dPanel.getWidth(), dPanel.getHeight(), BufferedImage.TYPE_INT_RGB);
Graphics2D cg = bImg.createGraphics();
dPanel.paintAll(cg);
try {
if (ImageIO.write(bImg, "png", new File("./output_image.png")))
{
System.out.println("-- saved");
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
答案 1 :(得分：6)
请参阅此示例：Draw an Image and save to png。
import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Font;
import java.awt.FontMetrics;
import java.awt.GradientPaint;
import java.awt.Graphics2D;
import java.awt.geom.Ellipse2D;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
public class WriteImageType {
static public void main(String args[]) throws Exception {
try {
int width = 200, height = 200;
// TYPE_INT_ARGB specifies the image format: 8-bit RGBA packed
// into integer pixels
BufferedImage bi = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
Graphics2D ig2 = bi.createGraphics();
Font font = new Font("TimesRoman", Font.BOLD, 20);
ig2.setFont(font);
String message = "www.java2s.com!";
FontMetrics fontMetrics = ig2.getFontMetrics();
int stringWidth = fontMetrics.stringWidth(message);
int stringHeight = fontMetrics.getAscent();
ig2.setPaint(Color.black);
ig2.drawString(message, (width - stringWidth) / 2, height / 2 + stringHeight / 4);
ImageIO.write(bi, "PNG", new File("c:\\yourImageName.PNG"));
ImageIO.write(bi, "JPEG", new File("c:\\yourImageName.JPG"));
ImageIO.write(bi, "gif", new File("c:\\yourImageName.GIF"));
ImageIO.write(bi, "BMP", new File("c:\\yourImageName.BMP"));
} catch (IOException ie) {
ie.printStackTrace();
}
}
}
答案 2 :(得分：4)
Screen Image将创建面板的缓冲图像并将图像写入文件。
答案 3 :(得分：1)
看来你实际上从未在saveGraph（..）例程中绘制到BufferedImage。
创建BufferedImage并检索该图像的Graphics对象后，调用传递该图形上下文的主类的paintComponent方法。您还创建了两个GraphDisplay对象，但从不使用任何一个。
GraphDisplay graphImg = new GraphDisplay(p);
//You don't need this one, you created one above named graphImg
// Object graph = new GraphDisplay(p);
BufferedImage buffGraph = new BufferedImage(500,500, BufferedImage.TYPE_INT_RGB);
//get the graphics context for the BufferedImage
Graphics2D graph = buffGraph.createGraphics();
//now tell your main class to draw the image onto the BufferedImage
graphImg.paintComponent(graph);
此时，您的BufferedImage现在应该具有与您的面板相同的图形，并且您应该能够保存内容。