I'm busy fiddling around with Java's Graphics2D and drawings and I although it works I am not sure how to create a BufferedImage from this graphic which it seems I need to do in order so save it somewhere.
I have something very basic because I'm trying to understand how this works
import javax.swing.*;
import javax.imageio.*;
import java.awt.*;
import java.awt.image.*;
import java.io.*;
public class myFrame {
public static void main(String[] args) {
JFrame lv_frame = new JFrame();
lv_frame.setTitle("Drawing");
lv_frame.setSize(300, 300);
lv_frame.setDefaultCloseOperation(JInternalFrame.DISPOSE_ON_CLOSE);
lv_frame.add(new drawingPanel(5, 5));
lv_frame.setVisible(true);
}
}
class drawingPanel extends JPanel {
public drawingPanel(int x, int y) {
}
public void draw(Graphics graphic) {
Graphics2D graphic2D = (Graphics2D) graphic;
graphic2D.fillArc(0, 0, 50, 50, 0, 45);
graphic2D.fillArc(0, 0, 50, 50, 135, 45);
BufferedImage image = new BufferedImage(100, 100, BufferedImage.TYPE_INT_BGR);
try {
graphic2D = image.createGraphics();
File output = new File("output.png");
ImageIO.write(image, "png", output);
} catch(IOException log) {
System.out.println(log);
}
}
public void paintComponent(Graphics graphic) {
super.paintComponent(graphic);
draw(graphic);
}
}
This works ok except I am getting a blank png as my output.png and I'm not sure why although I'm fairly certain my code is horribly wrong
WORKING VERSION
import javax.swing.*;
import javax.imageio.*;
import java.awt.*;
import java.awt.image.*;
import java.io.*;
public class myFrame {
public static void main(String[] args) {
JFrame lv_frame = new JFrame();
lv_frame.setTitle("Drawing");
lv_frame.setSize(300, 300);
lv_frame.setDefaultCloseOperation(JInternalFrame.DISPOSE_ON_CLOSE);
lv_frame.add(new drawingPanel());
lv_frame.setVisible(true);
}
}
class drawingPanel extends JPanel {
public void paintComponent(Graphics graphic) {
super.paintComponent(graphic);
draw(graphic);
saveImage();
}
public void draw(Graphics graphic) {
Graphics2D graphic2D = (Graphics2D) graphic;
Color color = Color.decode("#DDDDDD");
graphic2D.setPaint(color);
graphic2D.fillArc(0, 0, 50, 50, 0, 45);
graphic2D.fillArc(0, 0, 50, 50, 135, 45);
}
public void saveImage() {
BufferedImage image = new BufferedImage(100, 100, BufferedImage.TYPE_INT_BGR);
Graphics2D graphic2D = image.createGraphics();
try {
File output = new File("output.png");
draw(graphic2D);
ImageIO.write(image, "png", output);
} catch(IOException log) {
System.out.println(log);
}
}
}
解决方案
You are overwriting the Graphics2D Object with the one you get from image.createGraphics(), which is blank as you just created it.
Simplify the draw method to :
public void draw(Graphics graphic) {
Graphics2D graphic2D = (Graphics2D) graphic;
graphic2D.fillArc(0, 0, 50, 50, 0, 45);
graphic2D.fillArc(0, 0, 50, 50, 135, 45);
}
Then call it from another method, to perform the painting on your actual Image's Graphics2D :
public void saveAsImage(){
BufferedImage image = new BufferedImage(100, 100, BufferedImage.TYPE_INT_BGR);
try {
Graphics2D graphic = image.createGraphics();
File output = new File("output.png");
draw(graphic); // actual drawing on your image
ImageIO.write(image, "png", output);
} catch(IOException log) {
System.out.println(log);
}
}