无法将当前画布数据转换为java中的图像 [英] Cannot convert current canvas data into image in java
问题描述
我有一个简单的应用程序，允许用户在画布控件中绘图。
现在，我想要的是将画布转换为图像。所以这是我的代码。
public void paint（Graphics g）
{
//super.paint （G）;
Graphics2D draw =（Graphics2D）g;
if（this.is_beginning || this.to_save）
{
draw.setColor（Color.white）;
draw.fillRect（0,0，this.getWidth（），this.getHeight（））;
this.is_beginning = false;
}
if（this.m_alzada）
{
draw.setColor（Color.red）;
draw.drawLine（uX，uY，x，y）;
}
}
这是我保存的方法图像。
private void jButton2ActionPerformed（java.awt.event.ActionEvent evt）{
int w = canvas1。的getWidth（）;
int h = canvas1.getHeight（）;
int type = BufferedImage.TYPE_INT_BGR;
BufferedImage image = new BufferedImage（w，h，type）;
Graphics2D g2 = image.createGraphics（）;
canvas1.to_save = true;
canvas1.paint（g2）;
try {
ImageIO.write（image，png，new File（C：/Users/Uriel/Desktop/ejemplo.png））;
} catch（IOException ex）{
Logger.getLogger（main.class.getName（））。log（Level.SEVERE，null，ex）;
}
}
所有这些都会导致图像为空白，我知道绘画方法是如何工作的，我意识到那就是我的问题所在。但是我该如何绘制用户已经在paint方法中绘制的所有内容？
请原谅我的英语不好，我来自墨西哥。顺便说一句。谢谢。
我想知道如果你在使用Canvas og HTML5时做出类似的东西，你会得到一个带有RGB信息的矩阵画布中的每个像素。是否可以使用JAVA中的canvas组件执行此操作？
除了确保组件的大小正确外，请使用以了解一些基本内容概念。我还会通过在AWT和Swing中绘画来阅读以了解绘画的方式在Java中工作。
修改代码后，我能够得到这个......
要像这样保存......
package prueba_uno_graphics;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.Shape;
import java.awt.event。*;
import java.awt.geom.Path2D;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JPanel;
/ **
*
* @author Uriel
* /
//不要混合重量轻和重量轻的组件
public class Dibujo extends JPanel实现了ActionListener，MouseListener，MouseMotionListener {
// ArrayList lineas = new ArrayList（）;
//布尔m_alzada = true，is_beginning = true，to_save = false;
// int uX，uY，x，y;
私有Path2D形状;
Dibujo（）{
setBackground（Color.WHITE）;
shape = new Path2D.Float（）;
}
@Override
protected void paintComponent（Graphics g）{
super.paintComponent（g）;
Graphics2D draw =（Graphics2D）g;
// if（this.is_beginning || this.to_save）{
// draw.setColor（Color.white）;
// draw.fillRect（0,0，this.getWidth（），this.getHeight（））;
// this.is_beginning = false;
//}
// if（this.m_alzada）{
// draw.setColor（Color.red）;
// draw.drawLine（uX，uY，x，y）;
//
//}
draw.setColor（Color.RED）;
draw.draw（shape）;
}
// @Override
// public void paint（Graphics g）{
// //总是调用super.paint
// super.paint（g）;
// Graphics2D draw =（Graphics2D）g;
// if（this.is_beginning || this.to_save）{
// draw.setColor（Color.white）;
// draw.fillRect（0,0，this.getWidth（），this.getHeight（））;
// this.is_beginning = false;
//}
// if（this.m_alzada）{
// draw.setColor（Color.red）;
// draw.drawLine（uX，uY，x，y）;
//
//}
//}
@Override
public void actionPerformed（ActionEvent e）{
}
@Override
public void mouseClicked（MouseEvent e）{
}
@Override
public void mousePressed（MouseEvent e）{
// this.uX = e.getX（）;
// this.uY = e.getY（）;
Point point = e.getPoint（）;
shape.moveTo（point.x，point.y）;
}
@Override
public void mouseReleased（MouseEvent e）{
}
@Override
public void mouseEntered（MouseEvent e）{
}
@Override
public void mouseExited（MouseEvent e）{
}
@Override
public void mouseDragged（MouseEvent e）{
// this.x = e.getX（）;
// this.y = e.getY（）;
//不要这样做！
// this.paint（this.getGraphics（））;
// ArrayList ayuda = new ArrayList（）;
// ayuda.add（uX）;
// ayuda.add（uY）;
// ayuda.add（x）;
// ayuda.add（y）;
// this.lineas.add（ayuda）;
// uX = x;
// uY = y;
Point point = e.getPoint（）;
shape.lineTo（point.x，point.y）;
repaint（）;
}
@Override
public void mouseMoved（MouseEvent e）{
}
}
I have a simple application that allows the user to draw in the canvas control.
Now, what I want is converting that canvas into an image. So here's my code.
public void paint(Graphics g)
{
//super.paint(g);
Graphics2D draw = (Graphics2D) g;
if(this.is_beginning || this.to_save)
{
draw.setColor(Color.white);
draw.fillRect(0, 0, this.getWidth(), this.getHeight());
this.is_beginning= false;
}
if(this.m_alzada)
{
draw.setColor(Color.red);
draw.drawLine(uX, uY, x, y);
}
}
And this is my method for save the image.
private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {
int w = canvas1.getWidth();
int h = canvas1.getHeight();
int type = BufferedImage.TYPE_INT_BGR;
BufferedImage image = new BufferedImage(w,h,type);
Graphics2D g2 = image.createGraphics();
canvas1.to_save = true;
canvas1.paint(g2);
try {
ImageIO.write(image, "png", new File("C:/Users/Uriel/Desktop/ejemplo.png"));
} catch (IOException ex) {
Logger.getLogger(main.class.getName()).log(Level.SEVERE, null, ex);
}
}
All these result in a blank image, I know how the paint method works, and I realize that is in there where my problem is. But how can I do to drew everything the user have already drew in the paint method?
Excuse me for my bad english, I'm from Mexico. Thanks by the way.
I would like to knoe if there is anyway to make something like when you work with the Canvas og HTML5 and you get a matrix with the RGB info of each pixel in the canvas. Is it possible to do that with the canvas component in JAVA?
Apart from making sure the the component is sized properly, use JComponent#print and JComponent#printAll methods instead.
These will disable double buffering and over come some other native peer issues when it expects to be printing to the screen
UPDATED
From the example app...
I was able to produce this dump
Using this code
Container pane = frame.getContentPane();
BufferedImage img = new BufferedImage(pane.getWidth(), pane.getHeight(), BufferedImage.TYPE_INT_RGB);
Graphics2D g2d = img.createGraphics();
pane.printAll(g2d);
g2d.dispose();
try {
ImageIO.write(img, "png", new File("save.png"));
} catch (IOException ex) {
ex.printStackTrace();
}
UPDATED
I don't think you paint is the source of your problem. It's not as clean as it could though.
To start with, your "drawing" surface is extending from java.awt.Canvas, and you're adding it to a JFrame, mixing heavy and light weight components is never a good idea.
public class Dibujo extends Canvas ...
You're better of using something like a JPanel
public class Dibujo extends JPanel ...
NEVER DO THIS
public void paint(Graphics g) {
//super.paint(g);
You MUST call super.paint there is more going on in the back then simply filling the component. Once you start using something like JPanel, you'll want to override paintComponent instead.
You only ever draw the last line segment in you paint method...
if (this.m_alzada) {
draw.setColor(Color.
draw.drawLine(uX, uY, x, y);
}
This means when you try and save the component, you will only ever see the last segment. The paint method should be painting ALL the lines segments each time it's called.
In your mouseDragged method, you are doing this...
this.paint(this.getGraphics());
DON'T. You are not responsible for updating the graphics, that repaint manager is. All this does is basically doing is painting on to a scratch pad graphics context, as soon as the next repaint request is processed, it will all be wiped clean.
I think you need to have a read through Performing Custom Painting to understand some of the basic concepts. I would also read through Painting in AWT and Swing to understand how painting works in Java.
After modifying your code, I was able to get this...
To save like this...
package prueba_uno_graphics;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.Shape;
import java.awt.event.*;
import java.awt.geom.Path2D;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JPanel;
/**
*
* @author Uriel
*/
// Don't mix heavy and light weight components
public class Dibujo extends JPanel implements ActionListener, MouseListener, MouseMotionListener {
// ArrayList lineas = new ArrayList();
// boolean m_alzada = true, is_beginning = true, to_save = false;
// int uX, uY, x, y;
private Path2D shape;
Dibujo() {
setBackground(Color.WHITE);
shape = new Path2D.Float();
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D draw = (Graphics2D) g;
// if (this.is_beginning || this.to_save) {
// draw.setColor(Color.white);
// draw.fillRect(0, 0, this.getWidth(), this.getHeight());
// this.is_beginning = false;
// }
// if (this.m_alzada) {
// draw.setColor(Color.red);
// draw.drawLine(uX, uY, x, y);
//
// }
draw.setColor(Color.RED);
draw.draw(shape);
}
// @Override
// public void paint(Graphics g) {
// // ALWAYS call super.paint
// super.paint(g);
// Graphics2D draw = (Graphics2D) g;
// if (this.is_beginning || this.to_save) {
// draw.setColor(Color.white);
// draw.fillRect(0, 0, this.getWidth(), this.getHeight());
// this.is_beginning = false;
// }
// if (this.m_alzada) {
// draw.setColor(Color.red);
// draw.drawLine(uX, uY, x, y);
//
// }
// }
@Override
public void actionPerformed(ActionEvent e) {
}
@Override
public void mouseClicked(MouseEvent e) {
}
@Override
public void mousePressed(MouseEvent e) {
// this.uX = e.getX();
// this.uY = e.getY();
Point point = e.getPoint();
shape.moveTo(point.x, point.y);
}
@Override
public void mouseReleased(MouseEvent e) {
}
@Override
public void mouseEntered(MouseEvent e) {
}
@Override
public void mouseExited(MouseEvent e) {
}
@Override
public void mouseDragged(MouseEvent e) {
// this.x = e.getX();
// this.y = e.getY();
// Don't do this!
// this.paint(this.getGraphics());
// ArrayList ayuda = new ArrayList();
// ayuda.add(uX);
// ayuda.add(uY);
// ayuda.add(x);
// ayuda.add(y);
// this.lineas.add(ayuda);
// uX = x;
// uY = y;
Point point = e.getPoint();
shape.lineTo(point.x, point.y);
repaint();
}
@Override
public void mouseMoved(MouseEvent e) {
}
}
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