i am currently trying to make a canvas that i can draw stuff to and have it appear inside a JFrame.
To do this, i intend to have a BufferedImage inside a JPanel component that the paintComponent method can draw from.
Ideally from the given JFrame i want to be able to reference this buffered image, and then draw stuff to it using its Graphics2D that the paintComponent method can then show when it draws using the buffered image.
I'm doing this to avoid using the paintcomponent method directly, i want to be able to reference this canvas from anywhere in the program and have it be painted when the frames repaint() method is called.
class MyPanel extends JPanel {
BufferedImage img = new BufferedImage(500, 500, BufferedImage.TYPE_INT_ARGB);
Graphics2D imgG2 = img.createGraphics();
public Graphics2D getGraphics() {
return imgG2;
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
int w = img.getWidth();
int h = img.getHeight();
g2.drawImage(img, 0, 0, w, h, null);
}
}
class Main {
private static JFrame createAndShowGui() {
JFrame frame = new JFrame("droneFrame");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.add(new MyPanel());
frame.setSize(500, 500);
frame.setResizable(false);
frame.setVisible(true);
return frame;
}
public static void main(String args[]) {
JFrame frame = createAndShowGui();
//Something here to reference the inner Jpanels imgG2 field, and draw to it.
frame.repaint();
//Draw whatever is currently in the buffered image.
}
}
However, i'm at a loss at how to do this, since frame.getComponent(0) just returns a Component, rather than the specfic type of component it is.
Thanks in advance.
Just managed to figure this out, you need to set the content pane of your JFrame to the JPanel, then to reference the graphics of the buffered image, you need to get the content pane of the JFrame, and downcast it to the specific type MyPanel.
Now you have the content pane in the correct format, and can reference the graphics since it now has that field.
Related
I am still getting used to painting graphics on java and am trying to write a simple graphics program that paints a background using a buffered image. However, strangely enough, even though my jpanel size is set to 1200x400 and so are the buffered image and fillrect method, there is a small "gap" as you can see in the picture I have attached so the panel is clearly larger than 1200x400 but I don't understand why? What does the setPreferredSize method actually do? Also when I change my fillrect method and bufferedimage to 1300x500 there is no longer a gap so this is clearly the issue. If anyone has any advice as to where I am going wrong I would greatly appreciate it, thanks
Here is my code:
public class Q2 extends JPanel {
private BufferedImage image;
public static void main(String[] args) {
Q2 test = new Q2();
}
public Q2() {
this.init();
}
private void init() {
JFrame window = new JFrame();
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
window.setContentPane(this);
this.setPreferredSize(new Dimension(1200,400));
refreshCanvas();
window.pack();
window.setVisible(true);
window.setResizable(false);
}
public void paintComponent(Graphics g) {
Graphics2D twoD = (Graphics2D) g;
twoD.drawImage(image,0,0,null);
}
private void refreshCanvas() {
image = new BufferedImage(1200,400,BufferedImage.TYPE_INT_ARGB);
Graphics2D twoD = image.createGraphics();
twoD.setColor(Color.BLACK);
twoD.fillRect(0, 0, 1200,400);
repaint();
}
}
Have a look at this answer here.
You have to put window.setResizeable(false); before window.pack();. This should fix it.
I have a problem with full-screen : i create a frame and put it in a full-screen Window but i see nothing but the color of the frame's background.
here is the code i used:
PB frame = new PB();
win = new Window(frame);
gs.setFullScreenWindow(win);
frame.setVisible(true);
frame.repaint();
win.repaint();
and the PB class, my frame:
public class PB extends JFrame
{
PB()
{
super();
this.setBackground(Color.BLUE);
this.getContentPane().add(new JButton("button"));
JPanel jp = new JPanel();
jp.setBackground(Color.red);
jp.setSize(360, 200);
this.getContentPane().add(jp);
this.setVisible(true);
repaint();
pack();
}
#Override
public void paint(Graphics g)
{
Graphics2D g2d = (Graphics2D)g;
g2d.setPaint(new Color(0,0,0));
g.fillRect(0,0,200,200);
}
}
So all i can see, is a big screen with the background color (here blue);
Thanks for all help
I bet you didn't try your frame separately, did you?
This part of frame code:
public void paint(Graphics g)
{
Graphics2D g2d = (Graphics2D)g;
g2d.setPaint(new Color(0,0,0));
g.fillRect(0,0,200,200);
}
will never let it paint its own content, just the colored rect.
So my recomendations are:
Do not override JFrame's paint method - it will cause a lot of problems
Just set main container panel background to the desired color
Try the frame without full-screen window first to see if it displays what you need
I think you're mis-understading the purpose of the "owner" for the Window.
JFrame extends from Window.
So, instead of saying
win = new Window(frame);
gs.setFullScreenWindow(win);
You only need to use
gs.setFullScreenWindow(frame);
Oh, and what Mikle said as well.
my goal is to draw some bufferedimage onto another. then all this stuff draw onto some other bufferedimage and so on. And finally draw this on top of a panel.
For now i'm trying to draw bufferedimage onto panel and nothing works. My bufferedimage looks completely white:
public class Main2 {
public static void main(String[] args) {
JFrame frame = new JFrame("asdf");
final JPanel panel = (JPanel) frame.getContentPane();
frame.setSize(500,500);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
panel.addMouseListener(new MouseAdapter() {
#Override
public void mouseClicked(MouseEvent e) {
somepaint(panel);
}
});
}
private static void somepaint(JPanel panel) {
BufferedImage image = new BufferedImage(200,200,BufferedImage.TYPE_INT_ARGB);
image.getGraphics().setColor(Color.red);
image.getGraphics().fillRect(0, 0, 200, 200);
Graphics2D graphics = (Graphics2D) panel.getGraphics();
graphics.setColor(Color.magenta);
graphics.fillRect(0, 0, 500, 500);
graphics.drawImage(image, null, 0, 0); // draws white square instead of red one
}
}
thanks
Re:
private static void somepaint(JPanel panel) {
BufferedImage image = new BufferedImage(200,200,BufferedImage.TYPE_INT_ARGB);
image.getGraphics().setColor(Color.red);
image.getGraphics().fillRect(0, 0, 200, 200);
Graphics2D graphics = (Graphics2D) panel.getGraphics();
This is not how you draw inside of a JPanel or JComponent.
Don't call getGraphics() on a component as the Graphics object returned will be short-lived, and anything drawn with it will not persist. Instead do your JPanel's drawing inside of its paintComponent(Graphics G) method override. You will need to create a class that extends JPanel in order to override paintComponent(...).
Most importantly, to see how to do Swing graphics correctly, don't guess. You'll want to read the Swing Graphics Tutorials first as it will require you to toss out some incorrect assumptions (I know that this is what I had to do to get it right).
You need to rectify your parameters in the drawImage() call. Change this:
graphics.drawImage(image, null, 0, 0);
to
graphics.drawImage(image, 0, 0,null);
Check the Java docs for more details.
Can JPanels background be set to transparent?
My frame is has two JPanels:
Image Panel and
Feature Panel.
Feature Panel is overlapping Image Panel.
The Image Panel is working as a background and it loads image from a remote URL.
On Feature Panel I want to draw shapes. Now Image Panel cannot be seen due to Feature Panel's background color.
I need to make Feature Panel background transparent while still drawing its shapes and I want Image Panel to be visible (since it is doing tiling and cache function of images).
I'm using two JPanel's, because I need to seperate the image and shape drawing .
Is there a way the overlapping Jpanel have a transparent background?
Calling setOpaque(false) on the upper JPanel should work.
From your comment, it sounds like Swing painting may be broken somewhere -
First - you probably wanted to override paintComponent() rather than paint() in whatever component you have paint() overridden in.
Second - when you do override paintComponent(), you'll first want to call super.paintComponent() first to do all the default Swing painting stuff (of which honoring setOpaque() is one).
Example -
import java.awt.Color;
import java.awt.Graphics;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class TwoPanels {
public static void main(String[] args) {
JPanel p = new JPanel();
// setting layout to null so we can make panels overlap
p.setLayout(null);
CirclePanel topPanel = new CirclePanel();
// drawing should be in blue
topPanel.setForeground(Color.blue);
// background should be black, except it's not opaque, so
// background will not be drawn
topPanel.setBackground(Color.black);
// set opaque to false - background not drawn
topPanel.setOpaque(false);
topPanel.setBounds(50, 50, 100, 100);
// add topPanel - components paint in order added,
// so add topPanel first
p.add(topPanel);
CirclePanel bottomPanel = new CirclePanel();
// drawing in green
bottomPanel.setForeground(Color.green);
// background in cyan
bottomPanel.setBackground(Color.cyan);
// and it will show this time, because opaque is true
bottomPanel.setOpaque(true);
bottomPanel.setBounds(30, 30, 100, 100);
// add bottomPanel last...
p.add(bottomPanel);
// frame handling code...
JFrame f = new JFrame("Two Panels");
f.setContentPane(p);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setSize(300, 300);
f.setLocationRelativeTo(null);
f.setVisible(true);
}
// Panel with a circle drawn on it.
private static class CirclePanel extends JPanel {
// This is Swing, so override paint*Component* - not paint
protected void paintComponent(Graphics g) {
// call super.paintComponent to get default Swing
// painting behavior (opaque honored, etc.)
super.paintComponent(g);
int x = 10;
int y = 10;
int width = getWidth() - 20;
int height = getHeight() - 20;
g.drawArc(x, y, width, height, 0, 360);
}
}
}
Alternatively, consider The Glass Pane, discussed in the article How to Use Root Panes. You could draw your "Feature" content in the glass pane's paintComponent() method.
Addendum: Working with the GlassPaneDemo, I added an image:
//Set up the content pane, where the "main GUI" lives.
frame.add(changeButton, BorderLayout.SOUTH);
frame.add(new JLabel(new ImageIcon("img.jpg")), BorderLayout.CENTER);
and altered the glass pane's paintComponent() method:
protected void paintComponent(Graphics g) {
if (point != null) {
Graphics2D g2d = (Graphics2D) g;
g2d.setRenderingHint(
RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
g2d.setComposite(AlphaComposite.getInstance(
AlphaComposite.SRC_OVER, 0.3f));
g2d.setColor(Color.yellow);
g2d.fillOval(point.x, point.y, 120, 60);
}
}
As noted here, Swing components must honor the opaque property; in this variation, the ImageIcon completely fills the BorderLayout.CENTER of the frame's default layout.
In my particular case it was easier to do this:
panel.setOpaque(true);
panel.setBackground(new Color(0,0,0,0,)): // any color with alpha 0 (in this case the color is black
(Feature Panel).setOpaque(false);
Hope this helps.
To set transparent you can set opaque of panel to false like
JPanel panel = new JPanel();
panel.setOpaque(false);
But to make it transculent use alpha property of color attribute like
JPanel panel = new JPanel();
panel.setBackground(new Color(0,0,0,125));
where last parameter of Color is for alpha and alpha value ranges between 0 and 255 where 0 is full transparent and 255 is fully opaque
public void paintComponent (Graphics g)
{
((Graphics2D) g).setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER,0.0f)); // draw transparent background
super.paintComponent(g);
((Graphics2D) g).setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER,1.0f)); // turn on opacity
g.setColor(Color.RED);
g.fillRect(20, 20, 500, 300);
}
I have tried to do it this way, but it is very flickery
As Thrasgod correctly showed in his answer, the best way is to use the paintComponent, but also if the case is to have a semi transparent JPanel (or any other component, really) and have something not transparent inside. You have to also override the paintChildren method and set the alfa value to 1.
In my case I extended the JPanel like that:
public class TransparentJPanel extends JPanel {
private float panelAlfa;
private float childrenAlfa;
public TransparentJPanel(float panelAlfa, float childrenAlfa) {
this.panelAlfa = panelAlfa;
this.childrenAlfa = childrenAlfa;
}
#Override
public void paintComponent(Graphics g) {
Graphics2D g2d = (Graphics2D) g;
g2d.setColor(getBackground());
g2d.setRenderingHint(
RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
g2d.setComposite(AlphaComposite.getInstance(
AlphaComposite.SRC_OVER, panelAlfa));
super.paintComponent(g2d);
}
#Override
protected void paintChildren(Graphics g) {
Graphics2D g2d = (Graphics2D) g;
g2d.setColor(getBackground());
g2d.setRenderingHint(
RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
g2d.setComposite(AlphaComposite.getInstance(
AlphaComposite.SRC_ATOP, childrenAlfa));
super.paintChildren(g);
}
//getter and setter
}
And in my project I only need to instantiate Jpanel jp = new TransparentJPanel(0.3f, 1.0f);, if I want only the Jpanel transparent.
You could, also, mess with the JPanel shape using g2d.fillRoundRect and g2d.drawRoundRect, but it's not in the scope of this question.
How can I tell the paint method to draw background on JPanel only and not on the entire JFrame.
My JFrame size is bigger than the JPanel. When I try to paint a grid background for the JPanel, the grid seems to be painted all over the JFrame instead of just the JPanel.
Here parts of the code:
public class Drawing extends JFrame {
JPanel drawingPanel;
...........
public Drawing (){
drawingPanel = new JPanel();
drawingPanel.setPreferredSize(new Dimension(600,600));
}
public void paint(Graphics g)
{
super.paintComponents(g);
Graphics2D g2 = (Graphics2D) g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
paintBackground(g2); //call a METHOD to paint the for JPANEL
}
private void paintBackground(Graphics2D g2)
{
g2.setPaint(Color.GRAY);
for (int i = 0; i < drawingPanel.getSize().width; i += 300)
{
Shape line = new Line2D.Float(i, 0, i, drawingPanel.getSize().height);
g2.draw(line);
}
for (int i = 0; i < drawingPanel.getSize().height; i += 300)
{
Shape line = new Line2D.Float(0, i, drawingPanel.getSize().width, i);
g2.draw(line);
}
} //END private void paintBackground(Graphics2D g2)
}
If you want to do painting on the JPanel then override the JPanel, not the JFrame.
You should be overriding the paintComponent() method of JPanel. Read the section from the Swing tutorial on Custom Painting for a working example.
camickr is correct. So:
public class Drawing extends JFrame {
JPanel drawingPanel;
...........
public Drawing (){
drawingPanel = new MyPanel();
drawingPanel.setPreferredSize(new Dimension(600,600));
add(drawingPanel);
}
}
public class MyPanel extends JPanel {
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
myBackgroundRoutine(g2);
}
}
You need to strictly separate your drawing from different components. Swing is already
managing subcomponents, so there is absolutely no need to implement drawings in your
Panel in the Frame (calling paintComponents() is a severe error).
And you should never override paint(), because only paintComponent()
is used in Swing. Don't mix both until you absolutely know what you are doing.
super.paintComponents(g);
I would suggest as your first point of investigation.
The code you posted is not complete, it's missing how the panel is added to the JFrame and which LayoutManager is being used.
The code seams to be correct. Are you sure the JPanel is not occupying the whole JFrame? Add a System.out.println(drawingPanel.getSize()) to check this.
If you are using the BorderLayout, the default for JFrame, and has just added the panel without any constraint, the panel will use the whole area. The PreferredSize is ignored.
Try this, just for testing:
public Drawing (){
drawingPanel = new JPanel();
drawingPanel.setPreferredSize(new Dimension(600,600)); // ignored
drawingPanel.setBounds(0, 0, 600, 600); // location and size
setLayout(null);
add(drawingPanel);
}
but IMO this is not the best or correct way to do it. I would prefer to override the paintComponent() method from the JPanel, as suggested by Thorsten and camickr.
But it will still use the whole area of the JFrame until other Component is added to the JFrame or the LayoutManager changed.
You should override the JPanel, not the JFrame to do painting. You can override the paintComponent() method of the JPanel