I am currently trying to make it possible for a JPanel to be zoomed in. My idea is pretty much as follows :
I have a JPanel (custom with overriden paintComponent etc.) that I place inside my JScrollPane.
What I do to zoom in is to scale up my JPanel using the following code (overriding the paint method)
#Override
public void paint(Graphics g)
{
Graphics2D g2 = (Graphics2D) g;
if (m_hasBeenScaled)
{
m_transform.scale(m_zoomValue, m_zoomValue);
g2.setTransform(m_transform);
m_transform = new AffineTransform();
}
super.paint(g);
}
This works well, however my JScrollPane doesn't display scrollbars as I scale to bigger dimensions. How do I make the JScrollPane respond to this scale up of my JPanel ?
Here's the code I use to create both my JPanel and JScrollPan (Grid is my class extending JPanel):
m_gridPanel = new Grid();
m_gridContainer = new JScrollPane(m_gridPanel);
m_gridContainer.setPreferredSize(new Dimension(605, 605));
The size of the component will be affected by the zoom factor as well, to that end, setting the preferredSize to a "static" value makes no sense, instead, you should be overriding the getPreferredSize and adjusting the size returned by applying the zoom factor to it as well.
Zooming a component is much more complex than changing the transform, you should be translating the mouse events as well, see How to add MouseListener to item on Java Swing Canvas for example.
Related
I have a JScrollPanel and a JPanel added to it. I would like to draw to the JPanel and make the scrollbars of the JScrollPane appear whenever the drawing exceeds the size of the panel and be able to scroll the drawing both vertically and horizontally.
I have tried consulting with various forums and the official docs and tried a few things (setting the borders, the preferred size, etc.) but none seems to yield the desired effects.
I have a JFrame (with GridBagLayout, btw.) :
JFrame frame1 = new JFrame("Application");
frame1.setVisible(true);
frame1.setMinimumSize(new Dimension(580,620));
frame1.setResizable(false);
frame1.setLocationRelativeTo(null);
frame1.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
The relevant components are :
JPanel panel1 = new JPanel();
JScrollPane scrollPane = new JScrollPane(panel1);
frame1.add(scrollPane, gbc_panel1); //added with layout constraints
JPanel :
panel1.setBackground(Color.BLACK);
panel1.setPreferredSize(new Dimension(500,500));
panel1.setMinimumSize(new Dimension(360,360));
panel1.setMaximumSize(new Dimension(1000,1000));
JScrollPane :
scrollPane.setAutoscrolls(true);
The relevant code from the action event
of a button that does the drawing :
Graphics g;
g = panel1.getGraphics();
panel1.paint(g);
g.setColor(new Color(0,128,0));
/* this is followed by some more code that
does the drawing of a maze with g.drawLine() methods */
The code does the drawing perfectly, I just can't seem to figure it out how to make the scrolling and dynamic resizing happen.
I would appreciate any helpful comments or remarks!
Thank you!
Ultimately rewriting the paint method did the trick as #MadProgrammer suggested. I was just hoping that I could do the painting without having to define my custom JPanel class, but looks like it doesn't work that way.
The custom class looks like this:
class Drawing extends JPanel {
int mazeSize;
public Drawing(JTextField jtf)
{
try {
this.mazeSize = Integer.parseInt(jtf.getText());
}
catch (Exception e)
{
JOptionPane.showMessageDialog(this, "ERROR! Invalid size value!");
}
} // the constructor gets the size of the drawing from a textField
public Dimension getPreferredSize() {
return new Dimension(mazeSize*10,mazeSize*10);
} //getPreferredSize - this method is used by the scroll pane to adjust its own size automatically
public void drawMaze (Graphics g)
{
/* some irrelevant code that does the desired drawing to the panel by calling g.drawLine()*/
} // drawMaze method that does the de facto drawing
#Override
public void paintComponent(Graphics g)
{
super.paintComponent(g);
drawMaze(g);
}// paintComponent() #Override method - this was the tricky part
}//Drawing JPanel subclass
It is also worth noting (if some noob like myself happens to stumble upon this question), that after instantiating the new JPanel subclass in the action event, I had to add it to the JScrollPanel in the following way, instead of just simply using its add() method:
Drawing drawPanel = new Drawing(textfield1);
scrollPane.getViewport().add(drawPanel);
Again, thanks for the suggestion!
Once finished with the program (a random maze generator that uses a recursive backtracking algorithm), I will make the source code available at my github profile.
I'm painting my own component that extends JPanel:
protected void paintComponent(Graphics g) {
This works nicely.
I need to do quite a bit of work the prepare the component. This work depends on the dimensions of the component.
The dimensions of the component only seem to be available in the paintComponent() function. So I now do:
if(firstTime){
//do init
firstTime=false
}
//draw
In my paintComponent() function. I'm not in love with this solution.
Is there a way that I can get the dimensions before the paintComponent() function is called?
(it doesn't seem to be valid in the constructor)
There is an option to draw to a BufferedImage instead. Obviously (or at least, I hope it is obvious) we give the image a size when creating it.
We get a Graphics2D obect like this:
Graphics2D g = bi.creatGraphics();
The image can be displayed in a JLabel:
JLabel label == new JLabel(new ImageIcon(bi)); // now add the label to something..
To refresh the label after new painting call:
label.repaint();
But like #HovercraftFullOfEels I have doubts that this is the best approach.
It seems such code would work as expecting:
JPanel panel = new JPanel();
panel.addHierarchyListener((event) -> {
if((event.getChangeFlags() & HierarchyEvent.SHOWING_CHANGED) != 0) {
// before paintComponent
}
});
I have created a custom JPanel class called ImagePanel. I override the paintComponent method like this...
public void paintComponent(Graphics g)
{
super.paintComponent(g);
g.drawImage(image, 0,0, null);
}
The purpose of the custom panel is to simply draw an image.
In my JFrame, I create a ScollPane that is added to the JFrame. When I created the ScrollPane though, I pass in the instance of my imagePanel, like this...
ip = new ImagePanel();
JScrollPane jsp = new JScrollPane(ip);
this.add(jsp);
Now all I want as an easy to use way of using the scroll bars to scroll over my image. Right now the image is very large and scrollbars do not appear. I use the policy to make them visible, but the handles to the scrollbars are not there.
Does anyone know an easy way to do this?
Try with JPanel#setPreferredSize() that will force the JScrollPane to show the scroll bar if needed.
public void paintComponent(Graphics g)
{
super.paintComponent(g);
g.drawImage(image, 0,0, null);
// set the size of the panel based on image size
setPreferredSize(new Dimension(image.getWidth(), image.getHeight()));
}
EDIT
Setting setPreferredSize() inside overridden paintComponent() is not a good way.
You can do it in a simpler way using JLabel as suggested by #mKorbel. For more info have a look at the comments below.
BufferedImage image = ...
JLabel label = new JLabel(new ImageIcon(image)); // set the icon
JScrollPane jsp = new JScrollPane(label);
Screenshot:
I have some Graphics2D graphics displayed in my frame, and then I added a JPanel to the entire frame so that I can add a mouselistener to clicks anywhere in the panel. However, the graphics disappear, I assume blocked out by the frame. I tried setting the panel to visible false, but that didnt do anything. How can I keep my mouselistener listening on the entire window, and still display my graphics?
EDIT:
Heres a bit of code: EDIT:(and some more)
//adding the panel and mouselistener
JPanel allPanel = new JPanel();
allPanel.addMouseListener(this);
frame.add(allPanel);
//...
//drawing some of the graphics
public void draw() {
frame.add(new CustomPaintComponent());
// Display the frame
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.setExtendedState(JFrame.MAXIMIZED_BOTH);
frame.setVisible(true);
JPanel allPanel = new JPanel();
allPanel.addMouseListener(this);
frame.add(allPanel);
}
static class CustomPaintComponent extends Component {
private static final long serialVersionUID = 1L;
public void paint(Graphics g) {
Graphics2D g2d = (Graphics2D)g;
g2d.fillRoundRect(10, 10, 50, 50, 10,10);
//...
Three problems jump out...
First, JFrame uses a BorderLayout as its default layout manager, this means that only one component can occupy any of its available five positions. By using add(Component) you add each component to the CENTRE position, overriding the first component you added to it...
Second, JPanel is opaque by default, meaning, even if you did get both components to occupy the same space, the top component would block the lower one
Third, you should be using paintComponent instead of paint
Take a look at Performing Custom Painting for more details
The solution could be to add the MouseListener directly to the custom component
Another choice would be to use a BorderLayout on the lower component, make the top component transparent (using setOpaque(false)) and add it to the lower component directly...
I believe your problem is that JFrame can have only one component added to it (by default). You add a CustomPaintComponent, which paints your graphics. Then, you add the JPanel, which automatically removes the CustomPaintComponent
Are you trying to paint the custom drawing on top of the JPanel? If that is the case, simply move that code over to the JPanel (but instead of using a CustomPaintComponent, put it in the paintComponent(Graphics g) method of the JPanel)
So, I have a JLayeredPane (technically a class subclassing JLayeredPane actually). On that is a JPanel. I want to add a BufferedImage to the Jpanel.
public class BigMap extends JLayeredPane implements MouseListener
JPanel mapPanel;
BufferedImage theMap;
public BigMap (BufferedImage m){
theMap = m;
mapPanel = new JPanel();
add(mapPanel, 0);
mapPanel.setBounds(0, 0, 640, 640);
//other unimportant stuff
}
#Overrride
public void paintComponent (Graphics g){
super.paintComponent(g);
Graphics2D gmap = (Graphics2D) mapPanel.getGraphics();
gmap.drawImage(theMap, null, 0, 0);
//some other stuff which is working just fine
}
The issue is that the BufferedImage isn't displaying. The JPanel is definately present as I can set its backgroundColour and see it if I wish. I realise that JLayeredPane doesn't have a layout manager and have had to set the bounds for the JPanel but that shouldn't be an issue for the JPanel itself, surely? And given that BufferedImage lacks methods to control its size directly I don't see how I'd overcome that if it were.
Any help appreciated.
The problem here is that you override the paintComponent() method of your layered pane, not the JPanel. The JPanel will paint itself later, as one of the children of your layered pane, and this will wipe out what you painted.
In general, a paintComponent() method should paint into the Graphics that was given to it, not into some other component's graphics.