As part of an application I'm writing I need to mix the old (heavyweight) Canvas with swing components - specifically nesting them inside a JSplitPane. However, when I do this the divider refuses to resize anywhere as though neither canvas will accept a reduction in size. The code demonstrating the issue is thus:
JFrame frame = new JFrame();
JSplitPane pane = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT, new Canvas(), new Canvas());
pane.setResizeWeight(0.5);
frame.add(pane);
frame.pack();
frame.setVisible(true);
I initially assumed this was a simple thing to solve, however after doing a fair bit of research the options seem to present themselves as:
Use a JPanel instead (not always an option as in my case where I'm using vlcj to render directly onto a canvas)
Insert x dodgy hack that might work in some cases
Is there a better way of doing this? Or is it really just a case of resorting to hacks? I've debated other options such as if an alternative SplitPane implementation might be available that works, but there's no heavyweight implementation and I'd be surprised if a lightweight one avoided the problem.
A JSplitPane uses the "minimum size" of the component to determine if the component can shrink when using the divider.
I've never used a Canvas before, but itt appears that the minimum size always defaults to the preferred size.
Override the getMinimumSize(...) size method of the Canvas to return a reasonable minimum.
For a quick text you can use:
Canvas canvas = new Canvas();
canvas.setMinimumSize( new Dimension(50, 50) );
JSplitPane pane = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT, canvas, new Canvas());
and you will be able to move the divider left, but never back to the right.
Related
First, to get it out of the way, I absolutely NEED to use heavyweight AWT component with a swing application. I need features from both of them.
The task is simple - render a heavyweight AWT Canvas (or any other element), render OpenGL scene directly onto it, then display Swing buttons above it for the UI.
My problem is that it works half-way.
I don't seem to have problems with Z-ordering. I am using jLayeredPanes for it, and I can move Canvas between layers and it actually works, popping on top or below other elements.
The problems are with transparency.
The thing is, Swing elements have Opaque parameter, and when it's set to false (non-opaque) - it should basically be transparent and you should see the next element below it. In my case, however, the AWT Canvas gets ignored, and you instead only see the next underlying SWING element.
Here are a couple of screenshots. They are taken from a standalone test project of mine. The canvas is stretched to the size of the frame, and in the upper left there is a JLayeredPane dummy element that is a simplified version of the menu.
On the first screenshot, the JLayeredPane's Opaque setting is set to true, and you can see that it's background property is set to Blue color.
On the second screenshot, everything is exactly the same but Opaque is set to false. Instead of displaying whatever is on the Canvas - what gets drawn in empty grey jFrame background.
Lastly, on the third screenshot I have put Canvas into a jPanel instead of leaving it on its own. As you can see, the Panel's orange color is seen through the transparent jLayeredPane, but the Canvas is yet again hidden.
Here's the code for the Frame layout. I would not post my rendering/context code right now
frame = new JFrame("AWT test");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.setPreferredSize(new Dimension(width, height));
canvas = new Canvas();
canvas.setSize(width,height);
//this part exists only in the third example
JPanel p = new JPanel();
p.setSize(width,height);
p.setBackground(Color.orange);
p.add(canvas);
// third example end
JLayeredPane pane = new JLayeredPane();
JLayeredPane paneMenu = new JLayeredPane();
JButton button = new JButton();
button.setSize(20,20);
paneMenu.setSize(200,200);
paneMenu.add(button, new Integer(1));
paneMenu.setBackground(Color.BLUE);
paneMenu.setOpaque(false); //True for the first example
pane.add(p, new Integer(1)); // canvas for the first two examples
pane.add(paneMenu, new Integer(2));
pane.setOpaque(false);
frame.add(pane);
frame.pack();
frame.setVisible(true);
frame.transferFocus();
Could anyone please explain me what is going on and how to do what I need to do.
I will repeat again - I have to use heavyweight component as render target. I am aware of solutions like JOGL's GLPanel which is a lightweight Swing-compatible component. But I tried that method and the performance is really slow, because instead of directly rendering onto it as a context target - it reads FrameBuffer from memory, flips it, and then paints it as BufferedImage. This path is not fitting for the limited resources of an embedded system that I'll be running on.
c0der said: Please post minimal reproducible example
Errrrm.... Didn't I?
Here, you can have it in complete java class form if you want, but I literally changed some variables for constants.
import javax.swing.*;
import java.awt.*;
public class Main
{
public static void main(String[] args)
{
JFrame frame = new JFrame("AWT test");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.setPreferredSize(new Dimension(500, 500));
Canvas canvas = new Canvas();
canvas.setSize(500,500);
canvas.setBackground(Color.RED);
//this part exists only in the third example
JPanel p = new JPanel();
p.setSize(500,500);
p.setBackground(Color.orange);
p.add(canvas);
// third example end
JLayeredPane pane = new JLayeredPane();
JLayeredPane paneMenu = new JLayeredPane();
JButton button = new JButton();
button.setSize(20,20);
paneMenu.setSize(200,200);
paneMenu.add(button, new Integer(1));
paneMenu.setBackground(Color.BLUE);
paneMenu.setOpaque(false); //True for the first example
pane.add(p, new Integer(1)); // canvas for the first two examples
pane.add(paneMenu, new Integer(2));
pane.setOpaque(false);
frame.add(pane);
frame.pack();
frame.setVisible(true);
frame.transferFocus();
}
}
A little update:
I initially suspected that because Swing elements delegate all their drawing to the underlying heavyweight element (In my case JFrame), then what happens is that the frame generates a single frameBuffer for itself and then displays on top of Canvas. Canvas itself is not handled in this generation and thus the frame "covers" over the canvas.
That doesn't seem to be the case. I tried making the JFrame undecorated, all panels non-opaque, and display the picture. The result - canvas is still "cut", and through the hole you can see the underlying IDE menu.
This makes me think that somewhere during Drawing, the Canvas itself detects that it is obscured by another element, and that it doesn't need to draw that area. So it "optimizes" itself and doesn't update these pixels.
Maybe I'm wrong. But here's another screenshot. This is the same example as before, but I took out 3d rendering and simply trying to display Canvas with background set to Red.
Once again, going to reply to my own question.
It turned out that I need to do
setComponentMixingCutoutShape(paneMenu, new Rectangle());
for the menu pane that lies underneath the button. That essentially tells java not to cut out the element from the heavyweight underlying component.
So, I have been having trouble drawing multiple objects on a JFrame, and I know I need to use Layout managers, so I decided to test it with one object before I do multiple, however when I run this code:
fps = 30;
panel = new JPanel();
frame = new JFrame();
frame.setLayout(new BorderLayout());
frame.setDefaultCloseOperation(EXIT_ON_CLOSE);
frame.setSize(400,400);
frame.addKeyListener(new key());
running = true;
update = true;
ball = new Ball(0,0,1);
//panel.setBackground(Color.BLACK);
panel.add(ball);
panel.setVisible(true);
frame.add(panel, BorderLayout.CENTER);
frame.requestFocus();
frame.setVisible(true);
startTime = System.currentTimeMillis();
nothing draws (There is more to the code, i just didnt want to inlcude all of it). However, when I remove the comment and set the background to black, the JFrame turns black. So why is it that it wont draw my Ball object (which i know works) but will change the background? Is there a specific way you need to draw on a JPanel?
panel = new JPanel();
By default a JPanel uses a FlowLayout which respects the size of any component you add to the panel.
ball = new Ball(0,0,1);
I have no idea what the code in your Ball class looks like, but I would guess the preferred size is (0, 0).
You need to override the getPreferredSize() method of your Ball class to return the size of the Ball so that your layout manager can do its job.
Read the section from the Swing tutorial on Custom Painting for more information and working examples.
I know I need to use Layout managers,
The problem with a layout manager in this case is that the layout manager will control the position of the Ball which may or may not be what you want. If you want balls in random positions, then you will need to use a null layout. Then you will need to use the setSize() and setLocation() methods to control each Ball component.
Another option is to do custom painting of all your Balls. In this case you would add an object that you want to paint to an ArrayList. Then the custom painting code would iterate through the object in the list and paint them individually. See Playing With Shapes for ideas on this approach.
I'm a somewhat novice programmer and I'm have some trouble adding an image to my frame. While I know how to add images generally, this specific case it does not work.
public class Tutorial extends JFrame{
Tutorial(){
JFrame frame = new JFrame("ImageTutorial");
frame.setVisible(true);
frame.setSize(750,850);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(null);
ImageIcon image = new ImageIcon(getClass().getResource("Green Block.png"));
JLabel imagelabel = new JLabel(image);
imagelabel.setBounds(10, 10, 75, 75);
imagelabel.setOpaque(true);
frame.add(imagelabel);
Now, I've located the problem but I don't understand 'why' its a problem. When I remove
frame.setSize(750,850);
the image shows, but when its there it doesn't. How can the frame's size impact the image showing and how can I get around it?
Just curious, logically, what makes you think a frame should be visible before you add any components? Logically speaking, wouldn't it seem right to add your components first, then make the frame visible. It's like displaying a painting in an art gallery even before the painter has painted anything on it. It just makes no sense. I highly doubt setting the size has anything to do with it. IF you don't set the size of the frame, then the frame appears as small as possible. When you resize the frame, it causes a repaint, then showing the label you add. But generally, you want to always set frame visible after all you components are added, to avoid this problem.
Side note: You should stay away from null layouts. You need to learn to use Layout Managers and let them do the dynamic sizing and locating for you.
Current implementation layout:
((EDIT: added
Code: ))
private JPanel panelCenter;
private List<BufferedImage> listCreatedImages;
public ChooseCircuitPanel(List<BufferedImage> listCreatedImages) {
this.listCreatedImages = listCreatedImages;
initiate();
}
private void initiate() {
setLayout(new BorderLayout(50, 50));
panelCenter = new JPanel();
LayoutManager theLayout = new GridLayout(0, 3, 0, 0);
panelCenter.setLayout(theLayout);
panelCenter.setBorder(BorderFactory.createLineBorder(Color.BLACK));
for (BufferedImage bufferedImage : listCreatedImages) {
ImageIcon theImage = new ImageIcon(bufferedImage);
JLabel lblForImage = new JLabel(theImage);
lblForImage.setBorder(BorderFactory.createLineBorder(Color.BLACK));
panelCenter.add(lblForImage);
}
this.add(panelCenter, BorderLayout.CENTER);
}
Situation:
We want to display a race circuit here. A circuit should be displayed by placing standards tiles next to each other. It should be possible to resize the window, and with that, the circuit tiles should also resize.
((EDIT: bit more info: The race circuit data is stored on a server and the desktop application has to translate the data to a visual thing, by placing some standard tiles in the right order. ))
((EDIT: we are not allowed to use any external library. It should be doable by only using Java Swing code.))
I thought about placing the images in a JLabel and placing these JLabels in a panel with GridLayout as layout manager.
Using a GridLayout - I thought - it should be rather easy to get to a solution:
the components in the GridLayout (= JLabels) already scale and do exactly what I want.
Now, it would only be a matter of finding a way to resize the images so they fill the JLabels.
As you can see: right now, the images have a fixed size and don't scale at all.
I browsed a bit and saw lots of solutions that boil down to using Graphics2D and super.paintComponent, etc.
But most of these solutions had nothing to do with a GridLayout.
So conclusive question:
Is there an easier solution aside from using Graphics2D, etc. knowing that I use a GridLayout?
If not, I will of course use Graphics2D, etc. but I'm now just exploring my options. :)
((EDIT: SOLVED The tiles now neatly fit on each other. Don't mind the misalignments, that's our fault.))
There are no Swing components that do what you want so you will need to write your own code.
The easiest approach would be to use Darryl's Stretch Icon on your JLabel.
Or another approach is to create your own custom component that dynamically scales the image as it is painted. Something like the Background Panel which has code that allows you to scale or tile an image.
Given the nature of the view, I would recommend abandoning images altogether and instead implement the rendering in an Icon. Presuming you can make an icon scale with the label.
I have an AWT canvas which I cannot convert to a Swing component (it comes from VTK). I wish to display a few of these canvases inside of a JSplitPane. I've read about mixing heavy and light weight components in Java and know that it's a pain in the butt, but I don't have a choice. If I wrap the AWT canvas inside of a JPanel and then put that on the split pane the split pane doesn't function at all. However, if I put the AWT canvas inside of a JPanel and then that inside of a JScrollPane and then those scroll panes on the JSplitPane the split pane does function, but the AWT canvas components don't resize properly. I'm lost about how to get the AWT canvas components to resize properly when the JSplitPane's divider is moved. I can catch the divider moving operation and operate on the AWT canvases at that time, but I don't know what to do. I've tried calling invalidate() then validate() then repaint(), but that didn't work.
Any ideas?
Here's a example of the problem
import javax.swing.*;
import java.awt.*;
public class SwingAWTError {
public static void main(String[] args) {
Canvas leftCanvas = new Canvas();
Canvas rightCanvas = new Canvas();
leftCanvas.setBackground(Color.RED);
rightCanvas.setBackground(Color.BLUE);
JPanel leftPanel = new JPanel();
JPanel rightPanel = new JPanel();
leftPanel.setLayout(new BorderLayout());
rightPanel.setLayout(new BorderLayout());
leftPanel.add(leftCanvas, BorderLayout.CENTER);
rightPanel.add(rightCanvas, BorderLayout.CENTER);
JScrollPane leftScroll = new JScrollPane();
JScrollPane rightScroll = new JScrollPane();
leftScroll.getViewport().add(leftPanel);
rightScroll.getViewport().add(rightPanel);
JSplitPane split = new JSplitPane();
split.setLeftComponent(leftScroll);
split.setRightComponent(rightScroll);
split.setDividerLocation(400);
JFrame frame = new JFrame();
frame.getContentPane().setLayout(new BorderLayout());
frame.getContentPane().add(split, BorderLayout.CENTER);
frame.setSize(800, 800);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
}
It is a dirty way but this will solve it:
When you call pack() without resizing the window, not much happens. So, when you first resize the window and then call pack(), your components are correcly drawn. This means you can put this dirty method in your divider moved listener method:
frame.setPreferredSize(frame.getSize()); // store the current size to restore it after packing.
frame.setSize(frame.getWidth() + 1, frame.getHeight()); // resize it!!
frame.pack();
I don't know what it is exactly but it is a strange behavour in Java...
Hope this helps until you've found a better solution...
You are kind of out of luck here. There's a pretty good article on this on the sun/oracle website:
http://java.sun.com/products/jfc/tsc/articles/mixing/
Essentially it boils down to this guideline (taken from that link, under the z-ordering heading):
Do not mix lightweight (Swing) and
heavyweight (AWT) components within a
container where the lightweight
component is expected to overlap the
heavyweight one.
Edit: I kept browsing that site and came across another link, and it would appear that the situation has improved slightly: http://java.sun.com/developer/technicalArticles/GUI/mixing_components/ But I think your case is one of those listed at the bottom in the limitations section:
Limitations
A few situations are not supported:
* Non-opaque lightweight components that have translucent
pixels (0 < alpha < 255) are not
supported. If a partially translucent
lightweight component overlaps a
heavyweight component, the heavyweight
component will not show through.
* Embedded heavyweight components must belong to the process that
created the frame or applet. The
heavyweight component must have a
valid peer within the main process of
the application (or applet).
* Advanced Swing key events, such as those events maintained in an
InputMap, might not work correctly
where lightweight and heavyweight
components are being mixed. There are
no known workarounds.