I have a JPanel that contains a bunch of Swing JComponents, including some JSeparators that may be only one or two pixels wide. I want to let my users drag the items around, but it can be rather difficult to hit a one or two pixel wide line. Is there a way that I can give those JSeparators a wider "target" region for mouse clicks? The only thing I've been able to think of is to have my mouse handler listen for clicks on the JPanel, and if it gets any, run through the list of JSeparators, looking to see if any of them are within a couple of pixels of the mouse click.
Should that work? Is there a better way?
Add a fat EmptyBorder to the component.
If it already has a border, you can set a compound border using the current border then the empty border, or simpler, add the empty border (and listener) to a panel that contains the component. The latter will work better for components such as JButton, which have borders that change according to state and focus.
Related
I'm relatively new to developing GUI's within java so this may well be a stupid question or quite simply not possible to achieve but here we go.
I've created 1 single JPanel with no border layout set up or anything like that and I intended to paint a GUI on top of it using the graphics class. The JPanel is just plain black and then I've drawn a huge box over it leaving the black just as a border, and painted the whole GUI within this white box.
I want to add buttons within that white box GUI as well but I've no idea how. In fact they don't even have to be traditional buttons JButtons, if I could just draw a shape and have that act as a button then add an event handler to just that shape that would work also but I don't know how I'd do that either.
I have so much code for my whole program (it's a school coursework project) that I'm not sure which parts would even be worth sharing to assist with this question since there's so many GUI aspects I've already drawn so I've tried to just explain my issue in words.
Honestly I have no clue what I'm doing so any help would be appreciated.
EDIT: Here's a screenshot of my current GUI with a 'sketch' of how and where I'd like to be able to add buttons.
GUI Image
As with any suitably complex UI, you need to start by breaking it down into manageable chunks, focusing on areas of mutual interaction and functionality.
For example...
Says to me that you have two primary UI elements, the left and the right.
This could easily be established with a GridLayout, but, if the two sides are not equal in width, a GridBagLayout might be more appropriate
The right side to me says simply, JTable. You could place this within a container using a BorderLayout, allowing the table to occupy the CENTER position.
The key information would then a component laid out with either a GridLayout (top and bottom) or a GridBagLayout if the requirements are more complex. This component would then be added to the SOUTH position of the BorderLayout.
Again, this is pretty simple. The primary layout would probably be a BoderLayout, with the title in the NORTH position, the graph in the CENTER and the buttons wrapped in a component in the SOUTH.
You could use either a FlowLayout or GridBagLayout to layout the buttons depending on your how you want them to appear
Recommendations
Have a look at:
Laying Out Components Within a Container
How to Use Tables
And for the "border", I'd recommend you have a look at LineBorder. Take a look at How to use Borders more details
I create buttons using jlabels, so I can make a image into sort of a button. The only problem is, is that jlabels are square, therfore if i click somewhere within the square where the picture is not contained, it still runs the jlabel.MouseClickEvent. Is there any fix for this, or another component that i could use?
Ex. If i click this on the corner where the circle is not showing, but the square is still there, then the event fires.
Any fixes/different components to use? Thanks!
If you are just using simple Shapes for the images then you might be able to use the Shape Component found in Playing With Shapes.
The ShapeComponent will only respond to mouse events within the bounds of the Shape.
Otherwise the solution is to override the contains(...) method of your JLabel to check if the mouse point is in the bounds of your image, or in your case if the pixel at that location is not transparent.
I have a column of JPanel instances that has content in it, that when it is clicked, the selected Panel is set to have a border (in order to distinguish it), and only 1 at a time has the border.
The problem is that when it sets the border, it sets the outer section of the panel to the border, and shrinks the content inside. Although it seems minor it is not very professional, and I would much rather have it add more like an overlay, where the content will not shrink.
I am thinking maybe there is some method of graphics that will let me do this? I haven't been able to find any way of doing this.
Start by setting all the components to have a EmptyBorder set to a single pixel inset.
When you select a panel, simply set the newly selected panel's border as you are (presumably using a LineBorder) and the set the previously selected panel's border to the single pixel EmptyBorder.
If you're clever, you could get away with a single instance of EmptyBorder ;)
Basically I plan to place some buttons, textfields, labels, etc. on a JFrame and I would like to make it possible that a user can move the different components around on that JFrame with the mouse.
I have seen various ways with MouseListeners, subclassed JComponent code, DropSource/DropTarget implementations and so on, but I'm unsure which is the "recommended" way (I don't need to support "drag and drop" between different Frames/Applications which is what most examples seem to do).
The Component Mover can do this for you.
Use the GlassPane:
http://download.oracle.com/javase/tutorial/uiswing/components/rootpane.html
It's an invisible panel that sits on top of all other components. You can attach mouse listeners to it and then use SwingUtilities.getDeepestComponentAt() to figure out which component was clicked on beneath the GlassPane. Then use a mouseDragged listener on the glasspane and set the component location based on the mouse dragged event.
You will need to set the layout of your container to "null" so the components' setLocation will work.
A panel contains two labels which are generated by mouse clicks on the panel. I want to connect these two labels by drawing a line between them probably by dragging the mouse pointer from one label to another.
There are two events here - one is clicking on the panel to generate the labels and the second is connecting these two labels (mouse pressed, mouse dragged and mouse released events). Both these event need to call the repaint() method but for different purposes. But there can be only one paint() method. The problem is when I connect these two labels, the line comes up but the rest of the components on the panel disappear.
That is probably due to the fact that you're overriding the panels paint() method.
Override paintComponent() / paintComponents() instead. No matter if you're using paint or paintComponent, do not forget to call super.paint() or super.paintComponents() respectively.
You can use a JLayeredPane instead of JPanel to draw multiple objects above eachother.
You can add your original JPanel to the JLayeredPane, and then add another one, with a higher Z-index and the opaque property set to true. Then the highest panel can be easily repainted without the other, lower, panel to show weird things.