Can you make the background of a JScrollBar transparent? - java

I have a series of column labels that scrolls independently from the data that is displayed in a matrix below. I can make the whole scrollbar transparent except on hover. The labels are right up against the data, which I like, however, upon hover, unless I shift the vertical scroll (which I'd rather not do), the scrollbar obscures the beginning of all the labels.
I would like to set the background of the scrollbar as transparent so that only the "grabber" (or whatever it's called) is the only thing that is drawn. (It will obscure the beginning of the labels it is over, but would be a lot less so.)
Is there any way to do that? Here is what I tried:
Color bg = new Color(255,255,255,0);
colLabelScroll.setBackground(bg);
This does not seem to make the background of the scrollbar transparent.
What I'm shooting for is like how the iPhone's scrollbar grabber hovers over info in some apps. Is that even possible with JScrollBars?

Transparent JScrollBar can do it, but consider this: if column labels are related to the data and you can scroll them independently, beginner users may not understand what is going on and associate column labels with whatever is visually aligned beneath it. Either you will need some sort of visual indicator that makes it clear that the labels are disconnected from the data, or you should change the way labels are scrolled that never leaves them statically in 1 place.
Here's how I ended up making the relationship between the labels and the data clearer:
Instead of allowing the user to independently and intentionally scroll the labels, I decided to control the label scroll position via mouse hover. This eliminates the need for the obtrusive scrollbar.
I created a scroll-bar-like indicator that shows the portion of the data the labels represent.
I highlighted the currently hovered label that corresponds to the data below it, i.e. the only label that is ever correctly aligned with the data is the one that is under (or directly above) the cursor.
When the mouse is not hovered over (or dragging from) the column labels, do not display any labels. This helps prevent invalid label/data associations by the user.
A few nuanced notes: Implementing your own scrollbar-like indicator is somewhat involved, especially if your labels are painted and then rotated, because the paint position of 0 is at the bottom of the pane, yet the vertical scroll position of the pane is at the top. You will have to track the vertical scroll position to be able to recover it again when the cursor returns since you are blanking the labels on mouse out.

When developing a plugin for IntelliJ, I accomplished it with:
scrollPane.getVerticalScrollBar().setUI(ButtonlessScrollBarUI.createTransparent());
It takes advantage of the the:
ButtonlessScrollBarUI.createTransparent()
method, which is an IntelliJ specific method. However, if you can find a ScrollBarUI which has a transparent background, you can use the same trick.

Since I got a bit lost myself at first after reading #hepcat72's answer I'm posting a little explanation about the BasicScrollBarUI class:
JScrollBar scrollbar = scrollPaneConversation.getVerticalScrollBar();
scrollbar.setUI(new BasicScrollBarUI(){
// This function returns a JButton to be used as the increase button
// You could create your own customized button or return an empty(invisible) button
#Override
protected JButton createIncreaseButton(int orientation){
}
// Same as above for decrease button
#Override
protected JButton createDecreaseButton(int orientation){
}
// This function paints the "track" a.k.a the background of the scrollbar
// If you want no background just return from this function without doing anything
// If you want a custom background you can paint the 'Graphics g' object as you like
#Override
protected void paintTrack(Graphics g, JComponent c, Rectangle trackBounds)
{
}
// This function paints the "thumb" a.k.a the thingy that you drag up and down
// You can override this function to paint it as you like
#Override
protected void paintThumb(Graphics g, JComponent c, Rectangle thumbBounds)
{
}
});
Refer to the Transparent JScrollBar link posted by #hepcat72 for hints about what to do exactly in these functions.

Related

How to detect JPanel child component paint event?

I have a JPanel where I place components in it. I need to get notified every time when a sub component (even nested) is repainted. Is there an event for it that I can register when a component is added to the JPanel?
My purpose is to draw a scroll bar on the right and bottom edges of the JPanel but when the sub component is redrawn, it overlaps the scroll bars and makes a part of scroll bar invisible. I want to redraw the scroll bar when a component refreshes its view so it stays behind the scroll bar.
To make it a little bit more clear, this two are the screenshots of the UI.
The first image is incorrect but this happens only if I hover the components with the mouse. Otherwise, it's looking good. The image on the right is when the container is loaded. I want the components always appear behind the scroll bar but I just cannot detect when a specific component is repainted.
For those who encounter similar problem like this,
I've found the answer within Swing's own painting mechanism. If you want to receive component paint events from a container's child, override isPaintingOrigin() method.
#Override
protected boolean isPaintingOrigin() {
return true;
}
Only this will be sufficient and painting event will be called by the underlying container.

Jlabel Extra Clickable Space

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.

Forcing JScrollPane to scroll by (X) pixels

I have a JScrollPane scroller that I would like to make move a specified amount of pixels either vertically or horizontally.
Specifically, I'm making a tile-based game in which the tile panel is wrapped in a JScrollPane that has its scrollbars hidden from the user. I need the code to adjust the scrolling such that every time I call my movePlayer() method in the tile panel, the scrollbar(s) automatically move over by the length of one tile.
Most of my searches so far have only yielded results for scrollBy in javascript.
Is there a way to programmatically force the bar to scroll in Java?
Take a look at JViewport#getViewRect, JViewport#getViewPosition, and JViewport#setViewPosition
These will allow to adjust the JScrollPane's viewport position.
You can also take a look JComponent#scrollRectToVisible which allows to ask that a given area of a component be made visible if it is within a scrollpane/viewport
You can take a look at Moving a view port over a larger image; JLablel+JScrollPane for example

Resize code does not correspond with mouse movement

I have some code to resize a chatpanel dynamically, but it does not move according to the mouse. What happens is the mouse moves at a faster rate than the panel gets resized. For example, how I want it to be, is in any application, when you click on the border between two windows, and drag it, the mouse stays along with the piece you are clicking on, and currently this is not happening. here is my code. please let me know if you need more
public void mouseDragged(MouseEvent e) {
if(getCursor().getType() == Cursor.getPredefinedCursor(Cursor.N_RESIZE_CURSOR).getType()) {
owner.adjust((int)MouseInfo.getPointerInfo().getLocation().getY());
System.out.println("vertpanel: "+(int)MouseInfo.getPointerInfo().getLocation().getY());
}
}
public void adjust(int adjustment) {
int height = this.getHeight();
System.out.println((((double)(adjustment))/height)+":"+(((double)(height-adjustment))/height));
output.setHeightPercent((((double)(adjustment))/height));
output.componentResized(new ComponentEvent(this, 1));
input.setHeightPercent((((double)(height-adjustment))/height));
input.componentResized(new ComponentEvent(this, 2));
}
there is one main panel, a chatpanel, and within it, there are two smaller panels, a chat input and a chat output
Can't tell exactly what you are doing based on your code.
I would suggest that you should NOT be manually setting the dimensions of the output and input coponents. You should let the layout manager determine how to resize each component as the parent container is resized.
So in your resize code you would need to invoke revalidate() on the parent container as it is resized.
Check out Resizing Components. You should be able to use the ComponentResizer class as long as you use setAutoLayout(true).

How do I make a Swing JComponent a bigger mouse target?

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.

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