Develop Reference

How to set minimum size of scrollbar thumb slider on SWT ScrollBar?

Specifically on a Windows XP machine, The width of the SWT ScrollBar Slider becomes incredibly thin when the internal scroll composite is very large. Is there a way to set the minimum width of the thumb slider to like 10-15px so that it doesn't get that thin? My specific case with this is when using NatTables with large amounts of data.

The scrollbar in NatTable is managed by the ViewportLayer. It internally uses instances of ScrollBarScroller for this, which are wrappers around a ScrollBar. To support custom scrollbars like the one posted in the other answer, the ViewportLayer supports that you set a custom ScrollBarScroller. This is explained in one of my blog posts here: NatTable with custom scrollbars.
You could for example set a customized instance of ScrollBarScroller where you override #setThumb(int) and there you ensure that the value of the thumb never gets below a certain minimum. Not sure if that would have any side effects on scrolling. But it should be worth a try.

Hi I don't think you can do that, because the Scrollbar it's drawn by the OS.
I think you have two options here, if you really need this feature:
1) implement you custom Scrollbar.
2) try to use/modify an existing custom Scrollbar, for instance this one: http://www.codeaffine.com/2014/12/17/sacrilege-custom-swt-scrollbar/

Java JFreeChart: customize tooltip screen position

I implemented my own JFreeChart XYToolTipGenerator and, as the chart it is used on is almost full screen, sometimes the tooltip position (on screen) hides the point it is related to (e.g. in the bottom right corner, since it seems that tooltip is configured to be positioned South-East of the mouse / data point). This is a problem because the user needs to be able to click on the chart's data points (as it generates a specific action).
Is there a way to either define dynamically the position of the tooltip (e.g. for data points bottom right I would ask the tooltip to be shown North-West) or, alternatively, to define a systematic position (e.g. North-West instead of South-East as it is by default)?
This problem has given me headaches for the last few days - any help or hint is more than welcome.
Many thanks!
Thomas

Here's the answer I posted on the JFreeChart forum:
JFreeChart is using the standard Swing tool tip mechanism. In the ChartPanel class, the getToolTipText(mouseEvent) method is overridden to return the appropriate text for the tooltip, and that's it.
Swing also gives you the option to override the getToolTipLocation(mouseEvent) method, and that's probably what you need here.

Scaling an Address Form on Resize

My application has a form for filling in the names and addresses of a donor. Each donor gets a closable tab and each tab has an address form.
The problem is that the application runs in a regular application window and therefore gets scaled to all different sizes. If I make the width and height of the text fields static, they all stay in the upper left of the window on a big screen. If I make them dynamic, the form looks bad because of massive boxes for relatively small amounts of text (i.e. first name). If I space them out dynamically, I end up with large gaps in between the boxes.
What is the best way to deal with this issue? Is there a UI construct normally used for this (so far the only one I've seen used has been to put the form in a non-scalable modal dialog, which I can't do because of the tab-based UI).
Thanks

Just a suggestion- an easy way out, taken by lots of web designers *(I know your app is not browser-based):
Constrain the content to a fixed size (e.g. 800px), and center that box horizontally. If the user maximizes their window, they see the 800px content centered with large empty gaps to right and left.
IMHO, this is not the best, but it doesn't look as bad as if it were packed into the upper left.
This is a graphic design question, not so much about the technology...

SWT ScrolledComposite cutting off information.

I'm making an application that has many lines of data coming back from a Database stub(which will become an Oracle database), and for some reason the scroll bar stops at about the 500th element. I'm wondering if there's anyway to have all the elements show within the scroll bar.

I'm assuming here that you're using Windows, because there is a fairly general problem with scrollbars on Windows: the maximum value is a short int, 32,768. Therefore, if the height of the inner composite of a ScrolledComposite is greater than 32,768 pixels, the composite will be clipped.
I haven't found a robust way of fixing this, but there is a workaround: separate the scrollbar from the composite that you wish to scroll. You can't create a ScrollBar, but you can make a ScrolledComposite that is precisely as wide as a ScrollBar, then attach a ScrollListener to it and have it adjust the layout position of the scrolling composite.
Somewhere I have a snippet, but I'm not even exactly sure if this diagnosis applies to your scenario.

You might need to set the minimum and maximum values of the ScrollBar. You would use the setMinimum() and setMaximum() methods, respectively.
It's also a good idea to set the page increment. This is the number of scroll lines that the selected value changes by when the user clicks the area between the thumb and the arrow buttons, or presses the Page Up or Page Down buttons. You would use the setPageIncrement() method.
Finally, Oracle may impose a maximum number of rows you can retrieve from a table. I believe the default is 500 rows.

Raw Java 2D implementation of a scrollbar

How would I go about writing my own scrollbar using standard Java 2D.
I really don't want to use swing, and I've already made up my own component parts for everything else such as buttons etc.
I'm not really looking for code, rather the math involved in the event changes and the drawing.

Why on earth would you want to write your own java GUI toolkit? You already have the choice of Swing and SWT, can you really do better than these two teams?
If you've already written the rest of the toolkit, I don't understand why the scrollbar would stump you. Without knowing anything about your event system, or how your custom components are structured, it's impossible to give much advise. I don't see this being particularly maths intensive - just maintain the height of the scrollable component, and the view it's in, and the scrollbar size should match the proportion of the component that is visible. The position of the scrollbar should match which part of the component is visible (this will have to be scaled). Specifically, what do you want to know?

Java is now open. I'd go look at the source for the Swing and/or SWT as they are already implemented. The math seems fairly straight forward. You have a Bar and a Container. To simplify we will only discuss length (the dimension in which the scrollbar moves). The container is of a certain length. The bar is of a length that is equal to or less than the container. It is useful to define the center and the two endpoints of the scrollbar. You can have the scrollbar start at 0 at the top and 1 at the bottom or 0 at the top and 100 at the bottom with the important part being defining your scrollbar in the same manner. Then you can check the endpoints for collision with the edge to stop the bar from moving. If the mouse is held down with the cursor over the coordinates inside the bar, the bar starts caring about where the cursor is and will paint the scrollbar and whatever the scrollbar is ultimately supposed to be affecting. So, you would take the page to be affected and map it to 0 and 1 * the scale in pixels of the scrollbar. Then you get to worry about the arrows at either end and how big of a jump each click is and dealing with mousedown events etc.etc. Use what is given don't reinvent the wheel.

While not Java2D, this straightforward code snippet might help:
http://processing.org/learning/topics/scrollbar.html