How to modify the width or height of TableItem in pixels

[pcdlrzxx]

I can simply modify the width and height of TableItem through the code below

table.addListener(SWT.MeasureItem, new Listener() {
   public void handleEvent(Event event) {
      event.width = 100;
      event.height = 20;
   }
});

but it only works in points, and I just want to know how to make it work in pixels.

As for Table, although it also can't do this by "Public" method, but can be achieved by using reflection.
However the "Event" class doesn't provide similar methods.

Can anyone help me ,thanks very much!

[elsazac]

I believe you can't directly set sizes in pixels in SWT. By default, it uses points, which adjust based on the display's DPI. To get pixel sizes, you need to manually do may be, pixel conversions and apply some sort of scaling or so.. As far as I know, there's no API that automatically switches between points and pixels, but please do correct me if I'm mistaken.

[sravanlakkimsetti]

@pcdlrzxx Not making xxxInPixels methods as public is a conscious decision. In Linux and Mac we always work with points. The translation to pixels is at OS/native layer which we are not privy to. Only in case of Windows, SWT layer handles this translation. SWT API should be agnostic to underlying OS/windowing system. For this reason we have made the api to work points only.

We had to go though xxxInPixels approach as at the time of HiDpi development the Windows and Linux did not have good HiDpi support natively. By GTK 3.18(not sure) release the linux had good HiDpi support. We leveraged this and revamped Linux support to directly work with points only.

Using swt.autoScale you specify scaling factor as far as remember. In windows we support only two scaling factors 100% and 200%. When you provide a value up to 174 the scaling factor selected will be 100% and 175 and above the scaling factor selected is 200%.

[sravanlakkimsetti]

Also see https://eclipse.dev/eclipse/news/4.6/platform.php#swt-autoscale. By the way the tweaks mentioned here work with Windows only.

The tweaks will not work with either Linux or Mac

[pcdlrzxx]

@sravanlakkimsetti Hello sravanlakkimsetti, thanks for your reply. I have read the swt-autoscale-tweaks part of the article, and I noticed some discrepancies. According to the article, there are two cases in swt.autoScale=integer and swt.autoScale=<value>. When swt.autoScale=integer, 100% and 200% will only be used. But when swt.autoScale=<value>, the set value will be used.
In fact, the value I set in program whatever 192 or 198 is effective, this can be proved by the output in program.

So in my understanding, because of the not good HiDpi support of Windows natively, problems are inevitable at some scaling factors on Windows. And we can only hope for improvements in Windows' HiDpi support, right?

[sravanlakkimsetti]

@pcdlrzxx

So in my understanding, because of the not good HiDpi support of Windows natively, problems are inevitable at some scaling factors on Windows. And we can only hope for improvements in Windows' HiDpi support, right?

Yes you right. We went with 25% increments initially and it created lots of problems with the sizes. Converting pixels to points using integer arithmetic is bound cause trouble. Thats why we had to completely remove 25% increments and then supported integer scale factors only.

By the way Mac uses floating point arithmetic and Linux supports only integer scaling factors.

[pcdlrzxx]

@sravanlakkimsetti Fine, thanks for you answer! It seems that I don't need to dwell on this aspect for the time being. Hope the Windows' HiDpi support improvements come out as soon as possible.