Graphical behaviour of THistogramSeries changed

[Whookie]

This seems to go back beyond the last two major updates, but was reported by a customer.

Back then the THistogramSeries looked like this:

old_histo.png (19.19 KiB) Viewed 17477 times

With - at least - the last two versions (I can't go back this far with my project) it looks like this:

new_hist.png (50.77 KiB) Viewed 17475 times

As you can see the historam seems to be a TBarSeries with connected bars rather then a histogram. This is especially bad as - when more data gets added - only the border can be seen now (losing all the red areas!!).

I couln'd find an option to turn the old behaviour back on so I hope you do have that hidden somewhere - or can at least give me a patch do bring this back on!

In addition with the latest (Delphi Seattle) Version there is also an ugly offset, shifting the top border a few pixels to the right:

curr_hist.png (2.19 KiB) Viewed 17459 times

TIA

[Yeray]

Hello,

Do you have a simple example project we can run as-is to reproduce the problem here?
Thanks in advance.

[Whookie]

I added a demo project (and an exe-File which needs all the run time packages).

If you just run it as it is it generates 400 Samples and marks any value below 500 in red this looks like this:

A.png (8.93 KiB) Viewed 17431 times

I can't reproduce old behavior but the screen-shot from the last post was taken from an older version of my software.

I found out that removing the border does show the correct values (uncheck "Use Border") but then the bold outline is also gone and it looks like this:

B.png (9.55 KiB) Viewed 17422 times

Please see following post (as there is a limit of 3 files per post)...

[Whookie]

...follow up

No if you use 30 samples and turn the border back on you get:

C.png (9.88 KiB) Viewed 17420 times

Which shows the "bar-like" border and the shifted offset at the top...

Note: When experimenting you might need to press "Gen histogram:" a few times to get one with values below and above the current threshold! In addition you need to click "Threshold <" after generating a new histogram (or else all values stay in the original color).


While at it, I also found out that the Transparency of the border it self doesn't work and has a real strange behaviour:

Open the bars options:

btransp.png (54.65 KiB) Viewed 17417 times

like in the image above, klick the "Transpareny:" Trackbar und use the left-/right cursor keys of your keyboard to increment or decrement that Transparency value just by 1 each time.
This was the border "flips" between the selected color and black back and force with each value change.
If you compile and run the application there is no transparency of the border either way but in "black"-State it looks like this (showing the shift bug even sharper):

D.png (9.97 KiB) Viewed 17411 times

Note: I do not yous border transparency as I liked the old behaviour of the histogram, having a bold - nontransparent - outline and a proper colord semi-transparent interior.

[Yeray]

Hello,

I can see the border issue, but I can reproduce it with v2015.15 down to v2012.07.
Could you please specify with what TeeChart version this behaviour was different?

[Whookie]

I was lucky to find an older installation on my PC to show you how THistogramSeries worked before it got broken:

Old_Behaviour.png (57.45 KiB) Viewed 17400 times

In fact I was able to install a newer version of TChart and there its working too:

Old_Behaviour2012.05.png (37.52 KiB) Viewed 17392 times

...and as I was at it, I installed 2014.10 which also seems to be ok:

Old_Behaviour 2014.png (43.34 KiB) Viewed 17404 times

[Yeray]

Hello,

I see the problem appeared in v2014.12.
I've created a ticket for it and found a fix, so the next maintenance release will include it.
http://bugs.teechart.net/show_bug.cgi?id=1310

I also see the issue regarding the "ugly offset" has always been like that, isn't it?

[Whookie]

I also see the issue regarding the "ugly offset" has always been like that, isn't it?

Strange enough! I back checked with screen-shots from an older Version (the one in my initial post):

old_n_full.png (270.83 KiB) Viewed 17373 times

Even though its not of superior quality you can zoom in and see that there are "sharp" edges but maybe this impression is supported by the selection of colors. I'm pretty sure, that I never had that great offset i can see now (its also because the original software uses 3 as border width and my initial example used 4 - to make it better visible).

I found another screen shot and it seems that there is no offset either:

last_working.png (75.88 KiB) Viewed 17376 times

This is strange as that was made with my application released in May 2015 (compiled with XE7 and - thats what I'm not 100% sure off - a 2014.?? version of TChart).

I'm sorry but at the moment I cannot get better quality images, because there is an extensive machine required to get the data needed.

[Yeray]

Hello,

Excuse us for the delayed reply here.

If we could get access to the full code that gives a different result if would help us to check what's the difference in TeeChart's sources, if any.
We've seen setting a different Pen.EndStyle doesn't give that "offset". Could you please check if it gives the result you desire?

Code: Select all

Histogram1.Pen.EndStyle:=esFlat;

[Whookie]

Hi,
I'm sorry, I tried to go back and rebuild the Application but got stuck on some stuff not compiling anymore, so I had to give up for now.

I also tried your suggestion but setting the connection end style to flat produces "steps" instead of an offset.

flat.png (14.91 KiB) Viewed 17302 times

in conjunction with a border width of 3 they have just the size of a pixel (so that would be acceptable) but with thicker borders its highly visible (see attachment).

[Yeray]

Hello,

I've created a new ticket in the public tracker explaining the issue with these corners in the THistogramSeries:
http://bugs.teechart.net/show_bug.cgi?id=1320