Dukascopy Support Board

Short line rendering bug with price based periods
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Author:  scotpip [ Wed 03 Apr, 2019, 11:01 ]
Post subject:  Short line rendering bug with price based periods

This is a bug that I'm seeing with all price based periods such as tick bars, renko, kagi etc. Time based periods are working OK.

To replicate:

1) Draw a short line
2) Scroll one end of the line 3 bars past the right or left edge of the window
3) The part of the bar that should still be on screen disappears
4) Scroll back 1 bar and the line re-appears.


Scroll bug 3.PNG [19.41 KiB]
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Scroll bug 1.PNG [26.08 KiB]
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Scroll bug 2.PNG [16.78 KiB]
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Author:  API Support [ Thu 04 Apr, 2019, 15:10 ]
Post subject:  Re: Short line rendering bug with price based periods


This is not a bug, it's expected behavior. Under certain conditions drawing objects can be hidden from chart. You can see it in notification window, as the example below:


screenshot.png [23.87 KiB]
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Author:  scotpip [ Thu 04 Apr, 2019, 18:02 ]
Post subject:  Re: Short line rendering bug with price based periods

Thanks for responding, but I can't make any sense of your reply.

First, this issue doesn't happen with time based bars (see screenshot).

Second, it didn't happen in older releases - this is new behaviour.

Third, even if it was the expected behaviour, I would urge you to rethink. I've worked with literally dozens of graphics programmes over the years, and they **always** show all objects that are partially outside the window. Otherwise they would be unusable. I would argue that having objects that disappear when they partially scroll off the view panel is a major usability bug.

Fourth, no other trading platform I've tried has this issue.

Please have another think about this - the only sensible solution is to have objects remain in view when they are partially outside the window. Everyone one else can manage this so it must be relatively trivial.



Scrolling bug.PNG [20.01 KiB]
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Author:  Platform Support [ Fri 31 May, 2019, 14:48 ]
Post subject:  Re: Short line rendering bug with price based periods

We have improved this. We cache all the time scale coordinates within the chart buffer (from 2K to 10K candles) for the drawing objects now. It consumes a bit more memory and works just fine if the coordinate does not go outside the buffer, which can happen if you fully zoom out the chart and scroll very far.

Besides, the objects can be drawn in the future as well now in the price based charts. We extrapolate the time scale in the future based on the information in the buffer. Note that if the object has angle, which is not 0 or 90 degrees (like this short line in your example), and one of its coordinates is in the extrapolated time scale of the future, the angle can change with each new candle appearance (time passing).

Both features are available in version 3.5.12 or later.

Author:  scotpip [ Thu 13 Jun, 2019, 19:23 ]
Post subject:  Re: Short line rendering bug with price based periods

Seems to be working as expected now.

Many thanks for fixing this - much appreciated!

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