Pinch to Zoom

[HCCKPM_2020]

Good Morning Marc,

using the sample from Christopher he posted in August, zooming is working not good.
Let me explain according to the sample:

If you pinch to zoom the bar number 5 and put your finger on the left and on the right corner of the bar.
Than you start zooming.
You would expect to have the zoomed bar beneath your two fingers but you don't have.
And leaving both fingers on the screen, you can scroll.
This is also an irritating behaviour.

[Marc]

Hi,

Yes, for sure we're not seeing the same behaviour; it may be idiosyncrasies of different devices. Our modifications, making sensitivity (zoom speed-response) publicly accessible will help. Note though, as a test, that if you place a touch location on either side of the bar, bar 5, and keep the right touch fixed, only dragging the left finger (touch) out, you should see the zoom direction will open to the left. If you do it the other way you should see the zoom direction moving out to the right.

In all cases in our test, the zoom moves out from the location between the two touch points.

Regards,
Marc

[HCCKPM_2020_12]

Hello,

a new issue with zooming occured:
After version V4.2020.5.25 it is no longer possible to zoom a zoomed chart again.

To reproduce the error test the following:
- Chart not zoomed
- Rectangle with touch leads to a zoomed chart
- When touching the zoomed chart, it is immediately unzoomed and only then the new zooming is executed

This video shows the problem:
https://hcckpm-my.sharepoint.com/:v:/g/ ... A?e=j5VSCf

[Marc]

Hi,

We've tested that on latest source with your sample project; the zoom: first, second, third, etc, work perfectly acting on the previous zoom made.

We need to check with you on what version you're using and what the status is with the test code that we sent you (see http://support.steema.com/viewtopic.php ... 326#p77630) so that we can be sure to be working on the latest version together.

With thanks.
Regards,
Marc Meumann

[HCCKPM_2020_12]

Hello Marc,

we uploaded a new video showing the explained issue with the latest source code.
We tested with the source code and also with your latest DLL.
Both end up with the same problem.
We tested on two different systems with differnet touch screens.
Did you really test with a touch screen?

The video shows the issue.
At the end of the video we zoom in by mouse for a view times -> the color changes on zooming and at the very end, we end up with a white area?!

The video can be downloaded here:
https://hcckpm-my.sharepoint.com/:v:/g/ ... g?e=pXYGfP

BR
Jochen

[Marc]

Hello,

Re. "Did you really test with a touch screen?"

Yes. The test was run with your project on a touch screen. I can make a video to show you.

I'll take a look at your other video.

We need some feedback on your compilation with source related to the other thread:

http://support.steema.com/viewtopic.php ... f4515eccaf

Regards,
Marc

[Marc]

Hmmm.... I see you're zooming on the touch screen with a mouse action. I hadn't expected that. The touch screen zoom design that I tested is for two-finger zoom (touch-screen paradigm). ... I'll check the other method too.

[Marc]

Hello Jochen,

Ok, that behaves quite well in the local test here; single touch zoom is somewhat easier to run than double-touch because the Chart doesn't need to recalculate at each position, only once the zoom area is decided.

Two resources here:

Single touch zoom:

settings:

Code: Select all

TChart1.IsManipulationEnabled = false;
TChart1.Panning.Allow = Steema.TeeChart.WPF.ScrollModes.None;
TChart1.Zoom.Direction = Steema.TeeChart.WPF.ZoomDirections.Both;

https://www.steema.com/files/public/tee ... chZoom.MP4

Double touch zoom:

settings:

Code: Select all

TChart1.IsManipulationEnabled = true;
TChart1.Panning.Allow = Steema.TeeChart.WPF.ScrollModes.None;
TChart1.Zoom.Direction = Steema.TeeChart.WPF.ZoomDirections.Both;

https://www.steema.com/files/public/tee ... chZoom.MP4

Movement sensitivity can be improved here via the new Sensitivity property.
==========

In all cases, we recommend that you put a zoom limit in if extreme multiple-zoom is expected. Off-screen Axis scales can get so large that calculations become 'gigantic'. One can arrive at a situation where the next zoom gives no extra added-value to the person using the app. By using the zoom event you can decide a minimum axis scale that is acceptable and undo/not-run any zoom beyond that level.

Regards,
Marc