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 OnZoomIn/OnZoomOut issue		  New Topic  Reply to Topic
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PeterPanino

901 Posts
Posted - Mar 07 2024 :  12:04:03  Show Profile  Reply
The events TImageEnView.OnZoomIn and TImageEnView.OnZoomOut are not triggered when setting the Zoom programmatically, for example:

ImageEnView1.Zoom := ImageEnView1.Zoom + 10;


However, they are triggered when setting the Zoom with the mouse wheel.

This is shown in the following test project:

attach/PeterPanino/20243712229_MouseInteractionsTest_ZoomIssue.zip
76.92 KB

Is this a bug?

xequte

38418 Posts
Posted - Mar 07 2024 :  19:48:18  Show Profile  Reply
Hi Peter

As per the documentation, OnZoomIn/OnZoomOut only occur when the user changes the zoom.

Nigel
Xequte Software
www.imageen.com
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PeterPanino

901 Posts
Posted - Mar 08 2024 :  10:20:02  Show Profile  Reply
As per the definition, the user changes the zoom when clicking a button that executes:

ImageEnView1.Zoom := ImageEnView1.Zoom + 10;
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xequte

38418 Posts
Posted - Mar 08 2024 :  14:34:35  Show Profile  Reply
Then by definition, that is not a user activity that is changing zoom, it is your code.

You should just change your code to:

ImageEnView1.Zoom := ImageEnView1.Zoom + 10;
ImageEnView1ZoomIn( nil );

Which is nice and easy, unlike the counter which would be difficult. i.e. if OnZoomIn reacted to code changes, then how would you differentiate between the event occurring due to a code change or a user change?

Think about TEdit.OnChange or TCheckbox.OnClick, how do you determine whether the change was by the user or by your code?



Nigel
Xequte Software
www.imageen.com
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