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Bug 2592

Summary:	TChart.Canvas throws BeginScene error
Product:	FireMonkey TeeChart	Reporter:	Reini <reini>
Component:	Chart	Assignee:	Steema Issue Manager <issuemanager>
Status:	RESOLVED WONTFIX
Severity:	major	CC:	yeray
Priority:	High
Version:	unspecified
Target Milestone:	---
Hardware:	PC
OS:	Windows
Chart Series:	---	Delphi / C++ Builder RAD IDE Version:	RAD 11 Alexandria
Attachments:	Sample application to show BeginScene exception

Description Reini 2023-03-01 03:32:11 EST

Created attachment 1037 [details]
Sample application to show BeginScene exception

This bug is also reported to Embarcadero under:
https://quality.embarcadero.com/browse/RSP-40271
It should be solved in Delphi release 11.3 but it isn't.
It is reproducable with TChart Lite v2021.32.210722
The problem lies in TChart.Canvas that does not call BeginScene. Please build the attached application and notice the exception (under both Delphi 11.2 and Delphi 11.3). The error did not occur when compiled with Delphi 10.4
In the sample application, after pressing the button names "default", the application will try to draw a circle on the canvas of the TChart. Then the error occurs

Comment 1 yeray alonso 2023-03-13 13:26:20 EDT

We won't add `BeginScene`/`EndScene` in all our `TTeeCanvas3D` primitives. It wouldn't be a good design.

So I'd suggest to do it yourself as you did in the comments. Just note you need to use `ReferenceCanvas`:

  EqChart.Canvas.ReferenceCanvas.BeginScene;
  // Do your custom drawing here
  EqChart.Canvas.ReferenceCanvas.EndScene;

Also, I'd suggest you to do the custom drawings at the `OnAfterDraw` event instead of at the button `OnClick`.