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Bug 323183

Summary:

[GC] Font disposal breaks GC

Product:

[RT] RAP

Reporter:

Austin Riddle <austin.riddle>

Component:

RWT

Assignee:

Project Inbox <rap-inbox>

Status:

RESOLVED FIXED

QA Contact:

Severity:

normal

Priority:

Version:

1.3

Target Milestone:

1.4 M2

Hardware:

All

OS:

All

Whiteboard:

Attachments:

Description	Flags
Patch for potential solution 1	none

Description Austin Riddle

2010-08-19 15:00:39 EDT

Version: CVS HEAD

Steps to reproduce:

1. Set the font on the GC to a non-factory created font (i.e., user instantiated)
2. Draw text on the GC.
3. Dispose of the font.

If the dispose() call on the Font occurs before renderChanges() is called in the CanvasLCA an exception is thrown:

org.eclipse.swt.SWTException: Graphic is disposed
	at org.eclipse.swt.SWT.error(SWT.java:3190)
	at org.eclipse.swt.SWT.error(SWT.java:3110)
	at org.eclipse.swt.SWT.error(SWT.java:3081)
	at org.eclipse.swt.graphics.Font.getFontData(Font.java:177)
	at org.eclipse.swt.internal.widgets.canvaskit.GCOperationWriter.toCSSFont(GCOperationWriter.java:235)
	at org.eclipse.swt.internal.widgets.canvaskit.GCOperationWriter.setFont(GCOperationWriter.java:229)
	at org.eclipse.swt.internal.widgets.canvaskit.GCOperationWriter.write(GCOperationWriter.java:57)
	at org.eclipse.swt.internal.widgets.canvaskit.CanvasLCA.writeGCOperations(CanvasLCA.java:62)
	at org.eclipse.swt.internal.widgets.canvaskit.CanvasLCA.renderChanges(CanvasLCA.java:46)

This is a common use-case since the graphics operations are actually processed/accomplished after the code that called them is finished.  So the user-code actually is a good citizen by disposing the fonts as soon as they are not needed, and is unaware that the GC operations will need the "undisposed" font later during renderChanges().


Potential Solutions:

1. Do not throw an exception in Font.getFontData() since in RAP it does not really care if the font is disposed or not in terms of obtaining FontData.

2. Make an undisposed copy of the Font objects that are set into the GCOperationWriter in renderChanges().

Comment 1 Austin Riddle

2010-08-19 15:03:41 EDT

Created attachment 177039 [details]
Patch for potential solution 1

Comment 2 Austin Riddle

2010-08-19 15:06:47 EDT

(In reply to comment #0)
> 
> 2. Make an undisposed copy of the Font objects that are set into the
> GCOperationWriter in renderChanges().

In this case I am implying that there be some internal API that can obtain the font data without throwing an exception.

Comment 3 Austin Riddle

2010-08-19 15:08:10 EDT

This is related to https://bugs.eclipse.org/bugs/show_bug.cgi?id=321135

Comment 4 Ivan Furnadjiev

2010-08-23 04:19:40 EDT

Fixed by creating an "internal" copy of the external font in GC#setFont(). Changes are in CVS HEAD.