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Bug 126747

Summary:	NPE on shrinking a Thumbnail
Product:	[Tools] GEF	Reporter:	Johannes Quast <johannes.quast>
Component:	GEF-Legacy Draw2d	Assignee:	Alexander Nyßen <nyssen>
Status:	RESOLVED FIXED	QA Contact:
Severity:	normal
Priority:	P3	CC:	nyssen
Version:	3.1.1
Target Milestone:	3.6.0 (Helios) M7
Hardware:	PC
OS:	Windows XP
Whiteboard:

Description Johannes Quast

2006-02-07 11:45:28 EST

In our editor we use a Thumbnail in the Outline view like in the logic example.
In addition we have some documentation figures using a TextLayout to draw their content.

If you resize the outline view until the thumbnail is nearly zero in it's size,
the following error occurs:

Caused by: java.lang.NullPointerException
	at org.eclipse.draw2d.SWTGraphics.drawTextLayout(SWTGraphics.java:494)
	at org.eclipse.draw2d.ScaledGraphics.drawTextLayout(ScaledGraphics.java:294)
	at org.eclipse.draw2d.Graphics.drawTextLayout(Graphics.java:353)

The zoomTextLayout(layout) call in ScaledGraphics:293 returns null because zoomWidth == 0 (see line 736).
This null is passed to SWTGraphics.drawTextLayout which causes the NPE.

Possible solutions:
- no return of null in zoomTextLayout(..) (but what instead?)
- check the return value in ScaledGraphics.drawTextLayout and do not call underlying Graphics in case of null

Comment 1 Alexander Nyßen

2010-04-13 15:09:36 EDT

zoomTextLayout may legally return null in case the computed zoomWidth is 0, as this is no valid size for TextLayout. I thus added a null check to drawTextLayout and have it directly return in case the result of zoomTextLayout evaluates to null. 

Changes are committed to HEAD.