RFR: 8037965: NullPointerException in TextLayout.getBaselineFromGraphic() for JTextComponents

[Alexey Ivanov]

On Wed, 16 Feb 2022 07:44:27 GMT, Prasanta Sadhukhan <psadhukhan at openjdk.org> wrote:

> When invalid unicode codepoints 0xFFFF and 0x10000 are added to an empty javax.swing.JTextComponent (JTextArea or JTextField), the view cannot be updated due to a NullPointerException in TextLayout.getBaselineFromGraphic() 
> owing to the fact GraphicAttribute is null for these invalid codepoints. 
> 
> TextLayout.getBaselineFromGraphic() is called from [TextLayout.standardInit](https://github.com/openjdk/jdk/blame/master/src/java.desktop/share/classes/java/awt/font/TextLayout.java#L647) and [TextMeasurer.initAll](https://github.com/openjdk/jdk/blame/master/src/java.desktop/share/classes/java/awt/font/TextMeasurer.java#L249) where it relies on CHAR_REPLACEMENT TextAttribute 
> and its spec says "The default value is null, indicating that the standard glyphs provided by the font should be used. " so if invalid codepoints is used, the default value is not changed so we need to be ready for null value too.
> 
> Since TextAttribute_CHAR_REPLACEMENT says "It is required for correct positioning of 'inline' components within a line when bidirectional reordering is performed. Each character (Unicode code point) will be rendered using the provided GraphicAttribute." so 
> Fixed by checking if GraphicAttribute is null, then keep the baseline to default value (which is 0) by returning default baseline (which is ROMAN_BASELINE)
> 
> Existing jtreg,jck tests are green.

Marked as reviewed by aivanov (Reviewer).

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PR: https://git.openjdk.java.net/jdk/pull/7490