RFR: 8286867: Update #getGlyphCode return a negative number

[Kevin Rushforth]

On Fri, 13 May 2022 05:34:08 GMT, Tomator <duke at openjdk.org> wrote:

> When I used BlueJ, I found a problem with Chinese display. /javafx.graphics/com/sun/javafx/font/CompositeGlyphMapper.java#getGlyphCode may return a negative number when no font library is specified in Linux,and this could cause java.lang.ArrayIndexOutOfBoundsException error.So javafx.graphics/com/sun/prism/impl/GlyphCache.java#getCachedGlyph  shou check the glyphCode.
> The crash demo like this:
> `import javafx.application.Application;
> import javafx.scene.Scene;
> import javafx.scene.control.Menu;
> import javafx.scene.control.MenuBar;
> import javafx.scene.control.MenuItem;
> import javafx.scene.layout.BorderPane;
> import javafx.stage.Stage;
> 
> public class MenuExample extends Application {
>     public static void main(String[] args) {  
>     launch(args);  
>         }  
>   
>     @Override  
>     public void start(Stage primaryStage) throws Exception {
>         BorderPane root = new BorderPane();
>         Scene scene = new Scene(root,200,300);
>         MenuBar menubar = new MenuBar();
>         Menu FileMenu = new Menu("文本");
>         MenuItem filemenu1=new MenuItem("新建");
>         MenuItem filemenu2=new MenuItem("Save");  
>         MenuItem filemenu3=new MenuItem("Exit");  
>         Menu EditMenu=new Menu("Edit");  
>         MenuItem EditMenu1=new MenuItem("Cut");  
>         MenuItem EditMenu2=new MenuItem("Copy");  
>         MenuItem EditMenu3=new MenuItem("Paste");  
>         EditMenu.getItems().addAll(EditMenu1,EditMenu2,EditMenu3);  
>         root.setTop(menubar);  
>         FileMenu.getItems().addAll(filemenu1,filemenu2,filemenu3);  
>         menubar.getMenus().addAll(FileMenu,EditMenu);  
>         primaryStage.setScene(scene);  
>         primaryStage.setTitle("TEST");
>         primaryStage.show();  
>           
>     }     
> }  `
> 
> the error:
> `java.lang.ArrayIndexOutOfBoundsException: Index -25 out of bounds for length 32
>         at com.sun.prism.impl.GlyphCache.getCachedGlyph(GlyphCache.java:332)
>         at com.sun.prism.impl.GlyphCache.render(GlyphCache.java:148)
>         at com.sun.prism.impl.ps.BaseShaderGraphics.drawString(BaseShaderGraphics.java:2101)
>         at com.sun.javafx.sg.prism.NGText.renderText(NGText.java:312)
>         at com.sun.javafx.sg.prism.NGText.renderContent2D(NGText.java:270)
>         at com.sun.javafx.sg.prism.NGShape.renderContent(NGShape.java:261)
>         at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:2072)
>         at com.sun.javafx.sg.prism.NGNode.render(NGNode.java:1964)
>         at com.sun.javafx.sg.prism.NGGroup.renderContent(NGGroup.java:270)
>         at com.sun.javafx.sg.prism.NGRegion.renderContent(NGRegion.java:578)
>         at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:2072)
>         at com.sun.javafx.sg.prism.NGNode.render(NGNode.java:1964)
>         at com.sun.javafx.sg.prism.NGGroup.renderContent(NGGroup.java:270)
>         at com.sun.javafx.sg.prism.NGRegion.renderContent(NGRegion.java:578)
>         at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:2072)
>         at com.sun.javafx.sg.prism.NGNode.render(NGNode.java:1964)
>         at com.sun.javafx.sg.prism.NGGroup.renderContent(NGGroup.java:270)
>         at com.sun.javafx.sg.prism.NGRegion.renderContent(NGRegion.java:578)
>         at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:2072)
>         at com.sun.javafx.sg.prism.NGNode.render(NGNode.java:1964)
>         at com.sun.javafx.sg.prism.NGGroup.renderContent(NGGroup.java:270)
>         at com.sun.javafx.sg.prism.NGRegion.renderContent(NGRegion.java:578)
>         at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:2072)
>         at com.sun.javafx.sg.prism.NGNode.render(NGNode.java:1964)
>         at com.sun.javafx.sg.prism.NGGroup.renderContent(NGGroup.java:270)
>         at com.sun.javafx.sg.prism.NGRegion.renderContent(NGRegion.java:578)
>         at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:2072)
>         at com.sun.javafx.sg.prism.NGNode.render(NGNode.java:1964)
>         at com.sun.javafx.tk.quantum.ViewPainter.doPaint(ViewPainter.java:479)
>         at com.sun.javafx.tk.quantum.ViewPainter.paintImpl(ViewPainter.java:328)
>         at com.sun.javafx.tk.quantum.PresentingPainter.run(PresentingPainter.java:91)
> `

I left a question and style comment inline.

Can you provide an automated test case, or if that's not possible, a manual test case?

modules/javafx.graphics/src/main/java/com/sun/prism/impl/GlyphCache.java line 242:

> 240: 
> 241:     private GlyphData getCachedGlyph(int glyphCode, int subPixel) {
> 242:         if (glyphCode < 0) {return null;}

Have you ensured that all callers are prepared to deal with a `null` return value?

Minor: Please format this according to code conventions:


        if (glyphCode < 0) {
            return null;
        }

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PR: https://git.openjdk.org/jfx/pull/795