Re: [java-gnome-hackers] Possible Bug in Cairo bindings when exporting to PNG

[Andrew C. <an...@op...>]

On Tue, 2008-04-15 at 22:49 +0000, Vreixo Formoso Lopes wrote:

> +public class SVGSurface extends Surface
> 
Yup.

> +    public static final Status WRITE_ERROR = new ...

That's fine, of course. When a Constant is needed it's needed.

I usually try to do all the Constants when adding something, but
sometimes when it's a really long list of things that for which I don't
know what they all do, I do the ones I can figure out / am using.

You came across a case of needing that Constant, so add it, no question.

> -    public void writeToPNG(String filename) {
> +    public void writeToPNG(String filename) throws IOException {

That's fine, but maybe do the access check _before_ calling Cairo? ie
File's canWrite()

> 
> -        surface.writeToPNG(OUTPUT_FILENAME);
> +        try {
> +            surface.writeToPNG(OUTPUT_FILENAME);
> +        } catch (IOException e) {
> +            fail("Unexpected file write error");
> +        }
> 
That's fine, but we should probably improve the 


>      public final void testImageSurfaceWriteToPNG() {

test to actually verify this behaviour.

In other words, a better test would be to try writing to a known
unwritable path and test that the exception _does_ happen.

Then test writing to a path that known to work (ie, tmp/tests/) and make
sure that the exception does _not_ happen.

[That test case class is still rather a work in progress. What I wanted
to do was draw something and then positively test that the correct image
was drawn, but that's a bit of a tough proposition]

AfC
Sydney

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Andrew Frederick Cowie

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