Fix warning: Illegal string offset 'hex' by adding ternary fallback to white

[bassplayer7]

No description provided.

[bsweeney]

Can you rebase your branch on the develop branch?

[bsweeney]

Do you have some sample HTML + CSS that exhibits the issue?

[Mellthas]

No HTML/CSS, but I can reproduce the warning with manually setting styles:

$style = new Style(new Stylesheet(new Dompdf()));
$style->border_top_color = "rgb(1,2,3,4,5)";
var_dump($style->get_border_top_color()); /* null */
var_dump($style->border_top_color); /* rgb(1,2,3,4,5) */
var_dump($style->get_border_top()); /* 1px none r, Warning: Illegal string offset 'hex' in ... */
var_dump($style->border_top); /* 1px none #000000FF */

So there are some inconsistencies to how the getters and property accessors work. get_border_top() calls _get_border("top") which returns the invalid color value, leading to the string-offset access on a string. border_top running through __get() somehow falls back to black for the color though. If you switch the order of the last two lines, the warning is gone, because the fallback black seems to be saved.

[Mellthas]

So I think the commit as-is is probably not the right thing to do.

[bsweeney]

Good analysis. I've been focusing on issues reproducible during rendering, but we should avoid issues like this one even in direct-usage scenarios.

[Mellthas]

An example reproducing the issue is in #2367 (comment).

[bsweeney]

Per example in issue 2367 if a named color is known but not translated (e.g. transparent) the error is raised. Though I still can't trigger the error in the method modified in this PR. Also, the $color variable is referenced multiple times and if we're tweaking the logic here should we also tweak it in the other locations?

Anyway, I would expect this particular case would have a valid array since we're retrieving the color through the style color getter. So I think maybe we can fix this without the ternary by fixing the getter.

[bsweeney]

I think the small change I made in #2536 works better for the expected return values to address this issue.