Re: [Geotools-devel] SLD Stroke Dasharray Property

[Nuno O. <nun...@te...>]

Hi, 

Glad I could help :)

About your doubts, the dash-array use case is different from the one
solved by the parseCssParameter method. 
We actually want a list of expressions, so no need for the concat
function or other function. 

In my opinion the implementation of the parsing of the dash-array
property should look like this:


private List<Expression> parseDashArray(Node root) {
    NodeList children = root.getChildNodes();
    List<Expression> expressions = new ArrayList<>();
    for (int i = 0; i < children.getLength(); i++) {
        Node child = children.item(i);
        if (child == null) continue;
        switch (child.getNodeType()) {
            case Node.TEXT_NODE:
                handleDashArrayText(child.getNodeValue(), expressions);
            case Node.ELEMENT_NODE:
                handleDashArrayNode(child, expressions);
            case Node.CDATA_SECTION_NODE:
                handleDashArrayText(child.getNodeValue(), expressions);
        }
    }
    return expressions;
}

private void handleDashArrayText(String text, List<Expression> expressions) {
    if (text == null || text.isEmpty()) return;
    for (String textPart : text.split("\\s+")) {
        expressions.add(ff.literal(Float.valueOf(textPart)));
    }
}

private void handleDashArrayNode(Node child, List<Expression> expressions) {
    Expression expression = ExpressionDOMParser.parseExpression(child);
    if (expression instanceof Literal) {
        handleDashArrayLiteral((Literal) expression, expressions);
    } else {
        expressions.add(expression);
    }
}

private void handleDashArrayLiteral(Literal literal, List<Expression> expressions) {
    Object value = literal.getValue();
    if (value instanceof String) {
        handleDashArrayText((String) value, expressions);
    } else {
        expressions.add(literal);
    }
}


Best regards,

Nuno Oliveira

Le jeudi 13 août 2015 à 08:45 +0100, Igor Volkov a écrit :

> Thank you Nuno! Through your doubts I continued my search and found a nice
> solution, which is a symbiosis of my idea to use the argument of a function
> for storing expressions for dash array (list) and your desire to do without
> superfluous functions similar to that of the Label concatenation in SLD. I
> have found, that SLDParser while parsing value of Label creats internally
> the strConcat function. This is just what I need! Test showed, that it is
> working for stroke-dasharray CssParameter.
> I am ready to commit new implementation of dashArray expression list. But l
> have some doubts. 
> If implementation of expression concatenation for Label will  be changed in
> future  (for example the strConcat will be replaced by Concatenate which is
> more convenient) then my code will not work correctly and this will be
> difficult to discover. Also some strange person may wish to use strConcat
> for dasharray implicitly, but if he will nest strConcat's in second argument
> and not in the first as SLDParser does, then my code will faild again. I
> have tried to write universal processing of strConcat  and Concatenate (it
> was my fist approch to the problem of dasharray) but I am not shure that it
> is necessary to be so paranoid.
> So I am waiting for advice befor commiting of new implementation of
> dashArray.
> 
> 
> 
> --
> View this message in context: http://osgeo-org.1560.x6.nabble.com/SLD-Stroke-Dasharray-Property-tp5083512p5219634.html
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