Processing Placeholder Tags

In one of the previous chapters you learned how to process tag pairs (e.g. ) during file parsing (see Processing Inline Formatting). In this chapter you will learn how to process standalone placeholder tags, such as < img src="button.jpg" />

Enhance your Parser to Process Standalone Placeholder Tags

Let us assume that your sample text files sometimes contain tags for referencing images, e.g.:

HTML

<img src="button.jpg" alt="Click here" />

Below you see an example of a segment that contains a standalone placeholder tag:

HTML

Click the button <img src="button.jpg" alt="Open"/> to open 
the dialog box.

These tags are closed within themselves and occur as placeholders within the text. To keep this example as simple as possible let us proceed on the assumption that the IMG tag is the only placeholder tag that we can expect to find in any given document.

Start by making a small change to the ProcessFormatting() helper function: if the regular expression pattern found a match that starts on "<img", then the WritePlaceHolder() helper function (which we still need to implement) should be called, otherwise we call WriteInlineTag().

if (rxMatch.Value.StartsWith("<img"))
{
    WritePlaceholderTag(rxMatch.Value);
} else {
    bool IsOpening = rxMatch.Value.Contains("/") ? false : true;
    WriteInlineTag(rxMatch.Value, IsOpening);
}

The complete function now looks as shown below:

// this function uses regular expressions to identify
// what is 'normal' translatable content and which strings
// need to be marked up as inline tags, e.g. <b>
private string ProcessFormatting(string sLine)
{
    int LastPosition = 0;
    // search for opening and closing <b> tags
    Regex rx = new Regex(@"\<.*?\>", RegexOptions.Compiled);
    MatchCollection rxMatches = rx.Matches(sLine);

    foreach (Match rxMatch in rxMatches)
    {
        if (LastPosition != rxMatch.Index)
        {
            WriteText(sLine.Substring(LastPosition, rxMatch.Index - LastPosition));
        }
        #region "inline or placeholder"
        if (rxMatch.Value.StartsWith("<img"))
        {
            WritePlaceholderTag(rxMatch.Value);
        } else {
            bool IsOpening = rxMatch.Value.Contains("/") ? false : true;
            WriteInlineTag(rxMatch.Value, IsOpening);
        }
        #endregion

        LastPosition = rxMatch.Index + rxMatch.Length;
    }
    return sLine.Substring(LastPosition, sLine.Length - LastPosition);
}

Next, implement the method that outputs the IMG placeholder tag. The properties factory implements a CreatePlaceholderTagProperties method that creates properties for a standalone inline tag. When creating the tag property, the tag content is passed to the Create() method as a parameter. You can define the optional [DisplayText](../../api/filetypesupport/Sdl.FileTypeSupport.Framework.NativeApi.IAbstractBasicTagProperties.yml#Sdl_FileTypeSupport_Framework_NativeApi_IAbstractBasicTagProperties_DisplayText property, which specifies how the tag should be displayed in partial tag text mode. The tag property can be output using the method Output.InlinePlaceholderTag().

private void WritePlaceholderTag(string tagContent)
{
    IPlaceholderTagProperties placeProperties = PropertiesFactory.CreatePlaceholderTagProperties(tagContent);
    placeProperties.TagContent = tagContent;
    placeProperties.DisplayText = "img";

    // calculate offset and length
    int offset, length;
    offset = tagContent.IndexOf("alt=\"") + 5;
    length = tagContent.Substring(offset, tagContent.Length - offset - 4).Length;

    ISubSegmentProperties subSeg = PropertiesFactory.CreateSubSegmentProperties(offset, length);
    placeProperties.AddSubSegment(subSeg);
    Output.InlinePlaceholderTag(placeProperties);
}

The placeholder tag will appear in partial tag text mode as shown below:

ImgTag

And this is what the placeholder tag looks like when the full tag content is displayed (full tag text mode):

ImgFull

Expose Localizable Text Within a Tag As you can see in the above example tags may contain localizable text such as the text defined by the ALT attribute. In our current implementation this text is not exposed for translation, as the entire IMG tag with all its attributes is treated as a placeable, and thereby as a non-translatable element.

The API allows you to access localizable text that is embedded within a placeable, which is then treated as a so-called sub-segment, i.e. a segment within a segment. To do this you first have to create a sub-segment object through the properties factory. To this end, the properties factory implements the CreateSubSegmentProperties method, which takes two parameters: the offset and the length of the localizable string. Take a look at our example:

HTML

<img src="button.jpg" alt="img src="button.jgp" alt="Open dialog box" /"/>

The offset in this example is 27, the length of the localizable piece of text (Open dialog box) is 15. The sub-segment object can therefore be created as shown below:

ISubSegmentProperties subSeg = PropertiesFactory.CreateSubSegmentProperties(27, 15);

After creating the sub-segment object, you can add it to the placeable properties by applying the AddSubSegment method:

placeProperties.AddSubSegment(subSeg);

After adding the sub-segment object to the placeable properties you can output the placeable as shown below:

Output.InlinePlaceholderTag(placeProperties);

The File Type Support Framework API will then handle the extraction of these localizable sub-segments into separate translation units that are displayed to the translator. Therefore, the output in the editor of SDL Trados Studio will look as shown below:

SubSegment

Of course, you would have to implement the functionality to calculate the offset and length, so that your WritePlaceholderTag() helper function would look as shown below:

private void WritePlaceholderTag(string tagContent)
{
    IPlaceholderTagProperties placeProperties = PropertiesFactory.CreatePlaceholderTagProperties(tagContent);
    placeProperties.TagContent = tagContent;
    placeProperties.DisplayText = "img";

    // calculate offset and length
    int offset, length;
    offset = tagContent.IndexOf("alt=\"") + 5;
    length = tagContent.Substring(offset, tagContent.Length - offset - 4).Length;

    ISubSegmentProperties subSeg = PropertiesFactory.CreateSubSegmentProperties(offset, length);
    placeProperties.AddSubSegment(subSeg);
    Output.InlinePlaceholderTag(placeProperties);
}

Processing Placeholder Tags

Enhance your Parser to Process Standalone Placeholder Tags

See Also

Note