Increase y value of SVG drawing using XSLT iteration - xslt

Question

I asked a similar question earlier. I have made some changes to the code, but am still stuck.
I have part of an XSLT like this:
<xsl:variable name="y" select="0" />
<xsl:if test="units_display='true'">
<xsl:call-template name="DisplayBox">
<xsl:with-param name="current_y" select="$y" />
<xsl:with-param name="value" select="units" />
<xsl:with-param name="text" select="'Units'" />
</xsl:call-template>
</xsl:if>
<xsl:if test="sensor_display='true'">
<xsl:call-template name="DisplayBox">
<xsl:with-param name="current_y" select="$y" />
<xsl:with-param name="value" select="sensor" />
<xsl:with-param name="text" select="'Type'" />
</xsl:call-template>
</xsl:if>
<xsl:if test="offset_display='true'">
<xsl:call-template name="DisplayBox">
<xsl:with-param name="current_y" select="$y" />
<xsl:with-param name="value" select="offset" />
<xsl:with-param name="text" select="'Offset'" />
</xsl:call-template>
</xsl:if>
My call-template is like this:
<xsl:template name="DisplayBox">
<xsl:param name="current_y" />
<xsl:param name="value" />
<xsl:param name="text" />
<rect x="20" y="{150 + $current_y}" width="220" height="20" fill="#FFFFFF" stroke="black" stroke-width="1" />
<text x="25" y="{168 + $current_y}" font-family="arial" font-size="20px" fill="black">
<xsl:value-of select="$value"/>
</text>
<line x1="90" y1="{150 + $current_y}" x2="90" y2="{170 + $current_y}" stroke="black" stroke-width="1" />
<text x="95" y="{168 + $current_y}" font-family="arial" font-size="20px" fill="black"><xsl:value-of select="$text" /></text>
</xsl:template>
I can't work out how to increase the value of current_y depending on whether the if statements are true or not. E,g, if a statement is true, the y value needs to be increased by 20, but not if the statement is false.
So the output could be empty if all 3 statements are false or could be any of these permutations:
Any help would be greatly appreciated.

Answer 1

You have to move the whole thing into a recursion template. You are passing $y for "current_y" which has the value "0" into each call of the template. That recursive template would take the same arguments and two additional:
(1) The test to perform for that round of recursion
(2) Whether you have any additional tests to perform (or exit the recursion)
Then you do a choose and increment the "y" (or not) depending on the test.
* New Info *
After some more thought based on the comments below, what about using something like this:
<xsl:template match="units_display | sensor_display | offset_display">
<xsl:variable name="y-multiplier">
<xsl:value-of select="count(preceding-sibling::units_display[.='true']) + count(preceding-sibling::sensor_display[.='true']) + count(preceding-sibling::offset_display[.='true'])"/>
</xsl:variable>
<xsl:message>
<xsl:value-of select="$y-multiplier"/>
</xsl:message>
</xsl:template>
This counts all of the elements that meet you criteria as you go through the document. This should get you started toward writing the result without recursion.