Regarding ODF import and Export support for HistogramChart

[Devansh Varshney]

<chart:chart svg:width="16.001cm" svg:height="8.986cm" xlink:href="..">
  <chart:title>
    <text:p>Histogram Chart</text:p>
  </chart:title>
  <chart:plot-area>
    <chart:series chart:label-cell-address="'Sheet1'.$A$1"
chart:values-cell-range-address="'Sheet1'.$A$2:$A$101">
      <chart:data-point chart:repeated="100"/>
      <loext:histogram-configuration loext:histogram-frequency-type="2"
loext:histogram-bin-count="10">
        <loext:histogram-overflow-bin>60</loext:histogram-overflow-bin>
        <loext:histogram-underflow-bin>0</loext:histogram-underflow-bin>

<loext:histogram-interval-closed>true</loext:histogram-interval-closed>
      </loext:histogram-configuration>
    </chart:series>
    <chart:axis chart:dimension="x">
      <chart:title>
        <text:p>Values (units)</text:p>
      </chart:title>
    </chart:axis>
    <chart:axis chart:dimension="y">
      <chart:title>
        <text:p>Frequency</text:p>
      </chart:title>
    </chart:axis>
  </chart:plot-area>
</chart:chart>

On Thu, 2 Jan 2025 at 18:31, Regina Henschel <rb.henschel at t-online.de>
wrote:

> Hi Devansh,
>
> Devansh Varshney schrieb am 02.01.2025 um 09:14:
> > <chart:chart svg:width="16.001cm" svg:height="8.986cm" xlink:href="..">
> >    <chart:title>
> >      <text:p>Histogram Chart</text:p>
> >    </chart:title>
> >    <chart:plot-area>
>
> >      <!-- Series with label from A1 -->
> The generated XML does not contain any comments.
>
> >      <chart:series chart:label="Results">
> A 'chart:label' attribute does not exist for the <chart:series> element.
> Instead it has the attribute 'chart:label-cell-address'.
>
>
> >        <!-- Data points from A2:A101 -->
> The data values are not inside <chart:data-point> elements. The data
> values are given by the attribute 'chart:values-cell-range-address' of
> the <chart:series> element.
>
> The purpose of a <chart:data-point> element is, to specify the style of
> a data point. As the columns in the histogram do not directly reflect
> data points, a <chart:data-point> element is useless for an histogram.
> But it does not harm to keep the default, which would be
>         <chart:data-point chart:repeated="100"/>
> in the example. That means, that the style given in the
> 'chart:style-name' attribute of the <chart:series> element is used for
> all 100 data points. You can keep it although it will actually be the
> style of the rendered bins (at least I think you will use the
> 'chart:style-name' attribute of the <chart:series> element for this
> purpose).
>
> An element <chart:data-points> does not exist. If <chart:data-point>
> elements are needed, they are simply written one after the other. The
> RELAX NG has the element <rng:zeroOrMore> for this.
>
> >        <chart:data-points>
> >          <chart:data-point chart:value="5.3"/>   <!-- A2 -->
> >          <chart:data-point chart:value="12.7"/>  <!-- A3 -->
> >          <chart:data-point chart:value="8.4"/>   <!-- A4 -->
> >          <chart:data-point chart:value="15.2"/>  <!-- A5 -->
> >          <chart:data-point chart:value="22.6"/>  <!-- A6 -->
> >          <chart:data-point chart:value="30.1"/>  <!-- A7 -->
> >          <chart:data-point chart:value="45.7"/>  <!-- A8 -->
> >          <chart:data-point chart:value="60.3"/>  <!-- A9 -->
> >          <chart:data-point chart:value="75.9"/>  <!-- A10 -->
> >          <chart:data-point chart:value="95.1"/>  <!-- A11 -->
> >          <!-- Add more data points up to A101 -->
> >        </chart:data-points>
>
> >        <!-- Histogram-specific configuration -->
> >        <loext:histogram>
>
> I would use element name
>           loext:histogram-configuration
> to be more specific. Remember, there are no comments written, thus a
> meaningful name helps.
>
> >          <attribute name="loext:histogram-frequency-type">
> >            <value>2</value>
> >          </attribute>
> >          <attribute name="loext:histogram-bin-count">
> >            <data type="integer">10</data>
> >          </attribute>
> >          <optional>
> >            <attribute name="loext:histogram-overflow-bin">
> >              <data type="double">100</data>
> >            </attribute>
> >          </optional>
> >          <optional>
> >            <attribute name="loext:histogram-underflow-bin">
> >              <data type="double">0</data>
> >            </attribute>
> >          </optional>
> >          <optional>
> >            <attribute name="loext:histogram-interval-closed">
> >              <data type="boolean">true</data>
> >            </attribute>
> >          </optional>
> >        </loext:histogram>
>
> Here you have mixed up the content in the schema with the written out
> XML of the document. In the written out XML, it would be
>        <loext:histogram-configuration loext:histogram-frequency-type="2"
>           loext:histogram-bin-count="10" />
>
> The attributes underflow-bin and overflow-bin are only written out, when
> the user sets them explicitly. Otherwise a default is used. And default
> values need not be written out.
>
> The attribute interval-closed too should only be written out, if it is
> not the default.
>
>
>
> >      </chart:series>
> >      <!-- Define the X-axis -->
> >      <chart:axis chart:dimension="x">
> >        <chart:title>
> >          <text:p>Values</text:p>
>         It is more likely, that the user writes the unit of the data
> values into the axis title.
>
> >        </chart:title>
> >      </chart:axis>
> >      <!-- Define the Y-axis -->
> >      <chart:axis chart:dimension="y">
> >        <chart:title>
> >          <text:p>Frequency</text:p>
> >        </chart:title>
> >      </chart:axis>
> >    </chart:plot-area>
> > </chart:chart>
>
>
> So you want a structure were element <loext:histogram-configuration> is
> sub-element of the <chart:series> element. That is OK.
>
> You need to decide about the order. Where in the sequence of possible
> sub-elements of the <chart:series> element you want the
> <loext:histogram-configuration> sub-element to be written?
>
>
> Now about the schema. A useful source to learn more about RELAX NG is
> https://relaxng.org/tutorial-20011203.html.
>
> The <chart:series> element has no <rng:choice> for its sub-elements.
> Therefore a solution with combine="choice" is not possible. And as it is
> an element, a solution with combine="interleave" does neither work. You
> need to replace the existing <chart:series> element with an extended
> one. (See chapter 9.4 in the mentioned tutorial)
>
> For replacing, you need to copy the existing <rng:define> element, that
> specifies the <chart:series> element, from the file
> schema/odf1.4/OpenDocument-v1.4-schema.rng and add it as a new
> sub-element of the <rng:inlcude> element in
> schema/libreoffice/OpenDocument-v1.4+libreoffice-schema.rng. Then you
> extend it.
>
> You do not add the <loext:histogram-configuration> element directly, but
> add a reference to its definition. ODF uses for the name a pattern
> "prefix-elementname'. So in your case it would be a
>     <rng:ref name="loext-histogram-configuration" />
> Don't forget to mark it as optional.
>
> There exist no proposal to the ODF TC to integrate a chart type
> 'histogram' in ODF and if such existed, it would last several years to
> integrate it. Thus you add a comment with a pointer to that bug report,
> where the histogram chart was initially implemented in LO.
>
> Then go to the end of the OpenDocument-v1.4+libreoffice-schema.rng file
> and add the definition for histogram-configuration after the last
> </rng:element>. Again add a comment.
>
>
> In regard to loext:histogram-configuration itself:
> 1. <optional> is not here, but in <chart:series>
> 2. Your current version in Gerrit has two blocks about frequency-type.
> There must be only one. Please re-read the answer from Michael Stahl how
> to do it.
>
> Looking forward to your next version.
>
> Kind regards,
> Regina
>
>
>

-- 
*Regards,*
*Devansh*
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