MapGuide RFC 54 - Better Legend Control

This page contains an change request (RFC) for the MapGuide Open Source project. More MapGuide RFCs can be found on the RFCs page.

Status

RFC Template Version	(1.0)
Submission Date	July 30, 2008
Last Modified	Kenneth Skovhede Timestamp
Author	Kenneth Skovhede
RFC Status	Draft
Implementation Status	pending
Proposed Milestone	2.2
Assigned PSC guide(s)	Bruce Dechant?
Voting History	(vote date)
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+0
-0
-1

Overview

Change the schema of MapDefinition and LayerDefinition to contain properties that allow more control of the functionality and style in the legend.

Motivation

This RFC is an extension to RFC 50, and allows even more control over the legend. Some layer may not be turned off but might still be required to be visible in the legend. In the case where multiple layers comprise a single logical layer, the user should not be able to turn off the actual layers, but only the top level group. This is not possible with the current schema.

At times, it may be desireable to provide a custom image for a layer or group. This will allow a user to supply custom images for raster layers, without having to replace the raster layer image for the entire server. Providing a custom image for a group will enable map designers to make a more visually pleasing solution to the mentioned case, where multiple layers comprise a single logical layer.

The original proposal was submitted by Jason Birch: ​http://lists.osgeo.org/pipermail/mapguide-internals/2008-July/002576.html

Proposed Solution

Two additional tags are going to be added to the schema of MapDefinition. We will add an <EnableVisibilityChange> tag and a <!AlternativeImageURL> for MapLayerGroupCommonType. An additional tag named <!AlternativeImageURL> is going to be added to LayerDefiniton. In LayerDefinition there is no common base, so the tag will be added to <PointTypeStyleType>, <LineTypeStyleType>, <AreaTypeStyleType> and <CompositeTypeStyleType>.

The version of the MapDefinition will change from 1.0 to 1.1, i.e. MapDefinition-1.1.0.xsd. The version of the LayerDefinition will change from 1.3 to 1.4, i.e. LayerDefiniton-1.4.0.xsd.

Details of the changes are described below.

MapLayerGroupCommonType in MapDefinition:

<xs:complexType name="MapLayerGroupCommonType">
  <xs:annotation>
    <xs:documentation>MapLayerGroupCommonType is a common subclass of MapLayerGroupCommonType and BaseMapLayerGroupCommonType</xs:documentation>
  </xs:annotation>
  <xs:sequence>
    <xs:element name="Name" type="xs:string">
      <xs:annotation>
        <xs:documentation>The name of this LayerGroup</xs:documentation>
      </xs:annotation>
    </xs:element>
    <xs:element name="Visible" type="xs:boolean">
      <xs:annotation>
        <xs:documentation>Whether this group's visiblity should be visible or not when it first comes into range</xs:documentation>
      </xs:annotation>
    </xs:element>
    <xs:element name="ShowInLegend" type="xs:boolean">
      <xs:annotation>
        <xs:documentation>Whether or not the LayerGroup should be shown in the legend</xs:documentation>
      </xs:annotation>
    </xs:element>
    <xs:element name="ExpandInLegend" type="xs:boolean">
      <xs:annotation>
        <xs:documentation>Whether or not the LayerGroup should be initially expanded in the legend</xs:documentation>
      </xs:annotation>
    </xs:element>
    <xs:element name="LegendLabel" type="xs:string">
      <xs:annotation>
        <xs:documentation>Label to be shown for the LayerGroup in the legend</xs:documentation>
      </xs:annotation>
    </xs:element>
	
    <xs:element name="EnableVisibilityChange" type="xs:boolean" minOccurs="0" default="true" >
      <xs:annotation>
        <xs:documentation>Whether or not the user can toggle the visibility of the LayerGroup in the legend</xs:documentation>
      </xs:annotation>
    </xs:element>
    <xs:element name="AlternativeImageURL" type="xs:string" minOccurs="0" >
      <xs:annotation>
        <xs:documentation>An URL to an alternate image to display in the legend</xs:documentation>
      </xs:annotation>
    </xs:element>
	
  </xs:sequence>
</xs:complexType>

LineTypeStyle in LayerDefinition:

<xs:complexType name="LineTypeStyleType">
    <xs:annotation>
      <xs:documentation>Style specification of a line geometry type.</xs:documentation>
    </xs:annotation>
    <xs:sequence>
      <xs:element name="LineRule" type="LineRuleType" maxOccurs="unbounded">
        <xs:annotation>
          <xs:documentation>Rules to define a theme.</xs:documentation>
        </xs:annotation>
      </xs:element>
      <xs:element name="ShowInLegend" type="xs:boolean" minOccurs="0" default="true" />
      <xs:element name="AlternativeImageURL" type="xs:string" minOccurs="0" />
      <xs:element name="ExtendedData1" type="ExtendedDataType" minOccurs="0" />
    </xs:sequence>
</xs:complexType>

PointTypeStyle in LayerDefinition:

<xs:complexType name="PointTypeStyleType">
    <xs:annotation>
      <xs:documentation>Style specification of a point geometry type.</xs:documentation>
    </xs:annotation>
    <xs:sequence>
      <xs:element name="DisplayAsText" type="xs:boolean">
        <xs:annotation>
          <xs:documentation>Create a text layer.</xs:documentation>
        </xs:annotation>
      </xs:element>
      <xs:element name="AllowOverpost" type="xs:boolean">
        <xs:annotation>
          <xs:documentation>Allows labels from any map layer (including the current layer) to obscure features on the current layer.</xs:documentation>
        </xs:annotation>
      </xs:element>
      <xs:element name="PointRule" type="PointRuleType" maxOccurs="unbounded">
        <xs:annotation>
          <xs:documentation>One or more PointRules defining the PointTypeStyle.</xs:documentation>
        </xs:annotation>
      </xs:element>
      <xs:element name="ShowInLegend" type="xs:boolean" minOccurs="0" default="true" />
      <xs:element name="AlternativeImageURL" type="xs:string" minOccurs="0" />
      <xs:element name="ExtendedData1" type="ExtendedDataType" minOccurs="0" />
    </xs:sequence>
</xs:complexType>

AreaTypeStyle in LayerDefinition:

<xs:complexType name="AreaTypeStyleType">
    <xs:annotation>
      <xs:documentation>Style specification of a polygon geometry type.</xs:documentation>
    </xs:annotation>
    <xs:sequence>
      <xs:element name="AreaRule" type="AreaRuleType" maxOccurs="unbounded">
        <xs:annotation>
          <xs:documentation>Rules to define a theme.</xs:documentation>
        </xs:annotation>
      </xs:element>
      <xs:element name="ShowInLegend" type="xs:boolean" minOccurs="0" default="true"/>
      <xs:element name="AlternativeImageURL" type="xs:string" minOccurs="0" />
      <xs:element name="ExtendedData1" type="ExtendedDataType" minOccurs="0" />
    </xs:sequence>
</xs:complexType>

CompositeTypeStyle in LayerDefinition:

<xs:complexType name="CompositeTypeStyle">
  <xs:annotation>
    <xs:documentation>A style specification consisting of composite rules.</xs:documentation>
  </xs:annotation>
  <xs:sequence>
    <xs:element name="CompositeRule" type="CompositeRule" maxOccurs="unbounded">
      <xs:annotation>
        <xs:documentation>One or more CompositeRules defining the CompositeTypeStyle.</xs:documentation>
      </xs:annotation>
    </xs:element>
    <xs:element name="ShowInLegend" type="xs:boolean" minOccurs="0" default="true"/>
    <xs:element name="AlternativeImageURL" type="xs:string" minOccurs="0" />
    <xs:element name="ExtendedData1" type="ExtendedDataType" minOccurs="0"/>
  </xs:sequence>
</xs:complexType>

Implications

The existing schema documentation will be updated. Since these are all extensions to the schema, no existing functionality will be affected. Before these additions have any effect, they must be handled in the viewers, both the WebLayout based, as well as the Fusion based viewer has to be updated. The GetMapLegendImage function will also have to be updated to deal with these new properties as well.

Test Plan

No new unit tests will be created for this. However, the existing unit tests will be run to ensure that they still pass.

Funding/Resources

Autodesk