Port algorithm help to QgsProcessingAlgorithm

python/core/processing/qgsprocessingalgorithm.sip

@@ -76,6 +76,32 @@ class QgsProcessingAlgorithm
  :rtype: list of str
 %End
 
+    virtual QString shortHelpString() const;
+%Docstring
+ Returns a localised short helper string for the algorithm. This string should provide a basic description
+ about what the algorithm does and the parameters and outputs associated with it.
+.. seealso:: helpString()
+.. seealso:: helpUrl()
+ :rtype: str
+%End
+
+    virtual QString helpString() const;
+%Docstring
+ Returns a localised help string for the algorithm. Algorithm subclasses should implement either
+ helpString() or helpUrl().
+.. seealso:: helpUrl()
+.. seealso:: shortHelpString()
+ :rtype: str
+%End
+
+    virtual QString helpUrl() const;
+%Docstring
+ Returns a url pointing to the algorithm's help page.
+.. seealso:: helpString()
+.. seealso:: shortHelpString()
+ :rtype: str
+%End
+
     virtual QIcon icon() const;
 %Docstring
  Returns an icon for the algorithm.

python/plugins/processing/algs/gdal/GdalAlgorithm.py

@@ -77,7 +77,7 @@ class GdalAlgorithm(GeoAlgorithm):
             commands[i] = c
         GdalUtils.runGdal(commands, feedback)
 
-    def shortHelp(self):
+    def shortHelpString(self):
         helpPath = GdalUtils.gdalHelpPath()
         if helpPath == '':
             return
@@ -87,9 +87,9 @@ class GdalAlgorithm(GeoAlgorithm):
         else:
             url = helpPath + '{}.html'.format(self.commandName())
 
-        return self._formatHelp('''This algorithm is based on the GDAL {} module.
+        return '''This algorithm is based on the GDAL {} module.
                 For more info, see the <a href={}> module help</a>
-                '''.format(self.commandName(), url))
+                '''.format(self.commandName(), url)
 
     def commandName(self):
         for output in self.outputs:

python/plugins/processing/algs/grass7/Grass7Algorithm.py

@@ -112,15 +112,15 @@ class Grass7Algorithm(GeoAlgorithm):
     def svgIconPath(self):
         return QgsApplication.iconPath("providerGrass.svg")
 
-    def help(self):
+    def helpUrl(self):
         helpPath = Grass7Utils.grassHelpPath()
         if helpPath == '':
-            return False, None
+            return None
 
         if os.path.exists(helpPath):
-            return False, QUrl.fromLocalFile(os.path.join(helpPath, '{}.html'.format(self.grass7Name))).toString()
+            return QUrl.fromLocalFile(os.path.join(helpPath, '{}.html'.format(self.grass7Name))).toString()
         else:
-            return False, helpPath + '{}.html'.format(self.grass7Name)
+            return helpPath + '{}.html'.format(self.grass7Name)
 
     def getParameterDescriptions(self):
         descs = {}

python/plugins/processing/core/GeoAlgorithm.py

@@ -76,17 +76,8 @@ class GeoAlgorithm(QgsProcessingAlgorithm):
 
     # methods to overwrite when creating a custom geoalgorithm
 
-    def _formatHelp(self, text):
-        return "<h2>%s</h2>%s" % (self.displayName(), "".join(["<p>%s</p>" % s for s in text.split("\n")]))
-
-    def help(self):
-        return False, None
-
-    def shortHelp(self):
-        text = shortHelp.get(self.id(), None)
-        if text is not None:
-            text = self._formatHelp(text)
-        return text
+    def shortHelpString(self):
+        return shortHelp.get(self.id(), None)
 
     def processAlgorithm(self, context, feedback):
         """Here goes the algorithm itself.

python/plugins/processing/gui/AlgorithmDialogBase.py

@@ -104,7 +104,7 @@ class AlgorithmDialogBase(BASE, WIDGET):
         # if desktop.physicalDpiX() > 96:
         # self.txtHelp.setZoomFactor(desktop.physicalDpiX() / 96)
 
-        algHelp = self.alg.shortHelp()
+        algHelp = self.formatHelp(self.alg)
         if algHelp is None:
             self.textShortHelp.setVisible(False)
         else:
@@ -123,16 +123,16 @@ class AlgorithmDialogBase(BASE, WIDGET):
 
         self.textShortHelp.anchorClicked.connect(linkClicked)
 
-        isText, algHelp = self.alg.help()
-        if algHelp is not None:
-            algHelp = algHelp if isText else QUrl(algHelp)
+        if self.alg.helpString() is not None:
+            try:
+                self.txtHelp.setHtml(self.alg.helpString())
+            except Exception:
+                self.tabWidget.removeTab(2)
+        elif self.alg.helpUrl() is not None:
             try:
-                if isText:
-                    self.txtHelp.setHtml(algHelp)
-                else:
                 html = self.tr('<p>Downloading algorithm help... Please wait.</p>')
                 self.txtHelp.setHtml(html)
-                    rq = QNetworkRequest(algHelp)
+                rq = QNetworkRequest(QUrl(self.alg.helpUrl()))
                 self.reply = QgsNetworkAccessManager.instance().get(rq)
                 self.reply.finished.connect(self.requestFinished)
             except Exception:
@@ -143,6 +143,12 @@ class AlgorithmDialogBase(BASE, WIDGET):
         self.showDebug = ProcessingConfig.getSetting(
             ProcessingConfig.SHOW_DEBUG_IN_DIALOG)
 
+    def formatHelp(self, alg):
+        text = alg.shortHelpString()
+        if not text:
+            return None
+        return "<h2>%s</h2>%s" % (alg.displayName(), "".join(["<p>%s</p>" % s for s in text.split("\n")]))
+
     def requestFinished(self):
         """Change the webview HTML content"""
         reply = self.sender()

python/plugins/processing/modeler/ModelerAlgorithm.py

@@ -539,15 +539,15 @@ class ModelerAlgorithm(GeoAlgorithm):
         if self.modelerdialog:
             self.modelerdialog.repaintModel()
 
-    def help(self):
+    def helpString(self):
         try:
-            return True, getHtmlFromDescriptionsDict(self, self.helpContent)
+            return getHtmlFromDescriptionsDict(self, self.helpContent)
         except:
-            return False, None
+            return None
 
-    def shortHelp(self):
+    def shortHelpString(self):
         if 'ALG_DESC' in self.helpContent:
-            return self._formatHelp(str(self.helpContent['ALG_DESC']))
+            return str(self.helpContent['ALG_DESC'])
         return None
 
     def getParameterDescriptions(self):

python/plugins/processing/script/ScriptAlgorithm.py

@@ -198,16 +198,16 @@ class ScriptAlgorithm(GeoAlgorithm):
         for out in self.outputs:
             out.setValue(ns[out.name])
 
-    def help(self):
+    def helpString(self):
         if self.descriptionFile is None:
             return False, None
         helpfile = self.descriptionFile + '.help'
         if os.path.exists(helpfile):
-            return True, getHtmlFromHelpFile(self, helpfile)
+            return getHtmlFromHelpFile(self, helpfile)
         else:
-            return False, None
+            return None
 
-    def shortHelp(self):
+    def shortHelpString(self):
         if self.descriptionFile is None:
             return None
         helpFile = str(self.descriptionFile) + '.help'
@@ -216,7 +216,7 @@ class ScriptAlgorithm(GeoAlgorithm):
                 try:
                     descriptions = json.load(f)
                     if 'ALG_DESC' in descriptions:
-                        return self._formatHelp(str(descriptions['ALG_DESC']))
+                        return str(descriptions['ALG_DESC'])
                 except:
                     return None
         return None

src/core/processing/qgsnativealgorithms.cpp

@@ -70,6 +70,12 @@ QgsCentroidAlgorithm::QgsCentroidAlgorithm()
   addOutput( new QgsProcessingOutputVectorLayer( QStringLiteral( "OUTPUT_LAYER" ), QObject::tr( "Centroids" ), QgsProcessingParameterDefinition::TypeVectorPoint ) );
 }
 
+QString QgsCentroidAlgorithm::shortHelpString() const
+{
+  return QObject::tr( "This algorithm creates a new point layer, with points representing the centroid of the geometries in an input layer.\n\n"
+                      "The attributes associated to each point in the output layer are the same ones associated to the original features." );
+}
+
 QVariantMap QgsCentroidAlgorithm::run( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback ) const
 {
   QgsVectorLayer *layer = qobject_cast< QgsVectorLayer *>( parameterAsLayer( parameters, QStringLiteral( "INPUT" ), context ) );
@@ -129,6 +135,15 @@ QgsBufferAlgorithm::QgsBufferAlgorithm()
   addOutput( new QgsProcessingOutputVectorLayer( QStringLiteral( "OUTPUT_LAYER" ), QObject::tr( "Buffered" ), QgsProcessingParameterDefinition::TypeVectorPoint ) );
 }
 
+QString QgsBufferAlgorithm::shortHelpString() const
+{
+  return QObject::tr( "This algorithm computes a buffer area for all the features in an input layer, using a fixed or dynamic distance.\n\n"
+                      "The segments parameter controls the number of line segments to use to approximate a quarter circle when creating rounded offsets.\n\n"
+                      "The end cap style parameter controls how line endings are handled in the buffer.\n\n"
+                      "The join style parameter specifies whether round, mitre or beveled joins should be used when offsetting corners in a line.\n\n"
+                      "The mitre limit parameter is only applicable for mitre join styles, and controls the maximum distance from the offset curve to use when creating a mitred join." );
+}
+
 QVariantMap QgsBufferAlgorithm::run( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback ) const
 {
   QgsVectorLayer *layer = qobject_cast< QgsVectorLayer *>( parameterAsLayer( parameters, QStringLiteral( "INPUT" ), context ) );

src/core/processing/qgsnativealgorithms.h

@@ -57,6 +57,7 @@ class QgsCentroidAlgorithm : public QgsProcessingAlgorithm
     QString displayName() const override { return QObject::tr( "Centroids" ); }
     virtual QStringList tags() const override { return QObject::tr( "centroid,center,average,point,middle" ).split( ',' ); }
     QString group() const override { return QObject::tr( "Vector geometry tools" ); }
+    QString shortHelpString() const override;
 
     virtual QVariantMap run( const QVariantMap &parameters,
                              QgsProcessingContext &context, QgsProcessingFeedback *feedback ) const override;
@@ -77,6 +78,7 @@ class QgsBufferAlgorithm : public QgsProcessingAlgorithm
     QString displayName() const override { return QObject::tr( "Buffer" ); }
     virtual QStringList tags() const override { return QObject::tr( "buffer,grow" ).split( ',' ); }
     QString group() const override { return QObject::tr( "Vector geometry tools" ); }
+    QString shortHelpString() const override;
 
     virtual QVariantMap run( const QVariantMap &parameters,
                              QgsProcessingContext &context, QgsProcessingFeedback *feedback ) const override;

src/core/processing/qgsprocessingalgorithm.cpp

@@ -36,6 +36,21 @@ QString QgsProcessingAlgorithm::id() const
     return name();
 }
 
+QString QgsProcessingAlgorithm::shortHelpString() const
+{
+  return QString();
+}
+
+QString QgsProcessingAlgorithm::helpString() const
+{
+  return QString();
+}
+
+QString QgsProcessingAlgorithm::helpUrl() const
+{
+  return QString();
+}
+
 QIcon QgsProcessingAlgorithm::icon() const
 {
   return QgsApplication::getThemeIcon( "/processingAlgorithm.svg" );

src/core/processing/qgsprocessingalgorithm.h

@@ -95,6 +95,29 @@ class CORE_EXPORT QgsProcessingAlgorithm
     */
     virtual QStringList tags() const { return QStringList(); }
 
+    /**
+     * Returns a localised short helper string for the algorithm. This string should provide a basic description
+     * about what the algorithm does and the parameters and outputs associated with it.
+     * \see helpString()
+     * \see helpUrl()
+     */
+    virtual QString shortHelpString() const;
+
+    /**
+     * Returns a localised help string for the algorithm. Algorithm subclasses should implement either
+     * helpString() or helpUrl().
+     * \see helpUrl()
+     * \see shortHelpString()
+     */
+    virtual QString helpString() const;
+
+    /**
+     * Returns a url pointing to the algorithm's help page.
+     * \see helpString()
+     * \see shortHelpString()
+     */
+    virtual QString helpUrl() const;
+
     /**
      * Returns an icon for the algorithm.
      * \see svgIconPath()