[feature] Support img tags in HTML label text

Allows use of img tags in HTML label content. The following logic
is applied:

- Image path is set via the src="xxx" attribute. Local, HTTP, and
base64 encoded paths are permitted
- Any image format readable by QGIS can be used
- Image sizes can be specified via the width="##" and height="##"
attributes. If width or height is not specified it will automatically
be calculated from the original image size
- If width or height are specified, they are considered to be
in POINTS
- The css width/height settings are NOT respected (this is a Qt
limitation)
- Images are not supported for curved text labels
- Images are placed inline only, floating images are not supported

Sponsored by City of Freiburg im Breisgau

python/PyQt6/core/auto_generated/textrenderer/qgstextcharacterformat.sip.in

@@ -262,6 +262,62 @@ Returns whether the format has overline enabled.
 Sets whether the format has overline ``enabled``.
 
 .. seealso:: :py:func:`overline`
+%End
+
+    QString imagePath() const;
+%Docstring
+Returns the path to the image to render, if the format applies to a document image fragment.
+
+.. seealso:: :py:func:`QgsTextFragment.isImage`
+
+.. seealso:: :py:func:`imageSize`
+
+.. seealso:: :py:func:`setImagePath`
+
+.. versionadded:: 3.40
+%End
+
+    void setImagePath( const QString &path );
+%Docstring
+Sets the ``path`` to the image to render, if the format applies to a document image fragment.
+
+.. seealso:: :py:func:`QgsTextFragment.isImage`
+
+.. seealso:: :py:func:`setImageSize`
+
+.. seealso:: :py:func:`imagePath`
+
+.. versionadded:: 3.40
+%End
+
+    QSizeF imageSize() const;
+%Docstring
+Returns the image size, if the format applies to a document image fragment.
+
+The image size is always considered to be in :py:class:`Qgis`.RenderUnit.Points.
+
+.. seealso:: :py:func:`QgsTextFragment.isImage`
+
+.. seealso:: :py:func:`imagePath`
+
+.. seealso:: :py:func:`setImageSize`
+
+.. versionadded:: 3.40
+%End
+
+    void setImageSize( const QSizeF &size );
+%Docstring
+Sets the image ``size``, if the format applies to a document image fragment.
+
+The image size is always considered to be in :py:class:`Qgis`.RenderUnit.Points.
+
+.. seealso:: :py:func:`QgsTextFragment.isImage`
+
+.. seealso:: :py:func:`setImagePath`
+
+.. seealso:: :py:func:`imageSize`
+
+.. versionadded:: 3.40
 %End
 
     bool hasVerticalAlignmentSet() const;

python/PyQt6/core/auto_generated/textrenderer/qgstextdocumentmetrics.sip.in

@@ -99,6 +99,13 @@ Returns the vertical offset from a text block's baseline which should be applied
 to the fragment at the specified index within that block.
 
 .. versionadded:: 3.30
+%End
+
+    double fragmentFixedHeight( int blockIndex, int fragmentIndex, Qgis::TextLayoutMode mode ) const;
+%Docstring
+Returns the fixed height of the fragment at the specified block and fragment index, or -1 if the fragment does not have a fixed height.
+
+.. versionadded:: 3.40
 %End
 
     double verticalOrientationXOffset( int blockIndex ) const;

python/PyQt6/core/auto_generated/textrenderer/qgstextfragment.sip.in

@@ -12,7 +12,13 @@
 class QgsTextFragment
 {
 %Docstring(signature="appended")
-Stores a fragment of text along with formatting overrides to be used when rendering the fragment.
+Stores a fragment of document along with formatting overrides to be used when rendering the fragment.
+
+Text fragments consist of either a block of text or another atomic component of a document (such as an image).
+
+Each fragment has an associated :py:func:`~characterFormat`, which specifies the text formatting overrides
+to use when rendering the fragment. Additionally, the :py:func:`~characterFormat` may contain properties
+for other fragment types, such as image paths and sizes for image fragments.
 
 .. warning::
 
@@ -77,6 +83,13 @@ Returns the character formatting for the fragment.
 Sets the character ``format`` for the fragment.
 
 .. seealso:: :py:func:`characterFormat`
+%End
+
+    bool isImage() const;
+%Docstring
+Returns ``True`` if the fragment represents an image.
+
+.. versionadded:: 3.40
 %End
 
     double horizontalAdvance( const QFont &font, const QgsRenderContext &context, bool fontHasBeenUpdatedForFragment = false, double scaleFactor = 1.0 ) const;

python/core/auto_generated/textrenderer/qgstextcharacterformat.sip.in

@@ -262,6 +262,62 @@ Returns whether the format has overline enabled.
 Sets whether the format has overline ``enabled``.
 
 .. seealso:: :py:func:`overline`
+%End
+
+    QString imagePath() const;
+%Docstring
+Returns the path to the image to render, if the format applies to a document image fragment.
+
+.. seealso:: :py:func:`QgsTextFragment.isImage`
+
+.. seealso:: :py:func:`imageSize`
+
+.. seealso:: :py:func:`setImagePath`
+
+.. versionadded:: 3.40
+%End
+
+    void setImagePath( const QString &path );
+%Docstring
+Sets the ``path`` to the image to render, if the format applies to a document image fragment.
+
+.. seealso:: :py:func:`QgsTextFragment.isImage`
+
+.. seealso:: :py:func:`setImageSize`
+
+.. seealso:: :py:func:`imagePath`
+
+.. versionadded:: 3.40
+%End
+
+    QSizeF imageSize() const;
+%Docstring
+Returns the image size, if the format applies to a document image fragment.
+
+The image size is always considered to be in :py:class:`Qgis`.RenderUnit.Points.
+
+.. seealso:: :py:func:`QgsTextFragment.isImage`
+
+.. seealso:: :py:func:`imagePath`
+
+.. seealso:: :py:func:`setImageSize`
+
+.. versionadded:: 3.40
+%End
+
+    void setImageSize( const QSizeF &size );
+%Docstring
+Sets the image ``size``, if the format applies to a document image fragment.
+
+The image size is always considered to be in :py:class:`Qgis`.RenderUnit.Points.
+
+.. seealso:: :py:func:`QgsTextFragment.isImage`
+
+.. seealso:: :py:func:`setImagePath`
+
+.. seealso:: :py:func:`imageSize`
+
+.. versionadded:: 3.40
 %End
 
     bool hasVerticalAlignmentSet() const;

python/core/auto_generated/textrenderer/qgstextdocumentmetrics.sip.in

@@ -99,6 +99,13 @@ Returns the vertical offset from a text block's baseline which should be applied
 to the fragment at the specified index within that block.
 
 .. versionadded:: 3.30
+%End
+
+    double fragmentFixedHeight( int blockIndex, int fragmentIndex, Qgis::TextLayoutMode mode ) const;
+%Docstring
+Returns the fixed height of the fragment at the specified block and fragment index, or -1 if the fragment does not have a fixed height.
+
+.. versionadded:: 3.40
 %End
 
     double verticalOrientationXOffset( int blockIndex ) const;

python/core/auto_generated/textrenderer/qgstextfragment.sip.in

@@ -12,7 +12,13 @@
 class QgsTextFragment
 {
 %Docstring(signature="appended")
-Stores a fragment of text along with formatting overrides to be used when rendering the fragment.
+Stores a fragment of document along with formatting overrides to be used when rendering the fragment.
+
+Text fragments consist of either a block of text or another atomic component of a document (such as an image).
+
+Each fragment has an associated :py:func:`~characterFormat`, which specifies the text formatting overrides
+to use when rendering the fragment. Additionally, the :py:func:`~characterFormat` may contain properties
+for other fragment types, such as image paths and sizes for image fragments.
 
 .. warning::
 
@@ -77,6 +83,13 @@ Returns the character formatting for the fragment.
 Sets the character ``format`` for the fragment.
 
 .. seealso:: :py:func:`characterFormat`
+%End
+
+    bool isImage() const;
+%Docstring
+Returns ``True`` if the fragment represents an image.
+
+.. versionadded:: 3.40
 %End
 
     double horizontalAdvance( const QFont &font, const QgsRenderContext &context, bool fontHasBeenUpdatedForFragment = false, double scaleFactor = 1.0 ) const;

src/core/qgsabstractcontentcache_p.h

@@ -20,6 +20,7 @@
 
 #include "qgsabstractcontentcache.h"
 #include "qgssetrequestinitiator_p.h"
+#include <QRegularExpression>
 
 template<class T>
 QByteArray QgsAbstractContentCache<T>::getContent( const QString &path, const QByteArray &missingContent, const QByteArray &fetchingContent, bool blocking ) const
@@ -44,6 +45,16 @@ QByteArray QgsAbstractContentCache<T>::getContent( const QString &path, const QB
     const QByteArray base64 = path.mid( 7 ).toLocal8Bit(); // strip 'base64:' prefix
     return QByteArray::fromBase64( base64, QByteArray::OmitTrailingEquals );
   }
+  else
+  {
+    const thread_local QRegularExpression rx( QStringLiteral( "^data:image/.*;base64,(.*)$" ) );
+    const QRegularExpressionMatch base64Match = rx.match( path );
+    if ( base64Match.hasMatch() )
+    {
+      const QByteArray base64 = base64Match.captured( 1 ).toLocal8Bit(); // strip prefix
+      return QByteArray::fromBase64( base64, QByteArray::OmitTrailingEquals );
+    }
+  }
 
   // maybe it's a url...
   if ( !path.contains( QLatin1String( "://" ) ) ) // otherwise short, relative SVG paths might be considered URLs

src/core/qgsimagecache.cpp

@@ -162,6 +162,13 @@ QImage QgsImageCache::pathAsImagePrivate( const QString &f, const QSize size, co
 
   fitsInCache = true;
 
+  const thread_local QRegularExpression rx( QStringLiteral( "^data:image/.*;base64,(.*)$" ), QRegularExpression::DotMatchesEverythingOption );
+  const QRegularExpressionMatch base64Match = rx.match( file );
+  if ( base64Match.hasMatch() )
+  {
+    file = QStringLiteral( "base64:%1" ).arg( base64Match.captured( 1 ) );
+  }
+
   QgsImageCacheEntry *currentEntry = findExistingEntry( new QgsImageCacheEntry( file, size, keepAspectRatio, opacity, targetDpi, frameNumber ) );
 
   QImage result;
@@ -206,13 +213,22 @@ QImage QgsImageCache::pathAsImagePrivate( const QString &f, const QSize size, co
   return result;
 }
 
+bool isBase64Path( const QString &path )
+{
+  if ( path.startsWith( QLatin1String( "base64:" ) ) )
+    return true;
+
+  const thread_local QRegularExpression rx( QStringLiteral( "^data:image/.*;base64," ), QRegularExpression::DotMatchesEverythingOption );
+  return rx.match( path ).hasMatch();
+}
+
 QSize QgsImageCache::originalSize( const QString &path, bool blocking ) const
 {
   if ( path.isEmpty() )
     return QSize();
 
   // direct read if path is a file -- maybe more efficient than going the bytearray route? (untested!)
-  if ( !path.startsWith( QLatin1String( "base64:" ) ) && QFile::exists( path ) )
+  if ( !isBase64Path( path ) && QFile::exists( path ) )
   {
     const QImageReader reader( path );
     if ( reader.size().isValid() )
@@ -298,7 +314,7 @@ void QgsImageCache::prepareAnimation( const QString &path )
   std::unique_ptr< QImageReader > reader;
   std::unique_ptr< QBuffer > buffer;
 
-  if ( !path.startsWith( QLatin1String( "base64:" ) ) && QFile::exists( path ) )
+  if ( !isBase64Path( path ) && QFile::exists( path ) )
   {
     const QString basePart = QFileInfo( path ).baseName();
     int id = 1;
@@ -355,7 +371,7 @@ QImage QgsImageCache::renderImage( const QString &path, QSize size, const bool k
   isBroken = false;
 
   // direct read if path is a file -- maybe more efficient than going the bytearray route? (untested!)
-  if ( !path.startsWith( QLatin1String( "base64:" ) ) && QFile::exists( path ) )
+  if ( !isBase64Path( path ) && QFile::exists( path ) )
   {
     QImageReader reader( path );
     reader.setAutoTransform( true );

src/core/textrenderer/qgstextcharacterformat.cpp

@@ -65,6 +65,12 @@ QgsTextCharacterFormat::QgsTextCharacterFormat( const QTextCharFormat &format )
     if ( !families.isEmpty() )
       mFontFamily = families.at( 0 );
   }
+  if ( format.isImageFormat() )
+  {
+    const QTextImageFormat imageFormat = format.toImageFormat();
+    mImagePath = imageFormat.name();
+    mImageSize = QSizeF( imageFormat.width(), imageFormat.height() );
+  }
 }
 
 void QgsTextCharacterFormat::overrideWith( const QgsTextCharacterFormat &other )
@@ -168,6 +174,26 @@ void QgsTextCharacterFormat::setOverline( QgsTextCharacterFormat::BooleanValue e
   mOverline = enabled;
 }
 
+QString QgsTextCharacterFormat::imagePath() const
+{
+  return mImagePath;
+}
+
+void QgsTextCharacterFormat::setImagePath( const QString &path )
+{
+  mImagePath = path;
+}
+
+QSizeF QgsTextCharacterFormat::imageSize() const
+{
+  return mImageSize;
+}
+
+void QgsTextCharacterFormat::setImageSize( const QSizeF &size )
+{
+  mImageSize = size;
+}
+
 void QgsTextCharacterFormat::updateFontForFormat( QFont &font, const QgsRenderContext &context, const double scaleFactor ) const
 {
   // important -- MUST set family first