[FEATURE] Title label decoration

src/app/CMakeLists.txt

@@ -109,6 +109,8 @@ SET(QGIS_APP_SRCS
   qgsmaptooltextannotation.cpp
 
   decorations/qgsdecorationitem.cpp
+  decorations/qgsdecorationtitle.cpp
+  decorations/qgsdecorationtitledialog.cpp
   decorations/qgsdecorationcopyright.cpp
   decorations/qgsdecorationcopyrightdialog.cpp
   decorations/qgsdecorationlayoutextent.cpp
@@ -363,6 +365,8 @@ SET (QGIS_APP_MOC_HDRS
   qgsmaptoolregularpolygoncentercorner.h
 
   decorations/qgsdecorationitem.h
+  decorations/qgsdecorationtitle.h
+  decorations/qgsdecorationtitledialog.h
   decorations/qgsdecorationcopyright.h
   decorations/qgsdecorationcopyrightdialog.h
   decorations/qgsdecorationlayoutextent.h

src/app/decorations/qgsdecorationtitle.cpp

@@ -0,0 +1,207 @@
+/***************************************************************************
+  qgsdecorationtitle.cpp
+  --------------------------------------
+  Date                 : November 2018
+  Copyright            : (C) 2018 by Mathieu Pellerin
+  Email                : nirvn dot asia at gmail dot com
+ ***************************************************************************
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 2 of the License, or     *
+ *   (at your option) any later version.                                   *
+ *                                                                         *
+ ***************************************************************************/
+
+#include "qgsdecorationtitle.h"
+#include "qgsdecorationtitledialog.h"
+
+#include "qgisapp.h"
+#include "qgsapplication.h"
+#include "qgsexpression.h"
+#include "qgsexpressioncontext.h"
+#include "qgslogger.h"
+#include "qgsmapcanvas.h"
+#include "qgsproject.h"
+#include "qgsreadwritecontext.h"
+#include "qgssymbollayerutils.h"
+
+#include <QPainter>
+#include <QMenu>
+#include <QDate>
+#include <QDomDocument>
+#include <QMatrix>
+#include <QFile>
+
+//non qt includes
+#include <cmath>
+
+
+QgsDecorationTitle::QgsDecorationTitle( QObject *parent )
+  : QgsDecorationItem( parent )
+{
+  mPlacement = TopLeft;
+  mMarginUnit = QgsUnitTypes::RenderMillimeters;
+
+  setName( "Title Label" );
+  // initialize default values in the gui
+  projectRead();
+}
+
+void QgsDecorationTitle::projectRead()
+{
+  QgsDecorationItem::projectRead();
+
+  mLabelText = QgsProject::instance()->readEntry( mNameConfig, QStringLiteral( "/Label" ), QString() );
+  mBackgroundColor = QgsSymbolLayerUtils::decodeColor( QgsProject::instance()->readEntry( mNameConfig, QStringLiteral( "/BackgroundColor" ), QStringLiteral( "0,0,0,66" ) ) );
+
+  mMarginHorizontal = QgsProject::instance()->readNumEntry( mNameConfig, QStringLiteral( "/MarginH" ), 0 );
+  mMarginVertical = QgsProject::instance()->readNumEntry( mNameConfig, QStringLiteral( "/MarginV" ), 0 );
+
+  QDomDocument doc;
+  QDomElement elem;
+  QString textXml = QgsProject::instance()->readEntry( mNameConfig, QStringLiteral( "/Font" ) );
+  if ( !textXml.isEmpty() )
+  {
+    doc.setContent( textXml );
+    elem = doc.documentElement();
+    QgsReadWriteContext rwContext;
+    rwContext.setPathResolver( QgsProject::instance()->pathResolver() );
+    mTextFormat.readXml( elem, rwContext );
+  }
+}
+
+void QgsDecorationTitle::saveToProject()
+{
+  QgsDecorationItem::saveToProject();
+
+  QgsProject::instance()->writeEntry( mNameConfig, QStringLiteral( "/Label" ), mLabelText );
+  QgsProject::instance()->writeEntry( mNameConfig, QStringLiteral( "/BackgroundColor" ), QgsSymbolLayerUtils::encodeColor( mBackgroundColor ) );
+
+  QgsProject::instance()->writeEntry( mNameConfig, QStringLiteral( "/MarginH" ), mMarginHorizontal );
+  QgsProject::instance()->writeEntry( mNameConfig, QStringLiteral( "/MarginV" ), mMarginVertical );
+
+  QDomDocument textDoc;
+  QgsReadWriteContext rwContext;
+  rwContext.setPathResolver( QgsProject::instance()->pathResolver() );
+  QDomElement textElem = mTextFormat.writeXml( textDoc, rwContext );
+  textDoc.appendChild( textElem );
+  QgsProject::instance()->writeEntry( mNameConfig, QStringLiteral( "/Font" ), textDoc.toString() );
+}
+
+// Slot called when the buffer menu item is activated
+void QgsDecorationTitle::run()
+{
+  QgsDecorationTitleDialog dlg( *this, QgisApp::instance() );
+  dlg.exec();
+}
+
+
+void QgsDecorationTitle::render( const QgsMapSettings &mapSettings, QgsRenderContext &context )
+{
+  Q_UNUSED( mapSettings );
+  if ( !enabled() )
+    return;
+
+  context.painter()->save();
+  context.painter()->setRenderHint( QPainter::Antialiasing, true );
+
+  QString displayString = QgsExpression::replaceExpressionText( mLabelText, &context.expressionContext() );
+  QStringList displayStringList = displayString.split( QStringLiteral( "\n" ) );
+
+  QFontMetricsF fm( mTextFormat.scaledFont( context ) );
+  QFontMetricsF textMetrics = QgsTextRenderer::fontMetrics( context, mTextFormat );
+  double textDescent = textMetrics.descent();
+  double textWidth = QgsTextRenderer::textWidth( context, mTextFormat, displayStringList, &fm );
+  double textHeight = QgsTextRenderer::textHeight( context, mTextFormat, displayStringList, QgsTextRenderer::Point, &fm );
+
+  QPaintDevice *device = context.painter()->device();
+  int deviceHeight = device->height() / device->devicePixelRatioF();
+  int deviceWidth = device->width() / device->devicePixelRatioF();
+
+  float xOffset( 0 ), yOffset( 0 );
+
+  // Set  margin according to selected units
+  switch ( mMarginUnit )
+  {
+    case QgsUnitTypes::RenderMillimeters:
+    {
+      int pixelsInchX = context.painter()->device()->logicalDpiX();
+      int pixelsInchY = context.painter()->device()->logicalDpiY();
+      xOffset = pixelsInchX * INCHES_TO_MM * mMarginHorizontal;
+      yOffset = pixelsInchY * INCHES_TO_MM * mMarginVertical;
+      break;
+    }
+    case QgsUnitTypes::RenderPixels:
+    {
+      xOffset = mMarginHorizontal;
+      yOffset = mMarginVertical;
+      break;
+    }
+    case QgsUnitTypes::RenderPercentage:
+    {
+      xOffset = ( ( deviceWidth - textWidth ) / 100. ) * mMarginHorizontal;
+      yOffset = ( ( deviceHeight - textHeight ) / 100. ) * mMarginVertical;
+      break;
+    }
+    case QgsUnitTypes::RenderMapUnits:
+    case QgsUnitTypes::RenderPoints:
+    case QgsUnitTypes::RenderInches:
+    case QgsUnitTypes::RenderUnknownUnit:
+    case QgsUnitTypes::RenderMetersInMapUnits:
+      break;
+  }
+
+  QPolygonF backgroundBar;
+
+  // Determine placement of label from form combo box
+  QgsTextRenderer::HAlignment horizontalAlignment = QgsTextRenderer::AlignLeft;
+  switch ( mPlacement )
+  {
+    case BottomLeft: // Bottom Left, xOffset is set above
+      backgroundBar << QPointF( 0, deviceHeight )
+                    << QPointF( deviceWidth, deviceHeight )
+                    << QPointF( deviceWidth, deviceHeight - ( yOffset * 2 + textHeight ) )
+                    << QPointF( 0, deviceHeight - ( yOffset * 2 + textHeight ) );
+      yOffset = deviceHeight - yOffset - textDescent;
+      break;
+    case TopLeft: // Top left, xOffset is set above
+      backgroundBar << QPointF( 0, 0 )
+                    << QPointF( deviceWidth, 0 )
+                    << QPointF( deviceWidth, yOffset * 2 + textHeight )
+                    << QPointF( 0, yOffset * 2 + textHeight );
+      yOffset = yOffset + textHeight - textDescent;
+      break;
+    case TopRight: // Top Right
+      backgroundBar << QPointF( 0, 0 )
+                    << QPointF( deviceWidth, 0 )
+                    << QPointF( deviceWidth, yOffset * 2 + textHeight )
+                    << QPointF( 0, yOffset * 2 + textHeight );
+      yOffset = yOffset + textHeight - textDescent;
+      xOffset = deviceWidth - xOffset;
+      horizontalAlignment = QgsTextRenderer::AlignRight;
+      break;
+    case BottomRight: // Bottom Right
+      backgroundBar << QPointF( 0, deviceHeight )
+                    << QPointF( deviceWidth, deviceHeight )
+                    << QPointF( deviceWidth, deviceHeight - ( yOffset * 2 + textHeight ) )
+                    << QPointF( 0, deviceHeight - ( yOffset * 2 + textHeight ) );
+      yOffset = deviceHeight - yOffset - textDescent;
+      xOffset = deviceWidth - xOffset;
+      horizontalAlignment = QgsTextRenderer::AlignRight;
+      break;
+    default:
+      QgsDebugMsg( QStringLiteral( "Unknown placement index of %1" ).arg( static_cast<int>( mPlacement ) ) );
+  }
+
+  // Draw background bar
+  context.painter()->setPen( Qt::NoPen );
+  context.painter()->setBrush( QBrush( mBackgroundColor, Qt::SolidPattern ) );
+  context.painter()->drawPolygon( backgroundBar );
+
+  // Paint label to canvas
+  QgsTextRenderer::drawText( QPointF( xOffset, yOffset ), 0.0, horizontalAlignment, displayStringList, context, mTextFormat );
+
+  context.painter()->restore();
+}
+

src/app/decorations/qgsdecorationtitle.h

@@ -0,0 +1,81 @@
+/***************************************************************************
+  qgsdecorationtitle.h
+  --------------------------------------
+  Date                 : November 2018
+  Copyright            : (C) 2018 by Mathieu Pellerin
+  Email                : nirvn dot asia at gmail dot com
+ ***************************************************************************
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 2 of the License, or     *
+ *   (at your option) any later version.                                   *
+ *                                                                         *
+ ***************************************************************************/
+
+#ifndef QGSDECORATIONTITLE_H
+#define QGSDECORATIONTITLE_H
+
+#include "qgis_app.h"
+#include "qgsdecorationitem.h"
+#include "qgstextrenderer.h"
+
+#include <QColor>
+#include <QFont>
+#include <QObject>
+
+class QgsDecorationTitleDialog;
+
+class QAction;
+class QPainter;
+
+class APP_EXPORT QgsDecorationTitle : public QgsDecorationItem
+{
+    Q_OBJECT
+  public:
+
+    //! Constructor
+    QgsDecorationTitle( QObject *parent = nullptr );
+
+  public slots:
+    //! Sets values on the gui when a project is read or the gui first loaded
+    void projectRead() override;
+    //! save values to the project
+    void saveToProject() override;
+
+    //! Show the dialog box
+    void run() override;
+    //! render the title label
+    void render( const QgsMapSettings &mapSettings, QgsRenderContext &context ) override;
+
+    /**
+     * Returns the text format for extent labels.
+     * \see setTextFormat()
+     * \see labelExtents()
+     */
+    QgsTextFormat textFormat() const { return mTextFormat; }
+
+    /**
+     * Sets the text \a format for extent labels.
+     * \see textFormat()
+     * \see setLabelExtents()
+     */
+    void setTextFormat( const QgsTextFormat &format ) { mTextFormat = format; }
+
+  private:
+    //! This is the string that will be used for the title label
+    QString mLabelText;
+
+    //! The background bar color
+    QColor mBackgroundColor;
+
+    //! enable or disable use of position percentage for placement
+    int mMarginHorizontal = 0;
+    int mMarginVertical = 0;
+
+    QgsTextFormat mTextFormat;
+
+    friend class QgsDecorationTitleDialog;
+};
+
+#endif