qgstextrenderer.h

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/***************************************************************************
  qgstextrenderer.h
  -----------------
   begin                : September 2015
   copyright            : (C) Nyall Dawson
   email                : nyall dot dawson 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 QGSTEXTRENDERER_H
#define QGSTEXTRENDERER_H
 
#include "qgis.h"
#include "qgis_core.h"
#include "qgis_sip.h"
#include "qgsmapunitscale.h"
#include "qgstextblock.h"
 
#include <QPainterPath>
#include <QPicture>
 
class QgsTextDocument;
class QgsTextDocumentMetrics;
class QgsTextFormat;
class QgsRenderContext;
 
class QFontMetricsF;

class CORE_EXPORT QgsTextRenderer
{
  public:

    static Qgis::TextHorizontalAlignment convertQtHAlignment( Qt::Alignment alignment );

    static Qgis::TextVerticalAlignment convertQtVAlignment( Qt::Alignment alignment );

    static int sizeToPixel( double size, const QgsRenderContext &c, Qgis::RenderUnit unit, const QgsMapUnitScale &mapUnitScale = QgsMapUnitScale() );
 
    // TODO QGIS 4.0 -- remove drawAsOutlines from below methods!

    static void drawText( const QRectF &rect, double rotation, Qgis::TextHorizontalAlignment alignment, const QStringList &textLines,
                          QgsRenderContext &context, const QgsTextFormat &format,
                          bool drawAsOutlines = true, Qgis::TextVerticalAlignment vAlignment = Qgis::TextVerticalAlignment::Top,
                          Qgis::TextRendererFlags flags = Qgis::TextRendererFlags(),
                          Qgis::TextLayoutMode mode = Qgis::TextLayoutMode::Rectangle );

    static void drawDocument( const QRectF &rect,
                              const QgsTextFormat &format,
                              const QgsTextDocument &document,
                              const QgsTextDocumentMetrics &metrics,
                              QgsRenderContext &context,
                              Qgis::TextHorizontalAlignment horizontalAlignment = Qgis::TextHorizontalAlignment::Left,
                              Qgis::TextVerticalAlignment verticalAlignment = Qgis::TextVerticalAlignment::Top,
                              double rotation = 0,
                              Qgis::TextLayoutMode mode = Qgis::TextLayoutMode::Rectangle,
                              Qgis::TextRendererFlags flags = Qgis::TextRendererFlags() );

    static void drawText( QPointF point, double rotation, Qgis::TextHorizontalAlignment alignment, const QStringList &textLines,
                          QgsRenderContext &context, const QgsTextFormat &format,
                          bool drawAsOutlines = true );

    static void drawDocument( QPointF point,
                              const QgsTextFormat &format,
                              const QgsTextDocument &document,
                              const QgsTextDocumentMetrics &metrics,
                              QgsRenderContext &context,
                              Qgis::TextHorizontalAlignment alignment,
                              double rotation,
                              Qgis::TextLayoutMode mode = Qgis::TextLayoutMode::Point );

    static void drawTextOnLine( const QPolygonF &line, const QString &text,
                                QgsRenderContext &context, const QgsTextFormat &format,
                                double offsetAlongLine = 0, double offsetFromLine = 0,
                                Qgis::CurvedTextFlags flags = Qgis::CurvedTextFlag::UseBaselinePlacement | Qgis::CurvedTextFlag::TruncateStringWhenLineIsTooShort );

    static void drawDocumentOnLine( const QPolygonF &line,
                                    const QgsTextFormat &format,
                                    const QgsTextDocument &document,
                                    QgsRenderContext &context,
                                    double offsetAlongLine = 0,
                                    double offsetFromLine = 0,
                                    Qgis::CurvedTextFlags flags = Qgis::CurvedTextFlag::UseBaselinePlacement | Qgis::CurvedTextFlag::TruncateStringWhenLineIsTooShort );

    Q_DECL_DEPRECATED static void drawPart( const QRectF &rect, double rotation, Qgis::TextHorizontalAlignment alignment, const QStringList &textLines,
                                            QgsRenderContext &context, const QgsTextFormat &format,
                                            Qgis::TextComponent part, bool drawAsOutlines = true ) SIP_DEPRECATED;

    Q_DECL_DEPRECATED static void drawPart( QPointF origin, double rotation, Qgis::TextHorizontalAlignment alignment, const QStringList &textLines,
                                            QgsRenderContext &context, const QgsTextFormat &format,
                                            Qgis::TextComponent part, bool drawAsOutlines = true ) SIP_DEPRECATED;

    static QFontMetricsF fontMetrics( QgsRenderContext &context, const QgsTextFormat &format, double scaleFactor = 1.0 );

    static double textWidth( const QgsRenderContext &context, const QgsTextFormat &format, const QStringList &textLines,
                             QFontMetricsF *fontMetrics = nullptr );

    static double textHeight( const QgsRenderContext &context, const QgsTextFormat &format, const QStringList &textLines, Qgis::TextLayoutMode mode = Qgis::TextLayoutMode::Point,
                              QFontMetricsF *fontMetrics = nullptr, Qgis::TextRendererFlags flags = Qgis::TextRendererFlags(), double maxLineWidth = 0 );

    static double textHeight( const QgsRenderContext &context, const QgsTextFormat &format, QChar character, bool includeEffects = false );

    static bool textRequiresWrapping( const QgsRenderContext &context, const QString &text, double width, const QgsTextFormat &format );

    static QStringList wrappedText( const QgsRenderContext &context, const QString &text, double width, const QgsTextFormat &format );

    static constexpr double FONT_WORKAROUND_SCALE = 10;

    static double calculateScaleFactorForFormat( const QgsRenderContext &context, const QgsTextFormat &format );
 
    // to match QTextEngine handling of superscript/subscript font sizes

    static constexpr double SUPERSCRIPT_SUBSCRIPT_FONT_SIZE_SCALING_FACTOR = 2.0 / 3.0;
 
  private:
 
    struct Component
    {
      QgsTextBlock block;

      int blockIndex = 0;

      int firstFragmentIndex = 0;

      QPointF origin;
      bool useOrigin = false;
      double rotation = 0.0;
      double rotationOffset = 0.0;
      QPointF center;
      QSizeF size;
      QPointF offset;
      QPicture picture;

      double pictureBuffer = 0.0;
      double dpiRatio = 1.0;
      Qgis::TextHorizontalAlignment hAlign = Qgis::TextHorizontalAlignment::Left;

      double extraWordSpacing = 0;
      double extraLetterSpacing = 0;
    };
 
    static double textWidth( const QgsRenderContext &context, const QgsTextFormat &format, const QgsTextDocument &document );
    static double textHeight( const QgsRenderContext &context, const QgsTextFormat &format, const QgsTextDocument &document, Qgis::TextLayoutMode mode = Qgis::TextLayoutMode::Point );

    static void drawParts( const QRectF &rect, double rotation, Qgis::TextHorizontalAlignment alignment, Qgis::TextVerticalAlignment vAlignment, const QgsTextDocument &document, const QgsTextDocumentMetrics &metrics,
                           QgsRenderContext &context, const QgsTextFormat &format,
                           Qgis::TextComponents parts, Qgis::TextLayoutMode mode );

    static void drawParts( QPointF origin, double rotation, Qgis::TextHorizontalAlignment alignment, const QgsTextDocument &document,
                           const QgsTextDocumentMetrics &metrics,
                           QgsRenderContext &context, const QgsTextFormat &format,
                           Qgis::TextComponents parts,
                           Qgis::TextLayoutMode mode );
 
    static double drawBuffer( QgsRenderContext &context,
                              const Component &component,
                              const QgsTextFormat &format,
                              const QgsTextDocumentMetrics &metrics,
                              Qgis::TextLayoutMode mode );
 
    static void drawBackground( QgsRenderContext &context,
                                const Component &component,
                                const QgsTextFormat &format,
                                const QgsTextDocumentMetrics &metrics,
                                Qgis::TextLayoutMode mode = Qgis::TextLayoutMode::Rectangle );
 
    static void drawShadow( QgsRenderContext &context,
                            const Component &component,
                            const QgsTextFormat &format );
 
    static void drawMask( QgsRenderContext &context,
                          const Component &component,
                          const QgsTextFormat &format,
                          const QgsTextDocumentMetrics &metrics,
                          Qgis::TextLayoutMode mode );
 
    static void drawText( QgsRenderContext &context,
                          const Component &component,
                          const QgsTextFormat &format );
 
    static void drawTextInternal( Qgis::TextComponents components,
                                  QgsRenderContext &context,
                                  const QgsTextFormat &format,
                                  const Component &component,
                                  const QgsTextDocument &document,
                                  const QgsTextDocumentMetrics &metrics,
                                  Qgis::TextHorizontalAlignment alignment,
                                  Qgis::TextVerticalAlignment vAlignment,
                                  Qgis::TextLayoutMode mode = Qgis::TextLayoutMode::Rectangle );
 
    static Qgis::TextOrientation calculateRotationAndOrientationForComponent( const QgsTextFormat &format, const Component &component, double &rotation );
 
    static void calculateExtraSpacingForLineJustification( double spaceToDistribute, const QgsTextBlock &block, double &extraWordSpace, double &extraLetterSpace );
    static void applyExtraSpacingForLineJustification( QFont &font, double extraWordSpace, double extraLetterSpace );
 
    static void drawTextInternalHorizontal( QgsRenderContext &context,
                                            const QgsTextFormat &format,
                                            Qgis::TextComponents components,
                                            Qgis::TextLayoutMode mode,
                                            const Component &component,
                                            const QgsTextDocument &document,
                                            const QgsTextDocumentMetrics &metrics,
                                            double fontScale,
                                            Qgis::TextHorizontalAlignment hAlignment,
                                            Qgis::TextVerticalAlignment vAlignment,
                                            double rotation );
 
    static void drawTextInternalVertical( QgsRenderContext &context,
                                          const QgsTextFormat &format,
                                          Qgis::TextComponents components,
                                          Qgis::TextLayoutMode mode,
                                          const Component &component,
                                          const QgsTextDocument &document,
                                          const QgsTextDocumentMetrics &metrics,
                                          double fontScale,
                                          Qgis::TextHorizontalAlignment hAlignment,
                                          Qgis::TextVerticalAlignment vAlignment,
                                          double rotation );
 
    struct DeferredRenderFragment
    {
      // mandatory
      QColor color;
      QPointF point;
      // optional
      QPainterPath path;
      // optional
      QFont font;
      QString text;
    };
 
    struct BlockMetrics
    {
      double xOffset = 0;
      double backgroundXOffset = 0;
      double width = 0;
      double backgroundWidth = 0;
      double extraWordSpace = 0;
      double extraLetterSpace = 0;
    };
 
    static QVector< QgsTextRenderer::BlockMetrics > calculateBlockMetrics( const QgsTextDocument &document, const QgsTextDocumentMetrics &metrics, Qgis::TextLayoutMode mode, double targetWidth, const Qgis::TextHorizontalAlignment hAlignment );
 
    struct DeferredRenderBlock
    {
      QPointF origin;
      Component component;
      QVector< DeferredRenderFragment > fragments;
    };
 
    static QBrush createBrushForPath( QgsRenderContext &context, const QString &path );
 
    static void renderBlockHorizontal( const QgsTextBlock &block, int blockIndex,
                                       const QgsTextDocumentMetrics &metrics, QgsRenderContext &context,
                                       const QgsTextFormat &format,
                                       QPainter *painter, bool forceRenderAsPaths,
                                       double fontScale, double extraWordSpace, double extraLetterSpace,
                                       Qgis::TextLayoutMode mode,
                                       DeferredRenderBlock *deferredRenderBlock );
    static void renderDocumentBackgrounds( QgsRenderContext &context, const QgsTextDocument &document, const QgsTextDocumentMetrics &metrics, const Component &component, const QVector< QgsTextRenderer::BlockMetrics > &blockMetrics, Qgis::TextLayoutMode mode, double verticalAlignOffset, double rotation );
    static void renderDeferredBlocks( QgsRenderContext &context, const QgsTextFormat &format, Qgis::TextComponents components, const std::vector<DeferredRenderBlock> &deferredBlocks, bool usePathsForText, double fontScale, const Component &component, double rotation );
    static void renderDeferredBuffer( QgsRenderContext &context, const QgsTextFormat &format, Qgis::TextComponents components, const std::vector<DeferredRenderBlock> &deferredBlocks, double fontScale, const Component &component, double rotation );
    static void renderDeferredShadowForText( QgsRenderContext &context, const QgsTextFormat &format, const std::vector<DeferredRenderBlock> &deferredBlocks, double fontScale, const Component &component, double rotation );
    static void renderDeferredText( QgsRenderContext &context, const std::vector<DeferredRenderBlock> &deferredBlocks, bool usePathsForText, double fontScale, const Component &component, double rotation );
 
    friend class QgsVectorLayerLabelProvider;
    friend class QgsLabelPreview;
 
    static QgsTextFormat updateShadowPosition( const QgsTextFormat &format );

    static bool usePathsToRender( const QgsRenderContext &context, const QgsTextFormat &format, const QgsTextDocument &document );

    static bool usePictureToRender( const QgsRenderContext &context, const QgsTextFormat &format, const QgsTextDocument &document );
 
};
 
#endif // QGSTEXTRENDERER_H