qgstextrenderer.h

Go to the documentation of this file.

/***************************************************************************
  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 5.0 -- 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