QGIS API Documentation  3.23.0-Master (dd0cd13a00)
qgsdiagram.cpp
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1 /***************************************************************************
2  qgsdiagram.cpp
3  ---------------------
4  begin : March 2011
5  copyright : (C) 2011 by Marco Hugentobler
6  email : marco dot hugentobler at sourcepole dot ch
7  ***************************************************************************
8  * *
9  * This program is free software; you can redistribute it and/or modify *
10  * it under the terms of the GNU General Public License as published by *
11  * the Free Software Foundation; either version 2 of the License, or *
12  * (at your option) any later version. *
13  * *
14  ***************************************************************************/
15 #include "qgsdiagram.h"
16 #include "qgsdiagramrenderer.h"
17 #include "qgsrendercontext.h"
18 
19 #include <QPainter>
20 
21 QgsDiagram::QgsDiagram( const QgsDiagram & ): mExpressions{}
22 {
23  // do not copy the cached expression map - the expressions need to be created and prepared with getExpression(...) call
24 }
25 
26 
28 {
29  QMapIterator<QString, QgsExpression *> i( mExpressions );
30  while ( i.hasNext() )
31  {
32  i.next();
33  delete i.value();
34  }
35  mExpressions.clear();
36 }
37 
38 QgsExpression *QgsDiagram::getExpression( const QString &expression, const QgsExpressionContext &context )
39 {
40  if ( !mExpressions.contains( expression ) )
41  {
42  QgsExpression *expr = new QgsExpression( expression );
43  expr->prepare( &context );
44  mExpressions[expression] = expr;
45  }
46  return mExpressions[expression];
47 }
48 
49 void QgsDiagram::setPenWidth( QPen &pen, const QgsDiagramSettings &s, const QgsRenderContext &c )
50 {
51  pen.setWidthF( c.convertToPainterUnits( s.penWidth, s.lineSizeUnit, s.lineSizeScale ) );
52 }
53 
54 
55 QSizeF QgsDiagram::sizePainterUnits( QSizeF size, const QgsDiagramSettings &s, const QgsRenderContext &c )
56 {
57  return QSizeF( c.convertToPainterUnits( size.width(), s.sizeType, s.sizeScale ), c.convertToPainterUnits( size.height(), s.sizeType, s.sizeScale ) );
58 }
59 
61 {
62  return c.convertToPainterUnits( l, s.sizeType, s.sizeScale );
63 }
64 
66 {
67  QFont f = s.font;
69  {
70  const int pixelsize = s.font.pointSizeF() / c.mapToPixel().mapUnitsPerPixel();
71  f.setPixelSize( pixelsize > 0 ? pixelsize : 1 );
72  }
73  else
74  {
75  f.setPixelSize( s.font.pointSizeF() * 0.376 * c.scaleFactor() );
76  }
77 
78  return f;
79 }
80 
81 QSizeF QgsDiagram::sizeForValue( double value, const QgsDiagramSettings &s, const QgsDiagramInterpolationSettings &is ) const
82 {
83  double scaledValue = value;
84  double scaledLowerValue = is.lowerValue;
85  double scaledUpperValue = is.upperValue;
86 
87  // interpolate the squared value if scale by area
88  if ( s.scaleByArea )
89  {
90  scaledValue = std::sqrt( scaledValue );
91  scaledLowerValue = std::sqrt( scaledLowerValue );
92  scaledUpperValue = std::sqrt( scaledUpperValue );
93  }
94 
95  //interpolate size
96  const double scaledRatio = ( scaledValue - scaledLowerValue ) / ( scaledUpperValue - scaledLowerValue );
97 
98  QSizeF size = QSizeF( is.upperSize.width() * scaledRatio + is.lowerSize.width() * ( 1 - scaledRatio ),
99  is.upperSize.height() * scaledRatio + is.lowerSize.height() * ( 1 - scaledRatio ) );
100 
101  // Scale, if extension is smaller than the specified minimum
102  if ( size.width() <= s.minimumSize && size.height() <= s.minimumSize )
103  {
104  bool p = false; // preserve height == width
105  if ( qgsDoubleNear( size.width(), size.height() ) )
106  p = true;
107 
108  size.scale( s.minimumSize, s.minimumSize, Qt::KeepAspectRatio );
109 
110  // If height == width, recover here (overwrite floating point errors)
111  if ( p )
112  size.setWidth( size.height() );
113  }
114 
115  return size;
116 }
Additional diagram settings for interpolated size rendering.
Stores the settings for rendering a single diagram.
QgsUnitTypes::RenderUnit sizeType
Diagram size unit.
QgsMapUnitScale lineSizeScale
Line unit scale.
QgsMapUnitScale sizeScale
Diagram size unit scale.
QgsUnitTypes::RenderUnit lineSizeUnit
Line unit index.
double minimumSize
Scale diagrams smaller than mMinimumSize to mMinimumSize.
Base class for all diagram types.
Definition: qgsdiagram.h:40
void setPenWidth(QPen &pen, const QgsDiagramSettings &s, const QgsRenderContext &c)
Changes the pen width to match the current settings and rendering context.
Definition: qgsdiagram.cpp:49
void clearCache()
Definition: qgsdiagram.cpp:27
QSizeF sizePainterUnits(QSizeF size, const QgsDiagramSettings &s, const QgsRenderContext &c)
Calculates a size to match the current settings and rendering context.
Definition: qgsdiagram.cpp:55
QgsDiagram()=default
Constructor for QgsDiagram.
QgsExpression * getExpression(const QString &expression, const QgsExpressionContext &context)
Returns a prepared expression for the specified context.
Definition: qgsdiagram.cpp:38
QSizeF sizeForValue(double value, const QgsDiagramSettings &s, const QgsDiagramInterpolationSettings &is) const
Returns the scaled size of a diagram for a value, respecting the specified diagram interpolation sett...
Definition: qgsdiagram.cpp:81
QFont scaledFont(const QgsDiagramSettings &s, const QgsRenderContext &c)
Calculates a size to match the current settings and rendering context.
Definition: qgsdiagram.cpp:65
Expression contexts are used to encapsulate the parameters around which a QgsExpression should be eva...
Class for parsing and evaluation of expressions (formerly called "search strings").
bool prepare(const QgsExpressionContext *context)
Gets the expression ready for evaluation - find out column indexes.
Contains information about the context of a rendering operation.
@ RenderMapUnits
Map units.
Definition: qgsunittypes.h:170
As part of the API refactoring and improvements which landed in the Processing API was substantially reworked from the x version This was done in order to allow much of the underlying Processing framework to be ported into c
bool qgsDoubleNear(double a, double b, double epsilon=4 *std::numeric_limits< double >::epsilon())
Compare two doubles (but allow some difference)
Definition: qgis.h:1504