QGIS API Documentation  2.99.0-Master (f867b65)
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 #include "qgsexpression.h"
19 #include "qgssymbollayerutils.h"
20 
21 #include <QPainter>
22 
23 
24 
26 {
27 
28 }
29 
31 {
32  Q_UNUSED( other );
33  // do not copy the cached expression map - the expressions need to be created and prepared with getExpression(...) call
34 }
35 
36 
38 {
39  QMapIterator<QString, QgsExpression *> i( mExpressions );
40  while ( i.hasNext() )
41  {
42  i.next();
43  delete i.value();
44  }
45  mExpressions.clear();
46 }
47 
48 QgsExpression *QgsDiagram::getExpression( const QString &expression, const QgsExpressionContext &context )
49 {
50  if ( !mExpressions.contains( expression ) )
51  {
52  QgsExpression *expr = new QgsExpression( expression );
53  expr->prepare( &context );
54  mExpressions[expression] = expr;
55  }
56  return mExpressions[expression];
57 }
58 
59 void QgsDiagram::setPenWidth( QPen &pen, const QgsDiagramSettings &s, const QgsRenderContext &c )
60 {
61  pen.setWidthF( c.convertToPainterUnits( s.penWidth, s.lineSizeUnit, s.lineSizeScale ) );
62 }
63 
64 
65 QSizeF QgsDiagram::sizePainterUnits( QSizeF size, const QgsDiagramSettings &s, const QgsRenderContext &c )
66 {
67  return QSizeF( c.convertToPainterUnits( size.width(), s.sizeType, s.sizeScale ), c.convertToPainterUnits( size.height(), s.sizeType, s.sizeScale ) );
68 }
69 
71 {
72  return c.convertToPainterUnits( l, s.sizeType, s.sizeScale );
73 }
74 
76 {
77  QFont f = s.font;
79  {
80  int pixelsize = s.font.pointSizeF() / c.mapToPixel().mapUnitsPerPixel();
81  f.setPixelSize( pixelsize > 0 ? pixelsize : 1 );
82  }
83  else
84  {
85  f.setPixelSize( s.font.pointSizeF() * 0.376 * c.scaleFactor() );
86  }
87 
88  return f;
89 }
90 
91 QSizeF QgsDiagram::sizeForValue( double value, const QgsDiagramSettings &s, const QgsDiagramInterpolationSettings &is ) const
92 {
93  double scaledValue = value;
94  double scaledLowerValue = is.lowerValue;
95  double scaledUpperValue = is.upperValue;
96 
97  // interpolate the squared value if scale by area
98  if ( s.scaleByArea )
99  {
100  scaledValue = sqrt( scaledValue );
101  scaledLowerValue = sqrt( scaledLowerValue );
102  scaledUpperValue = sqrt( scaledUpperValue );
103  }
104 
105  //interpolate size
106  double scaledRatio = ( scaledValue - scaledLowerValue ) / ( scaledUpperValue - scaledLowerValue );
107 
108  QSizeF size = QSizeF( is.upperSize.width() * scaledRatio + is.lowerSize.width() * ( 1 - scaledRatio ),
109  is.upperSize.height() * scaledRatio + is.lowerSize.height() * ( 1 - scaledRatio ) );
110 
111  // Scale, if extension is smaller than the specified minimum
112  if ( size.width() <= s.minimumSize && size.height() <= s.minimumSize )
113  {
114  bool p = false; // preserve height == width
115  if ( qgsDoubleNear( size.width(), size.height() ) )
116  p = true;
117 
118  size.scale( s.minimumSize, s.minimumSize, Qt::KeepAspectRatio );
119 
120  // If height == width, recover here (overwrite floating point errors)
121  if ( p )
122  size.setWidth( size.height() );
123  }
124 
125  return size;
126 }
QSizeF sizePainterUnits(QSizeF size, const QgsDiagramSettings &s, const QgsRenderContext &c)
Calculates a size to match the current settings and rendering context.
Definition: qgsdiagram.cpp:65
QgsUnitTypes::RenderUnit lineSizeUnit
Line unit index.
double minimumSize
Scale diagrams smaller than mMinimumSize to mMinimumSize.
void clearCache()
Definition: qgsdiagram.cpp:37
bool qgsDoubleNear(double a, double b, double epsilon=4 *DBL_EPSILON)
Compare two doubles (but allow some difference)
Definition: qgis.h:210
QgsExpression * getExpression(const QString &expression, const QgsExpressionContext &context)
Returns a prepared expression for the specified context.
Definition: qgsdiagram.cpp:48
Expression contexts are used to encapsulate the parameters around which a QgsExpression should be eva...
QgsMapUnitScale sizeScale
Diagram size unit scale.
double mapUnitsPerPixel() const
Return current map units per pixel.
Base class for all diagram types.
Definition: qgsdiagram.h:37
QgsUnitTypes::RenderUnit sizeType
Diagram size unit.
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:91
Additional diagram settings for interpolated size rendering.
Contains information about the context of a rendering operation.
double convertToPainterUnits(double size, QgsUnitTypes::RenderUnit unit, const QgsMapUnitScale &scale=QgsMapUnitScale()) const
Converts a size from the specified units to painter units (pixels).
QFont scaledFont(const QgsDiagramSettings &s, const QgsRenderContext &c)
Calculates a size to match the current settings and rendering context.
Definition: qgsdiagram.cpp:75
const QgsMapToPixel & mapToPixel() const
QgsMapUnitScale lineSizeScale
Line unit scale.
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:59
double scaleFactor() const
Returns the scaling factor for the render to convert painter units to physical sizes.
Stores the settings for rendering a single diagram.