QGIS API Documentation 3.37.0-Master (4ace69f83af)
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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
21QgsDiagram::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
38QgsExpression *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
50{
51 pen.setWidthF( c.convertToPainterUnits( s.penWidth, s.lineSizeUnit, s.lineSizeScale ) );
52}
53
54
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
81QSizeF 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}
@ MapUnits
Map units.
Additional diagram settings for interpolated size rendering.
Stores the settings for rendering a single diagram.
Qgis::RenderUnit sizeType
Diagram size unit.
QgsMapUnitScale lineSizeScale
Line unit scale.
QgsMapUnitScale sizeScale
Diagram size unit scale.
Qgis::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.
void clearCache()
QSizeF sizePainterUnits(QSizeF size, const QgsDiagramSettings &s, const QgsRenderContext &c)
Calculates a size to match the current settings and rendering context.
QgsDiagram()=default
Constructor for QgsDiagram.
QgsExpression * getExpression(const QString &expression, const QgsExpressionContext &context)
Returns a prepared expression for the specified context.
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...
QFont scaledFont(const QgsDiagramSettings &s, const QgsRenderContext &c)
Calculates a size to match the current settings and rendering context.
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.
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:5144