QGIS API Documentation 3.28.0-Firenze (ed3ad0430f)
qgstextdiagram.cpp
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1/***************************************************************************
2 qgstextdiagram.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 "qgstextdiagram.h"
16#include "qgsdiagramrenderer.h"
17#include "qgsrendercontext.h"
18#include "qgsexpression.h"
19
20#include <QPainter>
21
23{
24 mPen.setWidthF( 2.0 );
25 mPen.setColor( QColor( 0, 0, 0 ) );
26 mPen.setCapStyle( Qt::FlatCap );
27 mBrush.setStyle( Qt::SolidPattern );
28}
29
31{
32 return new QgsTextDiagram( *this );
33}
34
36{
37 QgsExpressionContext expressionContext = c.expressionContext();
38 expressionContext.setFeature( feature );
39 if ( !feature.fields().isEmpty() )
40 expressionContext.setFields( feature.fields() );
41
42 QVariant attrVal;
44 {
45 QgsExpression *expression = getExpression( is.classificationAttributeExpression, expressionContext );
46 attrVal = expression->evaluate( &expressionContext );
47 }
48 else
49 {
50 attrVal = feature.attribute( is.classificationField );
51 }
52
53 bool ok = false;
54 const double val = attrVal.toDouble( &ok );
55 if ( !ok )
56 {
57 return QSizeF(); //zero size if attribute is missing
58 }
59
60 return sizeForValue( val, s, is );
61}
62
63double QgsTextDiagram::legendSize( double value, const QgsDiagramSettings &s, const QgsDiagramInterpolationSettings &is ) const
64{
65 const QSizeF size = sizeForValue( value, s, is );
66 return std::max( size.width(), size.height() );
67}
68
70{
71 return DIAGRAM_NAME_TEXT;
72}
73
75{
76 Q_UNUSED( c )
77 Q_UNUSED( attributes )
78
79 return s.size;
80}
81
82void QgsTextDiagram::renderDiagram( const QgsFeature &feature, QgsRenderContext &c, const QgsDiagramSettings &s, QPointF position )
83{
84 QPainter *p = c.painter();
85 if ( !p )
86 {
87 return;
88 }
89
90 //convert from mm / map units to painter units
91 const QSizeF spu = sizePainterUnits( s.size, s, c );
92 const double w = spu.width();
93 const double h = spu.height();
94
95 const double baseX = position.x();
96 const double baseY = position.y() - h;
97
98 QVector<QPointF> textPositions; //midpoints for text placement
99 const int nCategories = s.categoryAttributes.size();
100 for ( int i = 0; i < nCategories; ++i )
101 {
102 if ( mOrientation == Horizontal )
103 {
104 textPositions.push_back( QPointF( baseX + ( w / nCategories ) * i + w / nCategories / 2.0, baseY + h / 2.0 ) );
105 }
106 else //vertical
107 {
108 textPositions.push_back( QPointF( baseX + w / 2.0, baseY + h / nCategories * i + w / nCategories / 2.0 ) );
109 }
110 }
111
112 mPen.setColor( s.penColor );
113 setPenWidth( mPen, s, c );
114 p->setPen( mPen );
115 mBrush.setColor( s.backgroundColor );
116 p->setBrush( mBrush );
117
118 //draw shapes and separator lines first
119 if ( mShape == Circle )
120 {
121 p->drawEllipse( baseX, baseY, w, h );
122
123 //draw separator lines
124 QList<QPointF> intersect; //intersections between shape and separation lines
125 const QPointF center( baseX + w / 2.0, baseY + h / 2.0 );
126 const double r1 = w / 2.0;
127 const double r2 = h / 2.0;
128
129 for ( int i = 1; i < nCategories; ++i )
130 {
131 if ( mOrientation == Horizontal )
132 {
133 lineEllipseIntersection( QPointF( baseX + w / nCategories * i, baseY ), QPointF( baseX + w / nCategories * i, baseY + h ), center, r1, r2, intersect );
134 }
135 else //vertical
136 {
137 lineEllipseIntersection( QPointF( baseX, baseY + h / nCategories * i ), QPointF( baseX + w, baseY + h / nCategories * i ), center, r1, r2, intersect );
138 }
139 if ( intersect.size() > 1 )
140 {
141 p->drawLine( intersect.at( 0 ), intersect.at( 1 ) );
142 }
143 }
144 }
145 else if ( mShape == Rectangle )
146 {
147 p->drawRect( QRectF( baseX, baseY, w, h ) );
148 for ( int i = 1; i < nCategories; ++i )
149 {
150 if ( mOrientation == Horizontal )
151 {
152 p->drawLine( QPointF( baseX + w / nCategories * i, baseY ), QPointF( baseX + w / nCategories * i, baseY + h ) );
153 }
154 else
155 {
156 p->drawLine( QPointF( baseX, baseY + h / nCategories * i ), QPointF( baseX + w, baseY + h / nCategories * i ) );
157 }
158 }
159 }
160 else //triangle
161 {
162 QPolygonF triangle;
163 triangle << QPointF( baseX, baseY + h ) << QPointF( baseX + w, baseY + h ) << QPointF( baseX + w / 2.0, baseY );
164 p->drawPolygon( triangle );
165
166 const QLineF triangleEdgeLeft( baseX + w / 2.0, baseY, baseX, baseY + h );
167 const QLineF triangleEdgeRight( baseX + w, baseY + h, baseX + w / 2.0, baseY );
168 QPointF intersectionPoint1, intersectionPoint2;
169
170 for ( int i = 1; i < nCategories; ++i )
171 {
172 if ( mOrientation == Horizontal )
173 {
174 const QLineF verticalLine( baseX + w / nCategories * i, baseY + h, baseX + w / nCategories * i, baseY );
175 if ( baseX + w / nCategories * i < baseX + w / 2.0 )
176 {
177 verticalLine.intersects( triangleEdgeLeft, &intersectionPoint1 );
178 }
179 else
180 {
181 verticalLine.intersects( triangleEdgeRight, &intersectionPoint1 );
182 }
183 p->drawLine( QPointF( baseX + w / nCategories * i, baseY + h ), intersectionPoint1 );
184 }
185 else //vertical
186 {
187 const QLineF horizontalLine( baseX, baseY + h / nCategories * i, baseX + w, baseY + h / nCategories * i );
188 horizontalLine.intersects( triangleEdgeLeft, &intersectionPoint1 );
189 horizontalLine.intersects( triangleEdgeRight, &intersectionPoint2 );
190 p->drawLine( intersectionPoint1, intersectionPoint2 );
191 }
192 }
193 }
194
195 //draw text
196 const QFont sFont = scaledFont( s, c );
197 const QFontMetricsF fontMetrics( sFont );
198 p->setFont( sFont );
199
200 QgsExpressionContext expressionContext = c.expressionContext();
201 expressionContext.setFeature( feature );
202 if ( !feature.fields().isEmpty() )
203 expressionContext.setFields( feature.fields() );
204
205 for ( int i = 0; i < textPositions.size(); ++i )
206 {
207 QgsExpression *expression = getExpression( s.categoryAttributes.at( i ), expressionContext );
208 const QString val = expression->evaluate( &expressionContext ).toString();
209
210 //find out dimensions
211 const double textWidth = fontMetrics.horizontalAdvance( val );
212 const double textHeight = fontMetrics.height();
213
214 mPen.setColor( s.categoryColors.at( i ) );
215 p->setPen( mPen );
216 const QPointF position = textPositions.at( i );
217
218 // Calculate vertical placement
219 double xOffset = 0;
220
221 switch ( s.labelPlacementMethod )
222 {
224 xOffset = textHeight / 2.0;
225 break;
226
228 xOffset = fontMetrics.xHeight();
229 break;
230 }
231 p->drawText( QPointF( position.x() - textWidth / 2.0, position.y() + xOffset ), val );
232 }
233}
234
235void QgsTextDiagram::lineEllipseIntersection( QPointF lineStart, QPointF lineEnd, QPointF ellipseMid, double r1, double r2, QList<QPointF> &result ) const
236{
237 result.clear();
238
239 const double rrx = r1 * r1;
240 const double rry = r2 * r2;
241 const double x21 = lineEnd.x() - lineStart.x();
242 const double y21 = lineEnd.y() - lineStart.y();
243 const double x10 = lineStart.x() - ellipseMid.x();
244 const double y10 = lineStart.y() - ellipseMid.y();
245 const double a = x21 * x21 / rrx + y21 * y21 / rry;
246 const double b = x21 * x10 / rrx + y21 * y10 / rry;
247 const double c = x10 * x10 / rrx + y10 * y10 / rry;
248 const double d = b * b - a * ( c - 1 );
249 if ( d > 0 )
250 {
251 const double e = std::sqrt( d );
252 const double u1 = ( -b - e ) / a;
253 const double u2 = ( -b + e ) / a;
254 //work with a tolerance of 0.00001 because of limited numerical precision
255 if ( -0.00001 <= u1 && u1 < 1.00001 )
256 {
257 result.push_back( QPointF( lineStart.x() + x21 * u1, lineStart.y() + y21 * u1 ) );
258 }
259 if ( -0.00001 <= u2 && u2 <= 1.00001 )
260 {
261 result.push_back( QPointF( lineStart.x() + x21 * u2, lineStart.y() + y21 * u2 ) );
262 }
263 }
264}
A vector of attributes.
Definition: qgsattributes.h:59
Additional diagram settings for interpolated size rendering.
QString classificationField
Name of the field for classification.
Stores the settings for rendering a single diagram.
LabelPlacementMethod labelPlacementMethod
QList< QString > categoryAttributes
QList< QColor > categoryColors
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
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
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...
void setFeature(const QgsFeature &feature)
Convenience function for setting a feature for the context.
void setFields(const QgsFields &fields)
Convenience function for setting a fields for the context.
Class for parsing and evaluation of expressions (formerly called "search strings").
QVariant evaluate()
Evaluate the feature and return the result.
The feature class encapsulates a single feature including its unique ID, geometry and a list of field...
Definition: qgsfeature.h:56
QgsFields fields
Definition: qgsfeature.h:66
QVariant attribute(const QString &name) const
Lookup attribute value by attribute name.
Definition: qgsfeature.cpp:338
bool isEmpty() const
Checks whether the container is empty.
Definition: qgsfields.cpp:128
Contains information about the context of a rendering operation.
A text based diagram.
void renderDiagram(const QgsFeature &feature, QgsRenderContext &c, const QgsDiagramSettings &s, QPointF position) override
Draws the diagram at the given position (in pixel coordinates)
QgsTextDiagram * clone() const override
Returns an instance that is equivalent to this one.
QSizeF diagramSize(const QgsAttributes &attributes, const QgsRenderContext &c, const QgsDiagramSettings &s) override
Returns the size in map units the diagram will use to render.
QString diagramName() const override
Gets a descriptive name for this diagram type.
double legendSize(double value, const QgsDiagramSettings &s, const QgsDiagramInterpolationSettings &is) const override
Returns the size of the legend item for the diagram corresponding to a specified value.
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
#define DIAGRAM_NAME_TEXT