QGIS API Documentation 3.40.0-Bratislava (b56115d8743)
Loading...
Searching...
No Matches
qgstextdiagram.cpp
Go to the documentation of this file.
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
22const QString QgsTextDiagram::DIAGRAM_NAME_TEXT = QStringLiteral( "Text" );
23
25{
26 mPen.setWidthF( 2.0 );
27 mPen.setColor( QColor( 0, 0, 0 ) );
28 mPen.setCapStyle( Qt::FlatCap );
29 mBrush.setStyle( Qt::SolidPattern );
30}
31
33{
34 return new QgsTextDiagram( *this );
35}
36
38{
39 QgsExpressionContext expressionContext = c.expressionContext();
40 expressionContext.setFeature( feature );
41 if ( !feature.fields().isEmpty() )
42 expressionContext.setFields( feature.fields() );
43
44 QVariant attrVal;
46 {
47 QgsExpression *expression = getExpression( is.classificationAttributeExpression, expressionContext );
48 attrVal = expression->evaluate( &expressionContext );
49 }
50 else
51 {
52 attrVal = feature.attribute( is.classificationField );
53 }
54
55 bool ok = false;
56 const double val = attrVal.toDouble( &ok );
57 if ( !ok )
58 {
59 return QSizeF(); //zero size if attribute is missing
60 }
61
62 return sizeForValue( val, s, is );
63}
64
65double QgsTextDiagram::legendSize( double value, const QgsDiagramSettings &s, const QgsDiagramInterpolationSettings &is ) const
66{
67 const QSizeF size = sizeForValue( value, s, is );
68 return std::max( size.width(), size.height() );
69}
70
75
77{
78 Q_UNUSED( c )
79 Q_UNUSED( attributes )
80
81 return s.size;
82}
83
84void QgsTextDiagram::renderDiagram( const QgsFeature &feature, QgsRenderContext &c, const QgsDiagramSettings &s, QPointF position )
85{
86 QPainter *p = c.painter();
87 if ( !p )
88 {
89 return;
90 }
91
92 //convert from mm / map units to painter units
93 const QSizeF spu = sizePainterUnits( s.size, s, c );
94 const double w = spu.width();
95 const double h = spu.height();
96
97 const double baseX = position.x();
98 const double baseY = position.y() - h;
99
100 QVector<QPointF> textPositions; //midpoints for text placement
101 const int nCategories = s.categoryAttributes.size();
102 for ( int i = 0; i < nCategories; ++i )
103 {
104 if ( mOrientation == Horizontal )
105 {
106 textPositions.push_back( QPointF( baseX + ( w / nCategories ) * i + w / nCategories / 2.0, baseY + h / 2.0 ) );
107 }
108 else //vertical
109 {
110 textPositions.push_back( QPointF( baseX + w / 2.0, baseY + h / nCategories * i + w / nCategories / 2.0 ) );
111 }
112 }
113
114 mPen.setColor( s.penColor );
115 setPenWidth( mPen, s, c );
116 p->setPen( mPen );
117 mBrush.setColor( s.backgroundColor );
118 p->setBrush( mBrush );
119
120 //draw shapes and separator lines first
121 if ( mShape == Circle )
122 {
123 p->drawEllipse( baseX, baseY, w, h );
124
125 //draw separator lines
126 QList<QPointF> intersect; //intersections between shape and separation lines
127 const QPointF center( baseX + w / 2.0, baseY + h / 2.0 );
128 const double r1 = w / 2.0;
129 const double r2 = h / 2.0;
130
131 for ( int i = 1; i < nCategories; ++i )
132 {
133 if ( mOrientation == Horizontal )
134 {
135 lineEllipseIntersection( QPointF( baseX + w / nCategories * i, baseY ), QPointF( baseX + w / nCategories * i, baseY + h ), center, r1, r2, intersect );
136 }
137 else //vertical
138 {
139 lineEllipseIntersection( QPointF( baseX, baseY + h / nCategories * i ), QPointF( baseX + w, baseY + h / nCategories * i ), center, r1, r2, intersect );
140 }
141 if ( intersect.size() > 1 )
142 {
143 p->drawLine( intersect.at( 0 ), intersect.at( 1 ) );
144 }
145 }
146 }
147 else if ( mShape == Rectangle )
148 {
149 p->drawRect( QRectF( baseX, baseY, w, h ) );
150 for ( int i = 1; i < nCategories; ++i )
151 {
152 if ( mOrientation == Horizontal )
153 {
154 p->drawLine( QPointF( baseX + w / nCategories * i, baseY ), QPointF( baseX + w / nCategories * i, baseY + h ) );
155 }
156 else
157 {
158 p->drawLine( QPointF( baseX, baseY + h / nCategories * i ), QPointF( baseX + w, baseY + h / nCategories * i ) );
159 }
160 }
161 }
162 else //triangle
163 {
164 QPolygonF triangle;
165 triangle << QPointF( baseX, baseY + h ) << QPointF( baseX + w, baseY + h ) << QPointF( baseX + w / 2.0, baseY );
166 p->drawPolygon( triangle );
167
168 const QLineF triangleEdgeLeft( baseX + w / 2.0, baseY, baseX, baseY + h );
169 const QLineF triangleEdgeRight( baseX + w, baseY + h, baseX + w / 2.0, baseY );
170 QPointF intersectionPoint1, intersectionPoint2;
171
172 for ( int i = 1; i < nCategories; ++i )
173 {
174 if ( mOrientation == Horizontal )
175 {
176 const QLineF verticalLine( baseX + w / nCategories * i, baseY + h, baseX + w / nCategories * i, baseY );
177 if ( baseX + w / nCategories * i < baseX + w / 2.0 )
178 {
179 verticalLine.intersects( triangleEdgeLeft, &intersectionPoint1 );
180 }
181 else
182 {
183 verticalLine.intersects( triangleEdgeRight, &intersectionPoint1 );
184 }
185 p->drawLine( QPointF( baseX + w / nCategories * i, baseY + h ), intersectionPoint1 );
186 }
187 else //vertical
188 {
189 const QLineF horizontalLine( baseX, baseY + h / nCategories * i, baseX + w, baseY + h / nCategories * i );
190 horizontalLine.intersects( triangleEdgeLeft, &intersectionPoint1 );
191 horizontalLine.intersects( triangleEdgeRight, &intersectionPoint2 );
192 p->drawLine( intersectionPoint1, intersectionPoint2 );
193 }
194 }
195 }
196
197 //draw text
198 const QFont sFont = scaledFont( s, c );
199 const QFontMetricsF fontMetrics( sFont );
200 p->setFont( sFont );
201
202 QgsExpressionContext expressionContext = c.expressionContext();
203 expressionContext.setFeature( feature );
204 if ( !feature.fields().isEmpty() )
205 expressionContext.setFields( feature.fields() );
206
207 for ( int i = 0; i < textPositions.size(); ++i )
208 {
209 QgsExpression *expression = getExpression( s.categoryAttributes.at( i ), expressionContext );
210 const QString val = expression->evaluate( &expressionContext ).toString();
211
212 //find out dimensions
213 const double textWidth = fontMetrics.horizontalAdvance( val );
214 const double textHeight = fontMetrics.height();
215
216 mPen.setColor( s.categoryColors.at( i ) );
217 p->setPen( mPen );
218 const QPointF position = textPositions.at( i );
219
220 // Calculate vertical placement
221 double xOffset = 0;
222
223 switch ( s.labelPlacementMethod )
224 {
226 xOffset = textHeight / 2.0;
227 break;
228
230 xOffset = fontMetrics.xHeight();
231 break;
232 }
233 p->drawText( QPointF( position.x() - textWidth / 2.0, position.y() + xOffset ), val );
234 }
235}
236
237void QgsTextDiagram::lineEllipseIntersection( QPointF lineStart, QPointF lineEnd, QPointF ellipseMid, double r1, double r2, QList<QPointF> &result ) const
238{
239 result.clear();
240
241 const double rrx = r1 * r1;
242 const double rry = r2 * r2;
243 const double x21 = lineEnd.x() - lineStart.x();
244 const double y21 = lineEnd.y() - lineStart.y();
245 const double x10 = lineStart.x() - ellipseMid.x();
246 const double y10 = lineStart.y() - ellipseMid.y();
247 const double a = x21 * x21 / rrx + y21 * y21 / rry;
248 const double b = x21 * x10 / rrx + y21 * y10 / rry;
249 const double c = x10 * x10 / rrx + y10 * y10 / rry;
250 const double d = b * b - a * ( c - 1 );
251 if ( d > 0 )
252 {
253 const double e = std::sqrt( d );
254 const double u1 = ( -b - e ) / a;
255 const double u2 = ( -b + e ) / a;
256 //work with a tolerance of 0.00001 because of limited numerical precision
257 if ( -0.00001 <= u1 && u1 < 1.00001 )
258 {
259 result.push_back( QPointF( lineStart.x() + x21 * u1, lineStart.y() + y21 * u1 ) );
260 }
261 if ( -0.00001 <= u2 && u2 <= 1.00001 )
262 {
263 result.push_back( QPointF( lineStart.x() + x21 * u2, lineStart.y() + y21 * u2 ) );
264 }
265 }
266}
A vector of attributes.
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.
QSizeF sizePainterUnits(QSizeF size, const QgsDiagramSettings &s, const QgsRenderContext &c)
Calculates a size to match the current settings and rendering context.
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 &interpolationSettings) 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...
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:58
QgsFields fields
Definition qgsfeature.h:68
Q_INVOKABLE QVariant attribute(const QString &name) const
Lookup attribute value by attribute name.
bool isEmpty
Definition qgsfields.h:49
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)
double legendSize(double value, const QgsDiagramSettings &s, const QgsDiagramInterpolationSettings &interpolationSettings) const override
Returns the size of the legend item for the diagram corresponding to a specified value.
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.
static const QString DIAGRAM_NAME_TEXT
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