QGIS API Documentation 3.28.0-Firenze (ed3ad0430f)
qgsstackedbardiagram.cpp
Go to the documentation of this file.
1/***************************************************************************
2 qgsstackedbardiagram.cpp
3 ---------------------
4 begin : November 2019
5 copyright : (C) 2019 by Nyall Dawson
6 email : nyall dot dawson at gmail dot com
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
17#include "qgsdiagramrenderer.h"
18#include "qgsrendercontext.h"
19#include "qgsexpression.h"
20#include "qgssymbollayerutils.h"
21#include "qgslinesymbol.h"
22
23#include <QPainter>
24
26{
27 mCategoryBrush.setStyle( Qt::SolidPattern );
28 mPen.setStyle( Qt::SolidLine );
29}
30
32{
33 return new QgsStackedBarDiagram( *this );
34}
35
37{
38 if ( qgsDoubleNear( is.upperValue, is.lowerValue ) )
39 return QSizeF(); // invalid value range => zero size
40
41 QVariant attrVal;
43 {
44 QgsExpressionContext expressionContext = c.expressionContext();
45 if ( !feature.fields().isEmpty() )
46 expressionContext.setFields( feature.fields() );
47 expressionContext.setFeature( feature );
48
49 QgsExpression *expression = getExpression( is.classificationAttributeExpression, expressionContext );
50 attrVal = expression->evaluate( &expressionContext );
51 }
52 else
53 {
54 attrVal = feature.attribute( is.classificationField );
55 }
56
57 bool ok = false;
58 double value = fabs( attrVal.toDouble( &ok ) );
59 if ( !ok )
60 {
61 return QSizeF(); //zero size if attribute is missing
62 }
63
64 QSizeF size = sizeForValue( value, s, is );
65
66 // eh - this method returns size in unknown units ...! We'll have to fake it and use a rough estimation of
67 // a conversion factor to painter units...
68 // TODO QGIS 4.0 -- these methods should all use painter units, dependent on the render context scaling...
69 double painterUnitConversionScale = c.convertToPainterUnits( 1, s.sizeType );
70
71 const double spacing = c.convertToPainterUnits( s.spacing(), s.spacingUnit(), s.spacingMapUnitScale() ) / painterUnitConversionScale;
72 mApplySpacingAdjust = true;
73
74 switch ( s.diagramOrientation )
75 {
78 {
79 const double totalBarLength = size.height() + spacing * std::max( 0, static_cast<int>( s.categoryAttributes.size() ) - 1 );
80 size = QSizeF( s.barWidth, totalBarLength );
81 break;
82 }
83
86 {
87 const double totalBarLength = size.width() + spacing * std::max( 0, static_cast<int>( s.categoryAttributes.size() ) - 1 );
88 size = QSizeF( totalBarLength, s.barWidth );
89 break;
90 }
91 }
92
93 if ( s.showAxis() && s.axisLineSymbol() )
94 {
95 const double maxBleed = QgsSymbolLayerUtils::estimateMaxSymbolBleed( s.axisLineSymbol(), c ) / painterUnitConversionScale;
96 size.setWidth( size.width() + 2 * maxBleed );
97 size.setHeight( size.height() + 2 * maxBleed );
98 }
99
100 return size;
101}
102
104{
105 if ( qgsDoubleNear( is.upperValue, is.lowerValue ) )
106 return s.minimumSize; // invalid value range => zero size
107
108 // Scale, if extension is smaller than the specified minimum
109 if ( value < s.minimumSize )
110 {
111 value = s.minimumSize;
112 }
113
114 double scaleFactor = ( ( is.upperSize.width() - is.lowerSize.width() ) / ( is.upperValue - is.lowerValue ) );
115 return value * scaleFactor;
116}
117
119{
121}
122
124{
125 Q_UNUSED( c )
126 QSizeF size;
127
128 if ( attributes.isEmpty() )
129 {
130 return QSizeF(); //zero size if no attributes
131 }
132
133 // eh - this method returns size in unknown units ...! We'll have to fake it and use a rough estimation of
134 // a conversion factor to painter units...
135 // TODO QGIS 4.0 -- these methods should all use painter units, dependent on the render context scaling...
136 double painterUnitConversionScale = c.convertToPainterUnits( 1, s.sizeType );
137
138 const double spacing = c.convertToPainterUnits( s.spacing(), s.spacingUnit(), s.spacingMapUnitScale() ) / painterUnitConversionScale;
139
140 switch ( s.diagramOrientation )
141 {
144 size.scale( s.barWidth, s.size.height() + spacing * std::max( 0, static_cast<int>( s.categoryAttributes.size() ) - 1 ), Qt::IgnoreAspectRatio );
145 break;
146
149 size.scale( s.size.width() + spacing * std::max( 0, static_cast<int>( s.categoryAttributes.size() ) - 1 ), s.barWidth, Qt::IgnoreAspectRatio );
150 break;
151 }
152
153 return size;
154}
155
156void QgsStackedBarDiagram::renderDiagram( const QgsFeature &feature, QgsRenderContext &c, const QgsDiagramSettings &s, QPointF position )
157{
158 QPainter *p = c.painter();
159 if ( !p )
160 {
161 return;
162 }
163
164 QList< QPair<double, QColor> > values;
165 QList< QPair<double, QColor> > negativeValues;
166
167 QgsExpressionContext expressionContext = c.expressionContext();
168 expressionContext.setFeature( feature );
169 if ( !feature.fields().isEmpty() )
170 expressionContext.setFields( feature.fields() );
171
172 values.reserve( s.categoryAttributes.size() );
173 double total = 0;
174 double negativeTotal = 0;
175
176 QList< QColor >::const_iterator colIt = s.categoryColors.constBegin();
177 for ( const QString &cat : std::as_const( s.categoryAttributes ) )
178 {
179 QgsExpression *expression = getExpression( cat, expressionContext );
180 double currentVal = expression->evaluate( &expressionContext ).toDouble();
181 total += fabs( currentVal );
182 if ( currentVal >= 0 )
183 {
184 values.push_back( qMakePair( currentVal, *colIt ) );
185 }
186 else
187 {
188 negativeTotal += currentVal;
189 negativeValues.push_back( qMakePair( -currentVal, *colIt ) );
190 }
191 ++colIt;
192 }
193
194
195 const double spacing = c.convertToPainterUnits( s.spacing(), s.spacingUnit(), s.spacingMapUnitScale() );
196 const double totalSpacing = std::max( 0, static_cast<int>( s.categoryAttributes.size() ) - 1 ) * spacing;
197
198 double scaledMaxVal = 0;
199 switch ( s.diagramOrientation )
200 {
203 scaledMaxVal = sizePainterUnits( s.size.height(), s, c );
204 break;
205
208 scaledMaxVal = sizePainterUnits( s.size.width(), s, c );
209 break;
210 }
211 if ( mApplySpacingAdjust )
212 scaledMaxVal -= totalSpacing;
213
214 double axisOffset = 0;
215 if ( !negativeValues.isEmpty() )
216 {
217 axisOffset = -negativeTotal / total * scaledMaxVal + ( negativeValues.size() - 1 ) * spacing;
218 }
219 double scaledWidth = sizePainterUnits( s.barWidth, s, c );
220
221 double baseX = position.x();
222 double baseY = position.y();
223
224 if ( s.showAxis() && s.axisLineSymbol() )
225 {
226 // if showing axis, the diagram position needs shifting from the default base x so that the axis
227 // line stroke sits within the desired label engine rect (otherwise we risk overlaps of the axis line stroke)
228 const double maxBleed = QgsSymbolLayerUtils::estimateMaxSymbolBleed( s.axisLineSymbol(), c );
229 baseX += maxBleed;
230 baseY -= maxBleed;
231 }
232
233 mPen.setColor( s.penColor );
234 setPenWidth( mPen, s, c );
235 p->setPen( mPen );
236
237 while ( !negativeValues.isEmpty() )
238 {
239 values.push_front( negativeValues.takeLast() );
240 }
241
242 double currentOffset = 0;
243 QList< QPair<double, QColor> >::const_iterator valIt = values.constBegin();
244 for ( ; valIt != values.constEnd(); ++valIt )
245 {
246 double length = valIt->first / total * scaledMaxVal;
247
248 QColor brushColor( valIt->second );
249 brushColor.setAlphaF( brushColor.alphaF() * s.opacity );
250 mCategoryBrush.setColor( brushColor );
251 p->setBrush( mCategoryBrush );
252
253 switch ( s.diagramOrientation )
254 {
256 p->drawRect( QRectF( baseX, baseY - currentOffset, scaledWidth, length * -1 ) );
257 break;
258
260 p->drawRect( QRectF( baseX, baseY + currentOffset - scaledMaxVal - spacing * std::max( 0, static_cast<int>( values.size() ) - 1 ), scaledWidth, length ) );
261 break;
262
264 p->drawRect( QRectF( baseX + currentOffset, baseY - scaledWidth, length, scaledWidth ) );
265 break;
266
268 p->drawRect( QRectF( baseX + scaledMaxVal - currentOffset + spacing * std::max( 0, static_cast<int>( values.size() ) - 1 ), baseY - scaledWidth, 0 - length, scaledWidth ) );
269 break;
270 }
271
272 currentOffset += length + spacing;
273 }
274
275 if ( s.showAxis() && s.axisLineSymbol() )
276 {
278 QPolygonF axisPoints;
279 switch ( s.diagramOrientation )
280 {
282 axisPoints << QPointF( baseX, baseY - scaledMaxVal - spacing * std::max( 0, static_cast<int>( values.size() ) - 1 ) )
283 << QPointF( baseX, baseY - axisOffset )
284 << QPointF( baseX + scaledWidth, baseY - axisOffset );
285 break;
286
288 axisPoints << QPointF( baseX, baseY )
289 << QPointF( baseX, baseY - scaledMaxVal - spacing * std::max( 0, static_cast<int>( values.size() ) - 1 ) + axisOffset )
290 << QPointF( baseX + scaledWidth, baseY - scaledMaxVal - spacing * std::max( 0, static_cast<int>( values.size() ) - 1 ) + axisOffset );
291 break;
292
294 axisPoints << QPointF( baseX + scaledMaxVal + spacing * std::max( 0, static_cast<int>( values.size() ) - 1 ), baseY - scaledWidth )
295 << QPointF( baseX + axisOffset, baseY - scaledWidth )
296 << QPointF( baseX + axisOffset, baseY );
297 break;
298
300 axisPoints << QPointF( baseX, baseY - scaledWidth )
301 << QPointF( baseX + scaledMaxVal + spacing * std::max( 0, static_cast<int>( values.size() ) - 1 ) - axisOffset, baseY - scaledWidth )
302 << QPointF( baseX + scaledMaxVal + spacing * std::max( 0, static_cast<int>( values.size() ) - 1 ) - axisOffset, baseY );
303 break;
304 }
305
306 s.axisLineSymbol()->renderPolyline( axisPoints, nullptr, c );
308 }
309}
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.
QgsUnitTypes::RenderUnit spacingUnit() const
Returns the units for the content spacing.
QgsUnitTypes::RenderUnit sizeType
Diagram size unit.
bool showAxis() const
Returns true if the diagram axis should be shown.
double opacity
Opacity, from 0 (transparent) to 1.0 (opaque)
QgsLineSymbol * axisLineSymbol() const
Returns the line symbol to use for rendering axis in diagrams.
QList< QString > categoryAttributes
DiagramOrientation diagramOrientation
double spacing() const
Returns the spacing between diagram contents.
QList< QColor > categoryColors
const QgsMapUnitScale & spacingMapUnitScale() const
Returns the map unit scale for the content spacing.
double minimumSize
Scale diagrams smaller than mMinimumSize to mMinimumSize.
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
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
void renderPolyline(const QPolygonF &points, const QgsFeature *f, QgsRenderContext &context, int layer=-1, bool selected=false)
Renders the symbol along the line joining points, using the given render context.
Contains information about the context of a rendering operation.
A stacked bar chart diagram.
QgsStackedBarDiagram * 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.
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.
QString diagramName() const override
Gets a descriptive name for this diagram type.
void renderDiagram(const QgsFeature &feature, QgsRenderContext &c, const QgsDiagramSettings &s, QPointF position) override
Draws the diagram at the given position (in pixel coordinates)
static double estimateMaxSymbolBleed(QgsSymbol *symbol, const QgsRenderContext &context)
Returns the maximum estimated bleed for the symbol.
void stopRender(QgsRenderContext &context)
Ends the rendering process.
Definition: qgssymbol.cpp:873
void startRender(QgsRenderContext &context, const QgsFields &fields=QgsFields())
Begins the rendering process for the symbol.
Definition: qgssymbol.cpp:825
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:2527
#define DIAGRAM_NAME_STACKED