QGIS API Documentation  3.0.2-Girona (307d082)
qgsrendercontext.cpp
Go to the documentation of this file.
1 /***************************************************************************
2  qgsrendercontext.cpp
3  --------------------
4  begin : March 16, 2008
5  copyright : (C) 2008 by Marco Hugentobler
6  email : marco dot hugentobler at karto dot baug dot ethz dot ch
7  ***************************************************************************/
8 
9 /***************************************************************************
10  * *
11  * This program is free software; you can redistribute it and/or modify *
12  * it under the terms of the GNU General Public License as published by *
13  * the Free Software Foundation; either version 2 of the License, or *
14  * (at your option) any later version. *
15  * *
16  ***************************************************************************/
17 
18 
19 #include "qgsrendercontext.h"
20 
21 #include "qgsmapsettings.h"
22 #include "qgsexpression.h"
23 #include "qgsvectorlayer.h"
25 #include "qgslogger.h"
26 #include "qgspoint.h"
27 
28 #define POINTS_TO_MM 2.83464567
29 #define INCH_TO_MM 25.4
30 
32  : mFlags( DrawEditingInfo | UseAdvancedEffects | DrawSelection | UseRenderingOptimization )
33 {
35  // For RenderMetersInMapUnits support, when rendering in Degrees, the Ellipsoid must be set
36  // - for Previews/Icons the default Extent can be used
37  mDistanceArea.setEllipsoid( mDistanceArea.sourceCrs().ellipsoidAcronym() );
38 }
39 
41  : mFlags( rh.mFlags )
42  , mPainter( rh.mPainter )
43  , mCoordTransform( rh.mCoordTransform )
44  , mDistanceArea( rh.mDistanceArea )
45  , mExtent( rh.mExtent )
46  , mMapToPixel( rh.mMapToPixel )
47  , mRenderingStopped( rh.mRenderingStopped )
48  , mScaleFactor( rh.mScaleFactor )
49  , mRendererScale( rh.mRendererScale )
50  , mLabelingEngine( rh.mLabelingEngine )
51  , mSelectionColor( rh.mSelectionColor )
52  , mVectorSimplifyMethod( rh.mVectorSimplifyMethod )
53  , mExpressionContext( rh.mExpressionContext )
54  , mGeometry( rh.mGeometry )
55  , mFeatureFilterProvider( rh.mFeatureFilterProvider ? rh.mFeatureFilterProvider->clone() : nullptr )
56  , mSegmentationTolerance( rh.mSegmentationTolerance )
57  , mSegmentationToleranceType( rh.mSegmentationToleranceType )
58  , mTransformContext( rh.mTransformContext )
59  , mPathResolver( rh.mPathResolver )
60 #ifdef QGISDEBUG
61  , mHasTransformContext( rh.mHasTransformContext )
62 #endif
63 {
64 }
65 
67 {
68  mFlags = rh.mFlags;
69  mPainter = rh.mPainter;
70  mCoordTransform = rh.mCoordTransform;
71  mExtent = rh.mExtent;
72  mMapToPixel = rh.mMapToPixel;
73  mRenderingStopped = rh.mRenderingStopped;
74  mScaleFactor = rh.mScaleFactor;
75  mRendererScale = rh.mRendererScale;
76  mLabelingEngine = rh.mLabelingEngine;
77  mSelectionColor = rh.mSelectionColor;
78  mVectorSimplifyMethod = rh.mVectorSimplifyMethod;
79  mExpressionContext = rh.mExpressionContext;
80  mGeometry = rh.mGeometry;
81  mFeatureFilterProvider.reset( rh.mFeatureFilterProvider ? rh.mFeatureFilterProvider->clone() : nullptr );
82  mSegmentationTolerance = rh.mSegmentationTolerance;
83  mSegmentationToleranceType = rh.mSegmentationToleranceType;
84  mDistanceArea = rh.mDistanceArea;
85  mTransformContext = rh.mTransformContext;
86  mPathResolver = rh.mPathResolver;
87 #ifdef QGISDEBUG
88  mHasTransformContext = rh.mHasTransformContext;
89 #endif
90 
91  return *this;
92 }
93 
95 {
96  QgsRenderContext context;
97  context.setPainter( painter );
98  if ( painter && painter->device() )
99  {
100  context.setScaleFactor( painter->device()->logicalDpiX() / 25.4 );
101  }
102  else
103  {
104  context.setScaleFactor( 3.465 ); //assume 88 dpi as standard value
105  }
106  return context;
107 }
108 
110 {
111 #ifdef QGISDEBUG
112  if ( !mHasTransformContext )
113  qWarning( "No QgsCoordinateTransformContext context set for transform" );
114 #endif
115  return mTransformContext;
116 }
117 
119 {
120  mTransformContext = context;
121 #ifdef QGISDEBUG
122  mHasTransformContext = true;
123 #endif
124 }
125 
126 void QgsRenderContext::setFlags( QgsRenderContext::Flags flags )
127 {
128  mFlags = flags;
129 }
130 
132 {
133  if ( on )
134  mFlags |= flag;
135  else
136  mFlags &= ~flag;
137 }
138 
139 QgsRenderContext::Flags QgsRenderContext::flags() const
140 {
141  return mFlags;
142 }
143 
145 {
146  return mFlags.testFlag( flag );
147 }
148 
150 {
151  QgsRenderContext ctx;
152  ctx.setMapToPixel( mapSettings.mapToPixel() );
153  ctx.setExtent( mapSettings.visibleExtent() );
159  ctx.setSelectionColor( mapSettings.selectionColor() );
166  ctx.setScaleFactor( mapSettings.outputDpi() / 25.4 ); // = pixels per mm
167  ctx.setRendererScale( mapSettings.scale() );
168  ctx.setExpressionContext( mapSettings.expressionContext() );
169  ctx.setSegmentationTolerance( mapSettings.segmentationTolerance() );
171  ctx.mDistanceArea.setSourceCrs( mapSettings.destinationCrs(), mapSettings.transformContext() );
172  ctx.mDistanceArea.setEllipsoid( mapSettings.ellipsoid() );
173  ctx.setTransformContext( mapSettings.transformContext() );
174  ctx.setPathResolver( mapSettings.pathResolver() );
175  //this flag is only for stopping during the current rendering progress,
176  //so must be false at every new render operation
177  ctx.setRenderingStopped( false );
178 
179  return ctx;
180 }
181 
183 {
184  return mFlags.testFlag( ForceVectorOutput );
185 }
186 
188 {
189  return mFlags.testFlag( UseAdvancedEffects );
190 }
191 
193 {
194  setFlag( UseAdvancedEffects, enabled );
195 }
196 
198 {
199  return mFlags.testFlag( DrawEditingInfo );
200 }
201 
203 {
204  return mFlags.testFlag( DrawSelection );
205 }
206 
208 {
209  mCoordTransform = t;
210 }
211 
213 {
214  setFlag( DrawEditingInfo, b );
215 }
216 
218 {
219  setFlag( ForceVectorOutput, force );
220 }
221 
223 {
224  setFlag( DrawSelection, showSelection );
225 }
226 
228 {
229  return mFlags.testFlag( UseRenderingOptimization );
230 }
231 
233 {
234  setFlag( UseRenderingOptimization, enabled );
235 }
236 
238 {
239  if ( ffp )
240  {
241  mFeatureFilterProvider.reset( ffp->clone() );
242  }
243  else
244  {
245  mFeatureFilterProvider.reset( nullptr );
246  }
247 }
248 
250 {
251  return mFeatureFilterProvider.get();
252 }
253 
255 {
256  double conversionFactor = 1.0;
257  switch ( unit )
258  {
260  conversionFactor = mScaleFactor;
261  break;
262 
264  conversionFactor = mScaleFactor / POINTS_TO_MM;
265  break;
266 
268  conversionFactor = mScaleFactor * INCH_TO_MM;
269  break;
270 
272  {
273  size = convertMetersToMapUnits( size );
275  // Fall through to RenderMapUnits with size in meters converted to size in MapUnits
276  FALLTHROUGH;
277  }
279  {
280  double mup = scale.computeMapUnitsPerPixel( *this );
281  if ( mup > 0 )
282  {
283  conversionFactor = 1.0 / mup;
284  }
285  else
286  {
287  conversionFactor = 1.0;
288  }
289  break;
290  }
292  conversionFactor = 1.0;
293  break;
294 
297  //no sensible value
298  conversionFactor = 1.0;
299  break;
300  }
301 
302  double convertedSize = size * conversionFactor;
303 
304  if ( unit == QgsUnitTypes::RenderMapUnits )
305  {
306  //check max/min size
307  if ( scale.minSizeMMEnabled )
308  convertedSize = std::max( convertedSize, scale.minSizeMM * mScaleFactor );
309  if ( scale.maxSizeMMEnabled )
310  convertedSize = std::min( convertedSize, scale.maxSizeMM * mScaleFactor );
311  }
312 
313  return convertedSize;
314 }
315 
316 double QgsRenderContext::convertToMapUnits( double size, QgsUnitTypes::RenderUnit unit, const QgsMapUnitScale &scale ) const
317 {
318  double mup = mMapToPixel.mapUnitsPerPixel();
319 
320  switch ( unit )
321  {
323  {
324  size = convertMetersToMapUnits( size );
325  // Fall through to RenderMapUnits with values of meters converted to MapUnits
326  FALLTHROUGH;
327  }
329  {
330  // check scale
331  double minSizeMU = -DBL_MAX;
332  if ( scale.minSizeMMEnabled )
333  {
334  minSizeMU = scale.minSizeMM * mScaleFactor * mup;
335  }
336  if ( !qgsDoubleNear( scale.minScale, 0.0 ) )
337  {
338  minSizeMU = std::max( minSizeMU, size * ( mRendererScale / scale.minScale ) );
339  }
340  size = std::max( size, minSizeMU );
341 
342  double maxSizeMU = DBL_MAX;
343  if ( scale.maxSizeMMEnabled )
344  {
345  maxSizeMU = scale.maxSizeMM * mScaleFactor * mup;
346  }
347  if ( !qgsDoubleNear( scale.maxScale, 0.0 ) )
348  {
349  maxSizeMU = std::min( maxSizeMU, size * ( mRendererScale / scale.maxScale ) );
350  }
351  size = std::min( size, maxSizeMU );
352 
353  return size;
354  }
356  {
357  return size * mScaleFactor * mup;
358  }
360  {
361  return size * mScaleFactor * mup / POINTS_TO_MM;
362  }
364  {
365  return size * mScaleFactor * mup * INCH_TO_MM;
366  }
368  {
369  return size * mup;
370  }
371 
374  //no sensible value
375  return 0.0;
376  }
377  return 0.0;
378 }
379 
380 double QgsRenderContext::convertFromMapUnits( double sizeInMapUnits, QgsUnitTypes::RenderUnit outputUnit ) const
381 {
382  double mup = mMapToPixel.mapUnitsPerPixel();
383 
384  switch ( outputUnit )
385  {
387  {
388  return sizeInMapUnits / convertMetersToMapUnits( 1.0 );
389  }
391  {
392  return sizeInMapUnits;
393  }
395  {
396  return sizeInMapUnits / ( mScaleFactor * mup );
397  }
399  {
400  return sizeInMapUnits / ( mScaleFactor * mup / POINTS_TO_MM );
401  }
403  {
404  return sizeInMapUnits / ( mScaleFactor * mup * INCH_TO_MM );
405  }
407  {
408  return sizeInMapUnits / mup;
409  }
410 
413  //no sensible value
414  return 0.0;
415  }
416  return 0.0;
417 }
418 
419 double QgsRenderContext::convertMetersToMapUnits( double meters ) const
420 {
421  switch ( mDistanceArea.sourceCrs().mapUnits() )
422  {
424  return meters;
426  {
427  QgsPointXY pointCenter = mExtent.center();
428  // The Extent is in the sourceCrs(), when different from destinationCrs()
429  // - the point must be transformed, since DistanceArea uses the destinationCrs()
430  // Note: the default QgsCoordinateTransform() : authid() will return an empty String
431  if ( !mCoordTransform.isShortCircuited() )
432  {
433  pointCenter = mCoordTransform.transform( pointCenter );
434  }
435  return mDistanceArea.measureLineProjected( pointCenter, meters );
436  }
445  return ( meters * QgsUnitTypes::fromUnitToUnitFactor( QgsUnitTypes::DistanceMeters, mDistanceArea.sourceCrs().mapUnits() ) );
446  }
447  return meters;
448 }
void setForceVectorOutput(bool force)
Meters value as Map units.
Definition: qgsunittypes.h:109
double convertToMapUnits(double size, QgsUnitTypes::RenderUnit unit, const QgsMapUnitScale &scale=QgsMapUnitScale()) const
Converts a size from the specified units to map units.
Enable layer opacity and blending effects.
void setRenderingStopped(bool stopped)
double minSizeMM
The minimum size in millimeters, or 0.0 if unset.
Enable vector simplification and other rendering optimizations.
virtual QgsFeatureFilterProvider * clone() const =0
Create a clone of the feature filter provider.
QgsCoordinateTransformContext transformContext() const
Returns the coordinate transform context, which stores various information regarding which datum tran...
const QgsExpressionContext & expressionContext() const
Gets the expression context.
QgsCoordinateTransformContext transformContext() const
Returns the context's coordinate transform context, which stores various information regarding which ...
void setFlags(QgsRenderContext::Flags flags)
Set combination of flags that will be used for rendering.
Use antialiasing while drawing.
double convertFromMapUnits(double sizeInMapUnits, QgsUnitTypes::RenderUnit outputUnit) const
Converts a size from map units to the specified units.
void setCoordinateTransform(const QgsCoordinateTransform &t)
Sets coordinate transformation.
A class to represent a 2D point.
Definition: qgspointxy.h:43
void setSimplifyHints(SimplifyHints simplifyHints)
Sets the simplification hints of the vector layer managed.
void setRendererScale(double scale)
Sets the renderer map scale.
Whether to make extra effort to update map image with partially rendered layers (better for interacti...
void setPathResolver(const QgsPathResolver &resolver)
Sets the path resolver for conversion between relative and absolute paths during rendering operations...
void setTransformContext(const QgsCoordinateTransformContext &context)
Sets the context's coordinate transform context, which stores various information regarding which dat...
double computeMapUnitsPerPixel(const QgsRenderContext &c) const
Computes a map units per pixel scaling factor, respecting the minimum and maximum scales set for the ...
Flags flags() const
Return combination of flags used for rendering.
bool setEllipsoid(const QString &ellipsoid)
Sets the ellipsoid by its acronym.
Percentage of another measurement (e.g., canvas size, feature size)
Definition: qgsunittypes.h:105
Enable layer opacity and blending effects.
Whether vector selections should be shown in the rendered map.
void setExtent(const QgsRectangle &extent)
QgsRectangle visibleExtent() const
Return the actual extent derived from requested extent that takes takes output image size into accoun...
bool qgsDoubleNear(double a, double b, double epsilon=4 *DBL_EPSILON)
Compare two doubles (but allow some difference)
Definition: qgis.h:251
double maxScale
The maximum scale, or 0.0 if unset.
const QgsFeatureFilterProvider * featureFilterProvider() const
Get the filter feature provider used for additional filtering of rendered features.
bool minSizeMMEnabled
Whether the minimum size in mm should be respected.
QgsCoordinateReferenceSystem destinationCrs() const
returns CRS of destination coordinate reference system
Vector graphics should not be cached and drawn as raster images.
The QgsMapSettings class contains configuration for rendering of the map.
double convertMetersToMapUnits(double meters) const
Convert meter distances to active MapUnit values for QgsUnitTypes::RenderMetersInMapUnits.
void setSelectionColor(const QColor &color)
No simplification can be applied.
QString ellipsoidAcronym() const
Returns the ellipsoid acronym for the ellipsoid used by the CRS.
void setUseAdvancedEffects(bool enabled)
Used to enable or disable advanced effects such as blend modes.
void setScaleFactor(double factor)
Sets the scaling factor for the render to convert painter units to physical sizes.
#define FALLTHROUGH
Definition: qgis.h:548
QgsRenderContext & operator=(const QgsRenderContext &rh)
#define INCH_TO_MM
bool isShortCircuited() const
Returns true if the transform short circuits because the source and destination are equivalent...
Whether vector selections should be shown in the rendered map.
double scale() const
Returns the calculated map scale.
void setDrawEditingInformation(bool b)
Enable anti-aliasing for map rendering.
points (e.g., for font sizes)
Definition: qgsunittypes.h:107
static QgsRenderContext fromQPainter(QPainter *painter)
Creates a default render context given a pixel based QPainter destination.
bool drawEditingInformation() const
Draw bounds of symbols (for debugging/testing)
Degrees, for planar geographic CRS distance measurements.
Definition: qgsunittypes.h:51
void setPainter(QPainter *p)
Sets the destination QPainter for the render operation.
Abstract interface for use by classes that filter the features of a layer.
void setSegmentationToleranceType(QgsAbstractGeometry::SegmentationToleranceType type)
Sets segmentation tolerance type (maximum angle or maximum difference between curve and approximation...
Contains information about the context in which a coordinate transform is executed.
double mapUnitsPerPixel() const
Return current map units per pixel.
const QgsMapToPixel & mapToPixel() const
Draw bounds of symbols (for debugging/testing)
Vector graphics should not be cached and drawn as raster images.
Enable drawing of vertex markers for layers in editing mode.
QgsAbstractGeometry::SegmentationToleranceType segmentationToleranceType() const
Gets segmentation tolerance type (maximum angle or maximum difference between curve and approximation...
const QgsPathResolver & pathResolver() const
Returns the path resolver for conversion between relative and absolute paths during rendering operati...
bool forceVectorOutput() const
QgsCoordinateReferenceSystem sourceCrs() const
Returns the source spatial reference system.
void setSegmentationTolerance(double tolerance)
Sets the segmentation tolerance applied when rendering curved geometries.
bool useRenderingOptimization() const
Returns true if the rendering optimization (geometry simplification) can be executed.
Draw map such that there are no problems between adjacent tiles.
Unknown distance unit.
Definition: qgsunittypes.h:54
Render is a 'canvas preview' render, and shortcuts should be taken to ensure fast rendering...
double outputDpi() const
Return DPI used for conversion between real world units (e.g.
Render is a 'canvas preview' render, and shortcuts should be taken to ensure fast 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).
#define POINTS_TO_MM
QString ellipsoid() const
Returns ellipsoid's acronym.
double segmentationTolerance() const
Gets the segmentation tolerance applied when rendering curved geometries.
QPainter * painter()
Returns the destination QPainter for the render operation.
double maxSizeMM
The maximum size in millimeters, or 0.0 if unset.
Struct for storing maximum and minimum scales for measurements in map units.
Whether to make extra effort to update map image with partially rendered layers (better for interacti...
QgsPointXY transform(const QgsPointXY &point, TransformDirection direction=ForwardTransform) const
Transform the point from the source CRS to the destination CRS.
static QgsRenderContext fromMapSettings(const QgsMapSettings &mapSettings)
create initialized QgsRenderContext instance from given QgsMapSettings
double measureLineProjected(const QgsPointXY &p1, double distance=1, double azimuth=M_PI_2, QgsPointXY *projectedPoint=nullptr) const
Calculates the distance from one point with distance in meters and azimuth (direction) When the sourc...
bool useAdvancedEffects() const
Returns true if advanced effects such as blend modes such be used.
void setMapToPixel(const QgsMapToPixel &mtp)
Class for doing transforms between two map coordinate systems.
void setUseRenderingOptimization(bool enabled)
bool showSelection() const
Returns true if vector selections should be shown in the rendered map.
void setFlag(Flag flag, bool on=true)
Enable or disable a particular flag (other flags are not affected)
void setFeatureFilterProvider(const QgsFeatureFilterProvider *ffp)
Set a filter feature provider used for additional filtering of rendered features. ...
Enable vector simplification and other rendering optimizations.
void setSourceCrs(const QgsCoordinateReferenceSystem &crs, const QgsCoordinateTransformContext &context)
Sets source spatial reference system crs.
bool testFlag(Flag flag) const
Check whether a particular flag is enabled.
QColor selectionColor() const
Get color that is used for drawing of selected vector features.
QgsPointXY center() const
Returns the center point of the rectangle.
Definition: qgsrectangle.h:170
void setShowSelection(const bool showSelection)
Sets whether vector selections should be shown in the rendered map.
bool testFlag(Flag flag) const
Check whether a particular flag is enabled.
Terrestrial miles.
Definition: qgsunittypes.h:50
Draw map such that there are no problems between adjacent tiles.
Flag
Enumeration of flags that affect rendering operations.
static Q_INVOKABLE double fromUnitToUnitFactor(QgsUnitTypes::DistanceUnit fromUnit, QgsUnitTypes::DistanceUnit toUnit)
Returns the conversion factor between the specified distance units.
Enable drawing of vertex markers for layers in editing mode.
double minScale
The minimum scale, or 0.0 if unset.
bool maxSizeMMEnabled
Whether the maximum size in mm should be respected.
RenderUnit
Rendering size units.
Definition: qgsunittypes.h:100
void setExpressionContext(const QgsExpressionContext &context)
Sets the expression context.