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Mask renderer: make it work with on-the-fly reprojection
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Hugo Mercier committed May 23, 2014
1 parent acf2c45 commit 3ec7337e66bd57e03852b9856637965228b8e80d
Showing with 75 additions and 19 deletions.
  1. +69 −19 src/core/symbology-ng/qgsmaskrendererv2.cpp
  2. +6 −0 src/core/symbology-ng/qgsmaskrendererv2.h
@@ -67,6 +67,37 @@ void QgsMaskRendererV2::startRender( QgsRenderContext& context, const QgsFields&
mFeaturesCategoryMap.clear();
mFeatureDecorations.clear();
mFields = fields;

// We compute coordinates of the extent which will serve as exterior ring
// for the final polygon
// It must be computed in the destination CRS if reprojection is enabled.
const QgsMapToPixel& mtp( context.mapToPixel() );

// convert viewport to dest CRS
QRect e( context.painter()->viewport() );
// add some space to hide borders and tend to infinity
e.adjust( -e.width()*10, -e.height()*10, e.width()*10, e.height()*10 );
QgsPolyline exteriorRing;
exteriorRing << mtp.toMapCoordinates( e.topLeft() );
exteriorRing << mtp.toMapCoordinates( e.topRight() );
exteriorRing << mtp.toMapCoordinates( e.bottomRight() );
exteriorRing << mtp.toMapCoordinates( e.bottomLeft() );
exteriorRing << mtp.toMapCoordinates( e.topLeft() );

mTransform = context.coordinateTransform();
// If reprojection is enabled, we must reproject during renderFeature
// and act as if there is no reprojection
// If we don't do that, there is no need to have a simple rectangular extent
// that covers the whole screen
// (a rectangle in the destCRS cannot be expressed as valid coordinates in the sourceCRS in general)
if (mTransform)
{
// disable projection
context.setCoordinateTransform(0);
}

mExtentPolygon.clear();
mExtentPolygon.append(exteriorRing);
}

bool QgsMaskRendererV2::renderFeature( QgsFeature& feature, QgsRenderContext& context, int layer, bool selected, bool drawVertexMarker )
@@ -126,20 +157,9 @@ bool QgsMaskRendererV2::renderFeature( QgsFeature& feature, QgsRenderContext& co
// operations do not need geometries to be valid
if ( ! mFeaturesCategoryMap.contains(catId) )
{
// add the exterior ring
QgsRectangle e = context.extent();
// add some space to hide borders
e.scale(2.0);
QgsPolyline extent_ring;
extent_ring.push_back( QgsPoint(e.xMinimum(), e.yMinimum()) );
extent_ring.push_back( QgsPoint(e.xMaximum(), e.yMinimum()) );
extent_ring.push_back( QgsPoint(e.xMaximum(), e.yMaximum()) );
extent_ring.push_back( QgsPoint(e.xMinimum(), e.yMaximum()) );
extent_ring.push_back( QgsPoint(e.xMinimum(), e.yMinimum()) );
// the exterior ring must be a square in the destination CRS
CombinedFeature cFeat;
QgsPolygon exterior_ring_poly;
exterior_ring_poly.append(extent_ring);
cFeat.multiPolygon.append(exterior_ring_poly);
cFeat.multiPolygon.append( mExtentPolygon );
// store the first feature
cFeat.feature = feature;
mFeaturesCategoryMap.insert( catId, cFeat );
@@ -161,13 +181,37 @@ bool QgsMaskRendererV2::renderFeature( QgsFeature& feature, QgsRenderContext& co
(geom->wkbType() == QGis::WKBMultiPolygon25D) ) {
multi = geom->asMultiPolygon();
}

for ( int i = 0; i < multi.size(); i++ ) {
// add the exterior ring as interior ring to the first polygon
cFeat.multiPolygon[0].append( multi[i][0] );
if ( mTransform ) {
QgsPolyline new_ls;
QgsPolyline& old_ls = multi[i][0];
for ( int k = 0; k < old_ls.size(); k++ ) {
new_ls.append( mTransform->transform( old_ls[k] ) );
}
cFeat.multiPolygon[0].append( new_ls );
}
else
{
cFeat.multiPolygon[0].append( multi[i][0] );
}
// add interior rings as new polygons
for ( int j = 1; j < multi[i].size(); j++ ) {
QgsPolygon new_poly;
new_poly.append( multi[i][j] );
if ( mTransform ) {
QgsPolyline new_ls;
QgsPolyline& old_ls = multi[i][j];
for ( int k = 0; k < old_ls.size(); k++ ) {
new_ls.append( mTransform->transform( old_ls[k] ) );
}
new_poly.append( new_ls );
}
else
{
new_poly.append( multi[i][j] );
}

cFeat.multiPolygon.append( new_poly );
}
}
@@ -188,14 +232,14 @@ void QgsMaskRendererV2::stopRender( QgsRenderContext& context )
}

// when no features are visible, we still have to draw the exterior rectangle
// warning: when sub renderers have more than one possible symbols,
// there is no way to choose a correct one, because there is no attribute here
// in that case, nothing will be rendered
if ( mFeaturesCategoryMap.isEmpty() )
{
QgsRectangle e = context.extent();
// add some space to hide borders
e.scale(2.0);
// empty feature with default attributes
QgsFeature feat( mFields );
feat.setGeometry( QgsGeometry::fromRect(e) );
feat.setGeometry( QgsGeometry::fromPolygon( mExtentPolygon ) );
mSubRenderer->renderFeature( feat, context );
}

@@ -206,6 +250,12 @@ void QgsMaskRendererV2::stopRender( QgsRenderContext& context )
}

mSubRenderer->stopRender( context );

if ( mTransform )
{
// restore the coordinate transform if needed
context.setCoordinateTransform( mTransform );
}
}

QString QgsMaskRendererV2::dump() const
@@ -123,6 +123,12 @@ class CORE_EXPORT QgsMaskRendererV2 : public QgsFeatureRendererV2
/** where features are stored, based on their symbol category */
FeatureCategoryMap mFeaturesCategoryMap;

/** the polygon used as exterior ring that covers the current extent */
QgsPolygon mExtentPolygon;

/** the current coordinate transform (or null) */
const QgsCoordinateTransform* mTransform;

/** fields of each feature*/
QgsFields mFields;

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