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Rewrite grid decoration to consider map rotation
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Closes http://hub.qgis.org/issues/11817
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Sandro Santilli committed Jan 15, 2015
1 parent ca4a60a commit 0c767ad
Showing 1 changed file with 104 additions and 106 deletions.
210 changes: 104 additions & 106 deletions src/app/qgsdecorationgrid.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -222,6 +222,7 @@ void QgsDecorationGrid::render( QPainter * p )
QList< QPair< double, QLineF > >::const_iterator vIt = verticalLines.constBegin();
QList< QPair< double, QLineF > > horizontalLines;
xGridLines( horizontalLines, p );
//QgsDebugMsg( QString("grid has %1 vertical and %2 horizontal lines").arg( verticalLines.size() ).arg( horizontalLines.size() ) );
QList< QPair< double, QLineF > >::const_iterator hIt = horizontalLines.constBegin();

// QRectF thisPaintRect = QRectF( 0, 0, QGraphicsRectItem::rect().width(), QGraphicsRectItem::rect().height() );
Expand Down Expand Up @@ -514,10 +515,60 @@ void QgsDecorationGrid::drawAnnotation( QPainter* p, const QPointF& pos, int rot
p->restore();
}

const QgsMapCanvas& canvas()
{
return *QgisApp::instance()->mapCanvas();
}

QPolygonF canvasPolygon()
{
QPolygonF poly;

const QgsMapCanvas& mapCanvas = canvas();
const QgsMapSettings& mapSettings = mapCanvas.mapSettings();
const QSize& sz = mapSettings.outputSize();
const QgsMapToPixel& m2p = mapSettings.mapToPixel();

poly << m2p.toMapCoordinatesF( 0, 0 ).toQPointF();
poly << m2p.toMapCoordinatesF( sz.width(), 0 ).toQPointF();
poly << m2p.toMapCoordinatesF( sz.width(), sz.height() ).toQPointF();
poly << m2p.toMapCoordinatesF( 0, sz.height() ).toQPointF();

return poly;
}

bool clipByRect(QLineF& line, const QPolygonF& rect)
{
QVector<QLineF> borderLines;
borderLines << QLineF( rect.at( 0 ), rect.at( 1 ) );
borderLines << QLineF( rect.at( 1 ), rect.at( 2 ) );
borderLines << QLineF( rect.at( 2 ), rect.at( 3 ) );
borderLines << QLineF( rect.at( 3 ), rect.at( 0 ) );

QList<QPointF> intersectionList;
QVector<QLineF>::const_iterator it = borderLines.constBegin();
for ( ; it != borderLines.constEnd(); ++it )
{
QPointF intersectionPoint;
if ( it->intersect( line, &intersectionPoint ) == QLineF::BoundedIntersection )
{
intersectionList.push_back( intersectionPoint );
if ( intersectionList.size() >= 2 )
{
break; //we already have two intersections, skip further tests
}
}
}
if ( intersectionList.size() < 2 ) return false; // no intersection

line = QLineF( intersectionList.at( 0 ), intersectionList.at( 1 ) );
return true;
}

QPolygonF canvasExtent()
{
QPolygonF poly;
QgsRectangle extent = QgisApp::instance()->mapCanvas()->extent();
QgsRectangle extent = canvas().extent();
poly << QPointF( extent.xMinimum(), extent.yMaximum() );
poly << QPointF( extent.xMaximum(), extent.yMaximum() );
poly << QPointF( extent.xMaximum(), extent.yMinimum() );
Expand All @@ -527,145 +578,92 @@ QPolygonF canvasExtent()

int QgsDecorationGrid::xGridLines( QList< QPair< double, QLineF > >& lines, QPainter * p ) const
{
// prepare horizontal lines
lines.clear();
if ( mGridIntervalY <= 0.0 )
{
return 1;
}

// QPolygonF mapPolygon = transformedMapPolygon();
QPolygonF mapPolygon = canvasExtent();
QRectF mapBoundingRect = mapPolygon.boundingRect();
const QgsMapCanvas& mapCanvas = canvas();
const QgsMapSettings& mapSettings = mapCanvas.mapSettings();
const QgsMapToPixel& m2p = mapSettings.mapToPixel();

// draw nothing if the distance between grid lines would be less than 1px
// otherwise the grid lines would completely cover the whole map
if ( mapBoundingRect.width() / mGridIntervalX >= p->device()->width() )
//if ( mapBoundingRect.height() / mGridIntervalY >= p->device()->height() )
if ( mGridIntervalY / mapSettings.mapUnitsPerPixel() < 1 )
return 1;

//consider to round up to the next step in case the left boundary is > 0
double roundCorrection = mapBoundingRect.top() > 0 ? 1.0 : 0.0;
double currentLevel = ( int )(( mapBoundingRect.top() - mGridOffsetY ) / mGridIntervalY + roundCorrection ) * mGridIntervalY + mGridOffsetY;

// if ( qgsDoubleNear( mRotation, 0.0 ) )
// {
//no rotation. Do it 'the easy way'

double yCanvasCoord;

while ( currentLevel <= mapBoundingRect.bottom() )
{
yCanvasCoord = p->device()->height() * ( 1 - ( currentLevel - mapBoundingRect.top() ) / mapBoundingRect.height() );
lines.push_back( qMakePair( currentLevel, QLineF( 0, yCanvasCoord, p->device()->width(), yCanvasCoord ) ) );
currentLevel += mGridIntervalY;
}
// }

//the four border lines
QVector<QLineF> borderLines;
borderLines << QLineF( mapPolygon.at( 0 ), mapPolygon.at( 1 ) );
borderLines << QLineF( mapPolygon.at( 1 ), mapPolygon.at( 2 ) );
borderLines << QLineF( mapPolygon.at( 2 ), mapPolygon.at( 3 ) );
borderLines << QLineF( mapPolygon.at( 3 ), mapPolygon.at( 0 ) );
const QPolygonF& canvasPoly = canvasPolygon();
const QPolygonF& mapPolygon = canvasExtent();
const QRectF& mapBoundingRect = mapPolygon.boundingRect();
QLineF lineEast ( mapPolygon[2], mapPolygon[1] );
QLineF lineWest ( mapPolygon[3], mapPolygon[0] );

QList<QPointF> intersectionList; //intersects between border lines and grid lines
double len = lineEast.length();
Q_ASSERT( fabs(len - lineWest.length()) < 1e-6 ); // no shear

while ( currentLevel <= mapBoundingRect.bottom() )
double roundCorrection = mapBoundingRect.top() > 0 ? 1.0 : 0.0;
double dist = ( int )(( mapBoundingRect.top() - mGridOffsetY ) / mGridIntervalY + roundCorrection ) * mGridIntervalY + mGridOffsetY;
dist = dist - mapBoundingRect.top();
while ( dist < len )
{
intersectionList.clear();
QLineF gridLine( mapBoundingRect.left(), currentLevel, mapBoundingRect.right(), currentLevel );

QVector<QLineF>::const_iterator it = borderLines.constBegin();
for ( ; it != borderLines.constEnd(); ++it )
{
QPointF intersectionPoint;
if ( it->intersect( gridLine, &intersectionPoint ) == QLineF::BoundedIntersection )
{
intersectionList.push_back( intersectionPoint );
if ( intersectionList.size() >= 2 )
{
break; //we already have two intersections, skip further tests
}
}
}

if ( intersectionList.size() >= 2 )
{
lines.push_back( qMakePair( currentLevel, QLineF( intersectionList.at( 0 ), intersectionList.at( 1 ) ) ) );
}
currentLevel += mGridIntervalY;
double t = dist / len;
QPointF p0 = lineWest.pointAt( t );
QPointF p1 = lineEast.pointAt( t );
QLineF line( p0, p1 );
clipByRect(line, canvasPoly);
line = QLineF( m2p.transform(QgsPoint(line.pointAt(0))).toQPointF(), m2p.transform(QgsPoint(line.pointAt(1))).toQPointF() );
lines.push_back( qMakePair( p0.y(), line ) );
dist += mGridIntervalY;
}


return 0;
}

int QgsDecorationGrid::yGridLines( QList< QPair< double, QLineF > >& lines, QPainter * p ) const
{
// prepare vertical lines

lines.clear();
if ( mGridIntervalX <= 0.0 )
{
return 1;
}

// QPolygonF mapPolygon = transformedMapPolygon();
QPolygonF mapPolygon = canvasExtent();
QRectF mapBoundingRect = mapPolygon.boundingRect();
const QgsMapCanvas& mapCanvas = canvas();
const QgsMapSettings& mapSettings = mapCanvas.mapSettings();
const QgsMapToPixel& m2p = mapSettings.mapToPixel();

// draw nothing if the distance between grid lines would be less than 1px
// otherwise the grid lines would completely cover the whole map
if ( mapBoundingRect.height() / mGridIntervalY >= p->device()->height() )
//if ( mapBoundingRect.height() / mGridIntervalY >= p->device()->height() )
if ( mGridIntervalX / mapSettings.mapUnitsPerPixel() < 1 )
return 1;

//consider to round up to the next step in case the left boundary is > 0
double roundCorrection = mapBoundingRect.left() > 0 ? 1.0 : 0.0;
double currentLevel = ( int )(( mapBoundingRect.left() - mGridOffsetX ) / mGridIntervalX + roundCorrection ) * mGridIntervalX + mGridOffsetX;
const QPolygonF& canvasPoly = canvasPolygon();
const QPolygonF& mapPolygon = canvasExtent();
QLineF lineSouth ( mapPolygon[3], mapPolygon[2] );
QLineF lineNorth ( mapPolygon[0], mapPolygon[1] );

// if ( qgsDoubleNear( mRotation, 0.0 ) )
// {
// //no rotation. Do it 'the easy way'
double xCanvasCoord;
double len = lineSouth.length();
Q_ASSERT( fabs(len - lineNorth.length()) < 1e-6 ); // no shear

while ( currentLevel <= mapBoundingRect.right() )
{
xCanvasCoord = p->device()->width() * ( currentLevel - mapBoundingRect.left() ) / mapBoundingRect.width();
lines.push_back( qMakePair( currentLevel, QLineF( xCanvasCoord, 0, xCanvasCoord, p->device()->height() ) ) );
currentLevel += mGridIntervalX;
}
// }

//the four border lines
QVector<QLineF> borderLines;
borderLines << QLineF( mapPolygon.at( 0 ), mapPolygon.at( 1 ) );
borderLines << QLineF( mapPolygon.at( 1 ), mapPolygon.at( 2 ) );
borderLines << QLineF( mapPolygon.at( 2 ), mapPolygon.at( 3 ) );
borderLines << QLineF( mapPolygon.at( 3 ), mapPolygon.at( 0 ) );

QList<QPointF> intersectionList; //intersects between border lines and grid lines

while ( currentLevel <= mapBoundingRect.right() )
{
intersectionList.clear();
QLineF gridLine( currentLevel, mapBoundingRect.bottom(), currentLevel, mapBoundingRect.top() );

QVector<QLineF>::const_iterator it = borderLines.constBegin();
for ( ; it != borderLines.constEnd(); ++it )
{
QPointF intersectionPoint;
if ( it->intersect( gridLine, &intersectionPoint ) == QLineF::BoundedIntersection )
{
intersectionList.push_back( intersectionPoint );
if ( intersectionList.size() >= 2 )
{
break; //we already have two intersections, skip further tests
}
}
}

if ( intersectionList.size() >= 2 )
{
lines.push_back( qMakePair( currentLevel, QLineF( intersectionList.at( 0 ), intersectionList.at( 1 ) ) ) );
}
currentLevel += mGridIntervalX;
const QRectF& mapBoundingRect = mapPolygon.boundingRect();
double roundCorrection = mapBoundingRect.left() > 0 ? 1.0 : 0.0;
double dist = ( int )(( mapBoundingRect.left() - mGridOffsetX ) / mGridIntervalX + roundCorrection ) * mGridIntervalX + mGridOffsetX;
dist = dist - mapBoundingRect.left();
while ( dist < len )
{
double t = dist / len;
QPointF p0( lineNorth.pointAt( t ) );
QPointF p1( lineSouth.pointAt( t ) );
QLineF line( p0, p1 );
clipByRect(line, canvasPoly);
line = QLineF( m2p.transform(QgsPoint(line.pointAt(0))).toQPointF(), m2p.transform(QgsPoint(line.pointAt(1))).toQPointF() );
lines.push_back( qMakePair( p0.x(), line ) );
dist += mGridIntervalX;
}

return 0;
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