//the format defaults to "PNG" if not specified
void QgsMapCanvas::saveAsImage( const QString& theFileName, QPixmap * theQPixmap, const QString& theFormat )
{
//
//check if the optional QPaintDevice was supplied
//
if ( theQPixmap != NULL )
{
// render
QPainter painter;
painter.begin( theQPixmap );
QgsMapRendererCustomPainterJob job( mSettings, &painter );
job.start();
job.waitForFinished();
emit renderComplete( &painter );
painter.end();
theQPixmap->save( theFileName, theFormat.toLocal8Bit().data() );
}
else //use the map view
{
mMap->contentImage().save( theFileName, theFormat.toLocal8Bit().data() );
}
//create a world file to go with the image...
QgsRectangle myRect = mapSettings().visibleExtent();
QString myHeader;
// note: use 17 places of precision for all numbers output
//Pixel XDim
myHeader += qgsDoubleToString( mapUnitsPerPixel() ) + "\r\n";
//Rotation on y axis - hard coded
myHeader += "0 \r\n";
//Rotation on x axis - hard coded
myHeader += "0 \r\n";
//Pixel YDim - almost always negative - see
//http://en.wikipedia.org/wiki/World_file#cite_note-2
myHeader += '-' + qgsDoubleToString( mapUnitsPerPixel() ) + "\r\n";
//Origin X (center of top left cell)
myHeader += qgsDoubleToString( myRect.xMinimum() + ( mapUnitsPerPixel() / 2 ) ) + "\r\n";
//Origin Y (center of top left cell)
myHeader += qgsDoubleToString( myRect.yMaximum() - ( mapUnitsPerPixel() / 2 ) ) + "\r\n";
QFileInfo myInfo = QFileInfo( theFileName );
// allow dotted names
QString myWorldFileName = myInfo.absolutePath() + '/' + myInfo.completeBaseName() + '.' + theFormat + 'w';
QFile myWorldFile( myWorldFileName );
if ( !myWorldFile.open( QIODevice::WriteOnly ) ) //don't use QIODevice::Text
{
return;
}
QTextStream myStream( &myWorldFile );
myStream << myHeader;
} // saveAsImage
void QgsMapSettings::updateDerived()
{
QgsRectangle extent = mExtent;
if ( extent.isEmpty() || !extent.isFinite() )
{
mValid = false;
return;
}
// Don't allow zooms where the current extent is so small that it
// can't be accurately represented using a double (which is what
// currentExtent uses). Excluding 0 avoids a divide by zero and an
// infinite loop when rendering to a new canvas. Excluding extents
// greater than 1 avoids doing unnecessary calculations.
// The scheme is to compare the width against the mean x coordinate
// (and height against mean y coordinate) and only allow zooms where
// the ratio indicates that there is more than about 12 significant
// figures (there are about 16 significant figures in a double).
if ( extent.width() > 0 &&
extent.height() > 0 &&
extent.width() < 1 &&
extent.height() < 1 )
{
// Use abs() on the extent to avoid the case where the extent is
// symmetrical about 0.
double xMean = ( qAbs( extent.xMinimum() ) + qAbs( extent.xMaximum() ) ) * 0.5;
double yMean = ( qAbs( extent.yMinimum() ) + qAbs( extent.yMaximum() ) ) * 0.5;
double xRange = extent.width() / xMean;
double yRange = extent.height() / yMean;
static const double minProportion = 1e-12;
if ( xRange < minProportion || yRange < minProportion )
{
mValid = false;
return;
}
}
double myHeight = mSize.height();
double myWidth = mSize.width();
if ( !myWidth || !myHeight )
{
mValid = false;
return;
}
// calculate the translation and scaling parameters
double mapUnitsPerPixelY = mExtent.height() / myHeight;
double mapUnitsPerPixelX = mExtent.width() / myWidth;
mMapUnitsPerPixel = mapUnitsPerPixelY > mapUnitsPerPixelX ? mapUnitsPerPixelY : mapUnitsPerPixelX;
// calculate the actual extent of the mapCanvas
double dxmin = mExtent.xMinimum(), dxmax = mExtent.xMaximum(),
dymin = mExtent.yMinimum(), dymax = mExtent.yMaximum(), whitespace;
if ( mapUnitsPerPixelY > mapUnitsPerPixelX )
{
whitespace = (( myWidth * mMapUnitsPerPixel ) - mExtent.width() ) * 0.5;
dxmin -= whitespace;
dxmax += whitespace;
}
else
{
whitespace = (( myHeight * mMapUnitsPerPixel ) - mExtent.height() ) * 0.5;
dymin -= whitespace;
dymax += whitespace;
}
mVisibleExtent.set( dxmin, dymin, dxmax, dymax );
// update the scale
mScaleCalculator.setDpi( mDpi );
mScale = mScaleCalculator.calculate( mVisibleExtent, mSize.width() );
mMapToPixel.setParameters( mapUnitsPerPixel(),
visibleExtent().center().x(),
visibleExtent().center().y(),
outputSize().width(),
outputSize().height(),
mRotation );
#if 1 // set visible extent taking rotation in consideration
if ( mRotation )
{
QgsPoint p1 = mMapToPixel.toMapCoordinates( QPoint( 0, 0 ) );
QgsPoint p2 = mMapToPixel.toMapCoordinates( QPoint( 0, myHeight ) );
QgsPoint p3 = mMapToPixel.toMapCoordinates( QPoint( myWidth, 0 ) );
QgsPoint p4 = mMapToPixel.toMapCoordinates( QPoint( myWidth, myHeight ) );
dxmin = std::min( p1.x(), std::min( p2.x(), std::min( p3.x(), p4.x() ) ) );
dymin = std::min( p1.y(), std::min( p2.y(), std::min( p3.y(), p4.y() ) ) );
dxmax = std::max( p1.x(), std::max( p2.x(), std::max( p3.x(), p4.x() ) ) );
dymax = std::max( p1.y(), std::max( p2.y(), std::max( p3.y(), p4.y() ) ) );
mVisibleExtent.set( dxmin, dymin, dxmax, dymax );
}
#endif
QgsDebugMsg( QString( "Map units per pixel (x,y) : %1, %2" ).arg( qgsDoubleToString( mapUnitsPerPixelX ), qgsDoubleToString( mapUnitsPerPixelY ) ) );
QgsDebugMsg( QString( "Pixmap dimensions (x,y) : %1, %2" ).arg( qgsDoubleToString( mSize.width() ), qgsDoubleToString( mSize.height() ) ) );
QgsDebugMsg( QString( "Extent dimensions (x,y) : %1, %2" ).arg( qgsDoubleToString( mExtent.width() ), qgsDoubleToString( mExtent.height() ) ) );
QgsDebugMsg( mExtent.toString() );
QgsDebugMsg( QString( "Adjusted map units per pixel (x,y) : %1, %2" ).arg( qgsDoubleToString( mVisibleExtent.width() / myWidth ), qgsDoubleToString( mVisibleExtent.height() / myHeight ) ) );
QgsDebugMsg( QString( "Recalced pixmap dimensions (x,y) : %1, %2" ).arg( qgsDoubleToString( mVisibleExtent.width() / mMapUnitsPerPixel ), qgsDoubleToString( mVisibleExtent.height() / mMapUnitsPerPixel ) ) );
QgsDebugMsg( QString( "Scale (assuming meters as map units) = 1:%1" ).arg( qgsDoubleToString( mScale ) ) );
QgsDebugMsg( QString( "Rotation: %1 degrees" ).arg( mRotation ) );
mValid = true;
}
