bool QgsMapRenderer::setExtent( const QgsRectangle& extent )
{
//remember the previous extent
mLastExtent = mExtent;
// 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 )
return false;
}
mExtent = extent;
if ( !extent.isEmpty() )
adjustExtentToSize();
emit extentsChanged();
return true;
}
void QgsMapRenderer::setOutputSize( QSizeF size, double dpi )
{
mSize = size;
mScaleCalculator->setDpi( dpi );
adjustExtentToSize();
}
void QgsMapRenderer::setOutputSize( QSize size, int dpi )
{
mSize = QSizeF( size.width(), size.height() );
mScaleCalculator->setDpi( dpi );
adjustExtentToSize();
}
