void QgsEffectStack::draw( QgsRenderContext &context )
{
QPainter* destPainter = context.painter();
//first, we build up a list of rendered effects
//we do this moving backwards through the stack, so that each effect's results
//becomes the source of the previous effect
QPicture* sourcePic = new QPicture( *source() );
QPicture* currentPic = sourcePic;
QList< QPicture* > results;
for ( int i = mEffectList.count() - 1; i >= 0; --i )
{
QgsPaintEffect* effect = mEffectList.at( i );
if ( !effect->enabled() )
{
continue;
}
QPicture* pic;
if ( effect->type() == "drawSource" )
{
//draw source is always the original source, regardless of previous effect results
pic = sourcePic;
}
else
{
pic = currentPic;
}
QPicture *resultPic = new QPicture();
QPainter p( resultPic );
context.setPainter( &p );
//effect stack has it's own handling of the QPicture DPI issue, so
//we disable QgsPaintEffect's internal workaround
effect->requiresQPainterDpiFix = false;
effect->render( *pic, context );
effect->requiresQPainterDpiFix = true;
p.end();
results << resultPic;
if ( mEffectList.at( i )->drawMode() != QgsPaintEffect::Render )
{
currentPic = resultPic;
}
}
delete sourcePic;
sourcePic = nullptr;
context.setPainter( destPainter );
//then, we render all the results in the opposite order
for ( int i = 0; i < mEffectList.count(); ++i )
{
if ( !mEffectList[i]->enabled() )
{
continue;
}
QPicture* pic = results.takeLast();
if ( mEffectList.at( i )->drawMode() != QgsPaintEffect::Modifier )
{
context.painter()->save();
fixQPictureDpi( context.painter() );
context.painter()->drawPicture( 0, 0, *pic );
context.painter()->restore();
}
delete pic;
}
}
