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Unlock composition using transformed previewed cache image of labeling

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results as well as map layers

This extends the recent addition of smooth map updates for raster
layers to also apply to map labels. Now you'll see a scaled/transformed
version of the previous map render's labels while the new labeling
results are being generated in the background.

Avoids "flashy" redraws of map labels
This commit is contained in:
Nyall Dawson 2021-01-27 13:20:12 +10:00
parent 0edd4f94e8
commit c4818a0de7
4 changed files with 18 additions and 1 deletions
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1
python/core/auto_generated/qgsmaprendererjob.sip.in
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@ -156,6 +156,7 @@ Returns map settings with which this job was started.
%End
signals:
void renderingLayersFinished();

9
src/core/qgsmaprendererjob.cpp
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@ -47,6 +47,7 @@
///@cond PRIVATE
const QString QgsMapRendererJob::LABEL_CACHE_ID = QStringLiteral( "_labels_" );
const QString QgsMapRendererJob::LABEL_PREVIEW_CACHE_ID = QStringLiteral( "_preview_labels_" );
bool LayerRenderJob::imageCanBeComposed() const
{
@ -750,6 +751,7 @@ void QgsMapRendererJob::cleanupLabelJob( LabelRenderJob &job )
{
QgsDebugMsgLevel( QStringLiteral( "caching label result image" ), 2 );
mCache->setCacheImage( LABEL_CACHE_ID, *job.img, _qgis_listQPointerToRaw( job.participatingLayers ) );
mCache->setCacheImage( LABEL_PREVIEW_CACHE_ID, *job.img, _qgis_listQPointerToRaw( job.participatingLayers ) );
}
delete job.img;
@ -816,6 +818,13 @@ QImage QgsMapRendererJob::composeImage(
painter.setOpacity( 1.0 );
painter.drawImage( 0, 0, *labelJob.img );
}
else if ( cache && cache->hasAnyCacheImage( LABEL_PREVIEW_CACHE_ID ) )
{
const QImage labelCacheImage = cache->transformedCacheImage( LABEL_PREVIEW_CACHE_ID, settings.mapToPixel() );
painter.setCompositionMode( QPainter::CompositionMode_SourceOver );
painter.setOpacity( 1.0 );
painter.drawImage( 0, 0, labelCacheImage );
}
// render any layers with the renderAboveLabels flag now
for ( LayerRenderJobs::const_iterator it = jobs.constBegin(); it != jobs.constEnd(); ++it )

7
src/core/qgsmaprendererjob.h
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@ -325,6 +325,13 @@ class CORE_EXPORT QgsMapRendererJob : public QObject
*/
static const QString LABEL_CACHE_ID SIP_SKIP;
/**
* QgsMapRendererCache ID string for cached label image during preview compositions only.
* \note not available in Python bindings
* \since QGIS 3.18
*/
static const QString LABEL_PREVIEW_CACHE_ID SIP_SKIP;
signals:
/**

2
src/core/qgsmaprendererparalleljob.cpp
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@ -231,7 +231,7 @@ void QgsMapRendererParallelJob::renderLayersFinished()
// compose final image for labeling
if ( mSecondPassLayerJobs.isEmpty() )
{
mFinalImage = composeImage( mSettings, mLayerJobs, mLabelJob );
mFinalImage = composeImage( mSettings, mLayerJobs, mLabelJob, mCache );
}
QgsDebugMsgLevel( QStringLiteral( "PARALLEL layers finished" ), 2 );