[composer] Make sure entire page symbol border is included when exporting compositions. Previously half the page border would be cropped out. Also fix nIRV's infamous 1px bad row at bottom of composer exports bug.

nyalldawson · nyalldawson · commit 6d918a1acfba · 2014-01-04T14:44:32.000+11:00
diff --git a/src/core/composer/qgspaperitem.cpp b/src/core/composer/qgspaperitem.cpp
@@ -128,13 +128,13 @@ QgsPaperItem::QgsPaperItem( QgsComposition* c ): QgsComposerItem( c, false ),
 }
 
 QgsPaperItem::QgsPaperItem( qreal x, qreal y, qreal width, qreal height, QgsComposition* composition ): QgsComposerItem( x, y, width, height, composition, false ),
-    mPageGrid( 0 )
+    mPageGrid( 0 ), mPageMargin( 0 )
 {
   initialize();
 }
 
 QgsPaperItem::QgsPaperItem(): QgsComposerItem( 0, false ),
-    mPageGrid( 0 )
+    mPageGrid( 0 ), mPageMargin( 0 )
 {
   initialize();
 }
@@ -167,15 +167,28 @@ void QgsPaperItem::paint( QPainter* painter, const QStyleOptionGraphicsItem* ite
 
   painter->save();
   painter->setRenderHint( QPainter::Antialiasing );
-  QPolygonF pagePolygon = QPolygonF( QRectF( 0, 0, rect().width(), rect().height() ) );
   mComposition->pageStyleSymbol()->startRender( context );
+
+  calculatePageMargin();
+  QPolygonF pagePolygon = QPolygonF( QRectF( mPageMargin, mPageMargin, rect().width() - 2 * mPageMargin, rect().height() - 2 * mPageMargin ) );
   QList<QPolygonF> rings; //empty list
   mComposition->pageStyleSymbol()->renderPolygon( pagePolygon, &rings, 0, context );
   mComposition->pageStyleSymbol()->stopRender( context );
   painter->restore();
 
 }
 
+void QgsPaperItem::calculatePageMargin()
+{
+  //get max bleed from symbol
+  double maxBleed = QgsSymbolLayerV2Utils::estimateMaxSymbolBleed( mComposition->pageStyleSymbol() );
+
+  //Now subtract 1 pixel to prevent semi-transparent borders at edge of solid page caused by
+  //anti-aliased painting. This may cause a pixel to be cropped from certain edge lines/symbols,
+  //but that can be counteracted by adding a dummy transparent line symbol layer with a wider line width
+  mPageMargin = maxBleed - ( 25.4 / mComposition->printResolution() );
+}
+
 bool QgsPaperItem::writeXML( QDomElement& elem, QDomDocument & doc ) const
 {
   Q_UNUSED( elem );
diff --git a/src/core/composer/qgspaperitem.h b/src/core/composer/qgspaperitem.h
@@ -69,7 +69,10 @@ class CORE_EXPORT QgsPaperItem: public QgsComposerItem
     /**Set flags and z-value*/
     void initialize();
 
+    void calculatePageMargin();
+
     QgsPaperGrid* mPageGrid;
+    double mPageMargin;
 };
 
 #endif
