[composer] Hard code drawing a maximum of 1000 horizontal or vertical grid lines. Prevents hangs if grid settings are poorly chosen, resulting in millions of grid lines

nyalldawson · nyalldawson · commit c04a5400be59 · 2014-07-13T11:36:20.000+10:00
diff --git a/src/core/composer/qgscomposermapgrid.cpp b/src/core/composer/qgscomposermapgrid.cpp
@@ -28,6 +28,8 @@
 #include <QPainter>
 #include <QPen>
 
+#define MAX_GRID_LINES 1000 //maximum number of horizontal or vertical grid lines to draw
+
 QgsComposerMapGrid::QgsComposerMapGrid( const QString& name, QgsComposerMap* map ):
     mComposerMap( map ),
     mName( name ),
@@ -370,13 +372,13 @@ void QgsComposerMapGrid::drawGrid( QPainter* p ) const
 void QgsComposerMapGrid::drawGridNoTransform( QgsRenderContext &context, double dotsPerMM, QList< QPair< double, QLineF > > &horizontalLines,
     QList< QPair< double, QLineF > > &verticalLines ) const
 {
-//get line positions
+  //get line positions
   yGridLines( verticalLines );
   QList< QPair< double, QLineF > >::const_iterator vIt = verticalLines.constBegin();
   xGridLines( horizontalLines );
   QList< QPair< double, QLineF > >::const_iterator hIt = horizontalLines.constBegin();
 
-//simple approach: draw vertical lines first, then horizontal ones
+  //simple approach: draw vertical lines first, then horizontal ones
   if ( mGridStyle == QgsComposerMap::Solid )
   {
     //we need to scale line coordinates to dots, rather than mm, since the painter has already been scaled to dots
@@ -815,16 +817,18 @@ int QgsComposerMapGrid::xGridLines( QList< QPair< double, QLineF > >& lines ) co
   double roundCorrection = mapBoundingRect.top() > 0 ? 1.0 : 0.0;
   double currentLevel = ( int )(( mapBoundingRect.top() - gridOffsetY ) / gridIntervalY + roundCorrection ) * gridIntervalY + gridOffsetY;
 
+  int gridLineCount = 0;
   if ( qgsDoubleNear( mComposerMap->mapRotation(), 0.0 ) || mGridUnit != MapUnit )
   {
     //no rotation. Do it 'the easy way'
 
     double yCanvasCoord;
-    while ( currentLevel <= mapBoundingRect.bottom() )
+    while ( currentLevel <= mapBoundingRect.bottom() && gridLineCount < MAX_GRID_LINES )
     {
       yCanvasCoord = mComposerMap->rect().height() * ( 1 - ( currentLevel - mapBoundingRect.top() ) / mapBoundingRect.height() );
       lines.push_back( qMakePair( currentLevel * annotationScale, QLineF( 0, yCanvasCoord, mComposerMap->rect().width(), yCanvasCoord ) ) );
       currentLevel += gridIntervalY;
+      gridLineCount++;
     }
     return 0;
   }
@@ -838,7 +842,7 @@ int QgsComposerMapGrid::xGridLines( QList< QPair< double, QLineF > >& lines ) co
 
   QList<QPointF> intersectionList; //intersects between border lines and grid lines
 
-  while ( currentLevel <= mapBoundingRect.bottom() )
+  while ( currentLevel <= mapBoundingRect.bottom() && gridLineCount < MAX_GRID_LINES )
   {
     intersectionList.clear();
     QLineF gridLine( mapBoundingRect.left(), currentLevel, mapBoundingRect.right(), currentLevel );
@@ -860,6 +864,7 @@ int QgsComposerMapGrid::xGridLines( QList< QPair< double, QLineF > >& lines ) co
     if ( intersectionList.size() >= 2 )
     {
       lines.push_back( qMakePair( currentLevel, QLineF( mComposerMap->mapToItemCoords( intersectionList.at( 0 ) ), mComposerMap->mapToItemCoords( intersectionList.at( 1 ) ) ) ) );
+      gridLineCount++;
     }
     currentLevel += gridIntervalY;
   }
@@ -896,16 +901,17 @@ int QgsComposerMapGrid::yGridLines( QList< QPair< double, QLineF > >& lines ) co
   double roundCorrection = mapBoundingRect.left() > 0 ? 1.0 : 0.0;
   double currentLevel = ( int )(( mapBoundingRect.left() - gridOffsetX ) / gridIntervalX + roundCorrection ) * gridIntervalX + gridOffsetX;
 
+  int gridLineCount = 0;
   if ( qgsDoubleNear( mComposerMap->mapRotation(), 0.0 ) || mGridUnit != MapUnit )
   {
     //no rotation. Do it 'the easy way'
     double xCanvasCoord;
-
-    while ( currentLevel <= mapBoundingRect.right() )
+    while ( currentLevel <= mapBoundingRect.right() && gridLineCount < MAX_GRID_LINES )
     {
       xCanvasCoord = mComposerMap->rect().width() * ( currentLevel - mapBoundingRect.left() ) / mapBoundingRect.width();
       lines.push_back( qMakePair( currentLevel * annotationScale, QLineF( xCanvasCoord, 0, xCanvasCoord, mComposerMap->rect().height() ) ) );
       currentLevel += gridIntervalX;
+      gridLineCount++;
     }
     return 0;
   }
@@ -919,7 +925,7 @@ int QgsComposerMapGrid::yGridLines( QList< QPair< double, QLineF > >& lines ) co
 
   QList<QPointF> intersectionList; //intersects between border lines and grid lines
 
-  while ( currentLevel <= mapBoundingRect.right() )
+  while ( currentLevel <= mapBoundingRect.right() && gridLineCount < MAX_GRID_LINES )
   {
     intersectionList.clear();
     QLineF gridLine( currentLevel, mapBoundingRect.bottom(), currentLevel, mapBoundingRect.top() );
@@ -941,6 +947,7 @@ int QgsComposerMapGrid::yGridLines( QList< QPair< double, QLineF > >& lines ) co
     if ( intersectionList.size() >= 2 )
     {
       lines.push_back( qMakePair( currentLevel, QLineF( mComposerMap->mapToItemCoords( intersectionList.at( 0 ) ), mComposerMap->mapToItemCoords( intersectionList.at( 1 ) ) ) ) );
+      gridLineCount++;
     }
     currentLevel += gridIntervalX;
   }

Original file line number	Diff line number	Diff line change
`@@ -28,6 +28,8 @@`
`28`	`28`	`#include <QPainter>`
`29`	`29`	`#include <QPen>`
`30`	`30`
	`31`	`+#define MAX_GRID_LINES 1000 //maximum number of horizontal or vertical grid lines to draw`
	`32`	`+`
`31`	`33`	`QgsComposerMapGrid::QgsComposerMapGrid( const QString& name, QgsComposerMap* map ):`
`32`	`34`	`mComposerMap( map ),`
`33`	`35`	`mName( name ),`
`@@ -370,13 +372,13 @@ void QgsComposerMapGrid::drawGrid( QPainter* p ) const`
`370`	`372`	`void QgsComposerMapGrid::drawGridNoTransform( QgsRenderContext &context, double dotsPerMM, QList< QPair< double, QLineF > > &horizontalLines,`
`371`	`373`	`QList< QPair< double, QLineF > > &verticalLines ) const`
`372`	`374`	`{`
`373`		`-//get line positions`
	`375`	`+ //get line positions`
`374`	`376`	`yGridLines( verticalLines );`
`375`	`377`	`QList< QPair< double, QLineF > >::const_iterator vIt = verticalLines.constBegin();`
`376`	`378`	`xGridLines( horizontalLines );`
`377`	`379`	`QList< QPair< double, QLineF > >::const_iterator hIt = horizontalLines.constBegin();`
`378`	`380`
`379`		`-//simple approach: draw vertical lines first, then horizontal ones`
	`381`	`+ //simple approach: draw vertical lines first, then horizontal ones`
`380`	`382`	`if ( mGridStyle == QgsComposerMap::Solid )`
`381`	`383`	`{`
`382`	`384`	`//we need to scale line coordinates to dots, rather than mm, since the painter has already been scaled to dots`
`@@ -815,16 +817,18 @@ int QgsComposerMapGrid::xGridLines( QList< QPair< double, QLineF > >& lines ) co`
`815`	`817`	`double roundCorrection = mapBoundingRect.top() > 0 ? 1.0 : 0.0;`
`816`	`818`	`double currentLevel = ( int )(( mapBoundingRect.top() - gridOffsetY ) / gridIntervalY + roundCorrection ) * gridIntervalY + gridOffsetY;`
`817`	`819`
	`820`	`+ int gridLineCount = 0;`
`818`	`821`	`if ( qgsDoubleNear( mComposerMap->mapRotation(), 0.0 ) \|\| mGridUnit != MapUnit )`
`819`	`822`	`{`
`820`	`823`	`//no rotation. Do it 'the easy way'`
`821`	`824`
`822`	`825`	`double yCanvasCoord;`
`823`		`- while ( currentLevel <= mapBoundingRect.bottom() )`
	`826`	`+ while ( currentLevel <= mapBoundingRect.bottom() && gridLineCount < MAX_GRID_LINES )`
`824`	`827`	`{`
`825`	`828`	`yCanvasCoord = mComposerMap->rect().height() * ( 1 - ( currentLevel - mapBoundingRect.top() ) / mapBoundingRect.height() );`
`826`	`829`	`lines.push_back( qMakePair( currentLevel * annotationScale, QLineF( 0, yCanvasCoord, mComposerMap->rect().width(), yCanvasCoord ) ) );`
`827`	`830`	`currentLevel += gridIntervalY;`
	`831`	`+ gridLineCount++;`
`828`	`832`	`}`
`829`	`833`	`return 0;`
`830`	`834`	`}`
`@@ -838,7 +842,7 @@ int QgsComposerMapGrid::xGridLines( QList< QPair< double, QLineF > >& lines ) co`
`838`	`842`
`839`	`843`	`QList<QPointF> intersectionList; //intersects between border lines and grid lines`
`840`	`844`
`841`		`- while ( currentLevel <= mapBoundingRect.bottom() )`
	`845`	`+ while ( currentLevel <= mapBoundingRect.bottom() && gridLineCount < MAX_GRID_LINES )`
`842`	`846`	`{`
`843`	`847`	`intersectionList.clear();`
`844`	`848`	`QLineF gridLine( mapBoundingRect.left(), currentLevel, mapBoundingRect.right(), currentLevel );`
`@@ -860,6 +864,7 @@ int QgsComposerMapGrid::xGridLines( QList< QPair< double, QLineF > >& lines ) co`
`860`	`864`	`if ( intersectionList.size() >= 2 )`
`861`	`865`	`{`
`862`	`866`	`lines.push_back( qMakePair( currentLevel, QLineF( mComposerMap->mapToItemCoords( intersectionList.at( 0 ) ), mComposerMap->mapToItemCoords( intersectionList.at( 1 ) ) ) ) );`
	`867`	`+ gridLineCount++;`
`863`	`868`	`}`
`864`	`869`	`currentLevel += gridIntervalY;`
`865`	`870`	`}`
`@@ -896,16 +901,17 @@ int QgsComposerMapGrid::yGridLines( QList< QPair< double, QLineF > >& lines ) co`
`896`	`901`	`double roundCorrection = mapBoundingRect.left() > 0 ? 1.0 : 0.0;`
`897`	`902`	`double currentLevel = ( int )(( mapBoundingRect.left() - gridOffsetX ) / gridIntervalX + roundCorrection ) * gridIntervalX + gridOffsetX;`
`898`	`903`
	`904`	`+ int gridLineCount = 0;`
`899`	`905`	`if ( qgsDoubleNear( mComposerMap->mapRotation(), 0.0 ) \|\| mGridUnit != MapUnit )`
`900`	`906`	`{`
`901`	`907`	`//no rotation. Do it 'the easy way'`
`902`	`908`	`double xCanvasCoord;`
`903`		`-`
`904`		`- while ( currentLevel <= mapBoundingRect.right() )`
	`909`	`+ while ( currentLevel <= mapBoundingRect.right() && gridLineCount < MAX_GRID_LINES )`
`905`	`910`	`{`
`906`	`911`	`xCanvasCoord = mComposerMap->rect().width() * ( currentLevel - mapBoundingRect.left() ) / mapBoundingRect.width();`
`907`	`912`	`lines.push_back( qMakePair( currentLevel * annotationScale, QLineF( xCanvasCoord, 0, xCanvasCoord, mComposerMap->rect().height() ) ) );`
`908`	`913`	`currentLevel += gridIntervalX;`
	`914`	`+ gridLineCount++;`
`909`	`915`	`}`
`910`	`916`	`return 0;`
`911`	`917`	`}`
`@@ -919,7 +925,7 @@ int QgsComposerMapGrid::yGridLines( QList< QPair< double, QLineF > >& lines ) co`
`919`	`925`
`920`	`926`	`QList<QPointF> intersectionList; //intersects between border lines and grid lines`
`921`	`927`
`922`		`- while ( currentLevel <= mapBoundingRect.right() )`
	`928`	`+ while ( currentLevel <= mapBoundingRect.right() && gridLineCount < MAX_GRID_LINES )`
`923`	`929`	`{`
`924`	`930`	`intersectionList.clear();`
`925`	`931`	`QLineF gridLine( currentLevel, mapBoundingRect.bottom(), currentLevel, mapBoundingRect.top() );`
`@@ -941,6 +947,7 @@ int QgsComposerMapGrid::yGridLines( QList< QPair< double, QLineF > >& lines ) co`
`941`	`947`	`if ( intersectionList.size() >= 2 )`
`942`	`948`	`{`
`943`	`949`	`lines.push_back( qMakePair( currentLevel, QLineF( mComposerMap->mapToItemCoords( intersectionList.at( 0 ) ), mComposerMap->mapToItemCoords( intersectionList.at( 1 ) ) ) ) );`
	`950`	`+ gridLineCount++;`
`944`	`951`	`}`
`945`	`952`	`currentLevel += gridIntervalX;`
`946`	`953`	`}`