Do not allow invalid map settings (fixes #12757)

qgis · Jun 19, 2015 · 1bf9844 · 1bf9844
1 parent 9c73a22
commit 1bf9844
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Showing 2 changed files with 99 additions and 16 deletions.
diff --git a/src/core/qgsmaptopixel.cpp b/src/core/qgsmaptopixel.cpp
@@ -99,9 +99,16 @@ int QgsMapToPixel::mapWidth() const
   return mWidth;
 }
 
-void QgsMapToPixel::updateMatrix()
+bool QgsMapToPixel::updateMatrix()
 {
-  mMatrix = transform();
+  QTransform newMatrix = transform();
+
+  // http://hub.qgis.org/issues/12757
+  if ( !newMatrix.isInvertible() )
+    return false;
+
+  mMatrix = newMatrix;
+  return true;
 }
 
 QgsPoint QgsMapToPixel::toMapPoint( qreal x, qreal y ) const
@@ -133,8 +140,12 @@ QgsPoint QgsMapToPixel::toMapCoordinatesF( double x, double y ) const
 
 void QgsMapToPixel::setMapUnitsPerPixel( double mapUnitsPerPixel )
 {
+  double oldUnits = mMapUnitsPerPixel;
   mMapUnitsPerPixel = mapUnitsPerPixel;
-  updateMatrix();
+  if ( !updateMatrix() )
+  {
+    mMapUnitsPerPixel = oldUnits;
+  }
 }
 
 double QgsMapToPixel::mapUnitsPerPixel() const
@@ -144,6 +155,11 @@ double QgsMapToPixel::mapUnitsPerPixel() const
 
 void QgsMapToPixel::setMapRotation( double degrees, double cx, double cy )
 {
+  double oldRotation = mRotation;
+  double oldXCenter = xCenter;
+  double oldYCenter = yCenter;
+  double oldWidth = mWidth;
+
   mRotation = degrees;
   xCenter = cx;
   yCenter = cy;
@@ -152,7 +168,14 @@ void QgsMapToPixel::setMapRotation( double degrees, double cx, double cy )
     // set width not that we can compute it
     mWidth = (( xCenter - xMin ) * 2 ) / mMapUnitsPerPixel;
   }
-  updateMatrix();
+
+  if ( !updateMatrix() )
+  {
+    mRotation = oldRotation;
+    xCenter = oldXCenter;
+    yCenter = oldYCenter;
+    mWidth = oldWidth;
+  }
 }
 
 double QgsMapToPixel::mapRotation() const
@@ -163,30 +186,63 @@ double QgsMapToPixel::mapRotation() const
 // @deprecated in 2.8
 void QgsMapToPixel::setYMinimum( double ymin )
 {
+  double oldRotation = mRotation;
+  double oldYCenter = yCenter;
+
   yCenter = ymin + mHeight * mMapUnitsPerPixel / 2.0;
   mRotation = 0.0;
-  updateMatrix();
+  if ( !updateMatrix() )
+  {
+    mRotation = oldRotation;
+    yCenter = oldYCenter;
+  }
 }
 
 // @deprecated in 2.8
 void QgsMapToPixel::setXMinimum( double xmin )
 {
+  double oldRotation = mRotation;
+  double oldXCenter = xCenter;
+
   xCenter = xmin + mWidth * mMapUnitsPerPixel / 2.0;
   mRotation = 0.0;
-  updateMatrix();
+
+  if ( !updateMatrix() )
+  {
+    mRotation = oldRotation;
+    xCenter = oldXCenter;
+  }
 }
 
 // @deprecated in 2.8
 void QgsMapToPixel::setParameters( double mapUnitsPerPixel, double xmin, double ymin, double ymax )
 {
+  double oldMUPP = mMapUnitsPerPixel;
+  double oldXMin = xMin;
+  double oldYMin = yMin;
+  double oldHeight = mHeight;
+  double oldXCenter = xCenter;
+  double oldYCenter = yCenter;
+  double oldRotation = mRotation;
+
   mMapUnitsPerPixel = mapUnitsPerPixel;
   xMin = xmin;
   yMin = ymin;
   mHeight = ymax;
   xCenter = xmin + mWidth * mMapUnitsPerPixel / 2.0;
   yCenter = ymin + mHeight * mMapUnitsPerPixel / 2.0;
   mRotation = 0.0;
-  updateMatrix();
+
+  if ( !updateMatrix() )
+  {
+    mMapUnitsPerPixel = oldMUPP;
+    xMin = oldXMin;
+    yMin = oldYMin;
+    mHeight = oldHeight;
+    xCenter = oldXCenter;
+    yCenter = oldYCenter;
+    mRotation = oldRotation;
+  }
 }
 
 void QgsMapToPixel::setParameters( double mapUnitsPerPixel,
@@ -196,6 +252,15 @@ void QgsMapToPixel::setParameters( double mapUnitsPerPixel,
                                    int height,
                                    double rotation )
 {
+  double oldMUPP = mMapUnitsPerPixel;
+  double oldXCenter = xCenter;
+  double oldYCenter = yCenter;
+  double oldWidth = mWidth;
+  double oldHeight = mHeight;
+  double oldRotation = mRotation;
+  double oldXMin = xMin;
+  double oldYMin = yMin;
+
   mMapUnitsPerPixel = mapUnitsPerPixel;
   xCenter = xc;
   yCenter = yc;
@@ -204,7 +269,18 @@ void QgsMapToPixel::setParameters( double mapUnitsPerPixel,
   mRotation = rotation;
   xMin = xc - ( mWidth * mMapUnitsPerPixel / 2.0 );
   yMin = yc - ( mHeight * mMapUnitsPerPixel / 2.0 );
-  updateMatrix();
+
+  if ( !updateMatrix() )
+  {
+    mMapUnitsPerPixel = oldMUPP;
+    xCenter = oldXCenter;
+    yCenter = oldYCenter;
+    mWidth = oldWidth;
+    mHeight = oldHeight;
+    mRotation = oldRotation;
+    xMin = oldXMin;
+    yMin = oldYMin;
+  }
 }
 
 QString QgsMapToPixel::showParameters() const
@@ -250,18 +326,25 @@ void QgsMapToPixel::transformInPlace( qreal &x, qreal &y ) const
 
 QTransform QgsMapToPixel::transform() const
 {
+  // NOTE: operations are done in the reverse order in which
+  //       they are configured, so translation to geographical
+  //       center happens first, then scaling, then rotation
+  //       and finally translation to output viewport center
+
   double rotation = mapRotation();
   if ( qgsDoubleNear( rotation, 0.0 ) )
   {
     //no rotation, return a simplified matrix
     return QTransform::fromScale( 1.0 / mMapUnitsPerPixel, -1.0 / mMapUnitsPerPixel )
            .translate( -xMin, - ( yMin + mHeight * mMapUnitsPerPixel ) );
   }
-
-  double cy = mapHeight() / 2.0;
-  double cx = mapWidth() / 2.0;
-  return QTransform::fromTranslate( cx, cy )
-         .rotate( rotation )
-         .scale( 1 / mMapUnitsPerPixel, -1 / mMapUnitsPerPixel )
-         .translate( -xCenter, -yCenter );
+  else
+  {
+    double cy = mapHeight() / 2.0;
+    double cx = mapWidth() / 2.0;
+    return QTransform::fromTranslate( cx, cy )
+           .rotate( rotation )
+           .scale( 1 / mMapUnitsPerPixel, -1 / mMapUnitsPerPixel )
+           .translate( -xCenter, -yCenter );
+  }
 }
diff --git a/src/core/qgsmaptopixel.h b/src/core/qgsmaptopixel.h
@@ -226,7 +226,7 @@ class CORE_EXPORT QgsMapToPixel
     double yMin; //!< @deprecated in 2.8
     QTransform mMatrix;
 
-    void updateMatrix();
+    bool updateMatrix();
 };