[composer] Fix generation of world file when map is not on first page

nyalldawson · nyalldawson · commit 8538be61351f · 2015-09-16T22:53:53.000+10:00
fix #13262 (cherry-picked from d897624)
diff --git a/src/core/composer/qgscomposition.cpp b/src/core/composer/qgscomposition.cpp
@@ -2827,35 +2827,38 @@ QGraphicsView *QgsComposition::graphicsView() const
 
 void QgsComposition::computeWorldFileParameters( double& a, double& b, double& c, double& d, double& e, double& f ) const
 {
-  //
-  // Word file parameters : affine transformation parameters from pixel coordinates to map coordinates
+  // World file parameters : affine transformation parameters from pixel coordinates to map coordinates
 
   if ( !mWorldFileMap )
   {
     return;
   }
 
-  QRectF brect = mWorldFileMap->mapRectToScene( mWorldFileMap->rect() );
-  QgsRectangle extent = *mWorldFileMap->currentMapExtent();
+  double destinationHeight = paperHeight();
+  double destinationWidth = paperWidth();
+
+  QRectF mapItemSceneRect = mWorldFileMap->mapRectToScene( mWorldFileMap->rect() );
+  QgsRectangle mapExtent = *mWorldFileMap->currentMapExtent();
 
   double alpha = mWorldFileMap->mapRotation() / 180 * M_PI;
 
-  double xr = extent.width() / brect.width();
-  double yr = extent.height() / brect.height();
+  double xRatio = mapExtent.width() / mapItemSceneRect.width();
+  double yRatio = mapExtent.height() / mapItemSceneRect.height();
 
-  double XC = extent.center().x();
-  double YC = extent.center().y();
+  double xCenter = mapExtent.center().x();
+  double yCenter = mapExtent.center().y();
 
-  // get the extent for the page
-  double xmin = extent.xMinimum() - mWorldFileMap->pos().x() * xr;
-  double ymax = extent.yMaximum() + mWorldFileMap->pos().y() * yr;
-  QgsRectangle paperExtent( xmin, ymax - paperHeight() * yr, xmin + paperWidth() * xr, ymax );
+  // get the extent (in map units) for the page
+  QPointF mapItemPosOnPage = mWorldFileMap->pagePos();
+  double xmin = mapExtent.xMinimum() - mapItemPosOnPage.x() * xRatio;
+  double ymax = mapExtent.yMaximum() + mapItemPosOnPage.y() * yRatio;
+  QgsRectangle paperExtent( xmin, ymax - destinationHeight * yRatio, xmin + destinationWidth * xRatio, ymax );
 
   double X0 = paperExtent.xMinimum();
   double Y0 = paperExtent.yMinimum();
 
-  int widthPx = ( int )( printResolution() * paperWidth() / 25.4 );
-  int heightPx = ( int )( printResolution() * paperHeight() / 25.4 );
+  int widthPx = ( int )( printResolution() * destinationWidth / 25.4 );
+  int heightPx = ( int )( printResolution() * destinationHeight / 25.4 );
 
   double Ww = paperExtent.width() / widthPx;
   double Hh = paperExtent.height() / heightPx;
@@ -2873,10 +2876,10 @@ void QgsComposition::computeWorldFileParameters( double& a, double& b, double& c
   double r[6];
   r[0] = cos( alpha );
   r[1] = -sin( alpha );
-  r[2] = XC * ( 1 - cos( alpha ) ) + YC * sin( alpha );
+  r[2] = xCenter * ( 1 - cos( alpha ) ) + yCenter * sin( alpha );
   r[3] = sin( alpha );
   r[4] = cos( alpha );
-  r[5] = - XC * sin( alpha ) + YC * ( 1 - cos( alpha ) );
+  r[5] = - xCenter * sin( alpha ) + yCenter * ( 1 - cos( alpha ) );
 
   // result = rotation x scaling = rotation(scaling(X))
   a = r[0] * s[0] + r[1] * s[3];
diff --git a/tests/src/core/testqgscomposermap.cpp b/tests/src/core/testqgscomposermap.cpp
@@ -155,12 +155,23 @@ void TestQgsComposerMap::worldFileGeneration()
   double a, b, c, d, e, f;
   mComposition->computeWorldFileParameters( a, b, c, d, e, f );
 
-  QVERIFY( fabs( a - 4.18048 ) < 0.001 );
-  QVERIFY( fabs( b - 2.41331 ) < 0.001 );
-  QVERIFY( fabs( c - 779444 ) < 1 );
-  QVERIFY( fabs( d - 2.4136 ) < 0.001 );
-  QVERIFY( fabs( e + 4.17997 ) < 0.001 );
-  QVERIFY( fabs( f - 3.34241e+06 ) < 1e+03 );
+  QVERIFY( qgsDoubleNear( a, 4.18048, 0.001 ) );
+  QVERIFY( qgsDoubleNear( b, 2.41331, 0.001 ) );
+  QVERIFY( qgsDoubleNear( c, 779444, 1 ) );
+  QVERIFY( qgsDoubleNear( d, 2.4136, 0.001 ) );
+  QVERIFY( qgsDoubleNear( e, -4.17997, 0.001 ) );
+  QVERIFY( qgsDoubleNear( f, 3.34241e+06, 1e+03 ) );
+
+  //test with map on second page. Parameters should be the same
+  mComposerMap->setItemPosition( 20, 20, QgsComposerItem::UpperLeft, 2 );
+  mComposition->computeWorldFileParameters( a, b, c, d, e, f );
+
+  QVERIFY( qgsDoubleNear( a, 4.18048, 0.001 ) );
+  QVERIFY( qgsDoubleNear( b, 2.41331, 0.001 ) );
+  QVERIFY( qgsDoubleNear( c, 779444, 1 ) );
+  QVERIFY( qgsDoubleNear( d, 2.4136, 0.001 ) );
+  QVERIFY( qgsDoubleNear( e, -4.17997, 0.001 ) );
+  QVERIFY( qgsDoubleNear( f, 3.34241e+06, 1e+03 ) );
 
   mComposition->setGenerateWorldFile( false );
   mComposerMap->setMapRotation( 0.0 );
