Fix for #340.

Do correct translation in world matrix after every zoom in composer.
Also does full zoom when composer window gets resized.


git-svn-id: http://svn.osgeo.org/qgis/trunk/qgis@6197 c8812cc2-4d05-0410-92ff-de0c093fc19c

src/composer/qgscomposer.cpp

@@ -231,18 +231,34 @@ void QgsComposer::on_mActionZoomAll_activated(void)
   zoomFull();
 }
 
+QMatrix QgsComposer::updateMatrix(double scaleChange)
+{
+  double scale = mView->worldMatrix().m11() * scaleChange; // get new scale
+
+  double dx = ( mView->width() - scale * mComposition->canvas()->width() ) / 2;
+  double dy = ( mView->height() - scale * mComposition->canvas()->height() ) / 2;
+
+  // don't translate if composition is bigger than view
+  if (dx < 0) dx = 0;
+  if (dy < 0) dy = 0;
+
+  // create new world matrix:  
+  QMatrix m;
+  m.translate ( dx, dy );
+  m.scale ( scale, scale );
+  return m;
+}
+
 void QgsComposer::on_mActionZoomIn_activated(void)
 {
-  QMatrix m = mView->worldMatrix();
-  m.scale( 2.0, 2.0 );
+  QMatrix m = updateMatrix(2);
   mView->setWorldMatrix( m );
   mView->repaintContents();
 }
 
 void QgsComposer::on_mActionZoomOut_activated(void)
 {
-  QMatrix m = mView->worldMatrix();
-  m.scale( 0.5, 0.5 );
+  QMatrix m = updateMatrix(0.5);
   mView->setWorldMatrix( m );
   mView->repaintContents();
 }

src/composer/qgscomposer.h

@@ -169,6 +169,9 @@ public slots:
     //! Set buttons up
     void setToolActionsOff (void);
 
+    //! returns new world matrix for canvas view after zoom with factor scaleChange
+    QMatrix updateMatrix(double scaleChange);
+
     //! Pointer to composer view
     QgsComposerView *mView;
 

src/composer/qgscomposerview.cpp

@@ -60,3 +60,8 @@ void QgsComposerView::keyPressEvent ( QKeyEvent * e )
 {
     mComposer->composition()->keyPressEvent ( e );
 }
+
+void QgsComposerView::resizeEvent ( QResizeEvent *  )
+{
+    mComposer->zoomFull();
+}

src/composer/qgscomposerview.h

@@ -38,6 +38,7 @@ class QgsComposerView: public Q3CanvasView
     void contentsMouseMoveEvent(QMouseEvent*);
 
     void keyPressEvent ( QKeyEvent * e );
+    void resizeEvent ( QResizeEvent *  );
 
 private:
     QgsComposer *mComposer;