Fix #10524 (fix zoom to full)

Author: wonder-sk

python/core/qgsrectangle.sip

@@ -79,7 +79,8 @@ class QgsRectangle
     //! test if rectangle is empty
     //! Empty rectangle may still be non-null if it contains valid information (e.g. bounding box of a point)
     bool isEmpty() const;
-    //! test if the rectangle has all coordinates zero. Null rectangle is also an empty rectangle.
+    //! test if the rectangle is null (all coordinates zero or after call to setMinimal()).
+    //! Null rectangle is also an empty rectangle.
     //! @note added in 2.4
     bool isNull() const;
     //! returns string representation in Wkt form

src/core/qgsrectangle.cpp

@@ -196,7 +196,10 @@ bool QgsRectangle::isEmpty() const
 
 bool QgsRectangle::isNull() const
 {
-  return xmin == 0 && xmax == 0 && ymin == 0 && ymax == 0;
+  // rectangle created QgsRectangle() or with rect.setMinimal() ?
+  return ( xmin == 0 && xmax == 0 && ymin == 0 && ymax == 0 ) ||
+         ( xmin == std::numeric_limits<double>::max() && ymin == std::numeric_limits<double>::max() &&
+           xmax == -std::numeric_limits<double>::max() && ymax == -std::numeric_limits<double>::max() );
 }
 
 QString QgsRectangle::asWktCoordinates() const

src/core/qgsrectangle.h

@@ -102,7 +102,8 @@ class CORE_EXPORT QgsRectangle
     //! test if rectangle is empty.
     //! Empty rectangle may still be non-null if it contains valid information (e.g. bounding box of a point)
     bool isEmpty() const;
-    //! test if the rectangle has all coordinates zero. Null rectangle is also an empty rectangle.
+    //! test if the rectangle is null (all coordinates zero or after call to setMinimal()).
+    //! Null rectangle is also an empty rectangle.
     //! @note added in 2.4
     bool isNull() const;
     //! returns string representation in Wkt form