Merge pull request #3326 from henrikt-ma/icon-transformation

Simplified presentation of Transformation-annotation

chapters/annotations.tex

@@ -728,29 +728,29 @@ \subsection{Component Instance}\label{component-instance}
 
 A component instance can be placed within a diagram or icon layer.
 It has an annotation with a \lstinline!Placement! modifier to describe the placement.
-Placements are defined in term of coordinate systems transformations:
+Placements are defined in terms of coordinate system transformations:
 \begin{lstlisting}[language=modelica]
 record Transformation
-  Point origin = {0, 0};
   Extent extent;
   Real rotation(quantity = "angle", unit = "deg") = 0;
+  Point origin = {0, 0};
 end Transformation;
 \end{lstlisting}%
 \annotationindex{Transformation}
-The origin attribute defines the position of the component in the coordinate system of the enclosing class.
-The \lstinline!extent! defines the position, size and flipping of the component, relative to the \lstinline!origin! attribute.
-The \lstinline!extent! is defined relative to the \lstinline!origin! attribute of the component instance.
-Given an extent \lstinline!{{$x_{1}$, $y_{1}$}, {$x_{2}$, $y_{2}$}}!, $x_{2} < x_{1}$ defines horizontal flipping and $y_{2} < y_{1}$ defines vertical flipping around the center of the object.
-
-The \lstinline!rotation! attribute specifies rotation of the extent around the point defined by the \lstinline!origin! attribute.
-
-The graphical operations are applied in the order: scaling, flipping and rotation.
+The attributes are applied in the order \lstinline!extent!, \lstinline!rotation!, \lstinline!origin!, as follows:
+\begin{enumerate}
+\item
+  The \lstinline!extent! of the component icon is mapped to the \lstinline!extent! rectangle (possibly shifting, scaling, and flipping contents).
+\item
+  The \lstinline!rotation! specifies counter-clockwise rotation around the origin (that is \lstinline!{0, 0}!, not the \lstinline!origin! attribute).
+\item
+  The \lstinline!origin! specifies a shift (moving \lstinline!{0, 0}! to \lstinline!origin!).
+\end{enumerate}
 
 \begin{lstlisting}[language=modelica]
 record Placement
   Boolean visible = true;
   Transformation transformation "Placement in the diagram layer";
-
   Boolean iconVisible "Visible in icon layer; for public connector";
   Transformation iconTransformation
     "Placement in the icon layer; for public connector";