From c845be7976a319f23de6e87f9045bfa4b0596ace Mon Sep 17 00:00:00 2001
From: hneemann <helmut.neemann@arcor.de>
Date: Sun, 18 Mar 2018 23:34:28 +0100
Subject: [PATCH] uses double dispatch for vector transformation

---
 .../digital/draw/graphics/Polygon.java        |  2 +-
 .../digital/draw/graphics/Transform.java      | 19 +++----------------
 .../draw/graphics/TransformRotate.java        |  2 +-
 .../draw/graphics/TransformTranslate.java     |  2 +-
 .../neemann/digital/draw/graphics/Vector.java |  4 ++--
 .../digital/draw/graphics/VectorFloat.java    |  4 ++--
 .../draw/graphics/VectorInterface.java        |  8 ++++++--
 7 files changed, 16 insertions(+), 25 deletions(-)

diff --git a/src/main/java/de/neemann/digital/draw/graphics/Polygon.java b/src/main/java/de/neemann/digital/draw/graphics/Polygon.java
index fceccfe16..46bf0fd25 100644
--- a/src/main/java/de/neemann/digital/draw/graphics/Polygon.java
+++ b/src/main/java/de/neemann/digital/draw/graphics/Polygon.java
@@ -200,7 +200,7 @@ public class Polygon implements Iterable<VectorInterface> {
     public Polygon transform(Transform transform) {
         Polygon p = new Polygon(closed);
         for (VectorInterface v : points)
-            p.add(transform.transform(v));
+            p.add(v.transform(transform));
         p.isBezierStart.addAll(isBezierStart);
         return p;
     }
diff --git a/src/main/java/de/neemann/digital/draw/graphics/Transform.java b/src/main/java/de/neemann/digital/draw/graphics/Transform.java
index 7164e0a3c..80ebf2990 100644
--- a/src/main/java/de/neemann/digital/draw/graphics/Transform.java
+++ b/src/main/java/de/neemann/digital/draw/graphics/Transform.java
@@ -8,7 +8,7 @@ package de.neemann.digital.draw.graphics;
 /**
  * A simple transformation to a given vector
  */
-public abstract class Transform {
+public interface Transform {
 
     /**
      * Transforms an integer vector
@@ -16,7 +16,7 @@ public abstract class Transform {
      * @param v the vector to transform
      * @return the transformed vector
      */
-    public abstract Vector transform(Vector v);
+    Vector transform(Vector v);
 
     /**
      * Transforms an float vector
@@ -24,19 +24,6 @@ public abstract class Transform {
      * @param v the vector to transform
      * @return the transformed vector
      */
-    public abstract VectorFloat transform(VectorFloat v);
-
-    /**
-     * Transforms an vector interface
-     *
-     * @param v the vector to transform
-     * @return the transformed vector
-     */
-    public VectorInterface transform(VectorInterface v) {
-        if (v instanceof Vector)
-            return transform((Vector) v);
-        else
-            return transform(v.getVectorFloat());
-    }
+    VectorFloat transform(VectorFloat v);
 
 }
diff --git a/src/main/java/de/neemann/digital/draw/graphics/TransformRotate.java b/src/main/java/de/neemann/digital/draw/graphics/TransformRotate.java
index 9631cc44a..0a43cbf41 100644
--- a/src/main/java/de/neemann/digital/draw/graphics/TransformRotate.java
+++ b/src/main/java/de/neemann/digital/draw/graphics/TransformRotate.java
@@ -8,7 +8,7 @@ package de.neemann.digital.draw.graphics;
 /**
  * Implements a rotation and translation.
  */
-public class TransformRotate extends Transform {
+public class TransformRotate implements Transform {
 
     private final int sin;
     private final int cos;
diff --git a/src/main/java/de/neemann/digital/draw/graphics/TransformTranslate.java b/src/main/java/de/neemann/digital/draw/graphics/TransformTranslate.java
index bbeb61a31..68b4f3953 100644
--- a/src/main/java/de/neemann/digital/draw/graphics/TransformTranslate.java
+++ b/src/main/java/de/neemann/digital/draw/graphics/TransformTranslate.java
@@ -8,7 +8,7 @@ package de.neemann.digital.draw.graphics;
 /**
  * A translation
  */
-public class TransformTranslate extends Transform {
+public class TransformTranslate implements Transform {
     private final VectorInterface trans;
 
     /**
diff --git a/src/main/java/de/neemann/digital/draw/graphics/Vector.java b/src/main/java/de/neemann/digital/draw/graphics/Vector.java
index 7392b07e8..9c76303ad 100644
--- a/src/main/java/de/neemann/digital/draw/graphics/Vector.java
+++ b/src/main/java/de/neemann/digital/draw/graphics/Vector.java
@@ -245,7 +245,7 @@ public class Vector implements VectorInterface {
     }
 
     @Override
-    public VectorFloat getVectorFloat() {
-        return new VectorFloat(x, y);
+    public VectorInterface transform(Transform tr) {
+        return tr.transform(this);
     }
 }
diff --git a/src/main/java/de/neemann/digital/draw/graphics/VectorFloat.java b/src/main/java/de/neemann/digital/draw/graphics/VectorFloat.java
index c5835af8d..8eb47ff66 100644
--- a/src/main/java/de/neemann/digital/draw/graphics/VectorFloat.java
+++ b/src/main/java/de/neemann/digital/draw/graphics/VectorFloat.java
@@ -47,8 +47,8 @@ public class VectorFloat implements VectorInterface {
     }
 
     @Override
-    public VectorFloat getVectorFloat() {
-        return this;
+    public VectorInterface transform(Transform tr) {
+        return tr.transform(this);
     }
 
     /**
diff --git a/src/main/java/de/neemann/digital/draw/graphics/VectorInterface.java b/src/main/java/de/neemann/digital/draw/graphics/VectorInterface.java
index 3203caca3..86c31cbc0 100644
--- a/src/main/java/de/neemann/digital/draw/graphics/VectorInterface.java
+++ b/src/main/java/de/neemann/digital/draw/graphics/VectorInterface.java
@@ -31,7 +31,11 @@ public interface VectorInterface {
     float getYFloat();
 
     /**
-     * @return this vector as a {@link VectorFloat} instance
+     * Transforms the vector with the given transformation.
+     *
+     * @param tr the transformation to use
+     * @return the transformed vector
      */
-    VectorFloat getVectorFloat();
+    VectorInterface transform(Transform tr);
+
 }