Fix ParStyle equals & indent (#943)

Author: Jugen

richtextfx-demos/src/main/java/org/fxmisc/richtext/demo/richtext/Indent.java

@@ -4,4 +4,21 @@ public class Indent
 {
     double width = 15;
     int level = 1;
+
+    Indent() {}
+
+    Indent( int level )
+    {
+        if ( level > 0 ) this.level = level;
+    }
+
+    Indent increase()
+    {
+    	  return new Indent( level+1 );
+    }
+
+    Indent decrease()
+    {
+    	  return new Indent( level-1 );
+    }
 }

richtextfx-demos/src/main/java/org/fxmisc/richtext/demo/richtext/ParStyle.java

@@ -73,15 +73,16 @@ public ParStyle(Optional<TextAlignment> alignment, Optional<Color> backgroundCol
 
     @Override
     public int hashCode() {
-        return Objects.hash(alignment, backgroundColor);
+        return Objects.hash(alignment, backgroundColor, indent);
     }
 
     @Override
     public boolean equals(Object other) {
         if(other instanceof ParStyle) {
             ParStyle that = (ParStyle) other;
             return Objects.equals(this.alignment, that.alignment) &&
-                   Objects.equals(this.backgroundColor, that.backgroundColor);
+                   Objects.equals(this.backgroundColor, that.backgroundColor) &&
+                   Objects.equals(this.indent, that.indent);
         } else {
             return false;
         }
@@ -134,16 +135,12 @@ public ParStyle updateIndent(Indent indent) {
     }
 
     public ParStyle increaseIndent() {
-        if ( indent.isPresent() ) indent.get().level++;
-        else return updateIndent( new Indent() );
-        return this; 
+        return updateIndent( indent.map( Indent::increase ).orElseGet( Indent::new ) );
     }
 
     public ParStyle decreaseIndent() {
-        if ( indent.isPresent() && --indent.get().level == 0 ) {
-            return updateIndent( null );
-        }
-        return this; 
+        return updateIndent( indent.filter( in -> in.level > 1 )
+           .map( Indent::decrease ).orElse( null ) );
     }
 
 }