c++: add [], change ()

() used to return element zero, just return a vector

add [] overload

ChangeLog

@@ -11,6 +11,7 @@
 - rewritten tiff writer is about 3 - 4x faster at making pyramids
 - jpg, magick, png, tiff readers now use only 1 fd per input image
 - python: use [] to index and slice image bands
+- c++: use [] to band index, () returns a vector<double>
 
 6/2/15 started 7.42.3
 - bump version for back-compat ABI change

TODO

@@ -5,20 +5,15 @@
 
 - need to add [] overload to Ruby bindings
 
-- add
+- overload (x, y) to be getpoint()? py/rb
 
-	VImage &operator[]( int index ) 
-		throw( VError )
-	{ 
-		VImage result = this->extract_band( index ); 
+  c++ has:
 
-		return( result );
+	std::vector<double> operator()( int x, int y )
+	{
+		return( this->getpoint( x, y ) ); 
 	}
 
-  to cpp bindings
-
-- overload (x, y) to be getpoint()? c++/py/rb
-
 
 
 

cplusplus/examples/test_overloads.cpp

@@ -5,6 +5,10 @@
  *
  *      g++ -g -Wall test_overloads.cpp `pkg-config vips-cpp --cflags --libs`
  *
+ * run with:
+ *
+ * 	valgrind --leak-check=yes ./a.out ~/pics/k2.jpg ~/pics/shark.jpg 
+ *
  */
 
 /*
@@ -256,6 +260,8 @@ main( int argc, char **argv )
 		vips_error_exit( NULL );
 	}
 
+	g_option_context_free( context );
+
 {
 	VImage left = VImage::new_from_file( argv[1] ); 
 	VImage right = VImage::new_from_file( argv[2] ); 
@@ -264,6 +270,10 @@ main( int argc, char **argv )
 	test_binary_test_subtract( left, right );
 	test_binary_test_multiply( left, right );
 	test_binary_test_divide( left, right );
+
+	VImage band_one = left[1];
+
+	std::vector<double> point = left(0, 0);
 }
 
 	vips_shutdown();

cplusplus/include/vips/VImage8.h

@@ -776,9 +776,15 @@ public:
 
 	// Operator overloads
 
-	double operator()( int x, int y, int z = 0 )
+	VImage operator[]( int index ) 
+		throw( VError )
 	{
-		return( this->getpoint( x, y )[z] ); 
+		return( this->extract_band( index ) ); 
+	}
+
+	std::vector<double> operator()( int x, int y )
+	{
+		return( this->getpoint( x, y ) ); 
 	}
 
 	friend VImage operator+( VImage a, VImage b ) 

doc/using-cpp.xml

@@ -256,6 +256,30 @@ VImage a = (a < 128).ifthenelse( 128, a );
       The C++ API includes the usual range of arithmetic operator overloads. 
       You can mix constants, vectors and images freely.
     </para>
+
+    <para>
+      The API overloads <code>[]</code> to be vips_extract_band(). You can 
+      write:
+
+<programlisting language="C++">
+VImage xyz = VImage::xyz( 256, 256 ) - VImage::to_vectorv( 2, 128.0, 128.0 ); 
+VImage mask = (xyz[0].pow( 2 ) + xyz[1].pow( 2 )).pow( 0.5 ) &lt; 100;
+</programlisting>
+
+      to make a circular mask, for example.
+    </para>
+
+    <para>
+      The API overloads <code>()<code> to be vips_getpoint(). You can 
+      write:
+
+<programlisting language="C++">
+VImage xyz = VImage::xyz( 256, 256 ) - VImage::to_vectorv( 2, 128.0, 128.0 ); 
+// this will have the value [0, 0]
+std::vector<double> point = xyz(128, 128);
+</programlisting>
+    </para>
+
   </refsect3>
 
   <refsect3 id="cpp-enum">