Add Doxygen comments for the Fl_RGB_Image::alloc_array and ::array public attributes.

Also, document what is the value of alloc_array after construction of an Fl_RGB_Image object.

git-svn-id: file:///fltk/svn/fltk/branches/branch-1.3-porting@11897 ea41ed52-d2ee-0310-a9c1-e6b18d33e121

FL/Fl_Image.H

@@ -201,8 +201,12 @@ class FL_EXPORT Fl_RGB_Image : public Fl_Image {
   static size_t max_size_;
 public:
 
+  /** Points to the start of the object's data array
+   */
   const uchar *array;
-  int alloc_array; // Non-zero if array was allocated
+  /** If non-zero, the object's data array is delete[]'d when deleting the object.
+   */
+  int alloc_array;
 
 private:
   // These two variables are used to cache the image and mask for the main display graphics driver

src/Fl_Image.cxx

@@ -245,6 +245,10 @@ int fl_convert_pixmap(const char*const* cdata, uchar* out, Fl_Color bg);
  \param[in] LD     Line data size (default=0).<br>
     Line data is extra data that is included after each line
     of color image data and is normally not present.
+ 
+ This constructor sets Fl_RGB_Image::alloc_array to 0.
+ To have the image object control the deallocation of the data array,
+ set alloc_array to non-zero after construction.
  \see Fl_Image::data(), Fl_Image::w(), Fl_Image::h(), Fl_Image::d(), Fl_Image::ld()
  */
 Fl_RGB_Image::Fl_RGB_Image(const uchar *bits, int W, int H, int D, int LD) :
@@ -263,7 +267,8 @@ Fl_RGB_Image::Fl_RGB_Image(const uchar *bits, int W, int H, int D, int LD) :
  The constructor creates a new RGBA image from the specified Fl_Pixmap.
  
  The RGBA image is built fully opaque except for the transparent area
- of the pixmap that is assigned the \p bg color with full transparency 
+ of the pixmap that is assigned the \p bg color with full transparency.
+ This constructor sets Fl_RGB_Image::alloc_array to 1.
  */
 Fl_RGB_Image::Fl_RGB_Image(const Fl_Pixmap *pxm, Fl_Color bg):
   Fl_Image(pxm->w(), pxm->h(), 4),