Allow using an Fl_SVG_Image object as window icon.

Fix for issue #90: Setting an svg image as a window icon causes a segfault.

FL/Fl_Image.H

@@ -273,6 +273,7 @@ public:
   static bool register_images_done;
 };
 
+class Fl_SVG_Image;
 
 /**
   The Fl_RGB_Image class supports caching and drawing
@@ -291,6 +292,7 @@ class FL_EXPORT Fl_RGB_Image : public Fl_Image {
 public:
 
   /** Points to the start of the object's data array
+   \see class Fl_SVG_Image which delays initialization of this member variable.
    */
   const uchar *array;
   /** If non-zero, the object's data array is delete[]'d when deleting the object.
@@ -332,6 +334,12 @@ public:
    \sa  void Fl_RGB_Image::max_size(size_t)
    */
   static size_t max_size() {return max_size_;}
+  /** Returns whether an image is an Fl_SVG_Image or not.
+  This virtual method returns a pointer to the Fl_SVG_Image if this object is an instance of Fl_SVG_Image or NULL if not. */
+  virtual Fl_SVG_Image *as_svg_image() { return NULL; }
+  /** Makes sure the object is fully initialized.
+   In particular, makes sure member variable \ref array is non-null. */
+  virtual void normalize() {}
 };
 
 #endif // !Fl_Image_H

FL/Fl_SVG_Image.H

@@ -31,7 +31,7 @@ struct NSVGimage;
  if the file could not be opened or read, and ERR_FORMAT if the SVG format could not be decoded. 
  If the image has loaded correctly, w(), h(), and d() should return values greater than zero.
 
- Rasterization is not done until the image is first drawn or resize() is called. Therefore, 
+ Rasterization is not done until the image is first drawn or resize() or normalize() is called. Therefore, 
  \ref array is NULL until then. The delayed rasterization ensures an Fl_SVG_Image is always rasterized
  to the exact screen resolution at which it is drawn.
 
@@ -161,6 +161,8 @@ public:
   virtual void color_average(Fl_Color c, float i);
   virtual void draw(int X, int Y, int W, int H, int cx = 0, int cy = 0);
   void draw(int X, int Y) { draw(X, Y, w(), h(), 0, 0); }
+  virtual Fl_SVG_Image *as_svg_image() { return this; };
+  virtual void normalize();
 };
 
 #endif // FL_SVG_IMAGE_H

src/Fl_SVG_Image.cxx

@@ -266,6 +266,12 @@ void Fl_SVG_Image::color_average(Fl_Color c, float i) {
   Fl_RGB_Image::color_average(c, i);
 }
 
+/** Makes sure the object is fully initialized.
+ This function rasterizes the SVG image if that was not done before. */
+void Fl_SVG_Image::normalize() {
+  if (!array) resize(w(), h());
+}
+
 #endif // FLTK_USE_NANOSVG
 
 //

src/Fl_cocoa.mm

@@ -4516,6 +4516,7 @@ void Fl_Cocoa_Window_Driver::icons(const Fl_RGB_Image *icons[], int count) {
   [icon_image release];
   icon_image = nil;
   if (count >= 1 && pWindow->border() && pWindow->label() && strlen(pWindow->label())) {
+    ((Fl_RGB_Image*)icons[0])->normalize();
     icon_image = rgb_to_nsimage(icons[0]);
   }
 }

src/drivers/WinAPI/Fl_WinAPI_Window_Driver.cxx

@@ -379,8 +379,10 @@ void Fl_WinAPI_Window_Driver::icons(const Fl_RGB_Image *icons[], int count) {
     icon_->icons = new Fl_RGB_Image*[count];
     icon_->count = count;
     // FIXME: Fl_RGB_Image lacks const modifiers on methods
-    for (int i = 0;i < count;i++)
+    for (int i = 0;i < count;i++) {
       icon_->icons[i] = (Fl_RGB_Image*)((Fl_RGB_Image*)icons[i])->copy();
+      icon_->icons[i]->normalize();
+    }
   }
   
   if (Fl_X::i(pWindow))

src/drivers/X11/Fl_X11_Window_Driver.cxx

@@ -356,8 +356,10 @@ void Fl_X11_Window_Driver::icons(const Fl_RGB_Image *icons[], int count) {
     icon_->icons = new Fl_RGB_Image*[count];
     icon_->count = count;
     // FIXME: Fl_RGB_Image lacks const modifiers on methods
-    for (int i = 0;i < count;i++)
+    for (int i = 0;i < count;i++) {
       icon_->icons[i] = (Fl_RGB_Image*)((Fl_RGB_Image*)icons[i])->copy();
+      icon_->icons[i]->normalize();
+    }
   }
   
   if (Fl_X::i(pWindow))