Spot Removal tool

It is not working yet, but the GUI is (almost) done.
See issue #2239.

rtengine/alpha.h

@@ -0,0 +1,77 @@
+/*
+ *  This file is part of RawTherapee.
+ *
+ *  Copyright (c) 2004-2010 Gabor Horvath <hgabor@rawtherapee.com>
+ *
+ *  RawTherapee is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  RawTherapee is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with RawTherapee.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef _ALPHA_H_
+#define _ALPHA_H_
+
+#include <gtkmm.h>
+#include <assert.h>
+
+#define CHECK_BOUNDS 0
+
+namespace rtengine
+{
+
+/// Alpha channel class (8 bits)
+class Alpha
+{
+protected:
+    Cairo::RefPtr<Cairo::ImageSurface> surface;
+
+public:
+    Alpha ();
+    Alpha (int width, int height);
+    //~Alpha ();
+
+    void setSize(int width, int height);
+    int getWidth();
+    int getHeight();
+
+    const Cairo::RefPtr<Cairo::ImageSurface> getSurface ();
+
+    // TODO: to make the editing faster, we should add an iterator class
+
+    // Will send back the start of a row
+    unsigned char* operator () (unsigned row) const;
+    // Will send back a value at a given row, col position
+    unsigned char& operator () (unsigned row, unsigned col);
+    const unsigned char operator () (unsigned row, unsigned col) const;
+};
+
+
+
+inline const Cairo::RefPtr<Cairo::ImageSurface> Alpha::getSurface () {
+    return surface; // to be used in bitmap edition
+}
+
+inline const unsigned char Alpha::operator () (unsigned row,
+        unsigned col) const {
+    return *(surface->get_data () + row * surface->get_width () + col);
+}
+
+inline unsigned char& Alpha::operator () (unsigned row, unsigned col) {
+    return *(surface->get_data () + row * surface->get_width () + col);
+}
+
+inline unsigned char* Alpha::operator () (unsigned row) const {
+    return surface->get_data () + row * surface->get_width ();
+}
+
+}
+
+#endif