Pipette and "On Preview Widgets" branch. See issue 227

The pipette part is already working quite nice but need to be finished. The widgets part needs more work...

rtgui/colorprovider.h

@@ -0,0 +1,58 @@
+/*
+ *  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 _COLORPROVIDER_
+#define _COLORPROVIDER_
+
+#include <gtkmm.h>
+
+class ColorProvider;
+
+/*
+ * The ColorCaller is the class that will query the ColorProvider
+ */
+class ColorCaller {
+	protected:
+		// a class can handle several ColorCaller;
+		// colorCallerId will let the provider identify the caller
+		int colorCallerId;
+		ColorProvider* colorProvider;
+
+	public:
+		double ccRed;
+		double ccGreen;
+		double ccBlue;
+
+		ColorCaller() : colorCallerId(-1), colorProvider(NULL), ccRed(0.), ccGreen(0.), ccBlue(0.) {}
+		void setColorProvider (ColorProvider* p, int id) { colorProvider = p; colorCallerId = id; }
+};
+
+/*
+ * Use it to let your widget feed a colored bar or graph lines with the wanted colors
+ * If you doesn't need to dynamically feed a widget with colors (e.g. curve's graph),
+ * you don't need to declare the instanciator class as BEING a ColorProvider, you'll
+ * still be able to set gradients for e.g. ColoredBar(s)
+ */
+class ColorProvider {
+
+	public:
+		virtual ~ColorProvider() {};
+		virtual void colorForValue (double valX, double valY, int callerId, ColorCaller* caller) {};
+};
+
+#endif