WIP: Moved sources int src/, separated most of the source code from Perl.

The XS was left only for the unit / integration tests, and it links
libslic3r only. No wxWidgets are allowed to be used from Perl starting
from now.

src/slic3r/GUI/ProgressIndicator.hpp

@@ -0,0 +1,70 @@
+#ifndef IPROGRESSINDICATOR_HPP
+#define IPROGRESSINDICATOR_HPP
+
+#include <string>
+#include <functional>
+
+namespace Slic3r {
+
+/**
+ * @brief Generic progress indication interface.
+ */
+class ProgressIndicator {
+public:
+    using CancelFn = std::function<void(void)>; // Cancel function signature.
+
+private:
+    float state_ = .0f, max_ = 1.f, step_;
+    CancelFn cancelfunc_ = [](){};
+
+public:
+
+    inline virtual ~ProgressIndicator() {}
+
+    /// Get the maximum of the progress range.
+    float max() const { return max_; }
+
+    /// Get the current progress state
+    float state() const { return state_; }
+
+    /// Set the maximum of the progress range
+    virtual void max(float maxval) { max_ = maxval; }
+
+    /// Set the current state of the progress.
+    virtual void state(float val)  { state_ = val; }
+
+    /**
+     * @brief Number of states int the progress. Can be used instead of giving a
+     * maximum value.
+     */
+    virtual void states(unsigned statenum) {
+        step_ = max_ / statenum;
+    }
+
+    /// Message shown on the next status update.
+    virtual void message(const std::string&) = 0;
+
+    /// Title of the operation.
+    virtual void title(const std::string&) = 0;
+
+    /// Formatted message for the next status update. Works just like sprintf.
+    virtual void message_fmt(const std::string& fmt, ...);
+
+    /// Set up a cancel callback for the operation if feasible.
+    virtual void on_cancel(CancelFn func = CancelFn()) { cancelfunc_ = func; }
+
+    /**
+     * Explicitly shut down the progress indicator and call the associated
+     * callback.
+     */
+    virtual void cancel() { cancelfunc_(); }
+
+    /// Convenience function to call message and status update in one function.
+    void update(float st, const std::string& msg) {
+        message(msg); state(st);
+    }
+};
+
+}
+
+#endif // IPROGRESSINDICATOR_HPP