Progress.hh

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#ifndef PROGRESS_HH_
#define PROGRESS_HH_

#include <set>
#include <algorithm>

#ifdef USE_QT
#include <QProgressDialog>
#endif

namespace ACG {

class Progress {
    public:
        Progress(double maxProgress = 1.0) : parent(0), maxProgress(maxProgress), currentProgress(0.0), dialog_padding(0)
        {};
        virtual ~Progress() {
            if (parent) parent->childGoesBye(this);
        };

        void setMaxProgress(double value) {
            maxProgress = value;
            if (currentProgress != 0.0) progressChanged();
        }

#ifdef USE_QT
        void connectToDialog(QProgressDialog *dlg) {
            dialog = dlg;
            dialog->setMaximum(100000);
            updateDialog();
        }
#endif

        double getNormalizedProgress() const {
            return getProgress() / maxProgress;
        }

        double getProgress() const {
            double result = currentProgress;

            /*
             * Thread safety: Lock mutex on children!
             */
            for (std::set<ChildRecord>::const_iterator it = children.begin(); it != children.end(); ++it) {
                result += it->child->getNormalizedProgress() * it->contribution;
            }

            return std::min(maxProgress, result);
        }

        void addSubProgress(Progress *progress, double contribution) {
            progress->parent = this;

            /*
             * Thread safety: Lock mutex on children!
             */
            children.insert(ChildRecord(progress, contribution));
        }

        void increment(double amount) {
            currentProgress += amount;
            progressChanged();
        }

    protected:
        void onChildProgress(Progress *) {
            progressChanged();
        }

        inline void progressChanged() {
            if (parent) parent->onChildProgress(this);
            updateDialog();
        }

        inline void updateDialog() {
#ifdef USE_QT
            if (dialog)
                dialog->setValue(100000 * getNormalizedProgress());
#endif
        }

        inline void childGoesBye(Progress *child) {
            /*
             * Thread safety: Lock mutex on children!
             */
            std::set<ChildRecord>::iterator it = children.find(ChildRecord(child, 0));
            currentProgress += it->contribution;
            children.erase(it);
            progressChanged();
        }

    protected:
        Progress *parent;

        class ChildRecord {
            public:
                ChildRecord(Progress *child, double contribution) : child(child), contribution(contribution) {}

                bool operator==(const ChildRecord &rhs) const { return child == rhs.child; }
                bool operator<(const ChildRecord &rhs) const { return child < rhs.child; }

                Progress *child;
                double contribution;
        };
        std::set<ChildRecord> children;

        double maxProgress, currentProgress;

        union {
#ifdef USE_QT
            QProgressDialog *dialog;
#endif
            /*
             * Make sure the object has the same memory layout, no matter
             * whether USE_QT is defined or not.
             */
            void *dialog_padding;
        };

    private:
        /*
         * Progress objects are not copyable because
         * of the child-parent double linkage.
         */
        Progress(const Progress &rhs);
        Progress &operator=(const Progress &rhs);
};

} /* namespace ACG */
#endif /* PROGRESS_HH_ */