ConsoleStream.h

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 * CamiTK - Computer Assisted Medical Intervention ToolKit
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#ifndef ConsoleStream_H
#define ConsoleStream_H
 
// -- stl stuff
#include <iostream>
#include <streambuf>
#include <string>
#include <mutex>
 
// -- QT stuff
#include <QObject>
#include <QTextEdit>
#include <QMetaObject>
 
namespace camitk {
class ConsoleStream : public QObject, public std::basic_streambuf<char> {
public:
    ConsoleStream(QObject *parent = nullptr)
        : QObject(parent),
          myStream(nullptr),
          previousBuffer(nullptr),
          logTextEdit(nullptr) {}
 
    ~ConsoleStream() override {
        flushPending();
        free();
    }
 
    void setStream(std::ostream* stream) {
        free();
        myStream = stream;
        previousBuffer = stream->rdbuf();
        stream->rdbuf(this);
    }
 
    void setTextEdit(QTextEdit* textEdit) {
        logTextEdit = textEdit;
    }
 
    void init(std::ostream* stream, QTextEdit* textEdit) {
        setTextEdit(textEdit);
        setStream(stream);
    }
 
    void free() {
        if (previousBuffer != nullptr && myStream != nullptr) {
            myStream->rdbuf(previousBuffer);
            myStream = nullptr;
            previousBuffer = nullptr;
        }
    }
 
signals:
    void appendText(QString text);
 
protected:
 
    int_type overflow(int_type v) override {
        if (v == '\n') {
            flushPending();
        }
        else {
            buffer += static_cast<char>(v);
        }
        return v;
    }
 
    std::streamsize xsputn(const char* p, std::streamsize n) override {
        buffer.append(p, p + n);
 
        std::string::size_type pos = 0;
        while ((pos = buffer.find('\n')) != std::string::npos) {
            std::string line = buffer.substr(0, pos);
            buffer.erase(0, pos + 1);
            emitText(QString::fromLocal8Bit(line.c_str()));
        }
 
        return n;
    }
 
private:
    void emitText(const QString &text) {
        if (!logTextEdit)
            return;
 
        // emit across threads safely
        QMetaObject::invokeMethod(logTextEdit, [text, this]() {
            logTextEdit->moveCursor(QTextCursor::End);
            logTextEdit->insertPlainText(text + "\n");
            logTextEdit->moveCursor(QTextCursor::End);
        }, Qt::QueuedConnection);
    }
 
    void flushPending() {
        if (!buffer.empty()) {
            emitText(QString::fromLocal8Bit(buffer.c_str()));
            buffer.clear();
        }
    }
 
    std::ostream* myStream;
    std::streambuf* previousBuffer;
    std::string buffer;
    QTextEdit* logTextEdit;
};
 
}
 
 
 
#endif