Added QPlainTextEdit sink

QPlainTextEdit performs better than QTextEdit and its derivatives and also it has rich features

include/spdlog/sinks/qplaintextedit_sink.h

+// Copyright(c) 2015-present, Gabi Melman, mguludag and spdlog contributors.
+// Distributed under the MIT License (http://opensource.org/licenses/MIT)
+
+#pragma once
+
+//
+// Custom sink for QPlainTextEdit and its childs(QTextBrowser... etc)
+// Building and using requires Qt library.
+//
+
+#include "spdlog/common.h"
+#include "spdlog/details/log_msg.h"
+#include "spdlog/details/synchronous_factory.h"
+#include "spdlog/sinks/base_sink.h"
+
+#include "qplaintextedit_sink_p.h"
+
+namespace spdlog {
+namespace sinks {
+template <typename Mutex>
+class qplaintextedit_sink : public base_sink<Mutex> {
+public:
+    qplaintextedit_sink(QPlainTextEdit *textedit = nullptr) {
+        if (textedit != nullptr) {
+            textedit_p = std::make_shared<_spdlog_p::_sinks_p::qplaintextedit_sink_p>(textedit);
+        } else {
+            throw spdlog_ex("Error opening QPlainTextEdit");
+        }
+    }
+
+    ~qplaintextedit_sink() { flush_(); }
+
+protected:
+    void sink_it_(const details::log_msg &msg) override {
+        memory_buf_t formatted;
+        base_sink<Mutex>::formatter_->format(msg, formatted);
+        auto str = std::string(formatted.begin(), formatted.end() - 2);
+        textedit_p->append(str);
+    }
+
+    void flush_() override {}
+
+private:
+    std::shared_ptr<_spdlog_p::_sinks_p::qplaintextedit_sink_p> textedit_p = nullptr;
+};
+
+#include "spdlog/details/null_mutex.h"
+#include <mutex>
+
+using qplaintextedit_sink_mt = qplaintextedit_sink<std::mutex>;
+using qplaintextedit_sink_st = qplaintextedit_sink<spdlog::details::null_mutex>;
+
+} // namespace sinks
+
+template <typename Factory = spdlog::synchronous_factory>
+inline std::shared_ptr<logger>
+qplaintextedit_logger_mt(const std::string &logger_name,
+                    QPlainTextEdit *qplaintextedit = nullptr) {
+    return Factory::template create<sinks::qplaintextedit_sink_mt>(logger_name,
+                                                              qplaintextedit);
+}
+
+template <typename Factory = spdlog::synchronous_factory>
+inline std::shared_ptr<logger>
+qplaintextedit_logger_st(const std::string &logger_name,
+                    QPlainTextEdit *qplaintextedit = nullptr) {
+    return Factory::template create<sinks::qplaintextedit_sink_st>(logger_name,
+                                                              qplaintextedit);
+}
+
+} // namespace spdlog

include/spdlog/sinks/qplaintextedit_sink_p.h

+// Copyright(c) 2015-present, Gabi Melman, mguludag and spdlog contributors.
+// Distributed under the MIT License (http://opensource.org/licenses/MIT)
+
+#pragma once
+
+#include <QObject>
+#include <QPlainTextEdit>
+
+namespace _spdlog_p {
+namespace _sinks_p {
+class qplaintextedit_sink_p : public QObject {
+    Q_OBJECT
+public:
+    qplaintextedit_sink_p(QPlainTextEdit *textedit = nullptr) {
+        if (textedit != nullptr) {
+            textedit_ = textedit;
+            connect(this, &qplaintextedit_sink_p::append_text, textedit_,
+                    &QPlainTextEdit::appendPlainText);
+        }
+    }
+
+    ~qplaintextedit_sink_p() {}
+
+    void append(const std::string &str) {
+        emit append_text(QString::fromStdString(str));
+    }
+
+signals:
+    void append_text(const QString &);
+
+private:
+    QPlainTextEdit *textedit_ = nullptr;
+};
+} // namespace _sinks_p
+} // namespace _spdlog_p