introduce widget that shows logs

src/libcalamaresui/CMakeLists.txt

@@ -30,6 +30,7 @@ set( calamaresui_SOURCES
     widgets/ErrorDialog.cpp
     widgets/FixedAspectRatioLabel.cpp
     widgets/PrettyRadioButton.cpp
+    widgets/LogWidget.cpp
     widgets/TranslationFix.cpp
     widgets/WaitingWidget.cpp
     ${CMAKE_SOURCE_DIR}/3rdparty/waitingspinnerwidget.cpp

src/libcalamaresui/widgets/LogWidget.cpp

@@ -0,0 +1,75 @@
+#include "LogWidget.h"
+#include <QStackedLayout>
+#include "utils/Logger.h"
+#include <QTextStream>
+#include <QThread>
+#include <QFile>
+
+namespace Calamares
+{
+
+LogThread::LogThread(QObject *parent)
+    : QThread(parent) {
+
+}
+
+void LogThread::run()
+{
+    auto filePath = Logger::logFile();
+
+    qint64 lastPosition = 0;
+
+    while (!QThread::currentThread()->isInterruptionRequested()) {
+        auto filePath = Logger::logFile();
+        QFile file(filePath);
+
+        qint64 fileSize = file.size();
+        // Check whether the file size has changed since last time
+        // we read the file.
+        if (lastPosition != fileSize && file.open(QFile::ReadOnly | QFile::Text)) {
+
+            // Start reading at the position we ended up last time we read the file.
+            file.seek(lastPosition);
+
+            QTextStream in(&file);
+            auto chunk = in.readAll();
+            qint64 newPosition = in.pos();
+
+            lastPosition = newPosition;
+
+            onLogChunk(chunk);
+        }
+        QThread::msleep(100);
+    }
+}
+
+LogWidget::LogWidget(QWidget *parent)
+    : QWidget(parent)
+    , m_text( new QPlainTextEdit )
+    , m_log_thread( this )
+{
+    auto layout = new QStackedLayout(this);
+    setLayout(layout);
+
+    m_text->setReadOnly(true);
+
+    QFont monospaceFont("monospace");
+    monospaceFont.setStyleHint(QFont::Monospace);
+    m_text->setFont(monospaceFont);
+
+    layout->addWidget(m_text);
+
+    connect(&m_log_thread, &LogThread::onLogChunk, this, &LogWidget::handleLogChunk);
+
+    m_log_thread.start();
+}
+
+void
+LogWidget::handleLogChunk(const QString &logChunk)
+{
+    m_text->appendPlainText(logChunk);
+    m_text->moveCursor(QTextCursor::End);
+    m_text->ensureCursorVisible();
+}
+
+}

src/libcalamaresui/widgets/LogWidget.h

@@ -0,0 +1,37 @@
+#ifndef LIBCALAMARESUI_LOGWIDGET_H
+#define LIBCALAMARESUI_LOGWIDGET_H
+
+#include <QWidget>
+#include <QPlainTextEdit>
+#include <QThread>
+
+namespace Calamares
+{
+
+class LogThread : public QThread
+{
+    Q_OBJECT
+
+    void run() override;
+
+public:
+    explicit LogThread(QObject *parent = nullptr);
+
+signals:
+    void onLogChunk(const QString &logChunk);
+};
+
+class LogWidget : public QWidget
+{
+    Q_OBJECT
+
+    QPlainTextEdit* m_text;
+    LogThread m_log_thread;
+public:
+    explicit LogWidget(QWidget *parent = nullptr);
+
+    void handleLogChunk(const QString &logChunk);
+};
+
+}
+#endif // LOGWIDGET_H