[education/cantor] src/backends: Tag backend plot outputs

Git commit ff5f71dd3912c31be076553cf0f4f9bbd63055ca by Alexander Semke, on behalf of Nanhao Lv.
Committed on 26/07/2026 at 19:50.
Pushed by asemke into branch 'master'.

Tag backend plot outputs

M  +6    -2    src/backends/R/rexpression.cpp
M  +3    -1    src/backends/julia/juliaexpression.cpp
M  +63   -9    src/backends/maxima/maximaexpression.cpp
M  +5    -0    src/backends/maxima/maximaexpression.h
M  +1    -0    src/backends/octave/octaveexpression.cpp
M  +2    -0    src/backends/python/pythonexpression.cpp
M  +3    -1    src/backends/qalculate/qalculateexpression.cpp
M  +6    -2    src/backends/sage/sageexpression.cpp
M  +3    -1    src/backends/scilab/scilabexpression.cpp

https://invent.kde.org/education/cantor/-/commit/ff5f71dd3912c31be076553cf0f4f9bbd63055ca

diff --git a/src/backends/R/rexpression.cpp b/src/backends/R/rexpression.cpp
index 426feefb..4c194683 100644
--- a/src/backends/R/rexpression.cpp
+++ b/src/backends/R/rexpression.cpp
@@ -73,13 +73,17 @@ void RExpression::showFilesAsResult(const QStringList& files)
         qDebug()<<"MimeType: "<<type.name();
         if(type.name() == QLatin1String("application/pdf"))
         {
-            setResult(new Cantor::ImageResult(QUrl::fromLocalFile(file)));
+            auto* result = new Cantor::ImageResult(QUrl::fromLocalFile(file));
+            result->setRole(Cantor::Result::Role::Plot);
+            setResult(result);
             setStatus(Cantor::Expression::Done);
         }
         else
             if (type.name().contains(QLatin1String("image")))
         {
-            setResult(new Cantor::ImageResult(QUrl::fromLocalFile(file)));
+            auto* result = new Cantor::ImageResult(QUrl::fromLocalFile(file));
+            result->setRole(Cantor::Result::Role::Plot);
+            setResult(result);
             setStatus(Cantor::Expression::Done);
         }
         else if(type.inherits(QLatin1String("text/plain"))
diff --git a/src/backends/julia/juliaexpression.cpp b/src/backends/julia/juliaexpression.cpp
index 6d0bf915..374ebc1b 100644
--- a/src/backends/julia/juliaexpression.cpp
+++ b/src/backends/julia/juliaexpression.cpp
@@ -69,7 +69,9 @@ void JuliaExpression::finalize(const QString& output, const QString& error, bool
     } else {
         if (!m_plot_filename.isEmpty() && QFileInfo(m_plot_filename).exists()) {
             // If we have plot in result, show it
-            setResult(new Cantor::ImageResult(QUrl::fromLocalFile(m_plot_filename)));
+            auto* result = new Cantor::ImageResult(QUrl::fromLocalFile(m_plot_filename));
+            result->setRole(Cantor::Result::Role::Plot);
+            setResult(result);
         } else {
             if (!output.isEmpty())
                 setResult(new Cantor::TextResult(output));
diff --git a/src/backends/maxima/maximaexpression.cpp b/src/backends/maxima/maximaexpression.cpp
index 86e6c0d9..47053239 100644
--- a/src/backends/maxima/maximaexpression.cpp
+++ b/src/backends/maxima/maximaexpression.cpp
@@ -17,6 +17,8 @@
 #include <QApplication>
 #include <QDebug>
 #include <QDir>
+#include <QFileInfo>
+#include <QImage>
 #include <QRegularExpression>
 #include <QScreen>
 #include <QTemporaryFile>
@@ -46,6 +48,9 @@ void MaximaExpression::evaluate()
         m_isPlot = false;
         m_plotResult = nullptr;
         m_plotResultIndex = -1;
+        m_plotResultLoadScheduled = false;
+        m_plotFileLastSize = -1;
+        m_plotResultLoadAttempts = 0;
     }
 
     QString cmd = command();
@@ -434,7 +439,10 @@ void MaximaExpression::parseResult(const QString& resultContent)
             if (m_plotResult)
                 result = m_plotResult;
             else
+            {
+                schedulePlotResultLoad();
                 result = new Cantor::TextResult(i18n("Waiting for the plot result"));
+            }
         }
         else
             result = new Cantor::TextResult(textContent);
@@ -544,17 +552,63 @@ void MaximaExpression::addInformation(const QString& information)
 
 void MaximaExpression::imageChanged()
 {
-    if(m_tempFile->size()>0)
-    {
-        m_plotResult = new Cantor::ImageResult( QUrl::fromLocalFile(m_tempFile->fileName()) );
+    schedulePlotResultLoad();
+}
+
+void MaximaExpression::schedulePlotResultLoad()
+{
+    if (m_plotResult || m_plotResultLoadScheduled)
+        return;
+
+    m_plotResultLoadScheduled = true;
+    QTimer::singleShot(100, this, &MaximaExpression::loadPlotResult);
+}
+
+void MaximaExpression::loadPlotResult()
+{
+    m_plotResultLoadScheduled = false;
+
+    if (!m_tempFile || m_plotResult)
+        return;
 
-        // Check, that we already parse maxima output for this plot, and if not, keep it up to this moment
-        // If it's true, replace text info result by real plot and set status as Done
-        if (m_plotResultIndex != -1)
+    const QFileInfo plotFileInfo(m_tempFile->fileName());
+    if (!plotFileInfo.exists() || plotFileInfo.size() <= 0)
+    {
+        if (m_plotResultLoadAttempts < 10)
         {
-            replaceResult(m_plotResultIndex, m_plotResult);
-            if (status() != Cantor::Expression::Error)
-                setStatus(Cantor::Expression::Done);
+            ++m_plotResultLoadAttempts;
+            schedulePlotResultLoad();
         }
+        else if (m_plotResultIndex != -1 && status() == Cantor::Expression::Computing)
+            setStatus(Cantor::Expression::Done);
+
+        return;
+    }
+
+    // QFileSystemWatcher can notify before gnuplot finishes writing.
+    if (plotFileInfo.size() != m_plotFileLastSize)
+    {
+        m_plotFileLastSize = plotFileInfo.size();
+        schedulePlotResultLoad();
+        return;
+    }
+
+    auto* plotResult = new Cantor::ImageResult(QUrl::fromLocalFile(m_tempFile->fileName()));
+    if (plotResult->data().value<QImage>().isNull() && m_plotResultLoadAttempts < 10)
+    {
+        delete plotResult;
+        ++m_plotResultLoadAttempts;
+        schedulePlotResultLoad();
+        return;
+    }
+
+    m_plotResult = plotResult;
+    m_plotResult->setRole(Cantor::Result::Role::Plot);
+
+    if (m_plotResultIndex != -1)
+    {
+        replaceResult(m_plotResultIndex, m_plotResult);
+        if (status() == Cantor::Expression::Computing)
+            setStatus(Cantor::Expression::Done);
     }
 }
diff --git a/src/backends/maxima/maximaexpression.h b/src/backends/maxima/maximaexpression.h
index 3d3ac647..e7121442 100644
--- a/src/backends/maxima/maximaexpression.h
+++ b/src/backends/maxima/maximaexpression.h
@@ -35,9 +35,11 @@ public:
 
 private Q_SLOTS:
     void imageChanged();
+    void loadPlotResult();
 
 private:
     void parseResult(const QString&);
+    void schedulePlotResultLoad();
 
     QTemporaryFile* m_tempFile = nullptr;
     QFileSystemWatcher m_fileWatch;
@@ -47,6 +49,9 @@ private:
     bool m_isDraw = false;
     Cantor::Result* m_plotResult = nullptr;
     int m_plotResultIndex = -1;
+    bool m_plotResultLoadScheduled = false;
+    qint64 m_plotFileLastSize = -1;
+    int m_plotResultLoadAttempts = 0;
     QString m_errorBuffer;
 };
 
diff --git a/src/backends/octave/octaveexpression.cpp b/src/backends/octave/octaveexpression.cpp
index d548ab4d..121f1803 100644
--- a/src/backends/octave/octaveexpression.cpp
+++ b/src/backends/octave/octaveexpression.cpp
@@ -235,6 +235,7 @@ void OctaveExpression::imageChanged()
     const QUrl& url = QUrl::fromLocalFile(m_plotFilename);
     QByteArray pdfData = file.readAll();
     auto* newResult = new Cantor::PdfResult(url, pdfData);
+    newResult->setRole(Cantor::Result::Role::Plot);
 
     bool found = false;
     for (int i = 0; i < results().size(); i++)
diff --git a/src/backends/python/pythonexpression.cpp b/src/backends/python/pythonexpression.cpp
index 6f400578..5a5d97e3 100644
--- a/src/backends/python/pythonexpression.cpp
+++ b/src/backends/python/pythonexpression.cpp
@@ -143,6 +143,7 @@ void PythonExpression::imageChanged()
         return;
 
     auto* newResult = new Cantor::ImageResult(QUrl::fromLocalFile(m_tempFile->fileName()));
+    newResult->setRole(Cantor::Result::Role::Plot);
     if (result() == nullptr)
         setResult(newResult);
     else
@@ -153,6 +154,7 @@ void PythonExpression::imageChanged()
             {
                 replaceResult(i, newResult);
                 found = true;
+                break;
             }
         if (!found)
             addResult(newResult);
diff --git a/src/backends/qalculate/qalculateexpression.cpp b/src/backends/qalculate/qalculateexpression.cpp
index 8ceaea1e..6eefcc4a 100644
--- a/src/backends/qalculate/qalculateexpression.cpp
+++ b/src/backends/qalculate/qalculateexpression.cpp
@@ -646,7 +646,9 @@ void QalculateExpression::evaluatePlotCommand()
     deletePlotDataParameters(plotDataParameterList);
 
     if (plotInline) {
-        setResult(new Cantor::ImageResult(QUrl::fromLocalFile(QString::fromStdString(plotParameters.filename))));
+        auto* result = new Cantor::ImageResult(QUrl::fromLocalFile(QString::fromStdString(plotParameters.filename)));
+        result->setRole(Cantor::Result::Role::Plot);
+        setResult(result);
         setStatus(Cantor::Expression::Done);
     }
 }
diff --git a/src/backends/sage/sageexpression.cpp b/src/backends/sage/sageexpression.cpp
index b7addd4a..a6dedb21 100644
--- a/src/backends/sage/sageexpression.cpp
+++ b/src/backends/sage/sageexpression.cpp
@@ -220,12 +220,16 @@ void SageExpression::evalFinished()
         if(type.inherits(QLatin1String("image/gif")))
         {
             qDebug()<<"adding animation";
-            addResult( new Cantor::AnimationResult(QUrl::fromLocalFile(m_imagePath), i18n("Result of %1" , command() ) ) );
+            auto* result = new Cantor::AnimationResult(QUrl::fromLocalFile(m_imagePath), i18n("Result of %1" , command() ) );
+            result->setRole(Cantor::Result::Role::Plot);
+            addResult(result);
         }
         else
         {
             qDebug()<<"adding image";
-            addResult( new Cantor::ImageResult(QUrl::fromLocalFile(m_imagePath ), i18n("Result of %1" , command() ) ) );
+            auto* result = new Cantor::ImageResult(QUrl::fromLocalFile(m_imagePath ), i18n("Result of %1" , command() ) );
+            result->setRole(Cantor::Result::Role::Plot);
+            addResult(result);
         }
     }
     setStatus(Cantor::Expression::Done);
diff --git a/src/backends/scilab/scilabexpression.cpp b/src/backends/scilab/scilabexpression.cpp
index 5c60dcfe..4477b9f2 100644
--- a/src/backends/scilab/scilabexpression.cpp
+++ b/src/backends/scilab/scilabexpression.cpp
@@ -97,7 +97,9 @@ void ScilabExpression::parsePlotFile(QString filename)
     qDebug() << "parsePlotFile";
     qDebug() << "ScilabExpression::parsePlotFile: " << filename;
 
-    setResult(new ScilabPlotResult(QUrl::fromLocalFile(filename)));
+    auto* result = new ScilabPlotResult(QUrl::fromLocalFile(filename));
+    result->setRole(Cantor::Result::Role::Plot);
+    setResult(result);
 
     setPlotPending(false);