Save splitter sizes in the Execute SQL areas

Whenever the splitters between the SQL editor, the table result and the
last execution results panes are moved, the sizes are saved to memory (for
performance) so the next SQL tab to be opened restores them. When an area
is destroyed the last saved settings are saved to disk, so they are ready
for the next execution without much impact in disk utilisation.

Issue #1889

src/Settings.cpp

@@ -295,6 +295,14 @@ QVariant Settings::getDefaultValue(const std::string& group, const std::string&
     if(group == "editor" && name == "horizontal_tiling")
         return false;
 
+    // editor/splitter1_sizes?
+    if(group == "editor" && name == "splitter1_sizes")
+        return QVariant();
+
+    // editor/splitter2_sizes?
+    if(group == "editor" && name == "splitter2_sizes")
+        return QVariant();
+
     // extensions/list?
     if(group == "extensions" && name == "list")
         return QStringList();

src/SqlExecutionArea.cpp

@@ -40,6 +40,14 @@ SqlExecutionArea::SqlExecutionArea(DBBrowserDB& _db, QWidget* parent) :
 
     connect(&fileSystemWatch, &QFileSystemWatcher::fileChanged, this, &SqlExecutionArea::fileChanged);
 
+    // Save to settings when sppliter is moved, but only to memory.
+    connect(ui->splitter, &QSplitter::splitterMoved, this,  [this]() {
+            Settings::setValue("editor", "splitter1_sizes", ui->splitter->saveState(), /* dont_save_to_disk */ true);
+        });
+    connect(ui->splitter_2, &QSplitter::splitterMoved, this, [this]() {
+            Settings::setValue("editor", "splitter2_sizes", ui->splitter_2->saveState(), /* dont_save_to_disk */ true);
+        });
+
     // Set collapsible the editErrors panel
     ui->splitter_2->setCollapsible(1, true);
 
@@ -49,6 +57,10 @@ SqlExecutionArea::SqlExecutionArea(DBBrowserDB& _db, QWidget* parent) :
 
 SqlExecutionArea::~SqlExecutionArea()
 {
+    // Save to disk last stored splitter sizes
+    Settings::setValue("editor", "splitter1_sizes", Settings::getValue("editor", "splitter1_sizes"));
+    Settings::setValue("editor", "splitter2_sizes", Settings::getValue("editor", "splitter1_sizes"));
+
     delete ui;
 }
 
@@ -134,6 +146,9 @@ void SqlExecutionArea::reloadSettings()
     else
         ui->splitter->setOrientation(Qt::Vertical);
 
+    ui->splitter->restoreState(Settings::getValue("editor", "splitter1_sizes").toByteArray());
+    ui->splitter_2->restoreState(Settings::getValue("editor", "splitter2_sizes").toByteArray());
+
     // Set prefetch settings
     model->setChunkSize(static_cast<std::size_t>(Settings::getValue("db", "prefetchsize").toUInt()));