Add a small delay before processing the key input of search boxes

PR #20465.
Closes #20025.
Closes #20235.

src/gui/addnewtorrentdialog.cpp

@@ -33,6 +33,7 @@
 #include <functional>
 
 #include <QAction>
+#include <QByteArray>
 #include <QDateTime>
 #include <QDebug>
 #include <QDir>
@@ -41,6 +42,7 @@
 #include <QMessageBox>
 #include <QPushButton>
 #include <QShortcut>
+#include <QSize>
 #include <QString>
 #include <QUrl>
 #include <QVector>

src/gui/addnewtorrentdialog.h

@@ -38,13 +38,13 @@
 #include "base/path.h"
 #include "base/settingvalue.h"
 
+class LineEdit;
+
 namespace Ui
 {
     class AddNewTorrentDialog;
 }
 
-class LineEdit;
-
 class AddNewTorrentDialog final : public QDialog
 {
     Q_OBJECT

src/gui/lineedit.cpp

@@ -29,20 +29,41 @@
 
 #include "lineedit.h"
 
+#include <chrono>
+
 #include <QAction>
 #include <QKeyEvent>
+#include <QTimer>
 
 #include "base/global.h"
 #include "uithememanager.h"
 
+using namespace std::chrono_literals;
+
+namespace
+{
+    const std::chrono::milliseconds FILTER_INPUT_DELAY {400};
+}
+
 LineEdit::LineEdit(QWidget *parent)
     : QLineEdit(parent)
+    , m_delayedTextChangedTimer {new QTimer(this)}
 {
     auto *action = new QAction(UIThemeManager::instance()->getIcon(u"edit-find"_s), QString(), this);
     addAction(action, QLineEdit::LeadingPosition);
 
     setClearButtonEnabled(true);
     setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Preferred);
+
+    m_delayedTextChangedTimer->setSingleShot(true);
+    connect(m_delayedTextChangedTimer, &QTimer::timeout, this, [this]
+    {
+        emit textChanged(text());
+    });
+    connect(this, &QLineEdit::textChanged, this, [this]
+    {
+        m_delayedTextChangedTimer->start(FILTER_INPUT_DELAY);
+    });
 }
 
 void LineEdit::keyPressEvent(QKeyEvent *event)

src/gui/lineedit.h

@@ -31,6 +31,9 @@
 
 #include <QLineEdit>
 
+class QKeyEvent;
+class QTimer;
+
 class LineEdit final : public QLineEdit
 {
     Q_OBJECT
@@ -39,6 +42,11 @@ class LineEdit final : public QLineEdit
 public:
     explicit LineEdit(QWidget *parent = nullptr);
 
+signals:
+    void textChanged(const QString &text);
+
 private:
     void keyPressEvent(QKeyEvent *event) override;
+
+    QTimer *m_delayedTextChangedTimer = nullptr;
 };

src/gui/mainwindow.cpp

@@ -54,6 +54,7 @@
 #include <QShortcut>
 #include <QSplitter>
 #include <QStatusBar>
+#include <QString>
 #include <QTimer>
 
 #include "base/bittorrent/session.h"

src/gui/mainwindow.h

@@ -42,6 +42,7 @@ class QCloseEvent;
 class QComboBox;
 class QFileSystemWatcher;
 class QSplitter;
+class QString;
 class QTabWidget;
 class QTimer;
 

src/gui/search/searchjobwidget.cpp

@@ -126,9 +126,9 @@ SearchJobWidget::SearchJobWidget(SearchHandler *searchHandler, IGUIApplication *
     m_lineEditSearchResultsFilter->setPlaceholderText(tr("Filter search results..."));
     m_lineEditSearchResultsFilter->setContextMenuPolicy(Qt::CustomContextMenu);
     connect(m_lineEditSearchResultsFilter, &QWidget::customContextMenuRequested, this, &SearchJobWidget::showFilterContextMenu);
+    connect(m_lineEditSearchResultsFilter, &LineEdit::textChanged, this, &SearchJobWidget::filterSearchResults);
     m_ui->horizontalLayout->insertWidget(0, m_lineEditSearchResultsFilter);
 
-    connect(m_lineEditSearchResultsFilter, &LineEdit::textChanged, this, &SearchJobWidget::filterSearchResults);
     connect(m_ui->filterMode, qOverload<int>(&QComboBox::currentIndexChanged)
             , this, &SearchJobWidget::updateFilter);
     connect(m_ui->minSeeds, &QAbstractSpinBox::editingFinished, this, &SearchJobWidget::updateFilter);