feat(ui): open files dropped onto the window

mainwindow.cpp

@@ -2,6 +2,8 @@
 
 #include <QApplication>
 #include <QCloseEvent>
+#include <QDragEnterEvent>
+#include <QDropEvent>
 #include <QElapsedTimer>
 #include <QFile>
 #include <QFileDialog>
@@ -17,6 +19,7 @@
 #include <QListWidget>
 #include <QMenuBar>
 #include <QMessageBox>
+#include <QMimeData>
 #include <QProgressDialog>
 #include <QResizeEvent>
 #include <QSettings>
@@ -26,6 +29,7 @@
 #include <QStatusBar>
 #include <QStyle>
 #include <QToolBar>
+#include <QUrl>
 #include <QVBoxLayout>
 #include <cstdio>
 
@@ -43,6 +47,7 @@ MainWindow::~MainWindow() = default;
 void MainWindow::SetupUi() {
   setWindowTitle("Digital Image Analyzer - H.264/H.265 Bitstream Analyzer");
   resize(1400, 800);
+  setAcceptDrops(true);
 
   QMenu* fileMenu = menuBar()->addMenu("File");
   QAction* openAct = fileMenu->addAction("Open Bitstream...");
@@ -288,6 +293,29 @@ void MainWindow::OpenFile() {
   }
 }
 
+void MainWindow::dragEnterEvent(QDragEnterEvent* event) {
+  const QList<QUrl> urls = event->mimeData()->urls();
+  for (const QUrl& url : urls) {
+    if (url.isLocalFile()) {
+      event->acceptProposedAction();
+      return;
+    }
+  }
+  event->ignore();
+}
+
+void MainWindow::dropEvent(QDropEvent* event) {
+  const QList<QUrl> urls = event->mimeData()->urls();
+  for (const QUrl& url : urls) {
+    if (url.isLocalFile()) {
+      LoadFile(url.toLocalFile());
+      event->acceptProposedAction();
+      return;
+    }
+  }
+  event->ignore();
+}
+
 bool MainWindow::LoadFile(const QString& path) {
   std::string sp = path.toUtf8().toStdString();
 

mainwindow.h

@@ -37,6 +37,8 @@ class MainWindow : public QMainWindow {
 
  protected:
   void closeEvent(QCloseEvent* event) override;
+  void dragEnterEvent(QDragEnterEvent* event) override;
+  void dropEvent(QDropEvent* event) override;
 
  private slots:
   void OpenFile();

test/test_gui.cpp

@@ -1,7 +1,10 @@
 #include <gtest/gtest.h>
 
 #include <QApplication>
+#include <QDragEnterEvent>
+#include <QDropEvent>
 #include <QLabel>
+#include <QMimeData>
 #include <QPushButton>
 #include <QSignalSpy>
 #include <QSlider>
@@ -10,6 +13,7 @@
 #include <QStatusBar>
 #include <QTest>
 #include <QTreeView>
+#include <QUrl>
 #include <fstream>
 #include <string>
 
@@ -177,6 +181,31 @@ TEST(MainWindowTest, LoadsFileAndUpdatesViews) {
   EXPECT_TRUE(status_has_nal_count);
 }
 
+TEST(MainWindowTest, OpensFileByDrop) {
+  if (!exists(data_path("output.h264"))) {
+    GTEST_SKIP() << "H.264 fixture missing";
+  }
+
+  MainWindow window;
+  window.show();
+
+  QMimeData mime;
+  mime.setUrls(
+      {QUrl::fromLocalFile(QString::fromStdString(data_path("output.h264")))});
+
+  QDragEnterEvent enter(QPointF(10, 10), Qt::CopyAction, &mime, Qt::LeftButton,
+                        Qt::NoModifier);
+  QApplication::sendEvent(&window, &enter);
+  EXPECT_TRUE(enter.isAccepted());
+
+  QDropEvent drop(QPointF(10, 10), Qt::CopyAction, &mime, Qt::LeftButton,
+                  Qt::NoModifier);
+  QApplication::sendEvent(&window, &drop);
+  QApplication::processEvents();
+
+  EXPECT_TRUE(window.windowTitle().contains("output.h264"));
+}
+
 TEST(MainWindowTest, StepForwardUsesSpinBoxValue) {
   if (!exists(data_path("sample_720p.mp4"))) {
     GTEST_SKIP() << "MP4 fixture missing";