Preferences: warn if ffmpeg can't be loaded

In the preferences widget warn the user when they enter a non-executable
path to ffmpeg. Thus they don't have to start thumbnailing just to
find out that the path is wrong.

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>

2 files changed, 29 insertions, 1 deletions

diff --git a/desktop-widgets/preferences/preferences_defaults.cpp b/desktop-widgets/preferences/preferences_defaults.cpp
index 7ea704b96..c11927af8 100644
--- a/desktop-widgets/preferences/preferences_defaults.cpp
+++ b/desktop-widgets/preferences/preferences_defaults.cpp
@@ -8,6 +8,8 @@
 #include "core/settings/qPrefDiveComputer.h"
 
 #include <QFileDialog>
+#include <QProcess>
+#include <QMessageBox>
 
 PreferencesDefaults::PreferencesDefaults(): AbstractPreferencesWidget(tr("General"), QIcon(":preferences-other-icon"), 0 ), ui(new Ui::PreferencesDefaults())
 {
@@ -45,13 +47,37 @@ void PreferencesDefaults::on_localDefaultFile_toggled(bool toggle)
 	ui->chooseFile->setEnabled(toggle);
 }
 
+void PreferencesDefaults::checkFfmpegExecutable()
+{
+	QString s = ui->ffmpegExecutable->text().trimmed();
+
+	// If the user didn't provide a string they probably didn't intend to run ffmeg,
+	// so let's not give an error message.
+	if (s.isEmpty())
+		return;
+
+	// Try to execute ffmpeg. But wait at most 2 sec for startup and execution
+	// so that the UI doesn't hang unnecessarily.
+	QProcess ffmpeg;
+	ffmpeg.start(s);
+	if (!ffmpeg.waitForStarted(2000) || !ffmpeg.waitForFinished(3000))
+		QMessageBox::warning(this, tr("Warning"), tr("Couldn't execute ffmpeg at given location. Thumbnailing will not work."));
+}
+
 void PreferencesDefaults::on_ffmpegFile_clicked()
 {
 	QFileInfo fi(system_default_filename());
 	QString ffmpegFileName = QFileDialog::getOpenFileName(this, tr("Select ffmpeg executable"));
 
-	if (!ffmpegFileName.isEmpty())
+	if (!ffmpegFileName.isEmpty()) {
 		ui->ffmpegExecutable->setText(ffmpegFileName);
+		checkFfmpegExecutable();
+	}
+}
+
+void PreferencesDefaults::on_ffmpegExecutable_editingFinished()
+{
+	checkFfmpegExecutable();
 }
 
 void PreferencesDefaults::on_extractVideoThumbnails_toggled(bool toggled)
diff --git a/desktop-widgets/preferences/preferences_defaults.h b/desktop-widgets/preferences/preferences_defaults.h
index 0fa7bdc1b..48e633ceb 100644
--- a/desktop-widgets/preferences/preferences_defaults.h
+++ b/desktop-widgets/preferences/preferences_defaults.h
@@ -21,12 +21,14 @@ public slots:
 	void on_btnUseDefaultFile_toggled(bool toggled);
 	void on_localDefaultFile_toggled(bool toggled);
 	void on_ffmpegFile_clicked();
+	void on_ffmpegExecutable_editingFinished();
 	void on_extractVideoThumbnails_toggled(bool toggled);
 	void on_resetSettings_clicked();
 	void on_resetRememberedDCs_clicked();
 
 private:
 	Ui::PreferencesDefaults *ui;
+	void checkFfmpegExecutable();
 };