Add download button to ImageOverlay

When opening images in the full-screen overlay, there is now
a download button next to the close button.  This button utilizes
the same functionality as the right-click->save image button.

src/dialogs/ImageOverlay.cpp

@@ -76,6 +76,8 @@ ImageOverlay::paintEvent(QPaintEvent *event)
         content_ = QRect(outer_margin + diff_x / 2, diff_y / 2, image_.width(), image_.height());
         close_button_ =
           QRect(screen_.width() - margin - buttonSize, margin, buttonSize, buttonSize);
+        save_button_ =
+          QRect(screen_.width() - (2 * margin) - (2 * buttonSize), margin, buttonSize, buttonSize);
 
         // Draw main content_.
         painter.drawPixmap(content_, image_);
@@ -91,6 +93,12 @@ ImageOverlay::paintEvent(QPaintEvent *event)
         painter.setPen(pen);
         painter.drawLine(center - QPointF(15, 15), center + QPointF(15, 15));
         painter.drawLine(center + QPointF(15, -15), center - QPointF(15, -15));
+
+        // Draw download button
+        center = save_button_.center();
+        painter.drawLine(center - QPointF(0, 15), center + QPointF(0, 15));
+        painter.drawLine(center - QPointF(15, 0), center + QPointF(0, 15));
+        painter.drawLine(center + QPointF(0, 15), center + QPointF(15, 0));
 }
 
 void
@@ -101,6 +109,8 @@ ImageOverlay::mousePressEvent(QMouseEvent *event)
 
         if (close_button_.contains(event->pos()))
                 emit closing();
+        else if (save_button_.contains(event->pos()))
+                emit saving();
         else if (!content_.contains(event->pos()))
                 emit closing();
 }

src/dialogs/ImageOverlay.h

@@ -35,6 +35,7 @@ protected:
 
 signals:
         void closing();
+        void saving();
 
 private:
         QPixmap originalImage_;
@@ -42,6 +43,7 @@ private:
 
         QRect content_;
         QRect close_button_;
+        QRect save_button_;
         QRect screen_;
 };
 } // dialogs

src/timeline/widgets/ImageItem.cpp

@@ -158,6 +158,7 @@ ImageItem::mousePressEvent(QMouseEvent *event)
         } else {
                 auto imgDialog = new dialogs::ImageOverlay(image_);
                 imgDialog->show();
+                connect(imgDialog, &dialogs::ImageOverlay::saving, this, &ImageItem::saveAs);
         }
 }