Update comments.

app/widget/viewer/viewerdisplay.cpp

@@ -52,7 +52,7 @@ ViewerDisplayWidget::ViewerDisplayWidget(QWidget *parent) :
   zoomed_(false)
 {
   connect(Core::instance(), &Core::ToolChanged, this, &ViewerDisplayWidget::ToolChanged);
-
+  // Initilises hand_tool_ based on currently selected tool.
   ToolChanged(Core::instance()->tool());
 }
 
@@ -76,9 +76,9 @@ void ViewerDisplayWidget::SetMatrixZoom(const QMatrix4x4 &mat)
 void ViewerDisplayWidget::IsZoomed(bool flag)
 {
   zoomed_ = flag;
-  // If the image is smaller than the container widget we disable translation
+  // If the image is smaller than the container widget we reset the translation.
   if (!flag) {
-    QMatrix4x4 mat;
+    QMatrix4x4 mat; // defaults to identity matrix.
     SetMatrixTranslate(mat);
   }
 }
@@ -97,6 +97,7 @@ void ViewerDisplayWidget::ToolChanged(Tool::Item tool)
 QMatrix4x4 ViewerDisplayWidget::GetCompleteMatrix()
 {
   QMatrix4x4 mat;
+  // Images is scaled, the translated.
   return translate_matrix_ * scale_matrix_ * mat;
 }
 
@@ -183,13 +184,13 @@ void ViewerDisplayWidget::mousePressEvent(QMouseEvent *event)
     return;
   }
 
-  // reset translation
+  // Reset translation.
   if (event->button() == Qt::MiddleButton && event->modifiers() & Qt::ControlModifier) {
-    QMatrix4x4 mat;
+    QMatrix4x4 mat; // Identity matrix
     SetMatrixTranslate(mat);
   }
 
-  // If translation is enabled get current position in preperation for move event
+  // If translation is enabled get current position in preperation for move event.
   if ((event->button() == Qt::MiddleButton || hand_tool_) && zoomed_) {
     position_ = event->pos();
     return;

app/widget/viewer/viewerdisplay.h

@@ -117,8 +117,17 @@ public slots:
    */
   void SetImage(FramePtr in_buffer);
 
+  /**
+   * @brief Set zoomed_ flag if the viewersizer has zoomed the image to be larger than the widget.
+   *
+   * If the image is smaller than the widget the translation is reset so the image is centered.
+   */
   void IsZoomed(bool flag);
 
+  /**
+   * @brief Changes the pointer type if the tool is changed to the hand tool. Otherwise resets the pointer to it's
+   * normal type.
+   */
   void ToolChanged(Tool::Item tool);
 
 signals:
@@ -208,10 +217,13 @@ private:
   bool zoomed_;
 
   /**
-   * @brief position of mouse to calculate delta from.
+   * @brief Position of mouse to calculate delta from.
    */
   QPoint position_;
 
+  /**
+   * @brief Set if the hand tool is selected.
+   */
   bool hand_tool_;
 
 private slots:

app/widget/viewer/viewersizer.h

@@ -65,6 +65,10 @@ public:
 
 signals:
   void RequestMatrix(const QMatrix4x4& matrix);
+
+  /**
+   * @brief Tells the viewerdisplay widget if the image is enlarged to be bigger than the widget or not.
+   */
   void IsZoomed(bool flag);
 
 protected: