Empty pixel fix

Finally fixed not rendering some pixels in an effective way.
Added comments. Started making an adaptor to easly convert PDF info to gradient info.

Test/Applications/gradient/Gradient/mainwindow.h

@@ -96,8 +96,6 @@ private slots:
 
     void on_Reflected_CheckBox_clicked(bool checked);
 
-    void on_PeriodicCheckBox_clicked(bool checked);
-
 private:
     Ui::MainWindow *ui;
 };