New article: Graphical Interfaces IV – the Multi-Window Mode and System of Priorities (Chapter 2)

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New article Graphical Interfaces IV: the Multi-Window Mode and System of Priorities (Chapter 2) has been published:

In this chapter, we will extend the library implementation to the possibility of creating multi-window interfaces for the MQL applications. We will also develop a system of priorities for left mouse clicking on graphical objects. This is required to avoid problems when elements do not respond to the user's actions.

The Multi-Window Mode

Let us consider the multi-window mode of the graphical interface of the library under development. Up to now, the ENUM_WINDOW_TYPE enumeration provided two identifiers for the main (W_MAIN) and dialog (W_DIALOG) windows. The single-window mode was the only mode in use. After we introduce some additions, enabling the multi-window mode will simply involve the creation and addition of the required number of control forms to the base.

In the main class for event handling CWndEvents create a field for storing the index of the currently active window.

class CWndEvents : public CWndContainer
  {
protected:
   //--- Index of the active window
   int               m_active_window_index;
  };

Let us see how the index of the active window is going to be identified. For instance, the user assigns the opening of a dialog window (W_DIALOG) to some button. When the button is pressed, the ON_CLICK_BUTTON custom event is generated. This event can be tracked in the CProgram::OnEvent() event handler of the custom class. We will also use the CWindow::Show() method of the form which is to be shown. It is not sufficient in the current implementation of the library and we will introduce necessary additions.

Author: Anatoli Kazharski