da_main_events.c

Description

da_main_events.c is a source code file from the bpdemo application that acts as the event handler for the main drawing area widget (DA_main). It is not a standalone command-line tool. This file is responsible for capturing and responding to all user interactions that occur within this primary visualization window, including mouse movements, clicks, and keyboard presses.

Functionality

The file contains a single primary function, da_main_events, which is registered as the event handler for the DA_main widget. This function uses a switch statement to process different types of X11 events.

Event Handling

  • Expose: This event is triggered whenever the window or a part of it becomes visible and needs to be redrawn. The handler calls expose_main() to refresh the contents of the drawing area.

  • MotionNotify: This event fires when the mouse is moved within the window. Its primary use here is to update a “rubber band” selection box if the user is dragging the mouse with the left button held down.

  • ButtonPress and ButtonRelease: These events handle mouse clicks.
    • Button 1 (Left-click): Pressing initiates a rubber-band selection box, and releasing finalizes it.
    • Button 2 (Middle-click): Currently recognized but has no action associated with it.
    • Button 3 (Right-click): Opens a context-sensitive popup menu (da_main_popup) at the cursor’s location, allowing the user to change visualization modes.
  • KeyPress: This handles keyboard shortcuts when the drawing area has focus, providing real-time control over the simulation parameters:
    • + (Numpad): Increases the number of transducer elements.
    • - (Numpad): Decreases the number of transducer elements.
    • Left Arrow: Decreases the beam steering angle by 5 degrees.
    • Right Arrow: Increases the beam steering angle by 5 degrees.
    • Space Bar: Advances the animation by a single phase step.

After a parameter is changed via a key press, the relevant calculation functions (e.g., calc_element_positions, calc_beam_pattern) are called, and all drawing areas are updated to reflect the new state of the simulation. This file is central to the interactive nature of the bpdemo tool.