campy.graphics.gevents module¶

This file defines the event types used in the Stanford Portable Graphics Libraries. The structure of this package is adapted from the Java event model.

EventClassType¶

This _enumeration definest the vent classes. The element values are each a single bit and can be added or ORed together to generate an event mask. The CLICK_EVENT class responds only to the MOUSE_CLICKED event type. The ANY_EVENT class selects any event.

NULL_EVENT

ACTION_EVENT

KEY_EVENT

TIMER_EVENT

WINDOW_EVENT

MOUSE_EVENT

CLICK_EVENT

ANY_EVENT

EventType¶

This _enumeration type defines the event types for all events.

WINDOW_CLOSED

WINDOW_RESIZED

ACTION_PERFORMED

MOUSE_CLICKED

MOUSE_PRESSED

MOUSE_RELEASED

MOUSE_MOVED

MOUSE_DRAGGED

KEY_PRESSED

KEY_RELEASED

KEY_TYPED

TIMER_TICKED

ModifierCodes¶

This _enumeration type defines a set of constants used to check whether modifiers are in effect.

SHIFT_DOWN

CTRL_DOWN

META_DOWN

ALT_DOWN

ALT_GRAPH_DOWN

BUTTON1_DOWN

BUTTON2_DOWN

BUTTON3_DOWN

KeyCodes¶

This type defines the names of the key codes returned in a key event

BACKSPACE_KEY

TAB_KEY

ENTER_KEY

CLEAR_KEY

ESCAPE_KEY

PAGE_UP_KEY

PAGE_DOWN_KEY

END_KEY

HOME_KEY

LEFT_ARROW_KEY

UP_ARROW_KEY

RIGHT_ARROW_KEY

DOWN_ARROW_KEY

F1_KEY

F2_KEY

F3_KEY

F4_KEY

F5_KEY

F6_KEY

F7_KEY

F8_KEY

F9_KEY

F10_KEY

F11_KEY

F12_KEY

DELETE_KEY

HELP_KEY

TODO:: Reconsider using EventClassType. Instead use inheritance? Deduplicate events that capture a GWindow. Check for validity on property access.

class campy.graphics.gevents.EventClassType[source]¶

Bases: enum.Enum

ACTION_EVENT = 16¶

ANY_EVENT = 1008¶

CLICK_EVENT = 512¶

KEY_EVENT = 32¶

MOUSE_EVENT = 256¶

NULL_EVENT = 0¶

TIMER_EVENT = 64¶

WINDOW_EVENT = 128¶

class campy.graphics.gevents.EventType[source]¶

Bases: enum.Enum

ACTION_PERFORMED = 17¶

CONSOLE_CLOSED = 131¶

KEY_PRESSED = 33¶

KEY_RELEASED = 34¶

KEY_TYPED = 35¶

MOUSE_CLICKED = 257¶

MOUSE_DRAGGED = 261¶

MOUSE_MOVED = 260¶

MOUSE_PRESSED = 258¶

MOUSE_RELEASED = 259¶

TIMER_TICKED = 65¶

WINDOW_CLOSED = 129¶

WINDOW_RESIZED = 130¶

class campy.graphics.gevents.GActionEvent(event_type=None, source=None, action_command=None)[source]¶

Bases: campy.graphics.gevents.GEvent

This event subclass represents an action event. Action events are generated by the classes in the L{GInteractor} hierarchy. As an example, the following program displays a button that, when pushed, generates the message “Please do not press this button again” (with thanks to Douglas Adams’s Hitchhiker’s Guide to the Galaxy):

gw = _gwindow.GWindow
button = ginteractors.GButton("RED");
gw.addToRegion(button, "SOUTH");
while(True):
    e = gevents.waitForEvent(ACTION_EVENT | CLICK_EVENT);
    if(e.getEventType() == MOUSE_CLICKED):
        break;
    print("Please do not press this button again.")

Attributes:: source [GObject]: GInteractor from which event originated. action_command [string]: GInteractor command.

action_command¶

source¶

class campy.graphics.gevents.GEvent[source]¶

Bases: object

This class is the root of the hierarchy for all events.

The standard paradigm for using GEvent is illustrated by the following program, which allows the user to draw lines on the graphics window:

gw = _gwindow.GWindow()
print("This program lets the user draw lines by dragging.")
while(True):
    e = gevents.waitForEvent(gevents.EventClassType.MOUSE_EVENT)
    if(e.getEventType() == gevents.EventType.MOUSE_PRESSED):
        line = gobjects.GLine(e.getX(), e.getY(), e.getX(), e.getY());
        gw.add(line);
    elif (e.getEventType() == gevents.EventType.MOUSE_DRAGGED)
        line.setEndPoint(e.getrX(), e.getY());

Attributes:

event_class [EventClassType]: Enumerated type constant indicating the class of the event. event_type [EventType]: Enumerated type constant corresponding to the specific event type. time [float]: System time in milliseconds at which the event occurred. valid [bool]: Whether this event represents a fully-initialized valid event. modifiers [int]: Integer whose bits indicate what modifiers are in effect.

Notes:

To ensure portability among systems that represent time in different ways, this library uses a float to represent time, which is always encoded as the number of milliseconds that have elapsed since 00:00:00 UTC on January 1, 1970, which is the conventional zero point for computer-based time systems.

To check whether the shift key is down, for example, one could use the following code:

if e.modifiers & SHIFT_DOWN: ...

event_class¶

event_type¶

modifiers¶

time¶

valid¶

class campy.graphics.gevents.GKeyEvent(event_type=None, gwindow=None, key_char=None, key_code=None)[source]¶

Bases: campy.graphics.gevents.GEvent

This event subclass represents a key event. Each key event records the event type along with two representations of the key. The getKeyChar function is more generally useful and returns the character after taking into account modifier keys. The getKeyCode function returns an integer identifying the key, which can be a function key as well as a standard key. The codes return by getKeyCode are listed in the KeyCodes _enumeration.

Attributes:: gwindow [GWindow]: GWindow in which MouseEvent occurred. key_char [int]: Value of key. key_code [int]: Code of key.
Notes:: Returns the character represented by the keystroke, taking the modifier keys into account. For example, if the user types the ‘a’ key with the shift key down, getKeyChar will return ‘A’. If the key code in the event does not correspond to a character, getKeyChar returns the null character.

gwindow¶

key_char¶

key_code¶

class campy.graphics.gevents.GMouseEvent(event_type=None, gwindow=None, x=None, y=None)[source]¶

Bases: campy.graphics.gevents.GEvent

This event subclass represents a mouse event. Each mouse event records the event type (MOUSE_PRESSED, MOUSE_RELEASED, MOUSE_CLICKED, MOUSE_MOVED, MOUSE_DRAGGED) along with the coordinates of the event. Clicking the mouse generates three events in the following order: MOUSE_PRESSED, MOUSE_RELEASED, MOUSE_CLICKED.

As an example, the following program uses mouse events to let the user draw rectangles on the graphics window. The only complexity in this code is the use of the library functions min and abs to ensure that the dimensions of the rectangle are positive:

gw = _gwindow.GWindow
print("This program lets the user draw rectangles.")
while(True):
    e = gevents.waitForEvent();
    if (e.getEventType() == MOUSE_PRESSED):
        startX = e.getX();
        startY = e.getY();
        rect = gobjects.GRect(startX, startY, 0, 0);
        rect.setFilled(True);
        gw.add(rect);
    elif(e.getEventType() == MOUSE_DRAGGED):
        x = min(e.getX(), startX);
        y = min(e.getY(), startY);
        width = abs(e.getX() - startX);
        height = abs(e.getY() - startY);
        rect.setBounds(x, y, width, height);

Attributes:: gwindow [GWindow]: GWindow in which MouseEvent occurred. x [float]: The x-coordinate at which the event occurred. y [float]: The y-coordinate at which the event occurred.
Notes:: The x- and y-coordinates are given relative to the window origin at the upper left corner of the window.

gwindow¶

x¶

y¶

class campy.graphics.gevents.GTimerEvent(event_type=None, timer=None)[source]¶

Bases: campy.graphics.gevents.GEvent

This event subclass represents a timer event. Timer events are generated by a GTimer object, which produces a new event at a fixed interval measured in milliseconds. As an example, the following program generates a timer event every two seconds, stopping when the user clicks somewhere in the window:

print("This program generates timer events.")
timer = gtimer.GTimer(2000)
timer.start()
while(True):
    e = gevents.waitForEvent(CLICK_EVENT | TIMER_EVENT);
    if (e.getEventType() == MOUSE_CLICKED):
        break;
print("Timer ticked")

Attributes:: timer [GTimer]: GTimer from which this event originated.

timer¶

class campy.graphics.gevents.GWindowEvent(event_type=None, gwindow=None)[source]¶

Bases: campy.graphics.gevents.GEvent

This event subclass represents a window event. Each GWindowEvent keeps track of the event type (WINDOW_CLOSED, WINDOW_RESIZED) along with the identity of the window.

Attributes:: gwindow [GWindow]: Reference to the GWindow in which this event took place

gwindow¶

class campy.graphics.gevents.KeyCodes[source]¶

Bases: enum.Enum

BACKSPACE_KEY = 8¶

CLEAR_KEY = 12¶

DELETE_KEY = 127¶

DOWN_ARROW_KEY = 40¶

END_KEY = 35¶

ENTER_KEY = 10¶

ESCAPE_KEY = 27¶

F10_KEY = 121¶

F11_KEY = 122¶

F12_KEY = 123¶

F1_KEY = 112¶

F2_KEY = 113¶

F3_KEY = 114¶

F4_KEY = 115¶

F5_KEY = 116¶

F6_KEY = 117¶

F7_KEY = 118¶

F8_KEY = 119¶

F9_KEY = 120¶

HELP_KEY = 156¶

HOME_KEY = 36¶

LEFT_ARROW_KEY = 37¶

PAGE_DOWN_KEY = 34¶

PAGE_UP_KEY = 33¶

RIGHT_ARROW_KEY = 39¶

TAB_KEY = 9¶

UP_ARROW_KEY = 38¶

class campy.graphics.gevents.ModifierCodes[source]¶

Bases: enum.Enum

ALT_DOWN = 8¶

ALT_GRAPH_DOWN = 16¶

BUTTON1_DOWN = 32¶

BUTTON2_DOWN = 64¶

BUTTON3_DOWN = 128¶

CTRL_DOWN = 2¶

META_DOWN = 4¶

SHIFT_DOWN = 1¶

campy.graphics.gevents.get_next_event(mask=<EventClassType.ANY_EVENT: 1008>)[source]¶

Checks to see if there are any events of the desired type waiting on the event queue. If so, this function returns the event in exactly the same fashion as waitForEvent; if not, getNextEvent returns an invalid event. The mask parameter is optional. If it is missing, getNextEvent accepts any event.

@type mask: EventClassType @param mask: EventClasstype to check for, defaults to ANY_EVENT @rtype: GEvent

campy.graphics.gevents.wait_for_click()[source]¶

Waits for a mouse click in any window, discarding any other events.

@rtype: void

campy.graphics.gevents.wait_for_event(mask=<EventClassType.ANY_EVENT: 1008>)[source]¶

Dismisses the process until an event occurs whose type is covered by the event mask. The mask parameter is a combination of the events of interest. For example, to wait for a mouse event or an action event, clients can use the following call:

e = waitForEvent(MOUSE_EVENT + ACTION_EVENT);

The mask parameter is optional. If it is missing, waitForEvent accepts any event.

As a more sophisticated example, the following code is the canonical event loop for an animated application that needs to respond to mouse, key, and timer events:

timer = gtimer.GTimer(ANIMATION_DELAY_IN_MILLISECONDS);
timer.start()
while(True):
    e = gevents.waitForEvent(TIMER_EVENT + MOUSE_EVENT + KEY_EVENT)
    if(e.getEventClass == gevents.EventClassType.TIMER_EVENT):
        takeAnimationStep()
    elif(e.getEventClass == gevents.EventClassType.MOUSE_EVENT):
        handleMouseEvent(e)
    elif(e.getEventClass == gevents.EventClassType.KEY_EVENT):
        handleKeyEvent(e)

@type mask: EventClassType @param mask: EventClassType to wait for, defaults to ANY_EVENT @rtype: GEvent