Entry boxes

Entry boxes support the input of text or numerical values via the keyboard or similar input devices. They usually support the most common editing operations such as character input, deletion, etc.

Editable

The Editable class is an abstract base class, which takes care of dealing with keyboard events and text caret positioning. It is used as backend for the Entry widget class, which will be explained in the next section.

You usually will not create an Editable object directly, but rather use it as parent for your own classes.

It can store and operate on (unicode) text through its text attribute. The text usually will be set via this attribute or the set_text() method.

editable.text = "Text"
editable.set_text ("Text")
        

It also supports a virtual text caret position, which will be used by its internals to determine the position for editing operations. The caret attribute and set_caret() allow you to adjust the caret position.

editable.caret = 7
editable.set_caret (7)
        

Given both the text and caret attribute, the internals of the Editable will modify the text of it upon receiving keyboard events, if it has the input focus. Given an Editable, which contains the text "This is a Test." and its caret is set to 4, the processing of a pressed key ("D") causes:

  1. Check, whether text editing is allowed.

  2. If it is, insert a "D" at the fourth position in the text.

  3. The text of it now is "ThisD is a Test"

The previous list mentioned a check, whether the text of an Editable can be modified. To allow or disallow editing the hold text, you can adjust the value of the editable attribute.

editable.editable = True
editable.set_editable (True)
        
This however only prevents editing operations, which are received as events and not setting the text directly through the text attribute or set_text() method.

The Editable listens by default to the following signals:

  • SIG_KEYDOWN - Invoked, when a key gets pressed.

  • SIG_INPUT - Invoked, when the input is validated or aborted using RETURN or ESC.

Entry

The Entry widget is a single line text input box, that inherits from the Editable class. It fully supports the Editable features and enhances it by mouse event sensitivity.

To create a Entry widget, you usually will type

entry = Entry (text)
        

Entry widgets support a password-like mode, in which any typed character will be displayed as an asterisk ('*').

entry.password = True
        
This however does not enahcens security as the typed characters are stored as plain text. Only the display differs.

To allow a better look for some special fonts, the Entry can place an additional amount of pixels between its border and the text input area via the padding attribute or set_padding() method.

entry.padding = 5
entry.set_padding (10)
        
The gained space will be filled with the background color of the Entry by default.

The Entry supports the SIG_MOUSEDOWN signal to get the input focus upon a left mouse button press.

Below you will find an example to illustrate most of the abilities of the Entry widget class. You do not need to care about other widgets like the Frame class for now as those are explained later on.

You can find the following example as a python script under examples/entry.py.

# Entry examples.
from ocempgui.widgets import *
from ocempgui.widgets.Constants import *

def create_entry_view ():
    states = ("STATE_NORMAL", "STATE_ENTERED", "STATE_ACTIVE",
              "STATE_INSENSITIVE")

    table = Table (10, 10)
    table.spacing = 5

    # Frame with the states.
    frm_states = VFrame (Label ("States"))
    frm_states.spacing = 5
    frm_states.align = ALIGN_LEFT
    for i in xrange (len (states)):
        entry = Entry (states[i])
        if STATE_TYPES[i] == STATE_INSENSITIVE:
            entry.sensitive = False
        else:
            entry.state = STATE_TYPES[i]
        frm_states.add_child (entry)
    table.add_child (0, 0, frm_states)
    table.set_align (0, 0, ALIGN_TOP)

    # Frame with different padding.
    frm_padding = VFrame (Label ("Padding"))
    frm_padding.spacing = 5
    frm_padding.align = ALIGN_LEFT
    for i in xrange (5):
        entry = Entry ("Padding: %dpx" % (i * 2))
        entry.padding = i * 2
        frm_padding.add_child (entry)
    table.add_child (0, 1, frm_padding)
    table.set_align (0, 0, ALIGN_TOP)

    return table

if __name__ == "__main__":
    # Initialize the drawing window.
    re = Renderer ()
    re.create_screen (400, 400)
    re.title = "Entry examples"
    re.color = (234, 228, 223)
    re.add_widget (create_entry_view ())
    # Start the main rendering loop.
    re.start ()

Example 29. Entry example