Class GWindow

The GWindow class implements the background canvas for the Portable Graphics Library. Graphical applications begin by creating a new GWindow object and then assemble a collage-like display by adding instances of type GObject to the window. By convention, the first statement in an application that uses the Portable Graphics Library is

    gw = GWindow(GWINDOW_WIDTH, GWINDOW_HEIGHT)

in which GWINDOW_WIDTH and GWINDOW_HEIGHT are constants specifying the dimensions of the window in pixels.

As an example, the following program displays a blue rectangle on the screen:

    from pgl import GWindow, GRect

    GWINDOW_WIDTH = 500
    GWINDOW_HEIGHT = 200

    def BlueRectangle():
        gw = GWindow(GWINDOW_WIDTH, GWINDOW_HEIGHT)
        rect = GRect(150, 50, 200, 100)
        rect.setColor("Blue")
        rect.setFilled(True)
        gw.add(rect)

GWindow()

Creates a new GWindow with a default size.

Usage:

gw = GWindow()

 

GWindow(width, height)

Creates a new GWindow with the specified dimensions.

Usage:	gw = GWindow(width, height)
Parameters:	width   The width of the window in pixels height   The height of the window in pixels.

 

add(gobj)

Adds the graphical object to this canvas.

Usage:	gw.add(gobj)
Parameter:	gobj   The graphical object to add

 

add(gobj, x, y)

Adds the graphical object to this canvas and sets its location to the point (x, y).

Usage:	gw.add(gobj, x, y)
Parameters:	gobj   The graphical object to add x   The new x-coordinate for the object y   The new y-coordinate for the object

 

addEventListener(type, fn)

Registers a new listener for events of the specified type occuring in the window. The type parameter should be one of the strings "mousedown", "mouseup", "click", "mousemove", "mousemove", or "drag".

Usage:	timer = gw.addEventListener(type, fn)
Parameter:	type   The event type fn   The callback function

 

createTimer(fn, delay)

Creates a new timer object that calls fn after the specified delay, which is measured in milliseconds. The timer must be started by calling its start method.

Usage:	timer = gw.createTimer(fn, delay)
Parameter:	fn   The callback function delay   The delay, measured in milliseconds
Returns:	The GTimer object that implements the timer

 

getElement(k)

Returns the graphical object at index k, numbering from back to front in the the z dimension.

Usage:	gobj = gw.getElement(index)
Parameter:	index   The index of the component to return
Returns:	The graphical object at the specified index

 

getElementAt(x, y)

Returns the topmost graphical object that contains the point (x, y), or None if no such object exists.

Usage:	gobj = gw.getElementAt(x, y)
Parameters:	x   The x-coordinate of the point being tested y   The y-coordinate of the point being tested
Returns:	The graphical object at the specified location, or None if no such object exists

 

getElementCount()

Returns the number of graphical objects stored in this GWindow.

Usage:	n = gw.getElementCount()
Returns:	The number of graphical objects in this GWindow

 

getWindowHeight()

Returns the height of this window in pixels.

Usage:	height = gw.getWindowHeight()
Returns:	The height of this window in pixels

 

getWindowWidth()

Returns the width of this window in pixels.

Usage:	width = gw.getWindowWidth()
Returns:	The width of this window in pixels

 

remove(gobj)

Removes a graphical object from the window.

Usage:	gw.remove(gobj)
Parameter:	gobj   The graphical object to remove