git.saurik.com Git - wxWidgets.git/blame_incremental - wxPython/wx/lib/floatcanvas/__init_

... / ...

Commit	Line	Data
	1	"""
	2	This is the floatcanvas package. It provides two primary modules, and a
	3	support module.
	4
	5	FloatCanvas.py contains the main FloatCanvas class, and its supporting
	6	classes. NavCanvas.py contains a wrapper for the FloatCanvas that
	7	provides the canvas and a toolbar with tools that allow you to navigate
	8	the canvas (zooming, panning, etc.) Resources.py is a module that
	9	contains a few resources required by the FloatCanvas (icons, etc)
	10
	11	The FloatCanvas is a high level window for drawing maps and anything
	12	else in an arbitrary coordinate system.
	13
	14	The goal is to provide a convenient way to draw stuff on the screen
	15	without having to deal with handling OnPaint events, converting to pixel
	16	coordinates, knowing about wxWindows brushes, pens, and colors, etc. It
	17	also provides virtually unlimited zooming and scrolling
	18
	19	I am using it for two things:
	20	1) general purpose drawing in floating point coordinates
	21	2) displaying map data in Lat-long coordinates
	22
	23	If the projection is set to None, it will draw in general purpose
	24	floating point coordinates. If the projection is set to 'FlatEarth', it
	25	will draw a FlatEarth projection, centered on the part of the map that
	26	you are viewing. You can also pass in your own projection function.
	27
	28	It is double buffered, so re-draws after the window is uncovered by
	29	something else are very quick.
	30
	31	It relies on NumPy, which is needed for speed (maybe, I haven't profiled
	32	it). It will also use numarray, if you don't have Numeric, but it is
	33	slower.
	34
	35	Bugs and Limitations: Lots: patches, fixes welcome
	36
	37	For Map drawing: It ignores the fact that the world is, in fact, a
	38	sphere, so it will do strange things if you are looking at stuff near
	39	the poles or the date line. so far I don't have a need to do that, so I
	40	havn't bothered to add any checks for that yet.
	41
	42	Zooming: I have set no zoom limits. What this means is that if you zoom
	43	in really far, you can get integer overflows, and get weird results. It
	44	doesn't seem to actually cause any problems other than weird output, at
	45	least when I have run it.
	46
	47	Speed: I have done a couple of things to improve speed in this app. The
	48	one thing I have done is used NumPy Arrays to store the coordinates of
	49	the points of the objects. This allowed me to use array oriented
	50	functions when doing transformations, and should provide some speed
	51	improvement for objects with a lot of points (big polygons, polylines,
	52	pointsets).
	53
	54	The real slowdown comes when you have to draw a lot of objects, because
	55	you have to call the wx.DC.DrawSomething call each time. This is plenty
	56	fast for tens of objects, OK for hundreds of objects, but pretty darn
	57	slow for thousands of objects.
	58
	59	If you are zoomed in, it checks the Bounding box of an object before
	60	drawing it. This makes it a great deal faster when there are a lot of
	61	objects and you are zoomed in so that only a few are shown.
	62
	63	One solution is to be able to pass some sort of object set to the DC
	64	directly. I've used DC.DrawPointList(Points), and it helped a lot with
	65	drawing lots of points. However, when zoomed in, the Bounding boxes need
	66	to be checked, so I may some day write C++ code that does the loop and
	67	checks the BBs.
	68
	69	Mouse Events:
	70
	71	At this point, there are a full set of custom mouse events. They are
	72	just like the regular mouse events, but include an extra attribute:
	73	Event.GetCoords(), that returns the (x,y) position in world coordinates,
	74	as a length-2 NumPy vector of Floats.
	75
	76	There are also a full set of bindings to mouse events on objects, so
	77	that you can specify a given function be called when an objects is
	78	clicked, mouse-over'd, etc.
	79
	80	See the Demo for what it can do, and how to use it.
	81
	82	Copyright: Christopher Barker
	83
	84	License: Same as the version of wxPython you are using it with.
	85
	86	Check for updates at:
	87	http://home.comcast.net/~chrishbarker/FloatCanvas/
	88
	89	Please let me know if you're using this!!!
	90
	91	Contact me at:
	92
	93	Chris.Barker@noaa.gov
	94
	95	"""
	96
	97	__version__ = "0.8.7"
	98
	99