2a0495c9f7
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@29711 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
100 lines
3.8 KiB
Python
100 lines
3.8 KiB
Python
"""
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This is the floatcanvas package. It provides two primary modules, and a
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support module.
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FloatCanvas.py contains the main FloatCanvas class, and its supporting
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classes. NavCanvas.py contains a wrapper for the FloatCanvas that
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provides the canvas and a toolbar with tools that allow you to navigate
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the canvas (zooming, panning, etc.) Resources.py is a module that
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contains a few resources required by the FloatCanvas (icons, etc)
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The FloatCanvas is a high level window for drawing maps and anything
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else in an arbitrary coordinate system.
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The goal is to provide a convenient way to draw stuff on the screen
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without having to deal with handling OnPaint events, converting to pixel
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coordinates, knowing about wxWindows brushes, pens, and colors, etc. It
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also provides virtually unlimited zooming and scrolling
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I am using it for two things:
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1) general purpose drawing in floating point coordinates
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2) displaying map data in Lat-long coordinates
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If the projection is set to None, it will draw in general purpose
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floating point coordinates. If the projection is set to 'FlatEarth', it
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will draw a FlatEarth projection, centered on the part of the map that
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you are viewing. You can also pass in your own projection function.
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It is double buffered, so re-draws after the window is uncovered by
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something else are very quick.
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It relies on NumPy, which is needed for speed (maybe, I haven't profiled
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it). It will also use numarray, if you don't have Numeric, but it is
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slower.
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Bugs and Limitations: Lots: patches, fixes welcome
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For Map drawing: It ignores the fact that the world is, in fact, a
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sphere, so it will do strange things if you are looking at stuff near
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the poles or the date line. so far I don't have a need to do that, so I
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havn't bothered to add any checks for that yet.
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Zooming: I have set no zoom limits. What this means is that if you zoom
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in really far, you can get integer overflows, and get weird results. It
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doesn't seem to actually cause any problems other than weird output, at
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least when I have run it.
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Speed: I have done a couple of things to improve speed in this app. The
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one thing I have done is used NumPy Arrays to store the coordinates of
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the points of the objects. This allowed me to use array oriented
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functions when doing transformations, and should provide some speed
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improvement for objects with a lot of points (big polygons, polylines,
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pointsets).
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The real slowdown comes when you have to draw a lot of objects, because
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you have to call the wx.DC.DrawSomething call each time. This is plenty
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fast for tens of objects, OK for hundreds of objects, but pretty darn
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slow for thousands of objects.
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If you are zoomed in, it checks the Bounding box of an object before
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drawing it. This makes it a great deal faster when there are a lot of
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objects and you are zoomed in so that only a few are shown.
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One solution is to be able to pass some sort of object set to the DC
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directly. I've used DC.DrawPointList(Points), and it helped a lot with
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drawing lots of points. However, when zoomed in, the Bounding boxes need
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to be checked, so I may some day write C++ code that does the loop and
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checks the BBs.
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Mouse Events:
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At this point, there are a full set of custom mouse events. They are
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just like the regular mouse events, but include an extra attribute:
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Event.GetCoords(), that returns the (x,y) position in world coordinates,
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as a length-2 NumPy vector of Floats.
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There are also a full set of bindings to mouse events on objects, so
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that you can specify a given function be called when an objects is
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clicked, mouse-over'd, etc.
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See the Demo for what it can do, and how to use it.
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Copyright: Christopher Barker
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License: Same as the version of wxPython you are using it with.
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Check for updates at:
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http://home.comcast.net/~chrishbarker/FloatCanvas/
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Please let me know if you're using this!!!
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Contact me at:
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Chris.Barker@noaa.gov
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"""
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__version__ = "0.8.7"
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