wx.svg¶

The classes in this package facilitate the parsing, normalizing, drawing and rasterizing of Scalable Vector Graphics (SVG) images. The primary interface to this functionality is via the wx.svg.SVGimage class, which provides various integrations with wxPython. It, in turn, uses a set of wrappers around the NanoSVG library (https://github.com/memononen/nanosvg) to do the low-level work. There are a few features defined in the SVG spec that are not supported, but all the commonly used ones seem to be there.

Example 1¶

Drawing an SVG image to a window, scaled to fit the size of the window and using a wx.GraphicsContext can be done like this:

def __init__(self, ...):
    ...
    self.img = wx.svg.SVGimage.CreateFromFile(svg_filename)
    self.Bind(wx.EVT_PAINT, self.OnPaint)

def OnPaint(self, event):
    dc = wx.PaintDC(self)
    dc.SetBackground(wx.Brush('white'))
    dc.Clear()

    dcdim = min(self.Size.width, self.Size.height)
    imgdim = min(self.img.width, self.img.height)
    scale = dcdim / imgdim
    width = int(self.img.width * scale)
    height = int(self.img.height * scale)

    ctx = wx.GraphicsContext.Create(dc)
    self.img.RenderToGC(ctx, scale)

Since it is drawing the SVG shapes and paths using the equivalent GC primitives then any existing transformations that may be active on the context will be applied automatically to the SVG shapes.

Note that not all GraphicsContext backends are created equal. Specifically, the GDI+ backend (the default on Windows) simply can not support some features that are commonly used in SVG images, such as applying transforms to gradients. The Direct2D backend on Windows does much better, and the Cairo backend on Windows is also very good. The default backends on OSX and Linux do very good as well.

Example 2¶

If you’re not already using a wx.GraphicsContext then a wx.Bitmap can easily be created instead. For example, the last 2 lines in the code above could be replaced by the following, and accomplish basically the same thing:

bmp = self.img.ConvertToBitmap(scale=scale, width=width, height=height)
dc.DrawBitmap(bmp, 0, 0)

Example 3¶

The ConvertToBitmap shown above gives a lot of control around scaling, translating and sizing the SVG image into a bitmap, but most of the time you probably just want to get a bitmap of a certain size to use as an icon or similar. The ConvertToScaledBitmap provides an easier API to do just that for you. It automatically scales the SVG image into the requested size in pixels.:

bmp = img.ConvertToScaledBitmap(wx.Size(24,24))

Optionally, it can accept a window parameter that will automatically adjust the size according to the Content Scale Factor of that window, if supported by the platform and if the window is located on a HiDPI display the the bitmap’s size will be adjusted accordingly.:

bmp = img.ConvertToScaledBitmap(wx.Size(24,24), self)

Modules Summary¶

_nanosvg

NanoSVG is a “simple stupid single-header-file SVG parser” from

Classes Summary¶

SVGimage

The SVGimage class provides various ways to load and use SVG images

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