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API changes between v2.0 and v2.1

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Dane Springmeyer edited this page Feb 8, 2013 · 27 revisions

Removed

  • Python pickling support was removed for map/style/rule/symbolizers/fontset/query - these were poorly maintained and future support for fast, core deepcopy should handle most key use cases - see #1390 (map deepcopy)
  • MetaWriter - disabled in 2.1.x series - may be re-enabled in future releases
  • PointDatasource - Use MemoryDatasource instead. PointDatasource was an incomplete wrapper around MemoryDatasource, and is obsolete now that Feature objects can leverage WKB and WKT to create geometries and features can be added to MemoryDatasources.
  • GlyphSymbolizer - functionality can now be achieved with the TextSymbolizer
  • MarkersSymbolizer
  • marker-type is removed, built in ellipse and arrow types now can be referenced like file="shape://ellipse" and file="shape://arrow" - although this interface is unstable and may continue to change.
  • ShieldSymbolizer attribute no_text - Simply leave the text empty if you don't want any text to be rendered.
  • Removed XML DTD in utils/xml since it was unmaintained: https://github.com/mapnik/mapnik/issues/1402
  • RasterSymbolizer mode divide (see below)

Changed

  • MarkersSymbolizer
    • default marker-placement is now point instead of line - meaning if you want your symbols (like arrows) to be oriented along lines you now need to specify placement=line, whereas previously this was the default. This changes reflects the goal of making the MarkersSymbolizer default behavior more reasonable for any geometry type, including points, lines, and polygons and to make it consistent with the TextSymbolizer and ShieldSymbolizer which also default to point placement.
    • width and height are now optional expressions rather than raw floats and their values represent diameter in pixels not radii. If not set they will be None, but the default ellipse has a radius of 10 meaning that if you set width="20" and height="20" then there will be no change in the rendering size of the ellipse. The arrow default dimensions can be roughly maintained with width="15" height="10". But to get the exact rendering of the Mapnik 2.0.x arrow use this svg file. Altering width or height will build a new ellipse svg marker internally by default if no custom file type is provided. For non-ellipse types setting width and height will proportionally scale the marker, but ideally you should use `transform="scale(x,y)" instead.
    • A new fill-opacity setting is available and now opacity reverse to a new overall opacity that will be multiplied against the fill-opacity or stroke-opacity - this is to match how svg behaves.
  • In Python a mapnik.Feature now expects a mapnik.Context() as a first argument and a feature id as the second argument, which stores all attribute names (previously mapnik.Feature only needed a single argument of the feature id and redundantly stored feature attribute names per feature) #834.

Added

  • MarkersSymbolizer

  • fill-opacity is new.

  • opacity value now works to set the alpha of bitmap images.

  • Expression - you can now use the built in keyword of [mapnik::geometry_type] to filter features by geometry type either by name or integer key. The mapping is 0:no geometry, 1:point, 2:linestring, 3:polygon, and 4:collection. A collection indicates that the Feature has more than one geometry of different types. So a Feature with three linestrings will be reported as linestring but a Feature with a point and a linestring will be reported as a collection. - for more details see #546

  • To All symbolizers (in most cases)

    • comp-op - All symbolizers now support compositing in the AGG and Cairo renderers
    • clip - All(most) symbolizers - boolean of whether to clip geometries before rendering (defaults to true)
    • smooth - bezier smooth value - 0-1, 0 (default) means no smoothing, 1 means fully smoothed, higher values create wild loopbacks

  • LineSymbolizer

  • TextSymbolizer

    • New placement alogrithm: list
    • Text formatting

    Changes documented in TextSymbolizer documentation

  • Python Bindings:

    • mapnik.Image.get_pixel() - get unsigned int value representing the rgba value, useful for fast pixel comparisons
    • mapnik.Grid.get_pixel() - get int value representing the feature id encoded in the grid pixels
    • bindings for text placement and formatting work

Deprecated

  • TextSymbolizer - most attributes moved to either format or placements properties

    properties:

    • label-placement
    • horizontal-alignment
    • justify-alignment
    • vertical-alignment
    • orientation
    • displacement
    • label-spacing
    • label-position-tolerance
    • avoid-edges
    • minimum-distance
    • minimum-padding
    • minimum-path-length
    • maximum-angle-char-delta
    • force-odd-labels
    • allow-overlap
    • largest-bbox-only
    • text-ratio
    • wrap-width

    format:

    • face_name
    • fontset
    • text-size
    • character-spacing
    • line-spacing
    • text-opacity
    • wrap-char
    • wrap-before
    • text-transform
    • fill
    • halo-fill
    • halo-radius

    Backward compatibility is preserved by python wrappers, however a warning message is printed if the old name is used.

  • RasterSymbolizer

    • mode is deprecated, now use comp-op which supports many more compositing modes
    • The new mapping from mode to comp-op is:
      • normal -> src_over
      • grain_merge and grain_merge2 -> grain-merge
      • multiply -> multiply
      • screen -> screen
      • hard_light -> hard-light
      • divide and divide -> Not supported anymore, see: https://github.com/mapnik/mapnik/issues/1432
    • scaling=fast is deprecated. It has always been a synonym for near, use near going forward
    • scaling is now exposed in python as enumerations of mapnik.scaling_method not as bare strings
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