Metadata-Version: 2.1
Name: svg.elements
Version: 0.0.4
Summary: Svg Elements Parsing
Home-page: https://github.com/meerk40t/svg.elements
Author: Tatarize
Author-email: tatarize@gmail.com
License: MIT
Description: # svg.elements
        SVG Parsing for Elements, Paths, and other SVG Objects.
        
        The Path element of this project is based in part on the `regebro/svg.path` ( https://github.com/regebro/svg.path ) project. It is also may be based, in part, on some elements of `mathandy/svgpathtools` ( https://github.com/mathandy/svgpathtools ).
        
        The Zingl-Bresenham plotting algorithms are from Alois Zingl's "The Beauty of Bresenham's Algorithm"
        ( http://members.chello.at/easyfilter/bresenham.html ). They are all MIT Licensed and this library is
        also MIT licensed. In the case of Zingl's work this isn't explicit from his website, however from personal
        correspondence "'Free and open source' means you can do anything with it like the MIT licence."
        
        # Goals/Philsophy
        
        The goal of this project is to provide svg spec-like objects and structures. The svg standard 1.1 and elements of 2.0 will
        be used to provide much of the decisions making for implementation objects. If there is a question on
        implementation and the SVG documentation has a methodology, that is the preferred methodology.
        
        The primary goal is to make a more robust version of `svg.path` including other elements like `Point` and `Matrix` with clear emphasis on conforming to the SVG spec in all ways that realworld uses for SVG demands.
        
        `svg.elements` should conform to the SVG Conforming Interpretor class (2.5.4. Conforming SVG Interpreters):
        
        >An SVG interpreter is a program which can parse and process SVG document fragments. Examples of SVG interpreters are server-side transcoding tools or optimizers (e.g., a tool which converts SVG content into modified SVG content) or analysis tools (e.g., a tool which extracts the text content from SVG content, or a validity checker).
        
        For real world functionality we must correctly and reasonably provide the ability to do transcoding of svg as well as accessing and modifying content.
        
        This project began as part of `meerK40t` which does svg loading of files for laser cutting. It attempts to more fully map out the svg spec, objects, and paths, while remaining easy to use and highly backwards compatable.
        
        # Elements
        
        The core functionality of this class are the elements. These are svg-based objects which interact work in various reasonable methods.
        
        ## Path
        
        The base code for this is regebro's code and methods from the svg.path class. The primary methods is to use different PathSegment classes for the various elements within a pathd code. These should always have a high degree of backwards compatability. And for most purposes importing the relevant classes from svg_elements should be highly compatable with any existing code.
        
        There is a ``Path`` object that acts as a collection of the path segment objects.
        
        While `svg.path` objects used complex values for coordinate data. We use `Point` objects which are backwards compatible with other point objects, including complex numbers. Because of this, there should be a high degree of compatibility between this project and ones that used `svg.path`. You can use complex numbers as points, and they should seemlessly convert.
        
        ### Segments
        
        There are 6 path segment objects:
        ``Line``, ``Arc``, ``CubicBezier``, ``QuadraticBezier``, ``Move`` and ``Close``. These have a 1:1 correspondance to the commands in a `pathd`. 
        
            >>> from svg_elements import Path, Line, Arc, CubicBezier, QuadraticBezier, Close
        
        All of these objects have a ``.point()`` function which will return the
        coordinates of a point on the path, where the point is given as a floating
        point value where ``0.0`` is the start of the path and ``1.0`` is end.
        
        You can calculate the length of a Path or its segments with the
        ``.length()`` function. For CubicBezier and Arc segments this is done by
        geometric approximation and for this reason **may be very slow**. You can
        make it faster by passing in an ``error`` option to the method. If you
        don't pass in error, it defaults to ``1e-12``::
        
            >>> CubicBezier(300+100j, 100+100j, 200+200j, 200+300j).length(error=1e-5)
            297.2208145656899
        
        CubicBezier and Arc also has a ``min_depth`` option that specifies the
        minimum recursion depth. This is set to 5 by default, resulting in using a
        minimum of 32 segments for the calculation. Setting it to 0 is a bad idea for
        CubicBeziers, as they may become approximated to a straight line.
        
        ``Line.length()`` and ``QuadraticBezier.length()`` also takes these
        parameters, but they unneeded as direct values rather than approximations are returned.
        
        CubicBezier and QuadraticBezier also have ``is_smooth_from(previous)``
        methods, that check if the segment is a "smooth" segment compared to the
        given segment.
        
        Unlike `svg.path` the preferred method of getting an Path from a `pathd` string is
        as an argument:
        
            >>> from svg_elements import Path
            >>> Path('M 100 100 L 300 100')
            Path(Move(end=Point(100,100)), Line(start=Point(100,100), end=Point(300,100)))
        
        
        
        ### Segment Classes
        
        These are the SVG PathSegment classes. See the `SVG specifications
        <http://www.w3.org/TR/SVG/paths.html>`_ for more information on what each
        parameter means.
        
        * ``Move(start, end)`` The move object describes a move to the start of the next subpath. It may lack a start position but not en end position.
        
        * ``Close(start, end)`` The close object describes a close path element. It will have a length if and only if the end point is not equal to the subpath start point. Neither the start point or end point is required.
        
        * ``Line(start, end)`` The line object describes a line moving straight from one point to the next point. 
        
        * ``Arc(start, radius, rotation, arc, sweep, end)`` The arc object describes an arc across a circular path. This supports multiple types of parameterizations. The given default there is compatable with `svg.path` and has a complex radius. It is also valid to divide radius into `rx` and `ry` or Arc(start, end, center, prx, pry, sweep) where start, end, center, prx, pry are points and sweep is the radians value of the arc distance travelled.
        
        * ``QuadraticBezier(start, control, end)`` the quadraticbezier object describes a single control point bezier curve.
        
        * ``CubicBezier(start, control1, control2, end)`` the cubic bezier curve object describes a two control point bezier curve.
        
        ---
        
        In addition to that, there is the ``Path`` class, which is instantiated with a sequence of path segments:
        
        * ``Path(*segments)``
        
        The ``Path`` class is a mutable sequence, so it behaves like a list.
        You can add to it and replace path segments etc:
        
            >>> path = Path(Line(100+100j,300+100j), Line(100+100j,300+100j))
            >>> path.append(QuadraticBezier(300+100j, 200+200j, 200+300j))
            >>> path[0] = Line(200+100j,300+100j)
            >>> del path[1]
        
        The path object also has a ``d()`` method that will return the
        SVG representation of the Path segments:
        
            >>> path.d()
            'M 200,100 L 300,100 Q 200,200 200,300'
        
        In elements this is also the preferred result of `str()` typically `str(path)`.
        
        
        ### Examples
        
        This SVG path example draws a triangle:
        
            >>> path1 = Path('M 100 100 L 300 100 L 200 300 z')
        
        You can format SVG paths in many different ways, all valid paths should be
        accepted::
        
            >>> path2 = Path('M100,100L300,100L200,300z')
        
        And these paths should be equal:
        
            >>> path1 == path2
            True
        
        You can also build a path from objects:
        
            >>> path3 = Path(Move(100 + 100j), Line(100 + 100j, 300 + 100j), Line(300 + 100j, 200 + 300j), Close(200 + 300j, 100 + 100j))
        
        And it should again be equal to the first path::
        
            >>> path1 == path2
            True
        
        Paths are mutable sequences, you can slice and append::
        
            >>> path1.append(QuadraticBezier(300+100j, 200+200j, 200+300j))
            >>> len(path1[2:]) == 3
            True
        
        Note that there is no protection against you creating paths that are invalid.
        You can for example have a Close command that doesn't end at the path start:
        
            >>> wrong = Path(Line(100+100j,200+100j), Close(200+300j, 0))
        
        ## Matrix (Transformations)
        
        A large goal of this project is to provide a more robust modifications of Path objects including matrix transformations. This is done by three major shifts from `svg.path`s methods. 
        
        * Points are not stored as complex numbers. These are stored as Point objects, which have backwards compatability with complex numbers, without the data actually being backed by a `complex`.
        * A matrix is added which conforms to the SVGMatrix Element. The matrix contains valid versions of all the affline transformations elements required by the SVG Spec.
        * The `Arc` object is fundamentally backed by a different point-based parameterization.
        
        The objects themselves have robust dunder methods. So if you have a path object you may simply multiply it by a matrix.
        
            >>> Path(Line(0+0j, 100+100j)) * Matrix.scale(2)
            >>> Path(Line(start=Point(0.000000000000,0.000000000000), end=Point(200.000000000000,200.000000000000)))
        
        Or rotate a parsed path.
        
            >>> Path("M0,0L100,100") * Matrix.rotate(30)
            Path(Move(end=Point(0,0)), Line(start=Point(0,0), end=Point(114.228307398045,-83.378017420528)))
        
        Or modify an svg path.
        
            >>> str(Path("M0,0L100,100") * Matrix.rotate(30))
            'M 0,0 L 114.228,-83.378'
            
        ### Transform Parsing
        
        Within the SVG node schema where objects svg nodes are dictonaries. The `transform` tags within objects are combined together. This means that if you get a the 'd' object from an end-node in the SVG you can choose to apply the transformations. This list of transformations complies with the SVG spec. They merely aren't applied until requested.
        
            >>> node = { 'd': "M0,0 100,0, 0,100 z", 'transform': "scale(0.5)"}
            >>> print(Path(node['d']) * Matrix(node['transform']))
            M 0,0 L 50,0 L 0,50 Z
        
        ### Real Size scaling
        
        There is need in many applications to append a transformation for the viewbox, height, width. So as to prevent a variety of errors where the expected size is far vastly different from the actual size. If we have a viewbox of "0 0 100 100" but the height and width show that to be 50cm wide, then a path "M25,50L75,50" within that viewbox has a real size of length of 25cm which can be quite different from 50 (unitless value).
        
        `parse_viewbox_transform` performs this operation. It uses the conversion of the width and height to real world units. With a variable setting of `ppi` or pixels_per_inch. The standard default value for this is 96. Though other values have been used in other places. And this property can be configured.
        
        This can be easily invoked calling the `nodes` generator on the SVG object. If called with `viewport_transform=True` it will parse this viewport appending the required transformation to the SVG root object, which will be passed to all the child nodes. If you then apply the transform to the path object it will be scaled to the real size.
        
        The `parse_viewbox_transform` code conforms to the algorithm given in SVG 1.1 7.2, SVG 2.0 8.2 'equivalent transform of an SVG viewport.' This will also fully implement the `preserveAspectRatio`, `xMidYMid`, and `meetOrSlice` values.
        
        ## Distance
        
        The conversion of to distances to utilizes another parser element `Distance` It's a minor element and is a backed by a `float`. As such you can call Distance.mm(25) and it will convert 25mm to pixels with the default 96 pixels per inch. It provides conversions for `mm`, `cm`, `in`, `px`, `pt`, `pc`. You can also parse an element like the string '25mm' calling Distance.parse('25mm') and get the expected results. You can also call Distance.parse('25mm').as_inch which will return  25mm in inches.
        
            >>> Distance.parse('25mm').as_inch
            0.9842524999999999
        
        ## Color
        
        Color is another important element it is back by `int` in the form of an ARGB 32-bit integer. It will parse all the SVG color functions.
        
        If we get the fill or stroke of an object from a node be a text element. This needs to be converted to a consistent form. We could have a 3, 4, 6, or 8 digit hex. rgb(r,g,b) value, a static dictionary name or percent rgb(r,g,b). And must be properly parsed according to the spec.
        
            >>> Color.parse("red").hex
            '#ff0000'
        
        ## Angle
        
        Angle is backed by a 'float' and contains all the CSS angle values. 'deg', 'rad', 'grad', 'turn'.
        
            >>> Angle.degrees(360).as_radians
            Angle(6.283185307180)
        
        ## Point
        
        Point is used in all the SVG path segment objects. With regard to `svg.path` it is not back by, but implements all the same functionality as a `complex` and will take a complex as an input. So older `svg.path` code will remain valid. While also allowing for additional functionality like finding a distance.
        
            >>> Point(0+100j).distance_to([0,0])
            100.0
        
        The class supports `complex` subscriptable elements, .x and .y methods, and .imag and .real. As well as providing several of these indexing methods.
        
        # Interactions
        
        Most of the usefulness is in the simplicity of the implemented values.
        
            >>> Line((20,20), (40,40)) * Matrix("Rotate(45)")
            Line(start=Point(0,28.284271247462), end=Point(0,56.568542494924))
        
        Points, PathSegments, Paths can be multiplied by a matrix. 
        
        
        # License
        
        This module is under a MIT License.
        
Keywords: svg,path,elements,matrix
Platform: UNKNOWN
Classifier: Development Status :: 5 - Production/Stable
Classifier: Intended Audience :: Developers
Classifier: License :: OSI Approved :: MIT License
Classifier: Operating System :: OS Independent
Classifier: Programming Language :: Python
Classifier: Programming Language :: Python :: 2.7
Classifier: Programming Language :: Python :: 3.6
Classifier: Programming Language :: Python :: 3.7
Classifier: Programming Language :: Python :: Implementation :: PyPy
Classifier: Topic :: Multimedia :: Graphics
Classifier: Topic :: Multimedia :: Graphics :: Editors :: Vector-Based
Classifier: Topic :: Software Development :: Libraries :: Python Modules
Description-Content-Type: text/markdown
