Rename gerbonara/gerber package to just gerbonara

1 files changed, 403 insertions, 0 deletions

diff --git a/gerbonara/graphic_primitives.py b/gerbonara/graphic_primitives.py
new file mode 100644
index 0000000..65aa28c
--- /dev/null
+++ b/gerbonara/graphic_primitives.py
@@ -0,0 +1,403 @@
+
+import math
+import itertools
+
+from dataclasses import dataclass, KW_ONLY, replace
+
+
+@dataclass
+class GraphicPrimitive:
+    _ : KW_ONLY
+    polarity_dark : bool = True
+
+
+def rotate_point(x, y, angle, cx=0, cy=0):
+    """ rotate point (x,y) around (cx,cy) clockwise angle radians """
+
+    return (cx + (x - cx) * math.cos(-angle) - (y - cy) * math.sin(-angle),
+            cy + (x - cx) * math.sin(-angle) + (y - cy) * math.cos(-angle))
+
+def min_none(a, b):
+    if a is None:
+        return b
+    if b is None:
+        return a
+    return min(a, b)
+
+def max_none(a, b):
+    if a is None:
+        return b
+    if b is None:
+        return a
+    return max(a, b)
+
+def add_bounds(b1, b2):
+    (min_x_1, min_y_1), (max_x_1, max_y_1) = b1
+    (min_x_2, min_y_2), (max_x_2, max_y_2) = b2
+    min_x, min_y = min_none(min_x_1, min_x_2), min_none(min_y_1, min_y_2)
+    max_x, max_y = max_none(max_x_1, max_x_2), max_none(max_y_1, max_y_2)
+    return ((min_x, min_y), (max_x, max_y))
+
+def rad_to_deg(x):
+    return x/math.pi * 180
+
+@dataclass
+class Circle(GraphicPrimitive):
+    x : float
+    y : float
+    r : float # Here, we use radius as common in modern computer graphics, not diameter as gerber uses.
+
+    def bounding_box(self):
+        return ((self.x-self.r, self.y-self.r), (self.x+self.r, self.y+self.r))
+
+    def to_svg(self, tag, fg, bg):
+        color = fg if self.polarity_dark else bg
+        return tag('circle', cx=self.x, cy=self.y, r=self.r, style=f'fill: {color}')
+
+
+@dataclass
+class Obround(GraphicPrimitive):
+    x : float
+    y : float
+    w : float
+    h : float
+    rotation : float # radians!
+
+    def to_line(self):
+        if self.w > self.h:
+            w, a, b = self.h, self.w-self.h, 0
+        else:
+            w, a, b = self.w, 0, self.h-self.w
+        return Line(
+                *rotate_point(self.x-a/2, self.y-b/2, self.rotation, self.x, self.y),
+                *rotate_point(self.x+a/2, self.y+b/2, self.rotation, self.x, self.y),
+                w, polarity_dark=self.polarity_dark)
+
+    def bounding_box(self):
+        return self.to_line().bounding_box()
+
+    def to_svg(self, tag, fg, bg):
+        return self.to_line().to_svg(tag, fg, bg)
+
+
+def arc_bounds(x1, y1, x2, y2, cx, cy, clockwise):
+    # This is one of these problems typical for computer geometry where out of nowhere a seemingly simple task just
+    # happens to be anything but in practice.
+    #
+    # Online there are a number of algorithms to be found solving this problem. Often, they solve the more general
+    # problem for elliptic arcs. We can keep things simple here since we only have circular arcs.
+    # 
+    # This solution manages to handle circular arcs given in gerber format (with explicit center and endpoints, plus
+    # sweep direction instead of a format with e.g. angles and radius) without any trigonometric functions (e.g. atan2).
+    #
+    # cx, cy are relative to p1.
+
+    # Center arc on cx, cy
+    cx += x1
+    cy += y1
+    x1 -= cx
+    x2 -= cx
+    y1 -= cy
+    y2 -= cy
+    clockwise = bool(clockwise) # bool'ify for XOR/XNOR below
+
+    # Calculate radius
+    r = math.sqrt(x1**2 + y1**2)
+
+    # Calculate in which half-planes (north/south, west/east) P1 and P2 lie.
+    # Note that we assume the y axis points upwards, as in Gerber and maths.
+    # SVG has its y axis pointing downwards.
+    p1_west = x1 < 0
+    p1_north = y1 > 0
+    p2_west = x2 < 0
+    p2_north = y2 > 0
+
+    # Calculate bounding box of P1 and P2
+    min_x = min(x1, x2)
+    min_y = min(y1, y2)
+    max_x = max(x1, x2)
+    max_y = max(y1, y2)
+
+    #               North
+    #                 ^
+    #                 |
+    #                 |(0,0)
+    #      West <-----X-----> East
+    #                 |
+    #  +Y             |
+    #   ^             v
+    #   |           South
+    #   |
+    #   +-----> +X
+    #
+    # Check whether the arc sweeps over any coordinate axes. If it does, add the intersection point to the bounding box.
+    # Note that, since this intersection point is at radius r, it has coordinate e.g. (0, r) for the north intersection.
+    # Since we know that the points lie on either side of the coordinate axis, the '0' coordinate of the intersection
+    # point will not change the bounding box in that axis--only its 'r' coordinate matters. We also know that the
+    # absolute value of that coordinate will be greater than or equal to the old coordinate in that direction since the
+    # intersection with the axis is the point where the full circle is tangent to the AABB. Thus, we can blindly set the
+    # corresponding coordinate of the bounding box without min()/max()'ing first.
+
+    # Handle north/south halfplanes
+    if p1_west != p2_west: # arc starts in west half-plane, ends in east half-plane
+        if p1_west == clockwise: # arc is clockwise west -> east or counter-clockwise east -> west
+            max_y = r # add north to bounding box
+        else: # arc is counter-clockwise west -> east or clockwise east -> west
+            min_y = -r # south
+    else: # Arc starts and ends in same halfplane west/east
+        # Since both points are on the arc (at same radius) in one halfplane, we can use the y coord as a proxy for
+        # angle comparisons. 
+        small_arc_is_north_to_south = y1 > y2
+        small_arc_is_clockwise = small_arc_is_north_to_south == p1_west
+        if small_arc_is_clockwise != clockwise:
+            min_y, max_y = -r, r # intersect aabb with both north and south
+
+    # Handle west/east halfplanes
+    if p1_north != p2_north:
+        if p1_north == clockwise:
+            max_x = r # east
+        else:
+            min_x = -r # west
+    else:
+        small_arc_is_west_to_east = x1 < x2
+        small_arc_is_clockwise = small_arc_is_west_to_east == p1_north
+        if small_arc_is_clockwise != clockwise:
+            min_x, max_x = -r, r # intersect aabb with both north and south
+
+    return (min_x+cx, min_y+cy), (max_x+cx, max_y+cy)
+
+
+def point_line_distance(l1, l2, p):
+    # https://en.wikipedia.org/wiki/Distance_from_a_point_to_a_line
+    x1, y1 = l1
+    x2, y2 = l2
+    x0, y0 = p
+    length = math.dist(l1, l2)
+    if math.isclose(length, 0):
+        return math.dist(l1, p)
+    return ((x2-x1)*(y1-y0) - (x1-x0)*(y2-y1)) / length
+
+def svg_arc(old, new, center, clockwise):
+    r = math.hypot(*center)
+    # invert sweep flag since the svg y axis is mirrored
+    sweep_flag = int(not clockwise)
+    # In the degenerate case where old == new, we always take the long way around. To represent this "full-circle arc"
+    # in SVG, we have to split it into two.
+    if math.isclose(math.dist(old, new), 0):
+        intermediate = old[0] + 2*center[0], old[1] + 2*center[1]
+        # Note that we have to preserve the sweep flag to avoid causing self-intersections by flipping the direction of
+        # a circular cutin
+        return f'A {r:.6} {r:.6} 0 1 {sweep_flag} {intermediate[0]:.6} {intermediate[1]:.6} ' +\
+               f'A {r:.6} {r:.6} 0 1 {sweep_flag} {new[0]:.6} {new[1]:.6}'
+
+    else: # normal case
+        d = point_line_distance(old, new, (old[0]+center[0], old[1]+center[1]))
+        large_arc = int((d < 0) == clockwise)
+        return f'A {r:.6} {r:.6} 0 {large_arc} {sweep_flag} {new[0]:.6} {new[1]:.6}'
+
+@dataclass
+class ArcPoly(GraphicPrimitive):
+    """ Polygon whose sides may be either straight lines or circular arcs """
+
+    # list of (x : float, y : float) tuples. Describes closed outline, i.e. first and last point are considered
+    # connected.
+    outline : [(float,)]
+    # must be either None (all segments are straight lines) or same length as outline.
+    # Straight line segments have None entry.
+    arc_centers : [(float,)] = None
+
+    @property
+    def segments(self):
+        ol = self.outline
+        return itertools.zip_longest(ol, ol[1:] + [ol[0]], self.arc_centers or [])
+
+    def bounding_box(self):
+        bbox = (None, None), (None, None)
+        for (x1, y1), (x2, y2), arc in self.segments:
+            if arc:
+                clockwise, (cx, cy) = arc
+                bbox = add_bounds(bbox, arc_bounds(x1, y1, x2, y2, cx, cy, clockwise))
+
+            else:
+                line_bounds = (min(x1, x2), min(y1, y2)), (max(x1, x2), max(y1, y2))
+                bbox = add_bounds(bbox, line_bounds)
+        return bbox
+
+    def __len__(self):
+        return len(self.outline)
+
+    def __bool__(self):
+        return bool(len(self))
+
+    def _path_d(self):
+        if len(self.outline) == 0:
+            return
+
+        yield f'M {self.outline[0][0]:.6} {self.outline[0][1]:.6}'
+
+        for old, new, arc in self.segments:
+            if not arc:
+                yield f'L {new[0]:.6} {new[1]:.6}'
+            else:
+                clockwise, center = arc
+                yield svg_arc(old, new, center, clockwise)
+
+    def to_svg(self, tag, fg, bg):
+        color = fg if self.polarity_dark else bg
+        return tag('path', d=' '.join(self._path_d()), style=f'fill: {color}')
+
+class Polyline:
+    def __init__(self, *lines):
+        self.coords = []
+        self.polarity_dark = None
+        self.width = None
+
+        for line in lines:
+            self.append(line)
+
+    def append(self, line):
+        assert isinstance(line, Line)
+        if not self.coords:
+            self.coords.append((line.x1, line.y1))
+            self.coords.append((line.x2, line.y2))
+            self.polarity_dark = line.polarity_dark
+            self.width = line.width
+            return True
+
+        else:
+            x, y = self.coords[-1]
+            if self.polarity_dark == line.polarity_dark and self.width == line.width \
+                    and math.isclose(line.x1, x) and math.isclose(line.y1, y):
+                self.coords.append((line.x2, line.y2))
+                return True
+
+            else:
+                return False
+
+    def to_svg(self, tag, fg, bg):
+        color = fg if self.polarity_dark else bg
+        if not self.coords:
+            return None
+
+        (x0, y0), *rest = self.coords
+        d = f'M {x0:.6} {y0:.6} ' + ' '.join(f'L {x:.6} {y:.6}' for x, y in rest)
+        width = f'{self.width:.6}' if not math.isclose(self.width, 0) else '0.01mm'
+        return tag('path', d=d, style=f'fill: none; stroke: {color}; stroke-width: {width}; stroke-linejoin: round; stroke-linecap: round')
+
+@dataclass
+class Line(GraphicPrimitive):
+    x1 : float
+    y1 : float
+    x2 : float
+    y2 : float
+    width : float
+
+    def bounding_box(self):
+        r = self.width / 2
+        return add_bounds(Circle(self.x1, self.y1, r).bounding_box(), Circle(self.x2, self.y2, r).bounding_box())
+
+    def to_svg(self, tag, fg, bg):
+        color = fg if self.polarity_dark else bg
+        width = f'{self.width:.6}' if not math.isclose(self.width, 0) else '0.01mm'
+        return tag('path', d=f'M {self.x1:.6} {self.y1:.6} L {self.x2:.6} {self.y2:.6}',
+                style=f'fill: none; stroke: {color}; stroke-width: {width}; stroke-linecap: round')
+
+@dataclass
+class Arc(GraphicPrimitive):
+    x1 : float
+    y1 : float
+    x2 : float
+    y2 : float
+    # absolute coordinates
+    cx : float
+    cy : float
+    clockwise : bool
+    width : float
+
+    def bounding_box(self):
+        r = self.width/2
+        endpoints = add_bounds(Circle(self.x1, self.y1, r).bounding_box(), Circle(self.x2, self.y2, r).bounding_box())
+
+        arc_r = math.dist((self.cx, self.cy), (self.x1, self.y1))
+
+        # extend C -> P1 line by line width / 2 along radius
+        dx, dy = self.x1 - self.cx, self.y1 - self.cy
+        x1 = self.x1 + dx/arc_r * r
+        y1 = self.y1 + dy/arc_r * r
+
+        # same for C -> P2
+        dx, dy = self.x2 - self.cx, self.y2 - self.cy
+        x2 = self.x2 + dx/arc_r * r
+        y2 = self.y2 + dy/arc_r * r
+
+        arc = arc_bounds(x1, y1, x2, y2, self.cx, self.cy, self.clockwise)
+        return add_bounds(endpoints, arc) # FIXME add "include_center" switch
+
+    def to_svg(self, tag, fg, bg):
+        color = fg if self.polarity_dark else bg
+        arc = svg_arc((self.x1, self.y1), (self.x2, self.y2), (self.cx, self.cy), self.clockwise)
+        width = f'{self.width:.6}' if not math.isclose(self.width, 0) else '0.01mm'
+        return tag('path', d=f'M {self.x1:.6} {self.y1:.6} {arc}',
+                style=f'fill: none; stroke: {color}; stroke-width: {width}; stroke-linecap: round; fill: none')
+
+def svg_rotation(angle_rad, cx=0, cy=0):
+    return f'rotate({float(rad_to_deg(angle_rad)):.4} {float(cx):.6} {float(cy):.6})'
+
+@dataclass
+class Rectangle(GraphicPrimitive):
+    # coordinates are center coordinates
+    x : float
+    y : float
+    w : float
+    h : float
+    rotation : float # radians, around center!
+
+    def bounding_box(self):
+        return self.to_arc_poly().bounding_box()
+
+    def to_arc_poly(self):
+        sin, cos = math.sin(self.rotation), math.cos(self.rotation)
+        sw, cw = sin*self.w/2, cos*self.w/2
+        sh, ch = sin*self.h/2, cos*self.h/2
+        x, y = self.x, self.y
+        return ArcPoly([
+            (x - (cw+sh), y - (ch+sw)),
+            (x - (cw+sh), y + (ch+sw)),
+            (x + (cw+sh), y + (ch+sw)),
+            (x + (cw+sh), y - (ch+sw)),
+            ])
+
+    @property
+    def center(self):
+        return self.x + self.w/2, self.y + self.h/2
+
+    def to_svg(self, tag, fg, bg):
+        color = fg if self.polarity_dark else bg
+        x, y = self.x - self.w/2, self.y - self.h/2
+        return tag('rect', x=x, y=y, width=self.w, height=self.h,
+                transform=svg_rotation(self.rotation, self.x, self.y), style=f'fill: {color}')
+
+@dataclass
+class RegularPolygon(GraphicPrimitive):
+    x : float
+    y : float
+    r : float
+    n : int
+    rotation : float # radians!
+
+    def to_arc_poly(self):
+        ''' convert n-sided gerber polygon to normal ArcPoly defined by outline '''
+
+        delta = 2*math.pi / self.n
+
+        return ArcPoly([
+                (self.x + math.cos(self.rotation + i*delta) * self.r,
+                 self.y + math.sin(self.rotation + i*delta) * self.r)
+                for i in range(self.n) ])
+
+    def bounding_box(self):
+        return self.to_arc_poly().bounding_box()
+
+    def to_svg(self, tag, fg, bg):
+        return self.to_arc_poly().to_svg(tag, fg, bg)
+