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219 | class CairoEngine(DrawEngine):
"""基于 pycairo 的进程内栅格引擎。"""
name = "cairo"
kind = "raster"
requires = ("cairo", "numpy", "PIL")
description = "pycairo 进程内栅格化（原生抗锯齿）"
# ------------------------------------------------------------------
@staticmethod
def _new_surface(width: int, height: int):
import cairo
surface = cairo.ImageSurface(cairo.FORMAT_ARGB32, width, height)
ctx = cairo.Context(surface)
ctx.set_operator(cairo.OPERATOR_SOURCE)
ctx.set_source_rgba(0, 0, 0, 0)
ctx.paint()
ctx.set_operator(cairo.OPERATOR_OVER)
ctx.set_antialias(cairo.ANTIALIAS_DEFAULT)
return surface, ctx
@staticmethod
def _to_pil(surface, width: int, height: int):
"""ARGB32（预乘 BGRA）→ 非预乘 RGBA 的 ``PIL.Image``。"""
import numpy as np
from PIL import Image
surface.flush()
stride = surface.get_stride()
raw = np.frombuffer(
surface.get_data(), dtype=np.uint8, count=stride * height
).reshape(height, stride)
arr = raw[:, : width * 4].reshape(height, width, 4)
alpha = arr[:, :, 3].astype(np.float64)
with np.errstate(divide="ignore", invalid="ignore"):
scale = np.where(alpha > 0, 255.0 / np.maximum(alpha, 1.0), 0.0)
# 三个通道都必须乘上 scale 才能还原预乘；漏掉任何一个都会让半透明彩色
# 像素偏色（曾经漏掉 G，导致黑色 20% 描边渲染成洋红色）。
out = np.empty((height, width, 4), dtype=np.uint8)
out[:, :, 0] = np.clip(arr[:, :, 2] * scale, 0, 255) # R ← B
out[:, :, 1] = np.clip(arr[:, :, 1] * scale, 0, 255) # G
out[:, :, 2] = np.clip(arr[:, :, 0] * scale, 0, 255) # B ← R
out[:, :, 3] = arr[:, :, 3]
return Image.fromarray(out, "RGBA")
@staticmethod
def _set_color(ctx, rgba):
ctx.set_source_rgba(
rgba[0] / 255.0, rgba[1] / 255.0, rgba[2] / 255.0, rgba[3] / 255.0
)
# ------------------------------------------------------------------
def render_roundrect(self, spec: RoundRectSpec):
width = max(1, int(round(spec.width)))
height = max(1, int(round(spec.height)))
surface, ctx = self._new_surface(width, height)
stroke_width = float(spec.outline_width or 0.0)
inset = stroke_width / 2.0 if stroke_width > 0 else 0.0
rx = max(0.0, float(spec.rx) - inset)
ry = max(0.0, float(spec.effective_ry) - inset)
x0, y0 = inset, inset
w = max(1.0, width - 2 * inset)
h = max(1.0, height - 2 * inset)
fill = parse_color(spec.fill, spec.fill_opacity)
if fill:
_rounded_rect_path(ctx, x0, y0, w, h, rx, ry)
self._set_color(ctx, fill)
ctx.fill()
if stroke_width > 0:
outline = parse_color(spec.outline, spec.outline_opacity)
outline2 = (
parse_color(spec.outline2, spec.outline2_opacity)
if spec.outline2
else None
)
if outline:
if outline2 and outline2 != outline:
import cairo
gradient = cairo.LinearGradient(x0, y0, x0, y0 + h)
gradient.add_color_stop_rgba(
float(spec.gradient_stop1),
outline[0] / 255.0, outline[1] / 255.0,
outline[2] / 255.0, outline[3] / 255.0,
)
gradient.add_color_stop_rgba(
float(spec.gradient_stop2),
outline2[0] / 255.0, outline2[1] / 255.0,
outline2[2] / 255.0, outline2[3] / 255.0,
)
ctx.set_source(gradient)
else:
self._set_color(ctx, outline)
_rounded_rect_path(ctx, x0, y0, w, h, rx, ry)
ctx.set_line_width(stroke_width)
ctx.stroke()
return self._to_pil(surface, width, height)
# ------------------------------------------------------------------
def render_track(self, spec: TrackSpec):
width = max(1, int(round(spec.width)))
height = max(1, int(round(spec.height)))
surface, ctx = self._new_surface(width, height)
radius = max(0.0, float(spec.radius))
left = max(0.0, min(float(spec.width2), float(width)))
track = parse_color(spec.track_fill, spec.track_opacity)
if track and left > 0:
_rounded_rect_path(ctx, 0, 0, left, height, radius, radius)
self._set_color(ctx, track)
ctx.fill()
rail = parse_color(spec.rail_fill, spec.rail_opacity)
if rail and width - left > 0:
_rounded_rect_path(ctx, left, 0, width - left, height, radius, radius)
self._set_color(ctx, rail)
ctx.fill()
return self._to_pil(surface, width, height)
# ------------------------------------------------------------------
def render_thumb(self, spec: ThumbSpec):
width = max(1, int(round(spec.width)))
height = max(1, int(round(spec.height)))
surface, ctx = self._new_surface(width, height)
cx, cy = width / 2.0, height / 2.0
r1, r2 = float(spec.r1), float(spec.r2)
outline = parse_color(spec.outline, spec.outline_opacity)
outline2 = (
parse_color(spec.outline2, spec.outline2_opacity)
if spec.outline2
else None
)
if outline:
import cairo
if outline2 and outline2 != outline:
gradient = cairo.LinearGradient(
r1, 1.0, r1, max(1.0, r1 * 2.0 - 1.0)
)
gradient.add_color_stop_rgba(
0.500208,
outline[0] / 255.0, outline[1] / 255.0,
outline[2] / 255.0, outline[3] / 255.0,
)
gradient.add_color_stop_rgba(
0.954545,
outline2[0] / 255.0, outline2[1] / 255.0,
outline2[2] / 255.0, outline2[3] / 255.0,
)
ctx.set_source(gradient)
else:
self._set_color(ctx, outline)
ctx.arc(cx, cy, r1, 0, 2 * math.pi)
ctx.fill()
fill = parse_color(spec.fill, spec.fill_opacity)
if fill:
self._set_color(ctx, fill)
ctx.arc(cx, cy, max(0.0, r1 - 1.0), 0, 2 * math.pi)
ctx.fill()
inner = parse_color(spec.inner_fill, spec.inner_fill_opacity)
if inner:
self._set_color(ctx, inner)
ctx.arc(cx, cy, r2, 0, 2 * math.pi)
ctx.fill()
return self._to_pil(surface, width, height)
|