feat(渲染编辑): 修复保存、文字与渲染问题

ofdgo_geom_bounds.go

@@ -0,0 +1,129 @@
+// Copyright 2025-2026 肖其顿 (XIAO QI DUN)
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ofdgo
+
+import (
+	"fmt"
+	"math"
+)
+
+// Bounds 通过解析极值计算直线、贝塞尔和椭圆弧的轴对齐边界
+// 不进行曲线展开且不使用Tolerance，结果受float64舍入误差影响，不保证向外舍入
+// 返回: Box 浮点路径范围, error 无效路径、弧线或数值溢出
+func (p GeometryPath) Bounds() (Box, error) {
+	if err := p.validate(); err != nil {
+		return Box{}, err
+	}
+	left, top, right, bottom := math.Inf(1), math.Inf(1), math.Inf(-1), math.Inf(-1)
+	add := func(p Point) {
+		left, top = math.Min(left, p.X), math.Min(top, p.Y)
+		right, bottom = math.Max(right, p.X), math.Max(bottom, p.Y)
+	}
+	var current, start Point
+	for _, s := range p {
+		switch s.Verb {
+		case GeometryMove:
+			start = s.End
+		case GeometryClose:
+			s.End = start
+		case GeometryArc:
+			a, err := centerArc(current, s)
+			if err != nil {
+				return Box{}, err
+			}
+			if a.delta != 0 {
+				for _, angle := range []float64{math.Atan2(a.v.X, a.u.X), math.Atan2(a.v.Y, a.u.Y)} {
+					for _, angle := range []float64{angle, angle + math.Pi} {
+						if f := a.fraction(angle); f > 0 && f < 1 {
+							add(a.point(angle))
+						}
+					}
+				}
+			}
+		case GeometryQuad, GeometryCubic:
+			for _, axis := range [][4]float64{{current.X, s.Control1.X, s.Control2.X, s.End.X}, {current.Y, s.Control1.Y, s.Control2.Y, s.End.Y}} {
+				if s.Verb == GeometryQuad {
+					axis[2] = 0
+				}
+				scale := math.Max(math.Abs(axis[0]), math.Max(math.Abs(axis[1]), math.Max(math.Abs(axis[2]), math.Abs(axis[3]))))
+				if scale != 0 {
+					for i := range axis {
+						axis[i] /= scale
+					}
+				}
+				var roots []float64
+				if s.Verb == GeometryQuad {
+					roots = geometryRoots(0, axis[0]-2*axis[1]+axis[3], axis[1]-axis[0])
+				} else {
+					roots = geometryRoots(-axis[0]+3*axis[1]-3*axis[2]+axis[3], 2*(axis[0]-2*axis[1]+axis[2]), axis[1]-axis[0])
+				}
+				for _, t := range roots {
+					if t > 0 && t < 1 {
+						q := geometryLerp(current, s.Control1, t)
+						if s.Verb == GeometryQuad {
+							q = geometryLerp(q, geometryLerp(s.Control1, s.End, t), t)
+						} else {
+							r := geometryLerp(s.Control1, s.Control2, t)
+							q = geometryLerp(geometryLerp(q, r, t), geometryLerp(r, geometryLerp(s.Control2, s.End, t), t), t)
+						}
+						add(q)
+					}
+				}
+			}
+		}
+		add(s.End)
+		current = s.End
+	}
+	if len(p) == 0 {
+		return Box{}, nil
+	}
+	if !finite(left) || !finite(top) || !finite(right-left) || !finite(bottom-top) {
+		return Box{}, fmt.Errorf("geometry bounds overflow")
+	}
+	return Box{left, top, right - left, bottom - top}, nil
+}
+
+// geometryRoots 稳定求解一元二次方程的实根
+// 入参: a、b、c 方程系数
+// 返回: []float64 实根
+func geometryRoots(a, b, c float64) []float64 {
+	scale := math.Max(math.Abs(a), math.Max(math.Abs(b), math.Abs(c)))
+	if scale == 0 {
+		return nil
+	}
+	a, b, c = a/scale, b/scale, c/scale
+	if a == 0 {
+		if b == 0 {
+			return nil
+		}
+		return []float64{-c / b}
+	}
+	d := b*b - 4*a*c
+	if d < 0 {
+		return nil
+	}
+	q := -.5 * (b + math.Copysign(math.Sqrt(d), b))
+	if q == 0 {
+		return []float64{-b / (2 * a)}
+	}
+	return []float64{q / a, c / q}
+}
+
+// geometryLerp 线性插值坐标
+// 入参: a、b 端点, t 插值比例
+// 返回: Point 插值坐标
+func geometryLerp(a, b Point, t float64) Point {
+	return Point{(1-t)*a.X + t*b.X, (1-t)*a.Y + t*b.Y}
+}