refactor(重构提升): 优化图案着色降低内存占用

ofdgo_pdf_pattern.go

@@ -0,0 +1,128 @@
+// 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 (
+	"math"
+	"reflect"
+
+	"github.com/xiaoqidun/pdfgo"
+)
+
+// pdfPatternCellLimit 限制单页图案矢量快照的估算字节数
+const pdfPatternCellLimit = 8 << 20
+
+// pdfPatternCellKey 隔离图案来源、基色、坐标、精度与目标文档资源
+type pdfPatternCellKey struct {
+	source *pdfgo.TilingPattern
+	base   pdfgo.Paint
+	matrix pdfgo.Matrix
+	dpi    float64
+	editor *Editor
+}
+
+// pdfPatternInstanceRange 收缩已知路径及图片的实例范围，未知边界保留完整范围
+// 入参: columns 横向实例数, rows 纵向实例数, bounds 对象边界, width 单元宽, height 单元高, xstep 横向步距, ystep 纵向步距
+// 返回: int 左界, int 右界, int 上界, int 下界
+func pdfPatternInstanceRange(columns, rows float64, bounds []Box, width, height, xstep, ystep float64) (int, int, int, int) {
+	left, right, top, bottom := 0.0, 1-columns, 0.0, 1-rows
+	for _, box := range bounds {
+		if box.W <= 0 || box.H <= 0 || !finite(box.X) || !finite(box.Y) || !finite(box.X+box.W) || !finite(box.Y+box.H) {
+			return 1 - int(columns), 0, 1 - int(rows), 0
+		}
+		left = math.Min(left, math.Max(1-columns, math.Ceil(-(box.X+box.W)/xstep)-1))
+		right = math.Max(right, math.Min(0, math.Floor((width-box.X)/xstep)+1))
+		top = math.Min(top, math.Max(1-rows, math.Ceil(-(box.Y+box.H)/ystep)-1))
+		bottom = math.Max(bottom, math.Min(0, math.Floor((height-box.Y)/ystep)+1))
+	}
+	return int(left), int(right), int(top), int(bottom)
+}
+
+// tilingPattern 有界复用矢量图案，返回可独立编辑的对象副本
+// 入参: source 平铺图案, base 无色图案基色
+// 返回: *Pattern OFD图案, error 转换或取消错误
+func (p *pdfImporter) tilingPattern(source *pdfgo.TilingPattern, base pdfgo.Paint) (*Pattern, error) {
+	if err := p.ctx.Err(); err != nil {
+		return nil, err
+	}
+	if p.resolveFile != nil || p.resolveReference != nil {
+		return p.buildTilingPattern(source, base)
+	}
+	if p.patternCells == nil {
+		p.patternCells = &renderCache[pdfPatternCellKey, *Pattern]{limit: pdfPatternCellLimit}
+	}
+	key := pdfPatternCellKey{source: source, matrix: p.matrix, dpi: p.rasterDPI, editor: p.editor}
+	if source.PaintType == 2 {
+		base.Tiling, base.Axial, base.Radial, base.Mesh, base.Function, base.Shading = nil, nil, nil, nil, nil, nil
+		base.Alpha = 1
+		key.base = base
+	}
+	if cached, ok := p.patternCells.get(key); ok {
+		return cloneEditorData(cached), p.ctx.Err()
+	}
+	pattern, err := p.buildTilingPattern(source, base)
+	if err != nil {
+		return nil, err
+	}
+	if err := p.ctx.Err(); err != nil {
+		return nil, err
+	}
+	cost := pdfPatternCellCost(reflect.ValueOf(pattern), p.patternCells.limit, 0)
+	if cost <= p.patternCells.limit {
+		p.patternCells.put(key, cloneEditorData(pattern), cost)
+	}
+	return pattern, p.ctx.Err()
+}
+
+// pdfPatternCellCost 有界估算公开数据的快照成本，不扫描共享的私有排版来源
+// 入参: value 对象值, budget 剩余预算, depth 嵌套深度
+// 返回: int 字节成本，超预算时返回预算加一
+func pdfPatternCellCost(value reflect.Value, budget, depth int) int {
+	if depth > 128 || budget < 0 {
+		return budget + 1
+	}
+	cost := int(value.Type().Size())
+	if cost > budget {
+		return budget + 1
+	}
+	switch value.Kind() {
+	case reflect.String:
+		if value.Len() > budget-cost {
+			return budget + 1
+		}
+		cost += value.Len()
+	case reflect.Pointer:
+		if !value.IsNil() {
+			cost += pdfPatternCellCost(value.Elem(), budget-cost, depth+1)
+		}
+	case reflect.Slice, reflect.Array:
+		for i := range value.Len() {
+			cost += pdfPatternCellCost(value.Index(i), budget-cost, depth+1)
+			if cost > budget {
+				return budget + 1
+			}
+		}
+	case reflect.Struct:
+		for i := range value.NumField() {
+			if value.Type().Field(i).IsExported() {
+				cost += pdfPatternCellCost(value.Field(i), budget-cost, depth+1)
+				if cost > budget {
+					return budget + 1
+				}
+			}
+		}
+	}
+	return cost
+}