feat(渲染压缩): 完善字体三维动作导航及压缩

ofdgo_pdf_destination.go

@@ -0,0 +1,124 @@
+// 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"
+
+	"github.com/xiaoqidun/pdfgo"
+)
+
+// pdfDestinationFontBackend 禁止内容度量忽略实际绘制所需的缺失字体
+type pdfDestinationFontBackend struct {
+	FontBackend
+}
+
+// ResolveFont 沿用字体匹配，只在实际绘制缺少字体数据时中止度量
+// 入参: renderer 度量渲染器, id 字体标识, exact 是否禁止无关回退
+// 返回: ResolvedFont 字体资源, error 解析或缺失错误
+func (b pdfDestinationFontBackend) ResolveFont(renderer *Renderer, id string, exact bool) (ResolvedFont, error) {
+	font, err := b.FontBackend.ResolveFont(renderer, id, exact)
+	if err == nil && len(font.Data) == 0 {
+		err = fmt.Errorf("PDF destination font %q unavailable", id)
+	}
+	return font, err
+}
+
+// destinationBounds 度量目标页内容并缓存页面内范围，不包含注解或像素取整
+// 入参: page PDF目标页
+// 返回: Box OFD内容范围, error 度量错误
+func (p *pdfImporter) destinationBounds(page *pdfgo.Page) (Box, error) {
+	if err := p.ctx.Err(); err != nil {
+		return Box{}, err
+	}
+	if box, ok := p.destinationBoxes[page.Reference]; ok {
+		return box, nil
+	}
+	if index, ok := p.pageIndexes[page.Reference]; ok {
+		previous := p.page
+		p.page = index
+		defer func() { p.page = previous }()
+	}
+	matrix, width, height := pdfPageMatrix(page)
+	editor := NewEditor()
+	editor.SetRenderBackends(p.editor.Backends())
+	editor.SetFontDirs(p.editor.fontDirs...)
+	editor.SetFontFS(p.editor.fontFS...)
+	editor.fontSourcesCache = p.renderer.fontSourcesCache
+	editor.validatedPaths = p.editor.pathValidationCache()
+	if _, err := editor.AddPage(width, height); err != nil {
+		return Box{}, err
+	}
+	local := pdfImporter{
+		ctx: p.ctx, reader: p.reader, editor: editor, renderer: p.renderer,
+		matrix: matrix, pageBox: page.CropBox, pageWidth: width, pageHeight: height,
+		rasterDPI: p.rasterDPI, fontIDs: make(map[*pdfgo.Font]string),
+		resolveFile: p.resolveFile, resolveReference: p.resolveReference,
+		referenceReaders: make(map[[32]byte]*pdfgo.Reader),
+		referenceStreams: make(map[*pdfgo.Stream]*pdfgo.Reader),
+		referencePages:   make(map[pdfReferencePageKey]*pdfgo.Page),
+		halftones:        p.halftones, halftoneWarnings: make(map[*pdfgo.Halftone]bool),
+	}
+	defer local.closeReferenceReaders()
+	if err := local.compositePage(nil, func(visitor pdfgo.Visitor) error {
+		return p.reader.WalkPage(p.ctx, page, visitor)
+	}); err != nil {
+		return Box{}, fmt.Errorf("PDF destination content: %w", err)
+	}
+	if err := local.commitObjects(); err != nil {
+		return Box{}, err
+	}
+	reader, err := editor.resourceReader()
+	if err != nil {
+		return Box{}, err
+	}
+	defer reader.Close()
+	renderer := p.renderer.childRenderer(reader)
+	renderer.TransparentBackground = true
+	renderer.RenderAnnotations = false
+	if renderer.backends.Fonts != nil {
+		renderer.backends.Fonts = pdfDestinationFontBackend{renderer.backends.Fonts}
+	}
+	scene, err := renderer.CompilePage(&editor.pages[0])
+	if err != nil {
+		return Box{}, err
+	}
+	if scene == nil {
+		return Box{}, fmt.Errorf("PDF destination content scene unavailable")
+	}
+	geometry, err := renderer.Geometry()
+	if err != nil {
+		return Box{}, err
+	}
+	box, err := scene.BoundsContext(p.ctx, geometry)
+	if err != nil {
+		return Box{}, err
+	}
+	left, top := math.Max(0, box.X), math.Max(0, box.Y)
+	right, bottom := math.Min(width, box.X+box.W), math.Min(height, box.Y+box.H)
+	box = Box{X: left, Y: top, W: right - left, H: bottom - top}
+	if !finite(left) || !finite(top) || !finite(right) || !finite(bottom) || box.W <= 0 || box.H <= 0 {
+		return Box{}, fmt.Errorf("PDF destination content bounds empty or invalid")
+	}
+	if err := p.ctx.Err(); err != nil {
+		return Box{}, err
+	}
+	if p.destinationBoxes == nil {
+		p.destinationBoxes = make(map[pdfgo.Reference]Box)
+	}
+	p.destinationBoxes[page.Reference] = box
+	return box, nil
+}