feat(裁剪合成): 优化裁剪合成与取消响应

go.mod

@@ -10,7 +10,7 @@ require (
 	github.com/tdewolff/canvas v0.0.0-20260923214215-09804640d00c
 	github.com/tdewolff/font v0.0.0-20260913163313-54f98bb59ee6
 	github.com/xiaoqidun/jbig2 v1.1.1
-	github.com/xiaoqidun/pdfgo v0.0.0-20261008045044-ada80114c916
+	github.com/xiaoqidun/pdfgo v0.0.0-20261008072006-d519e7a38749
 	golang.org/x/crypto v0.57.0
 	golang.org/x/image v0.46.0
 	golang.org/x/text v0.42.0

go.sum

@@ -62,8 +62,8 @@ github.com/tdewolff/test v1.0.12 h1:7F21DqIajswxuche0geHdrUZRCWE4oko4b7bcmkkrxk=
 github.com/tdewolff/test v1.0.12/go.mod h1:XPuWBzvdUzhCuxWO1ojpXsyzsA5bFoS3tO/Q3kFuTG8=
 github.com/xiaoqidun/jbig2 v1.1.1 h1:SjliS9ZO0e9HX5oYUfBuXrfFsXhWricrSz+XY4zORDI=
 github.com/xiaoqidun/jbig2 v1.1.1/go.mod h1:8QonVWtENmh2kc6l+leqeGl7psb79DWlHDkCpdChjfQ=
-github.com/xiaoqidun/pdfgo v0.0.0-20261008045044-ada80114c916 h1:SwXbZ6zLtTCxMeV7A5GBSxgNhyVfdzWLhPh38IdkVTc=
+github.com/xiaoqidun/pdfgo v0.0.0-20261008072006-d519e7a38749 h1:jWImuld2SXZp826sudLJJUUOEEMPj/Jy77ItAE778Sg=
-github.com/xiaoqidun/pdfgo v0.0.0-20261008045044-ada80114c916/go.mod h1:4Pf0JO0BEf1uzRY+uZjlMjN/OPn3PYa0YMi6cqPPTLQ=
+github.com/xiaoqidun/pdfgo v0.0.0-20261008072006-d519e7a38749/go.mod h1:4Pf0JO0BEf1uzRY+uZjlMjN/OPn3PYa0YMi6cqPPTLQ=
 github.com/xyproto/randomstring v1.0.5 h1:YtlWPoRdgMu3NZtP45drfy1GKoojuR7hmRcnhZqKjWU=
 github.com/xyproto/randomstring v1.0.5/go.mod h1:rgmS5DeNXLivK7YprL0pY+lTuhNQW3iGxZ18UQApw/E=
 github.com/yuin/goldmark v1.8.5 h1:r6N5afV5qj/5S4UTch8agZHJ8UxNCMwX7WjkkJam2NA=

ofdgo_backend.go

@@ -15,6 +15,7 @@
 package ofdgo
 
 import (
+	"context"
 	"errors"
 	"fmt"
 	"image"
@@ -188,10 +189,31 @@ func WithRasterBackend(backend RasterBackend) RendererOption {
 // 入参: page 页面内容
 // 返回: *RasterPage 只读绘制页面, error 编译错误
 func (r *Renderer) CompilePage(page *PageContent) (*RasterPage, error) {
+	return r.CompilePageContext(r.pageContext, page)
+}
+
+// CompilePageContext 编译页面并在对象遍历间响应取消，不返回未完成场景
+// 单次后端操作完成后检查取消，nil使用后台上下文
+// 入参: ctx 取消上下文, page 页面内容
+// 返回: *RasterPage 只读绘制页面, error 编译或取消错误
+func (r *Renderer) CompilePageContext(ctx context.Context, page *PageContent) (*RasterPage, error) {
+	if ctx == nil {
+		ctx = context.Background()
+	}
+	if err := ctx.Err(); err != nil {
+		return nil, err
+	}
 	if r.backends.Compiler == nil {
 		return nil, fmt.Errorf("page compiler: %w", ErrBackendUnavailable)
 	}
-	return r.backends.Compiler.CompilePage(r, page)
+	previous := r.pageContext
+	r.pageContext = ctx
+	defer func() { r.pageContext = previous }()
+	result, err := r.backends.Compiler.CompilePage(r, page)
+	if canceled := ctx.Err(); canceled != nil {
+		return nil, canceled
+	}
+	return result, err
 }
 
 // backendName 获取已配置的后端标识

ofdgo_pdf_composite.go

@@ -231,6 +231,38 @@ func (c *pdfCompositor) geometryBounds(node pdfCompositeNode, stroke bool) (Box,
 	return geometry.box, err
 }
 
+// coverageBounds 合并实际覆盖边界并复用图元编译缓存，不采用字体估算范围
+// 入参: node 图元或透明组
+// 返回: Box 覆盖范围, error 编译或取消错误
+func (c *pdfCompositor) coverageBounds(node pdfCompositeNode) (Box, error) {
+	if err := c.importer.ctx.Err(); err != nil {
+		return Box{}, err
+	}
+	var box Box
+	if node.group != nil {
+		for _, child := range node.children {
+			bounds, err := c.coverageBounds(child)
+			if err != nil {
+				return Box{}, err
+			}
+			box = unionTextBox(box, bounds)
+		}
+		return box, nil
+	}
+	_, fill, stroke := node.style()
+	for _, outline := range []bool{false, true} {
+		if outline && !stroke || !outline && !fill {
+			continue
+		}
+		bounds, err := c.geometryBounds(node, outline)
+		if err != nil {
+			return Box{}, err
+		}
+		box = unionTextBox(box, bounds)
+	}
+	return box, nil
+}
+
 // groupBounds 缓存组内实际覆盖范围，外部字体沿用描述符保守边界
 // 入参: node 透明组
 // 返回: Box 组覆盖范围, error 几何编译错误
@@ -749,12 +781,24 @@ func (n pdfCompositeNode) coverage(p *pdfImporter, stroke bool) error {
 	return p.path(pdfgo.PathMark{Path: path, Style: style, Fill: true})
 }
 
-// compositeRegion 按原始背景计算局部效果，不将组外文字和图形栅格化
+// compositeRegionBounds 复用内置后端的图元覆盖，自定义后端保留整组度量
-// 入参: backdrop 前序图元, node 当前效果, space 页面混合空间, flatten 是否合并页面背景
+// 入参: node 当前效果
-// 返回: error 合成或保存错误
+// 返回: Box 覆盖范围, error 编译或取消错误
-func (p *pdfImporter) compositeRegion(backdrop []pdfCompositeNode, node pdfCompositeNode, space *pdfgo.ColorSpace, flatten bool) error {
+func (p *pdfImporter) compositeRegionBounds(node pdfCompositeNode) (Box, error) {
 	if err := p.ctx.Err(); err != nil {
-		return err
+		return Box{}, err
+	}
+	switch p.editor.Backends().Compiler.(type) {
+	case CanvasBackend, *CanvasBackend, OFDCompiler, *OFDCompiler:
+		geometry, err := p.renderer.Geometry()
+		if err != nil {
+			return Box{}, err
+		}
+		switch geometry.(type) {
+		case CanvasBackend, *CanvasBackend:
+			c := pdfCompositor{importer: p, cache: p.compositingCache()}
+			return c.coverageBounds(node)
+		}
 	}
 	scene, box, err := p.compileGroup(func(local *pdfImporter) error {
 		if node.group != nil {
@@ -772,6 +816,17 @@ func (p *pdfImporter) compositeRegion(backdrop []pdfCompositeNode, node pdfCompo
 		return nil
 	})
 	if err != nil || scene == nil {
+		return Box{}, err
+	}
+	return box, nil
+}
+
+// compositeRegion 按原始背景计算局部效果，不将组外文字和图形栅格化
+// 入参: backdrop 前序图元, node 当前效果, space 页面混合空间, flatten 是否合并页面背景
+// 返回: error 合成或保存错误
+func (p *pdfImporter) compositeRegion(backdrop []pdfCompositeNode, node pdfCompositeNode, space *pdfgo.ColorSpace, flatten bool) error {
+	box, err := p.compositeRegionBounds(node)
+	if err != nil || box.W <= 0 || box.H <= 0 {
 		return err
 	}
 	inverse, ok := p.matrix.Inverse()

ofdgo_pdf_destination.go

@@ -92,7 +92,7 @@ func (p *pdfImporter) destinationBounds(page *pdfgo.Page) (Box, error) {
 	if renderer.backends.Fonts != nil {
 		renderer.backends.Fonts = pdfDestinationFontBackend{renderer.backends.Fonts}
 	}
-	scene, err := renderer.CompilePage(&editor.pages[0])
+	scene, err := renderer.CompilePageContext(p.ctx, &editor.pages[0])
 	if err != nil {
 		return Box{}, err
 	}

ofdgo_pdf_group.go

@@ -393,7 +393,7 @@ func (p *pdfImporter) compileGroup(build func(*pdfImporter) error) (*RasterPage,
 	page := &editor.pages[0]
 	renderer := p.renderer.childRenderer(reader)
 	renderer.TransparentBackground = true
-	scene, err := renderer.CompilePage(page)
+	scene, err := renderer.CompilePageContext(p.ctx, page)
 	if canceled := p.ctx.Err(); canceled != nil {
 		return nil, box, canceled
 	}

ofdgo_render_walk.go

@@ -47,6 +47,11 @@ type PageGroups interface {
 // 入参: page 页面内容, visitor 页面访问器
 // 返回: error 遍历或访问器错误
 func (r *Renderer) WalkPage(page *PageContent, visitor PageVisitor) error {
+	if r.pageContext != nil {
+		if err := r.pageContext.Err(); err != nil {
+			return err
+		}
+	}
 	for order := range 3 {
 		if r.Reader.doc != nil {
 			for _, ref := range page.Template {
@@ -83,6 +88,11 @@ func (r *Renderer) WalkPage(page *PageContent, visitor PageVisitor) error {
 		}
 	}
 	for _, stamp := range r.Reader.Stamps[page.ID] {
+		if r.pageContext != nil {
+			if err := r.pageContext.Err(); err != nil {
+				return err
+			}
+		}
 		if err := visitor.DrawStamp(stamp); err != nil {
 			return err
 		}
@@ -160,6 +170,11 @@ func (r *Renderer) walkLayers(layers []Layer, order int, visitor PageVisitor) er
 // 入参: object 源对象, state 继承状态, visitor 页面访问器, references 当前资源引用链
 // 返回: error 遍历或访问器错误
 func (r *Renderer) walkObject(object *GraphicObject, state RenderState, visitor PageVisitor, references map[string]bool) error {
+	if r.pageContext != nil {
+		if err := r.pageContext.Err(); err != nil {
+			return err
+		}
+	}
 	if groups, ok := visitor.(PageGroups); ok && groups.BeginObject(object) {
 		defer groups.EndObject()
 	}

ofdgo_renderer.go

@@ -43,6 +43,7 @@ type Renderer struct {
 	fontFS                []fs.FS
 	decodeImages          bool
 	pageText              *PageText
+	pageContext           context.Context
 	textOnly              bool
 	backends              RenderBackends
 	backendStates         map[any]any
@@ -107,6 +108,7 @@ func (r *Renderer) childRenderer(reader *Reader) *Renderer {
 	renderer.fontMetrics = r.fontMetrics
 	renderer.fontSourcesCache = r.fontSourcesCache.child()
 	renderer.decodeImages = r.decodeImages
+	renderer.pageContext = r.pageContext
 	renderer.TransparentBackground = r.TransparentBackground
 	return renderer
 }

ofdgo_renderer_clip_canvas.go

@@ -217,6 +217,8 @@ func intersectClipPath(parent, current *canvas.Path) *canvas.Path {
 	if slices.Equal(parent.Data(), current.Data()) {
 		return parent
 	}
+	parent = pruneCanvasContours(parent, current)
+	current = pruneCanvasContours(current, parent)
 	parentRect, parentOK := rectangularPath(parent)
 	currentRect, currentOK := rectangularPath(current)
 	if parentOK && currentOK {
@@ -295,6 +297,8 @@ func applyClipPath(path, clip *canvas.Path) *canvas.Path {
 	if path.Empty() || clip.Empty() {
 		return &canvas.Path{}
 	}
+	path = pruneCanvasContours(path, clip)
+	clip = pruneCanvasContours(clip, path)
 	if rect, ok := rectangularPath(clip); ok {
 		bounds := path.Bounds()
 		if rect.Contains(bounds) {
@@ -319,6 +323,37 @@ func applyClipPath(path, clip *canvas.Path) *canvas.Path {
 	return path.And(clip)
 }
 
+// pruneCanvasContours 排除与裁剪边界分离的完整轮廓，保留相交轮廓的曲线和绕向
+// 入参: path 填充路径, clip 裁剪路径
+// 返回: *canvas.Path 待求交路径
+func pruneCanvasContours(path, clip *canvas.Path) *canvas.Path {
+	if path == nil || clip == nil || len(path.Data()) < 256 || !path.HasSubpaths() {
+		return path
+	}
+	bounds := clip.Bounds()
+	parts := path.Split()
+	count := 0
+	for _, part := range parts {
+		if !part.Closed() {
+			return path
+		}
+		box := part.Bounds()
+		if box.X1 < bounds.X0 || bounds.X1 < box.X0 || box.Y1 < bounds.Y0 || bounds.Y1 < box.Y0 {
+			continue
+		}
+		parts[count] = part
+		count++
+	}
+	if count == len(parts) {
+		return path
+	}
+	result := &canvas.Path{}
+	for _, part := range parts[:count] {
+		result = result.Append(part)
+	}
+	return result
+}
+
 // reduceRepeatedNonZeroPath 将完全相同的闭合轮廓约为一份，保持非零填充区域
 // 入参: path 非零填充路径
 // 返回: *canvas.Path 等价填充路径

ofdgo_renderer_geom_canvas.go

@@ -311,7 +311,7 @@ func geometryToCanvasPath(path *GeometryPath) (*canvas.Path, error) {
 	if err := path.validate(); err != nil {
 		return nil, err
 	}
-	p := &canvas.Path{}
+	p := canvas.NewPathFromData(make([]float64, 0, canvasPathCapacity(*path)))
 	for _, s := range *path {
 		switch s.Verb {
 		case GeometryMove:
@@ -337,7 +337,7 @@ func geometryToCanvasPath(path *GeometryPath) (*canvas.Path, error) {
 // 入参: path 独立路径
 // 返回: *canvas.Path 适配路径, error 不支持的指令
 func canvasObjectPath(path GeometryPath) (*canvas.Path, error) {
-	var data []float64
+	data := make([]float64, 0, canvasPathCapacity(path))
 	for _, s := range path {
 		end := s.End
 		switch s.Verb {
@@ -364,6 +364,24 @@ func canvasObjectPath(path GeometryPath) (*canvas.Path, error) {
 	return canvas.NewPathFromData(data), nil
 }
 
+// canvasPathCapacity 按指令估算路径容量，避免长路径逐段扩容
+// 入参: path 独立几何路径
+// 返回: int 坐标存储容量
+func canvasPathCapacity(path GeometryPath) int {
+	count := 0
+	for _, segment := range path {
+		switch segment.Verb {
+		case GeometryMove, GeometryLine, GeometryClose:
+			count += 4
+		case GeometryQuad:
+			count += 6
+		default:
+			count += 8
+		}
+	}
+	return count
+}
+
 // geometryFromCanvasPath 将默认引擎路径转换为独立的页面坐标路径，保留曲线和椭圆弧
 // 入参: path 默认引擎路径
 // 返回: *GeometryPath 独立路径，nil表示不裁剪