feat(渲染能力): 支持文字裁剪，完善字体统计

ofdgo_font_info.go

@@ -240,6 +240,12 @@ func (r *Renderer) countLayerFonts(layer Layer, usage map[string]int) {
 	for _, text := range layer.TextObject {
 		r.countTextFont(text, usage)
 	}
+	for _, path := range layer.PathObject {
+		r.countClipFonts(path.Clips, usage)
+	}
+	for _, image := range layer.ImageObject {
+		r.countClipFonts(image.Clips, usage)
+	}
 	for _, cgu := range layer.CompositeGraphicUnit {
 		r.countCompositeFonts(cgu, usage, nil)
 	}
@@ -251,6 +257,10 @@ func (r *Renderer) countObjectFonts(obj GraphicObject, usage map[string]int) {
 	switch obj.Type {
 	case "TextObject":
 		r.countTextFont(obj.TextObject, usage)
+	case "PathObject":
+		r.countClipFonts(obj.PathObject.Clips, usage)
+	case "ImageObject":
+		r.countClipFonts(obj.ImageObject.Clips, usage)
 	case "CompositeGraphicUnit", "CompositeObject":
 		r.countCompositeFonts(obj.CompositeGraphicUnit, usage, nil)
 	}
@@ -259,6 +269,7 @@ func (r *Renderer) countObjectFonts(obj GraphicObject, usage map[string]int) {
 // countCompositeFonts 统计复合图元字体使用次数
 // 入参: cgu 复合图元, usage 字体使用次数, visited 已访问资源
 func (r *Renderer) countCompositeFonts(cgu CompositeGraphicUnit, usage map[string]int, visited map[string]bool) {
+	r.countClipFonts(cgu.Clips, usage)
 	if cgu.ResourceID != "" {
 		if visited == nil {
 			visited = make(map[string]bool)
@@ -280,6 +291,12 @@ func (r *Renderer) countCompositeFonts(cgu CompositeGraphicUnit, usage map[strin
 	for _, text := range cgu.TextObject {
 		r.countTextFont(text, usage)
 	}
+	for _, path := range cgu.PathObject {
+		r.countClipFonts(path.Clips, usage)
+	}
+	for _, image := range cgu.ImageObject {
+		r.countClipFonts(image.Clips, usage)
+	}
 	for _, sub := range cgu.CompositeGraphicUnit {
 		r.countCompositeFonts(sub, usage, visited)
 	}
@@ -291,4 +308,20 @@ func (r *Renderer) countTextFont(text TextObject, usage map[string]int) {
 	if fontID := r.textObjectFontID(text); fontID != "" {
 		usage[fontID]++
 	}
+	r.countClipFonts(text.Clips, usage)
+}
+
+// countClipFonts 统计裁剪文字字体使用次数
+// 入参: clips 裁剪区域集合, usage 字体使用次数
+func (r *Renderer) countClipFonts(clips *Clips, usage map[string]int) {
+	if clips == nil {
+		return
+	}
+	for _, clip := range clips.Clip {
+		for _, area := range clip.Area {
+			for _, text := range area.Text {
+				r.countTextFont(text, usage)
+			}
+		}
+	}
 }

ofdgo_page.go

@@ -72,6 +72,7 @@ type Clip struct {
 
 // ClipArea 裁剪区域
 type ClipArea struct {
+	DrawParam string       `xml:"DrawParam,attr"`
 	CTM       string       `xml:"CTM,attr"`
 	Path      []PathObject `xml:"Path"`
 	Text      []TextObject `xml:"Text"`

ofdgo_renderer_clip.go

@@ -0,0 +1,65 @@
+// 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 (
+	"image"
+
+	"github.com/tdewolff/canvas"
+)
+
+// clipRenderer 收集图形和文字的绘制轮廓
+type clipRenderer struct {
+	path *canvas.Path
+	clip *canvas.Path
+}
+
+// Size 返回不限定边界的裁剪画布尺寸
+// 返回: float64 宽度, float64 高度
+func (r *clipRenderer) Size() (float64, float64) {
+	return 0, 0
+}
+
+// RenderPath 合并路径填充及描边轮廓
+// 入参: path 路径, style 绘制样式, m 变换矩阵
+func (r *clipRenderer) RenderPath(path *canvas.Path, style canvas.Style, m canvas.Matrix) {
+	if style.HasFill() {
+		r.add(applyClipPath(path.Copy().Transform(m), r.clip))
+	}
+	if style.HasStroke() {
+		p := path.Dash(style.DashOffset, style.Dashes...).Stroke(style.StrokeWidth, style.StrokeCapper, style.StrokeJoiner, canvas.Tolerance)
+		r.add(applyClipPath(p.Transform(m), r.clip))
+	}
+}
+
+// add 合并裁剪轮廓
+// 入参: path 裁剪路径
+func (r *clipRenderer) add(path *canvas.Path) {
+	if r.path == nil {
+		r.path = path
+	} else {
+		r.path = unionClipPath(r.path, path)
+	}
+}
+
+// RenderText 合并文字字形轮廓
+// 入参: text 文字, m 变换矩阵
+func (r *clipRenderer) RenderText(text *canvas.Text, m canvas.Matrix) {
+	text.RenderTo(r, m, 0)
+}
+
+// RenderImage 裁剪区不包含图像对象
+// 入参: img 图像, m 变换矩阵
+func (r *clipRenderer) RenderImage(img image.Image, m canvas.Matrix) {}

ofdgo_renderer_path.go

@@ -467,7 +467,7 @@ func (r *Renderer) buildClipPath(clips *Clips, pageH float64, bx, by float64, ob
 	}
 	var p *canvas.Path
 	for _, clip := range clips.Clip {
-		var clipPath *canvas.Path
+		renderer := &clipRenderer{}
 		for _, area := range clip.Area {
 			areaCTM := NewMatrix(area.CTM)
 			if clips.TransFlag == nil || *clips.TransFlag {
@@ -481,20 +481,30 @@ func (r *Renderer) buildClipPath(clips *Clips, pageH float64, bx, by float64, ob
 				if pathObj.Rule == "Even-Odd" {
 					cp = cp.Settle(canvas.EvenOdd)
 				}
-				if clipPath == nil {
+				renderer.add(cp)
-					clipPath = cp
+			}
-				} else {
+			for _, textObj := range area.Text {
-					clipPath = unionClipPath(clipPath, cp)
+				box, _ := ParseBox(textObj.Boundary)
+				ctm := NewMatrix(textObj.CTM)
+				m := areaCTM.Multiply(TranslationMatrix(box.X, box.Y)).Multiply(ctm)
+				ctx := canvas.NewContext(renderer)
+				ctx.SetView(canvas.Matrix{{m.a, -m.c, bx + m.e}, {-m.b, m.d, pageH - by - m.f}})
+				renderer.clip = r.buildObjectClipPath(textObj.Clips, pageH, box.X, box.Y, ctm, &areaCTM, true)
+				if renderer.clip != nil {
+					renderer.clip = renderer.clip.Translate(bx, -by)
+				}
+				textObj.Boundary, textObj.CTM = "", ""
+				textObj.Clips = nil
+				textObj.Alpha = nil
+				textObj.FillColor = &FillColor{Value: "0 0 0"}
+				textObj.StrokeColor = &StrokeColor{Value: "0 0 0"}
+				r.renderText(ctx, textObj, 0, r.drawParamDefaults(area.DrawParam, nil), nil, false, nil)
 			}
 		}
+		if renderer.path == nil {
+			renderer.path = &canvas.Path{}
 		}
-		if clipPath != nil {
+		p = intersectClipPath(p, renderer.path)
-			if p == nil {
-				p = clipPath
-			} else {
-				p = intersectClipPath(p, clipPath)
-			}
-		}
 	}
 	return p
 }