feat(后端架构): 接入GoGPU渲染，支持后端切换

ofdgo_renderer_bounds.go

@@ -14,12 +14,7 @@
 
 package ofdgo
 
-import (
-	"fmt"
-	"image"
-
-	"github.com/tdewolff/canvas"
-)
+import "fmt"
 
 // ObjectBounds 获取文字、路径、图片或复合对象在页面坐标中的轴对齐范围，不修改对象
 // 文字采用字形范围，路径包含描边与裁剪，图片采用裁剪后的几何范围，不解码像素或排除透明像素
@@ -28,7 +23,8 @@ import (
 // 入参: object 图形对象, drawParam 图层绘制参数标识，无继承时为空
 // 返回: Box 毫米坐标范围, error 错误信息
 func (r *Renderer) ObjectBounds(object GraphicObject, drawParam string) (Box, error) {
-	return r.measureObject(object, drawParam, &boundsRenderer{})
+	result, err := r.MeasureObject(object, MeasureOptions{Defaults: r.drawParamDefaults(drawParam, nil)})
+	return result.Bounds, err
 }
 
 // ObjectContour 页面坐标中的填充轮廓，Path为SVG路径，EvenOdd表示奇偶填充
@@ -57,7 +53,7 @@ func (r *Renderer) AnnotationGeometry(annotation Annotation) (Box, []ObjectConto
 				continue
 			}
 			if path == "" {
-				path = canvas.Rectangle(region.W, region.H).Translate(region.X, region.Y).ToSVG()
+				path = fmt.Sprintf("M%g %gH%gV%gH%gZ", region.X, region.Y, region.X+region.W, region.Y+region.H, region.X)
 			}
 			box = unionTextBox(box, region)
 			contours = append(contours, ObjectContour{Path: path})
@@ -82,161 +78,16 @@ func (r *Renderer) ObjectGeometry(object GraphicObject, drawParam string) (Box,
 	if object.Type != "PathObject" && object.Type != "ImageObject" && object.Type != "CompositeObject" && object.Type != "CompositeGraphicUnit" {
 		return Box{}, nil, fmt.Errorf("contours require a path, image or composite object")
 	}
-	bounds := &boundsRenderer{collect: true}
-	box, err := r.measureObject(object, drawParam, bounds)
-	return box, bounds.contours, err
+	result, err := r.MeasureObject(object, MeasureOptions{Defaults: r.drawParamDefaults(drawParam, nil), Contours: true})
+	return result.Bounds, result.Contours, err
 }
 
-// measureObject 复用渲染逻辑收集对象范围与可选轮廓
-// 入参: object 对象, drawParam 图层绘制参数标识, bounds 度量目标
-// 返回: Box 毫米范围, error 错误信息
-func (r *Renderer) measureObject(object GraphicObject, drawParam string, bounds *boundsRenderer) (Box, error) {
-	if object.Type != "TextObject" && object.Type != "PathObject" && object.Type != "ImageObject" && object.Type != "CompositeObject" && object.Type != "CompositeGraphicUnit" {
-		return Box{}, fmt.Errorf("unsupported object type %q", object.Type)
+// MeasureObject 使用当前页面编译器度量对象，保持绘制与选区的字体和几何语义一致
+// 入参: object 图形对象, options 度量上下文
+// 返回: ObjectMeasurement 度量结果, error 错误信息
+func (r *Renderer) MeasureObject(object GraphicObject, options MeasureOptions) (ObjectMeasurement, error) {
+	if r.backends.Compiler == nil {
+		return ObjectMeasurement{}, fmt.Errorf("%w: object measurement", ErrBackendUnavailable)
 	}
-	boundary, ctm := editorGeometry(object)
-	if _, err := creationBox(boundary); err != nil {
-		return Box{}, err
-	}
-	if ctm != "" {
-		if _, err := creationNumbers(ctm, 6); err != nil {
-			return Box{}, err
-		}
-	}
-	renderer := *r
-	renderer.pageText = nil
-	renderer.textOnly = false
-	defaults := renderer.drawParamDefaults(drawParam, nil)
-	ctx := canvas.NewContext(bounds)
-	switch object.Type {
-	case "TextObject":
-		renderer.pageText = &PageText{}
-		renderer.textOnly = true
-		renderer.renderText(ctx, object.TextObject, 0, defaults, nil, false, nil)
-		var box Box
-		for _, run := range renderer.pageText.Runs {
-			for _, glyph := range run.Boxes {
-				box = unionTextBox(box, glyph)
-			}
-		}
-		return box, nil
-	case "PathObject":
-		obj := object.PathObject
-		defaults = renderer.drawParamDefaults(obj.DrawParam, defaults)
-		obj.DrawParam = ""
-		if defaults != nil {
-			style := *defaults
-			style.FillColor = boundsColor(style.FillColor)
-			style.StrokeColor = (*StrokeColor)(boundsColor((*FillColor)(style.StrokeColor)))
-			defaults = &style
-		}
-		obj.FillColor = boundsColor(obj.FillColor)
-		obj.StrokeColor = (*StrokeColor)(boundsColor((*FillColor)(obj.StrokeColor)))
-		renderer.renderPath(ctx, obj, 0, defaults, nil, false, nil)
-	case "ImageObject":
-		renderer.measureImage(ctx, object.ImageObject, 0, nil, false, nil)
-	case "CompositeObject", "CompositeGraphicUnit":
-		renderer.renderCompositeGraphicUnit(ctx, object.CompositeGraphicUnit, 0, defaults, nil, false, nil)
-	}
-	return bounds.box, nil
+	return r.backends.Compiler.MeasureObject(r, object, options)
 }
-
-// measureImage 复用图片变换与裁剪语义度量范围，不读取像素数据
-// 入参: ctx 度量画布, obj 图片, pageH 页面高度, parentCTM 父变换, boundaryInCTM 边界是否参与变换, parentClip 父裁剪
-func (r *Renderer) measureImage(ctx *canvas.Context, obj ImageObject, pageH float64, parentCTM *Matrix, boundaryInCTM bool, parentClip *canvas.Path) {
-	if obj.Visible != nil && !*obj.Visible || obj.Alpha != nil && *obj.Alpha == 0 {
-		return
-	}
-	box, _ := ParseBox(obj.Boundary)
-	ctm := NewMatrix(obj.CTM)
-	if obj.CTM == "" {
-		ctm = Matrix{a: box.W, d: box.H}
-	}
-	m := TranslationMatrix(box.X, box.Y).Multiply(ctm)
-	if parentCTM != nil {
-		if boundaryInCTM {
-			m = parentCTM.Multiply(m)
-		} else {
-			m = TranslationMatrix(box.X, box.Y).Multiply(*parentCTM).Multiply(ctm)
-		}
-	}
-	p := canvas.Rectangle(1, 1).Transform(canvas.Matrix{{m.a, m.c, m.e}, {-m.b, -m.d, pageH - m.f}})
-	clip := intersectClipPath(parentClip, r.buildObjectClipPath(obj.Clips, pageH, box.X, box.Y, ctm, parentCTM, boundaryInCTM))
-	ctx.Renderer.(*boundsRenderer).add(applyClipPath(p, clip))
-	if obj.Border != nil {
-		border := *obj.Border
-		border.BorderColor = (*StrokeColor)(boundsColor((*FillColor)(border.BorderColor)))
-		obj.Border = &border
-		r.renderImageBorder(ctx, obj, box, pageH, parentCTM, boundaryInCTM, clip)
-	}
-}
-
-// boundsColor 以底纹的基础颜色和透明度度量轮廓，不修改原画刷
-// 入参: color 填充或描边颜色
-// 返回: *FillColor 用于度量的颜色
-func boundsColor(color *FillColor) *FillColor {
-	if color == nil || color.Pattern == nil {
-		return color
-	}
-	return &FillColor{Value: color.Value, Index: color.Index, ColorSpace: color.ColorSpace, Alpha: color.Alpha}
-}
-
-// boundsRenderer 收集绘制范围，不分配页面像素或合并独立图形轮廓
-type boundsRenderer struct {
-	box      Box
-	collect  bool
-	contours []ObjectContour
-}
-
-// Size 返回不限定边界的度量画布尺寸
-// 返回: float64 宽度, float64 高度
-func (r *boundsRenderer) Size() (float64, float64) {
-	return 0, 0
-}
-
-// add 合并路径的精确曲线范围并转换为向下的纵轴
-// 入参: path 绘制路径
-func (r *boundsRenderer) add(path *canvas.Path) {
-	r.addContour(path, false)
-}
-
-// addContour 合并范围并按需保留独立填充区域
-// 入参: path 绘制路径, evenOdd 是否使用奇偶规则
-func (r *boundsRenderer) addContour(path *canvas.Path, evenOdd bool) {
-	if path.Empty() {
-		return
-	}
-	rect := path.Bounds()
-	r.box = unionTextBox(r.box, Box{X: rect.X0, Y: -rect.Y1, W: rect.W(), H: rect.H()})
-	if r.collect {
-		outline := &canvas.Path{}
-		for _, subpath := range path.Split() {
-			subpath = subpath.Copy()
-			subpath.Close()
-			outline = outline.Append(subpath)
-		}
-		r.contours = append(r.contours, ObjectContour{Path: outline.Transform(canvas.Matrix{{1, 0, 0}, {0, -1, 0}}).ToSVG(), EvenOdd: evenOdd})
-	}
-}
-
-// RenderPath 收集填充与描边范围，保持线帽、连接和虚线语义
-// 入参: path 路径, style 绘制样式, m 变换矩阵
-func (r *boundsRenderer) RenderPath(path *canvas.Path, style canvas.Style, m canvas.Matrix) {
-	if style.HasFill() {
-		r.addContour(path.Copy().Transform(m), style.FillRule == canvas.EvenOdd)
-	}
-	if style.HasStroke() {
-		p := path.Dash(style.DashOffset, style.Dashes...).Stroke(style.StrokeWidth, style.StrokeCapper, style.StrokeJoiner, canvas.Tolerance)
-		r.add(p.Transform(m))
-	}
-}
-
-// RenderText 收集绘制文字范围
-// 入参: text 文字, m 变换矩阵
-func (r *boundsRenderer) RenderText(text *canvas.Text, m canvas.Matrix) {
-	text.RenderTo(r, m, 0)
-}
-
-// RenderImage 度量不展开底纹图片
-// 入参: img 图片, m 变换矩阵
-func (r *boundsRenderer) RenderImage(img image.Image, m canvas.Matrix) {}