refactor(重构代码): 拆分代码，提升代码质量

ofdgo_renderer_text.go

@@ -0,0 +1,248 @@
+// 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/color"
+	"strings"
+
+	"github.com/tdewolff/canvas"
+)
+
+const ptPerMM = 72.0 / 25.4
+
+// renderText 渲染文本
+// 入参: ctx 画布上下文, obj 文本对象, pageH 页面高度, defaultFill 默认填充色, defaultStroke 默认描边色, parentCTM 父级CTM, boundaryInCTM 边界是否参与父级CTM
+func (r *Renderer) renderText(ctx *canvas.Context, obj TextObject, pageH float64, defaultFill, defaultStroke color.Color, parentCTM *Matrix, boundaryInCTM bool) {
+	if obj.Visible != nil && !*obj.Visible {
+		return
+	}
+	ctx.Push()
+	bx, by := 0.0, 0.0
+	if obj.Boundary != "" {
+		if box, err := ParseBox(obj.Boundary); err == nil {
+			bx, by = box.X, box.Y
+		}
+	}
+	localCTM := NewMatrix(obj.CTM)
+	ctm := localCTM
+	if parentCTM != nil {
+		ctm = parentCTM.Multiply(ctm)
+	}
+	var dp *DrawParam
+	if obj.DrawParam != "" {
+		dp = r.getDrawParam(obj.DrawParam, nil)
+	}
+	sizeMM := obj.Size
+	if sizeMM == 0 && dp != nil && dp.Size > 0 {
+		sizeMM = dp.Size
+	}
+	if sizeMM == 0 {
+		sizeMM = 3.5
+	}
+	if obj.VScale != 0 {
+		sizeMM *= obj.VScale
+	}
+	hScale := obj.HScale
+	if hScale == 0 {
+		hScale = 1
+	}
+	useTextMatrix := hasTextMatrix(ctm)
+	if scale := ctm.YScale(); scale > 0 && !useTextMatrix {
+		sizeMM *= scale
+	}
+	sizePt := sizeMM * ptPerMM
+	fillColor := colorWithAlpha(defaultFill, obj.Alpha)
+	if fillColor == nil {
+		fillColor = colorWithAlpha(canvas.Black, obj.Alpha)
+	}
+	var fillPaint any = fillColor
+	var fillColorNode *FillColor
+	if dp != nil && dp.FillColor != nil {
+		fillColorNode = withFillAlpha(dp.FillColor, obj.Alpha)
+		fillColor = parseFillColor(fillColorNode)
+		fillPaint = parseFillPaint(fillColorNode, bx, by, pageH, 0, 0)
+	}
+	if obj.FillColor != nil {
+		fillColorNode = withFillAlpha(obj.FillColor, obj.Alpha)
+		fillColor = parseFillColor(fillColorNode)
+		fillPaint = parseFillPaint(fillColorNode, bx, by, pageH, 0, 0)
+	}
+	if fillPaint == nil {
+		fillPaint = fillColor
+	}
+	fontStyle := canvas.FontRegular
+	weight := obj.Weight
+	if weight == 0 && dp != nil && dp.Weight > 0 {
+		weight = dp.Weight
+	}
+	syntheticBold := weight >= 700
+	italic := obj.Italic
+	if !italic && dp != nil && dp.Italic {
+		italic = true
+	}
+	if italic {
+		fontStyle |= canvas.FontItalic
+	}
+	fontID := r.textObjectFontID(obj)
+	embeddedFont := false
+	if of, ok := r.Reader.fontCache[fontID]; ok {
+		embeddedFont = of.FontFile != ""
+		if !embeddedFont && fontNoSyntheticBold(of.FontName, of.FamilyName) {
+			syntheticBold = false
+		}
+		if of.Bold {
+			fontStyle |= canvas.FontBold
+		}
+		if of.Italic {
+			fontStyle |= canvas.FontItalic
+		}
+	}
+	if syntheticBold {
+		fontStyle |= canvas.FontBold
+	}
+	ff := r.loadFont(fontID)
+	if ff == nil {
+		return
+	}
+	face := ff.Face(sizePt, fillPaint, fontStyle, canvas.FontNormal)
+	glyphTransforms := r.textObjectGlyphTransforms(fontID, obj)
+	hasUnderline := strings.Contains(obj.Decoration, "Underline")
+	useGlyphFillPaint := fillColorNode != nil && fillColorNode.AxialShd != nil
+	codePos := 0
+	for _, tc := range obj.TextCode {
+		var runes []rune
+		var glyphs []textGlyph
+		if tc.Index != "" {
+			runes = r.parseIndexRunes(tc.Index, fontID)
+			glyphs = textRuneGlyphs(runes)
+		} else {
+			runes = textCodeRunes(tc.Value)
+			glyphs = textCodeGlyphs(runes, glyphTransforms, codePos)
+		}
+		dxs, dys := parseFloats(tc.DeltaX), parseFloats(tc.DeltaY)
+		xs, ys := parseFloats(tc.X), parseFloats(tc.Y)
+		drawAsPath := embeddedFont || textCodePositioned(tc, xs, ys)
+		cx, cy := 0.0, 0.0
+		if len(xs) > 0 {
+			cx = xs[0]
+		}
+		if len(ys) > 0 {
+			cy = ys[0]
+		}
+		for i, glyph := range glyphs {
+			str := glyph.Text
+			if i < len(xs) {
+				cx = xs[i]
+			} else if i > 0 {
+				if dx, ok := textDelta(dxs, i-1); ok {
+					cx += dx
+				} else if len(dys) == 0 {
+					cx += textGlyphWidth(face, glyph) * hScale
+				}
+			}
+			if i < len(ys) {
+				cy = ys[i]
+			} else if i > 0 {
+				if dy, ok := textDelta(dys, i-1); ok {
+					cy += dy
+				}
+			}
+			var canvasX, canvasY float64
+			if boundaryInCTM && parentCTM != nil {
+				tx, ty := localCTM.Transform(cx, cy)
+				tx, ty = parentCTM.Transform(tx+bx, ty+by)
+				canvasX, canvasY = tx, pageH-ty
+			} else {
+				tx, ty := ctm.Transform(cx, cy)
+				canvasX, canvasY = tx+bx, pageH-(ty+by)
+			}
+			textWidth := textGlyphWidth(face, glyph) * hScale
+			glyphFillPaint := fillPaint
+			if useGlyphFillPaint {
+				glyphFillPaint = parseFillPaint(fillColorNode, bx, by, pageH, canvasX, canvasY)
+			}
+			advanceLimit := textGlyphAdvanceLimit(dxs, dys, xs, i, len(glyphs), cx)
+			if glyphFillPaint != nil {
+				ctx.SetFill(glyphFillPaint)
+				drawGlyph := func(x, y float64) {
+					if drawAsPath || glyph.GlyphID >= 0 {
+						path, width := textGlyphPath(face, glyph)
+						scaleX := hScale
+						if advanceLimit > 0 && width*scaleX > advanceLimit {
+							scaleX = advanceLimit / width
+						}
+						textWidth = width * scaleX
+						if scaleX != 1 {
+							ctx.Push()
+							ctx.Translate(x, y)
+							ctx.Scale(scaleX, 1)
+							ctx.DrawPath(0, 0, path)
+							ctx.Pop()
+						} else {
+							ctx.DrawPath(x, y, path)
+						}
+					} else {
+						scaled := hScale != 1
+						if scaled {
+							ctx.Push()
+							ctx.Translate(x, y)
+							ctx.Scale(hScale, 1)
+							x, y = 0, 0
+						}
+						textFace := face
+						if useGlyphFillPaint {
+							textFace = ff.Face(sizePt, glyphFillPaint, fontStyle, canvas.FontNormal)
+						}
+						text := canvas.NewTextLine(textFace, str, canvas.Left)
+						ctx.DrawText(x, y, text)
+						if scaled {
+							ctx.Pop()
+						}
+					}
+				}
+				if useTextMatrix {
+					ctx.Push()
+					ctx.Translate(canvasX, canvasY)
+					ctx.ComposeView(textMatrix(ctm))
+					drawGlyph(0, 0)
+					if hasUnderline {
+						uw := sizeMM * 0.05
+						ctx.SetStrokeWidth(uw)
+						ctx.SetStrokeColor(fillColor)
+						off := sizeMM * 0.1
+						ctx.MoveTo(0, -off)
+						ctx.LineTo(textWidth, -off)
+						ctx.Stroke()
+					}
+					ctx.Pop()
+					continue
+				}
+				drawGlyph(canvasX, canvasY)
+			}
+			if hasUnderline {
+				uw := sizeMM * 0.05
+				ctx.SetStrokeWidth(uw)
+				ctx.SetStrokeColor(fillColor)
+				off := sizeMM * 0.1
+				ctx.MoveTo(canvasX, canvasY-off)
+				ctx.LineTo(canvasX+textWidth, canvasY-off)
+				ctx.Stroke()
+			}
+		}
+		codePos += len(runes)
+	}
+	ctx.Pop()
+}