feat(归并文件): 归并根包文件，保持接口不变

ofdgo_paint.go

@@ -30,6 +30,12 @@ type PatternPaint struct {
 	Alpha *int
 }
 
+// profileGradient 保存独立色标和只读配置，延伸及重复由几何采样器处理
+type profileGradient struct {
+	positions []float64
+	colors    []MeshVertex
+}
+
 // ResolveColor 按文档颜色空间和调色板解析颜色，返回预乘透明度的RGBA
 // 入参: value 颜色分量, index 调色板索引, space 颜色空间标识, alpha 透明度
 // 返回: color.RGBA 标准颜色, error 颜色定义或配置错误
@@ -394,3 +400,70 @@ func colorToRGBA(c color.Color) color.RGBA {
 	r, g, b, a := c.RGBA()
 	return color.RGBA{R: uint8(r >> 8), G: uint8(g >> 8), B: uint8(b >> 8), A: uint8(a >> 8)}
 }
+
+// profileGradient 准备ICC渐变的源分量采样，不用转换后的端点近似非线性色彩变换
+// 入参: segments 原色标, alpha 外层透明度
+// 返回: func(float64) color.RGBA 单位区间采样器，无ICC时为nil, error 配置错误
+func (r *Renderer) profileGradient(segments []ShdSegment, alpha *int) (func(float64) color.RGBA, error) {
+	profiled := false
+	for _, segment := range segments {
+		if space := r.colorDefinition(segment.Color.ColorSpace); space != nil && space.Profile != "" {
+			profiled = true
+			break
+		}
+	}
+	if !profiled {
+		return nil, nil
+	}
+	gradient := &profileGradient{positions: gradientPositions(segments), colors: make([]MeshVertex, len(segments))}
+	for i, segment := range segments {
+		kind, values, err := r.colorComponents(segment.Color.Value, segment.Color.Index, segment.Color.ColorSpace)
+		if err != nil {
+			return nil, err
+		}
+		profile, err := r.Reader.colorProfile(r.colorDefinition(segment.Color.ColorSpace))
+		if err != nil {
+			return nil, err
+		}
+		opacity := 1.0
+		if value := mergeAlpha(segment.Color.Alpha, alpha); value != nil {
+			opacity = float64(clampColor(*value)) / 255
+		}
+		gradient.colors[i] = MeshVertex{Space: kind, Values: values, Alpha: opacity, profile: profile}
+	}
+	return gradient.At, nil
+}
+
+// At 在相同源空间内插值，不同空间先转换为sRGB，保留重复位置的右侧色标
+// 入参: t 单位区间位置
+// 返回: color.RGBA 预乘采样颜色
+func (g *profileGradient) At(t float64) color.RGBA {
+	if len(g.colors) == 0 || math.IsNaN(t) {
+		return color.RGBA{}
+	}
+	first := g.colors[0]
+	if t < g.positions[0] {
+		r, green, b := first.rgb(first.Values)
+		return profileColor([3]float64{r, green, b}, first.Alpha)
+	}
+	for i := 1; i < len(g.colors); i++ {
+		if t < g.positions[i] {
+			before, after := g.colors[i-1], g.colors[i]
+			x := (t - g.positions[i-1]) / (g.positions[i] - g.positions[i-1])
+			if before.sameSpace(after) {
+				var values [4]float64
+				for j := range values {
+					values[j] = before.Values[j]*(1-x) + after.Values[j]*x
+				}
+				r, green, b := before.rgb(values)
+				return profileColor([3]float64{r, green, b}, before.Alpha*(1-x)+after.Alpha*x)
+			}
+			r0, g0, b0 := before.rgb(before.Values)
+			r1, g1, b1 := after.rgb(after.Values)
+			return color.RGBA{meshByte(r0*before.Alpha*(1-x) + r1*after.Alpha*x), meshByte(g0*before.Alpha*(1-x) + g1*after.Alpha*x), meshByte(b0*before.Alpha*(1-x) + b1*after.Alpha*x), meshByte(before.Alpha*(1-x) + after.Alpha*x)}
+		}
+	}
+	last := g.colors[len(g.colors)-1]
+	r, green, b := last.rgb(last.Values)
+	return profileColor([3]float64{r, green, b}, last.Alpha)
+}