feat(归并文件): 归并根包文件

ofdgo_raster.go

@@ -16,12 +16,16 @@ package ofdgo
 
 import (
 	"context"
+	"crypto/sha256"
+	"encoding/binary"
 	"fmt"
 	"image"
 	"image/color"
 	"math"
 
 	basegeom "github.com/xiaoqidun/ofdgo/internal/base/geom"
+	baseimage "github.com/xiaoqidun/ofdgo/internal/base/image"
+	"golang.org/x/image/draw"
 )
 
 // 光栅后端接收的路径指令
@@ -382,3 +386,131 @@ func rasterCommandGeometry(geometry GeometryBackend, command RasterCommand) (Geo
 	}
 	return path, nil
 }
+
+// rasterClipKey 区分页面尺寸、分辨率和裁剪路径
+// 入参: page 页面, path 页面坐标路径
+// 返回: [32]byte 缓存键
+func rasterClipKey(page *RasterPage, path []RasterSegment) [32]byte {
+	hash := sha256.New()
+	var data [8]byte
+	number := func(v float64) {
+		binary.LittleEndian.PutUint64(data[:], math.Float64bits(v))
+		hash.Write(data[:])
+	}
+	number(page.Width)
+	number(page.Height)
+	number(page.DPI)
+	for _, s := range path {
+		hash.Write([]byte{byte(s.Verb)})
+		for _, p := range []RasterPoint{s.End, s.Control1, s.Control2} {
+			number(p.X)
+			number(p.Y)
+		}
+	}
+	var key [32]byte
+	copy(key[:], hash.Sum(nil))
+	return key
+}
+
+// rasterClipMask 使用所选后端生成区域化透明度蒙版，同页相同裁剪可复用
+// 入参: backend 光栅后端, page 页面, path 页面坐标裁剪, cache 蒙版缓存
+// 返回: *image.Alpha 页面像素坐标蒙版, error 绘制错误
+func rasterClipMask(backend RasterBackend, page *RasterPage, path []RasterSegment, cache *renderCache[[32]byte, *image.Alpha]) (*image.Alpha, error) {
+	key := rasterClipKey(page, path)
+	if mask, ok := cache.get(key); ok {
+		return mask, nil
+	}
+	w, h, err := page.PixelSize()
+	if err != nil {
+		return nil, err
+	}
+	matrix := page.PixelTransform(RasterMatrix{1, 0, 0, 1, 0, 0}, h)
+	minX, minY, maxX, maxY := math.Inf(1), math.Inf(1), math.Inf(-1), math.Inf(-1)
+	include := func(p RasterPoint) {
+		p = matrix.Apply(p)
+		minX = math.Min(minX, p.X)
+		minY = math.Min(minY, p.Y)
+		maxX = math.Max(maxX, p.X)
+		maxY = math.Max(maxY, p.Y)
+	}
+	for _, s := range path {
+		switch s.Verb {
+		case RasterMove, RasterLine:
+			include(s.End)
+		case RasterQuad:
+			include(s.End)
+			include(s.Control1)
+		case RasterCubic:
+			include(s.End)
+			include(s.Control1)
+			include(s.Control2)
+		case RasterClose:
+		default:
+			return nil, fmt.Errorf("invalid clip path command %d", s.Verb)
+		}
+	}
+	if len(path) == 0 || minX > maxX || minY > maxY {
+		return image.NewAlpha(image.Rectangle{}), nil
+	}
+	if !finite(minX) || !finite(minY) || !finite(maxX) || !finite(maxY) {
+		return nil, fmt.Errorf("invalid clip coordinates")
+	}
+	bounds := image.Rect(int(math.Max(0, math.Min(float64(w), math.Floor(minX)-1))), int(math.Max(0, math.Min(float64(h), math.Floor(minY)-1))), int(math.Max(0, math.Min(float64(w), math.Ceil(maxX)+1))), int(math.Max(0, math.Min(float64(h), math.Ceil(maxY)+1))))
+	mask := image.NewAlpha(bounds)
+	if !bounds.Empty() {
+		scale := page.DPI / 25.4
+		local := &RasterPage{Width: float64(bounds.Dx()) / scale, Height: float64(bounds.Dy()) / scale, DPI: page.DPI}
+		local.Commands = []RasterCommand{{Path: path, Paint: RasterPaint{Color: color.RGBA{255, 255, 255, 255}}, Transform: RasterMatrix{1, 0, 0, 1, -float64(bounds.Min.X) / scale, (matrix[5] - float64(bounds.Min.Y)) / scale}}}
+		pixels, err := backend.Render(local)
+		if err != nil {
+			return nil, err
+		}
+		for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
+			start := mask.PixOffset(bounds.Min.X, y)
+			row := mask.Pix[start : start+bounds.Dx()]
+			for x := range row {
+				row[x] = uint8(baseimage.AlphaAt(pixels, x, y-bounds.Min.Y) >> 8)
+			}
+		}
+	}
+	cache.put(key, mask, len(mask.Pix)+256)
+	return mask, nil
+}
+
+// PixelTransform 将页面毫米变换转换为像素变换，保留尺寸取整后的原点位置
+// 入参: m 局部到页面变换, height 目标像素高度
+// 返回: RasterMatrix 局部到像素变换
+func (p *RasterPage) PixelTransform(m RasterMatrix, height int) RasterMatrix {
+	scale := p.DPI / 25.4
+	for i := range m {
+		m[i] *= scale
+	}
+	m[5] += float64(height) - p.Height*scale
+	return m
+}
+
+// drawRasterImageCommand 使用当前后端生成裁剪蒙版，共用高质量图像采样
+// 入参: backend 当前后端, page 页面, dst 目标图像, src 原始图像, command 图像指令, cache 蒙版缓存
+// 返回: error 裁剪绘制错误
+func drawRasterImageCommand(backend RasterBackend, page *RasterPage, dst draw.Image, src image.Image, command RasterCommand, cache *renderCache[[32]byte, *image.Alpha]) error {
+	m := page.PixelTransform(command.Transform, dst.Bounds().Dy())
+	if command.Clip == nil {
+		baseimage.DrawPixels(dst, src, m, draw.Over)
+		return nil
+	}
+	mask, err := rasterClipMask(backend, page, command.Clip, cache)
+	if err != nil {
+		return err
+	}
+	if mask.Rect.Empty() {
+		return nil
+	}
+	bounds := mask.Rect.Intersect(dst.Bounds()).Intersect(baseimage.TransformBounds(src.Bounds(), m, dst.Bounds()))
+	if bounds.Empty() {
+		return nil
+	}
+	layer := image.NewRGBA64(bounds)
+	baseimage.DrawPixels(layer, baseimage.PixelSource(src), m, draw.Src)
+	draw.DrawMask(dst, bounds, layer, bounds.Min, mask, bounds.Min, draw.Over)
+	return nil
+}