feat(后端架构): 优化多后端渲染，修复描边与字形校验

ofdgo_raster_image.go

@@ -16,7 +16,6 @@ package ofdgo
 
 import (
 	"image"
-	"image/color"
 
 	"golang.org/x/image/draw"
 	"golang.org/x/image/math/f64"
@@ -29,18 +28,21 @@ func drawRasterImage(dst draw.Image, src image.Image, m RasterMatrix) {
 }
 
 // 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
+// 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) error {
+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 {
 		drawRasterImage(dst, src, m)
 		return nil
 	}
-	mask, err := backend.Render(&RasterPage{Width: page.Width, Height: page.Height, DPI: page.DPI, Commands: []RasterCommand{{Path: command.Clip, Paint: RasterPaint{Color: color.RGBA{255, 255, 255, 255}}, Transform: RasterMatrix{1, 0, 0, 1, 0, 0}}}})
+	mask, err := rasterClipMask(backend, page, command.Clip, cache)
 	if err != nil {
 		return err
 	}
+	if mask.Rect.Empty() {
+		return nil
+	}
 	draw.CatmullRom.Transform(dst, f64.Aff3{m[0], m[2], m[4], m[1], m[3], m[5]}, imagePixelSource(src), src.Bounds(), draw.Over, &draw.Options{DstMask: mask})
 	return nil
 }