完善生图5.0的功能

lib/client/seedream-markup.ts

@@ -0,0 +1,56 @@
+import { materialContentUrl } from "@/lib/client/asset-urls";
+import type { PromptMaterial } from "@/lib/prompt/assembler";
+import type { SeedreamAnnotation } from "@/lib/seedream/creation";
+
+const markerColor = "#2563eb";
+
+export async function createSeedreamMarkedFile(
+  source: PromptMaterial,
+  annotations: SeedreamAnnotation[],
+  imageIndex: number
+) {
+  const strokes = annotations.filter((annotation) => annotation.kind === "stroke" && annotation.points && annotation.points.length > 1);
+  if (!strokes.length) return null;
+
+  const response = await fetch(materialContentUrl(source), { credentials: "same-origin" });
+  if (!response.ok) throw new Error(`读取图${imageIndex}失败，无法合成蓝色标记`);
+  const bitmap = await createImageBitmap(await response.blob());
+  try {
+    const canvas = document.createElement("canvas");
+    canvas.width = bitmap.width;
+    canvas.height = bitmap.height;
+    const context = canvas.getContext("2d");
+    if (!context) throw new Error("当前浏览器无法创建标记画布");
+    context.drawImage(bitmap, 0, 0);
+    context.strokeStyle = markerColor;
+    context.fillStyle = markerColor;
+    context.lineCap = "round";
+    context.lineJoin = "round";
+    context.lineWidth = Math.max(5, Math.round(Math.min(bitmap.width, bitmap.height) * 0.012));
+
+    for (const stroke of strokes) {
+      const points = stroke.points || [];
+      if (!points.length) continue;
+      context.beginPath();
+      context.moveTo(points[0].x / 1000 * bitmap.width, points[0].y / 1000 * bitmap.height);
+      for (const point of points.slice(1)) {
+        context.lineTo(point.x / 1000 * bitmap.width, point.y / 1000 * bitmap.height);
+      }
+      context.stroke();
+    }
+
+    const blob = await canvasBlob(canvas, "image/png");
+    return new File([blob], `seedream-marked-image-${imageIndex}.png`, { type: "image/png" });
+  } finally {
+    bitmap.close();
+  }
+}
+
+function canvasBlob(canvas: HTMLCanvasElement, type: string) {
+  return new Promise<Blob>((resolve, reject) => {
+    canvas.toBlob((blob) => {
+      if (blob) resolve(blob);
+      else reject(new Error("生成标记图片失败"));
+    }, type);
+  });
+}