Why pack_product.py Renders Both a 1280x720 Cover and a 600x600 Thumbnail

说明与用途

单张图片不够：方形裁剪会切掉副标题，使商品列表看起来不完整。pack_product.py 现在为每个产品生成两个图片：1280x720 封面和 600x600 缩略图。两者均为 JPEG，文件名分别为 <slug>-cover.jpg 和 <slug>-thumb.jpg。一次读取源文件，两次写入磁盘。先合成方形图像，使裁剪决策只做出一次。

问题

A single-image render produces a cover that gets cropped by square containers, cutting off the subtitle and making the listing look unfinished next to competitors.

结果

Two images per product: 1280x720 cover keeps title readable with subtitle visible, 600x600 thumbnail drops subtitle to avoid four-pixel noise when cropped by square containers. Same folder feeds Adobe 5-column, Vecteezy 4-column, or Dreamstime 15-column CSVs without manual renaming.

工作流

• Read source art once.
• Resize to 600x600 with center cover crop, draw title, save thumbnail as <slug>-thumb.jpg.
• Build 1280x720 canvas in background color, paste composed square region at natural size, draw title and subtitle at wide-layout positions, save cover as <slug>-cover.jpg.
• Run gc.collect() after each product.
• Peak memory checked via resource.getrusage(RUSAGE_SELF).ru_maxrss.

证据

First pack I shipped was a zip and a 1280x720 cover. Clean render, centered title, subtitle underneath. Storefront grid showed it as a square. The crop took the middle of the frame and cut the subtitle off at both edges.

If I render one image and let the platform crop it, I lose control of where the crop lands. Text near the edge is the first thing to go.

The square one drops the subtitle entirely, because a subtitle at 600x600 is four pixels tall and reads as noise.

Source read is one, disk writes are two.

I used to render a preview at the largest size I could, then downscale. That was wasted work. A preview is for eyeballing placement, and 60 dpi is enough for that.

39 finished products, 856 MB of output, and a stack of orphan cover files I could not match to anything. If the zip does not exist, the cover does not get made.

The cover step is the last thing that runs. Metadata first, because a wrong CSV header gets a batch rejected immediately and wasted renders do not help.