PDF to JPG and Images to PDF now show a paged canvas preview of the conversion result before download.

Date: 2026-09-06 16:03 Summary: PDF to JPG and Images to PDF now show a paged canvas preview of the conversion result before download. Visibility: people

[question] http://127.0.0.1:8788/zh/tools/pdf-to-jpg http://127.0.0.1:8788/zh/tools/images-to-pdf 增加预览

Tool links (English)

[try to solve]

Context

Both tools already converted in the browser and enabled Download after the auto sample, but the interactive area only showed a status line. Users could not check page order or JPEG quality without downloading. Sibling PDF tools (combine / merge style) already use the shared OftPdfWork canvas with Previous / Next.

Process

Compared pdfToJpgPage.ts and imagesToPdfPage.ts with combineFilesIntoOnePdfPage.ts, which injects pdfWorkUiBlockHtml + pdfWorkUiClientScript and calls work.showPreview(bytes) after the result exists.
Images to PDF already kept resultBytes as a PDF. Wired the same progress + canvas block (idPrefix: imgPdf) and show the generated PDF after convert. Clear / reorder / orientation / fit still drop the result and hide the preview.
PDF to JPG outputs JPEG blobs (or a ZIP), not a PDF, so OftPdfWork.showPreview cannot render the deliverable. Reused the shared preview markup (idPrefix: pdfToJpgJpg) and painted the same JPEG blobs onto the canvas with Previous / Next. Progress still uses OftPdfWork.bind('pdfToJpg') during rasterize.
Preview labels come from core pdf_work_* keys (already localized in all ten languages). No new tool i18n keys.
Prerendered both slugs, gzipped, seeded the local R2 bucket, and cleared .wrangler/state/v3/cache so port 8788 served the new HTML. Playwright on the Chinese pages: sample preview visible, canvas non-zero, page text 第 1 / 2 页 (JPG) and 第 1 / 3 页 (images PDF), Next advances, Clear hides the wrap and disables Download. No pageerror.

Root cause / analysis

The conversion pipelines already produced the bytes/blobs users need to inspect. The gap was UI: status text is not a substitute for seeing pages. PDF output can share OftPdfWork; JPEG output needs a small gallery on the same chrome so users see the actual JPG, not a second pdf.js render of the source file.

Solution

After convert (including the auto sample), both pages show a paged preview. Images to PDF previews the result PDF. PDF to JPG previews each exported JPEG. Download stays the same. Clear / new files hide the preview until the next successful convert.

Notes / boundaries

Shared preview copy is pdf_work_preview / pdf_work_prev / pdf_work_next / pdf_work_page, not per-tool strings.
Did not bump PAGES_CACHE_VERSION; local Cache API was cleared by deleting .wrangler/state/v3/cache. Production still needs the usual R2 upload plus Worker version bump on deploy.
How-step (how_item_*) gaps noted in the 2026-09-06 QA report were out of scope.

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