From ab602b301469f693ba153a01dd5b0973fd7acfd2 Mon Sep 17 00:00:00 2001
From: Justin Miller <16829344+jmilljr24@users.noreply.github.com>
Date: Sat, 21 Mar 2026 13:00:31 -0400
Subject: [PATCH 1/2] use mupdf first for previews

---
 Dockerfile                                       | 1 +
 config/initializers/active_storage_previewers.rb | 5 +++++
 2 files changed, 6 insertions(+)
 create mode 100644 config/initializers/active_storage_previewers.rb

diff --git a/Dockerfile b/Dockerfile
index f11923f7a..83471eb62 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -81,6 +81,7 @@ FROM base AS server
 RUN apt-get update -qq && apt-get install --no-install-recommends -y \
   libvips \
   poppler-utils \
+  mupdf-tools \
   tzdata \
   libxml2 \
   libxslt1.1 \
diff --git a/config/initializers/active_storage_previewers.rb b/config/initializers/active_storage_previewers.rb
new file mode 100644
index 000000000..e3cb92ecf
--- /dev/null
+++ b/config/initializers/active_storage_previewers.rb
@@ -0,0 +1,5 @@
+Rails.application.config.active_storage.previewers = [
+  ActiveStorage::Previewer::MuPDFPreviewer,    # move MuPDF to first for high-quality PDFs
+  ActiveStorage::Previewer::PopplerPDFPreviewer,
+  ActiveStorage::Previewer::VideoPreviewer
+]

From 30f53211fa46fe67cdb2be9bd03a6ae5437e3cd1 Mon Sep 17 00:00:00 2001
From: Justin Miller <16829344+jmilljr24@users.noreply.github.com>
Date: Mon, 23 Mar 2026 09:52:53 -0400
Subject: [PATCH 2/2] use 300 dpi

---
 Dockerfile                                    |  1 -
 .../high_res_poppler_pdf_previewer.rb         | 38 +++++++++++++++++++
 .../initializers/active_storage_previewers.rb |  8 ++--
 3 files changed, 41 insertions(+), 6 deletions(-)
 create mode 100644 app/previewers/high_res_poppler_pdf_previewer.rb

diff --git a/Dockerfile b/Dockerfile
index 83471eb62..f11923f7a 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -81,7 +81,6 @@ FROM base AS server
 RUN apt-get update -qq && apt-get install --no-install-recommends -y \
   libvips \
   poppler-utils \
-  mupdf-tools \
   tzdata \
   libxml2 \
   libxslt1.1 \
diff --git a/app/previewers/high_res_poppler_pdf_previewer.rb b/app/previewers/high_res_poppler_pdf_previewer.rb
new file mode 100644
index 000000000..3880130bd
--- /dev/null
+++ b/app/previewers/high_res_poppler_pdf_previewer.rb
@@ -0,0 +1,38 @@
+class HighResPopplerPdfPreviewer < ActiveStorage::Previewer
+  class << self
+    def accept?(blob)
+      blob.content_type == "application/pdf" && pdftoppm_exists?
+    end
+
+    def pdftoppm_path
+      ActiveStorage.paths[:pdftoppm] || "pdftoppm"
+    end
+
+    def pdftoppm_exists?
+      return @pdftoppm_exists if defined?(@pdftoppm_exists)
+
+      @pdftoppm_exists = system(pdftoppm_path, "-v", out: File::NULL, err: File::NULL)
+    end
+  end
+
+  def preview(**options)
+    download_blob_to_tempfile do |input|
+      draw_first_page_from input do |output|
+        yield io: output, filename: "#{blob.filename.base}.png", content_type: "image/png", **options
+      end
+    end
+  end
+
+  private
+
+  def draw_first_page_from(file, &block)
+    # High-DPI Poppler rendering
+    draw self.class.pdftoppm_path,
+         "-singlefile",
+         "-cropbox",
+         "-r", "300",
+         "-png",
+         file.path,
+         &block
+  end
+end
diff --git a/config/initializers/active_storage_previewers.rb b/config/initializers/active_storage_previewers.rb
index e3cb92ecf..8e6068335 100644
--- a/config/initializers/active_storage_previewers.rb
+++ b/config/initializers/active_storage_previewers.rb
@@ -1,5 +1,3 @@
-Rails.application.config.active_storage.previewers = [
-  ActiveStorage::Previewer::MuPDFPreviewer,    # move MuPDF to first for high-quality PDFs
-  ActiveStorage::Previewer::PopplerPDFPreviewer,
-  ActiveStorage::Previewer::VideoPreviewer
-]
+Rails.application.config.after_initialize do
+  Rails.application.config.active_storage.previewers.unshift HighResPopplerPdfPreviewer
+end