Add Generate Sample PDFs With ReportLab as a Python TIL

python/generate-sample-pdfs-with-reportlab.md

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+# Generate Sample PDFs With ReportLab
+
+The `reportlab` package has a `pdfgen` module that provides a `Canvas` API for
+programmatically constructing a PDF.
+
+I recently needed the most basic use of this to quickly construct a sample PDF
+that I could use as I experimented with [different `qpdf`
+commands](/workflow/remove-pages-from-a-pdf.md). I wanted to generate a 10-page
+PDF where each page included a large font number in the center. This way I could
+clearly see what was the first, second, third, and so on pages. Then I could
+quickly verify that the `qpdf` manipulations I was doing were working as
+expected.
+
+I was able to do this without any setup or install. Using a `uv` one-liner (does
+a 10-line heredoc count as a one-liner?), I generated a PDF with some basic
+canvas rendering on each page.
+
+```python
+❯ uv run --with reportlab python - <<'EOF'
+from reportlab.pdfgen import canvas
+N, W, H = 10, 612, 792
+c = canvas.Canvas("test.pdf", pagesize=(W, H))
+for i in range(1, N + 1):
+    c.setFont("Helvetica-Bold", 220)
+    c.drawCentredString(W / 2, H / 2 - 80, str(i))
+    c.setFont("Helvetica", 28)
+    c.drawCentredString(W / 2, 100, f"page {i} of {N}")
+    c.showPage()
+c.save()
+EOF
+```
+
+The `--with` makes the `reportlab` package available to the command being run.
+The command being run is `python` which evaluates that block of heredoc text.
+
+Within the heredoc, I import `canvas` from the `reportlab` package that has been
+made available. I then create an in-memory PDF of a standard size. Then for-loop
+10 times to build each page of the PDF with a big number in the middle and a
+smaller `page x of N` lower down on the page. Finally, I save the PDF which
+writes it to the directory I executed this whole command from.
+
+I had Claude help with the `canvas` API, however there are some decent
+[`reportlab.pdfgen` docs
+here](https://docs.reportlab.com/reportlab/userguide/ch2_graphics/).