miscs (Interro02) : horizontal cutting resolution

copienator/pdf_cut.py

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+"""Split a PDF along its cumulative visible page height, in reading order."""
+
+import math
+from pathlib import Path
+
+import pymupdf
+
+from copienator.commands.splitting_int import _prepare_split_pages
+
+# Percentages emitted by the GUI have six decimal places. Recover exact page
+# boundaries despite rounding, without turning nearby in-page cuts into breaks.
+BOUNDARY_TOLERANCE_PERCENT = 0.000001
+
+
+def cut_position(heights: list[float], percent: float) -> tuple[int, float]:
+    """Return (page index, offset); offset zero denotes an exact page break."""
+    if not heights or any(height <= 0 for height in heights):
+        raise ValueError("Le PDF doit contenir des pages non vides.")
+    if not math.isfinite(percent) or not 0 < percent < 100:
+        raise ValueError("Le pourcentage de coupe doit être strictement entre 0 et 100.")
+    total = sum(heights)
+    position = total * percent / 100
+    start = 0.0
+    for index, height in enumerate(heights):
+        if index and abs(percent - start / total * 100) <= BOUNDARY_TOLERANCE_PERCENT:
+            return index, 0.0
+        end = start + height
+        if index + 1 < len(heights) and abs(percent - end / total * 100) <= BOUNDARY_TOLERANCE_PERCENT:
+            return index + 1, 0.0
+        if position < end:
+            return index, position - start
+        start = end
+    raise ValueError("Coupe hors du document.")
+
+
+def split_pdf(source: Path, percent: float, first_path: Path, second_path: Path) -> None:
+    """Preserve whole pages; clip only the page actually crossed by the cut."""
+    with pymupdf.open(source) as document, pymupdf.open() as first, pymupdf.open() as second:
+        index, offset = cut_position([page.rect.height for page in document], percent)
+        if index:
+            first.insert_pdf(document, from_page=0, to_page=index - 1)
+        if offset == 0:
+            second.insert_pdf(document, from_page=index)
+        else:
+            with pymupdf.open() as page_document:
+                page_document.insert_pdf(document, from_page=index, to_page=index)
+                visible = _prepare_split_pages(page_document)[0]
+                for target, clip in (
+                    (first, pymupdf.Rect(visible.x0, visible.y0, visible.x1, visible.y0 + offset)),
+                    (second, pymupdf.Rect(visible.x0, visible.y0 + offset, visible.x1, visible.y1)),
+                ):
+                    page = target.new_page(width=clip.width, height=clip.height)
+                    page.show_pdf_page(page.rect, page_document, 0, clip=clip)
+            if index + 1 < len(document):
+                second.insert_pdf(document, from_page=index + 1)
+        first.save(first_path)
+        second.save(second_path)