91 lines
3.1 KiB
Python
91 lines
3.1 KiB
Python
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"""Row-based layout for the continuous reader view — the TUI's terminal-grid
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analogue of the browser's pixel-based getBoundingClientRect() geometry (see
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blocks.py's module docstring for why blockIndex is exact but innerFraction is
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only an approximation here).
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Each block is wrapped independently at a known width, once, into a flat list
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of pre-rendered Strip objects (one per terminal row) that book_view.py's
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Line-API widget indexes directly in render_line() — this is what makes very
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large books (tens of thousands of blocks) open in seconds rather than
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minutes: Textual only ever renders the rows actually on screen, instead of
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laying out the whole book up front the way a single giant Static would.
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"""
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from __future__ import annotations
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from dataclasses import dataclass
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from rich.console import Console
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from rich.text import Text
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from textual.strip import Strip
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_SEPARATOR_ROWS = 1 # one blank row between blocks, matching the old "\n\n".join style
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@dataclass
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class BookLayout:
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starts: list[int] # row where block i begins
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heights: list[int] # rendered row count for block i
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row_strips: list[Strip] # one Strip per absolute row, len == total_rows
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total_rows: int
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width: int
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def build_layout(block_texts: list[str], width: int, console: Console) -> BookLayout:
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width = max(1, width)
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starts: list[int] = []
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heights: list[int] = []
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row_strips: list[Strip] = []
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blank = Strip.blank(width)
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row = 0
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for text in block_texts:
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starts.append(row)
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wrapped_lines = list(Text(text).wrap(console, width)) if text else []
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if not wrapped_lines:
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wrapped_lines = [Text("")]
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heights.append(len(wrapped_lines))
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for line in wrapped_lines:
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strip = Strip(line.render(console), None).adjust_cell_length(width)
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row_strips.append(strip)
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row_strips.append(blank)
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row += len(wrapped_lines) + _SEPARATOR_ROWS
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return BookLayout(starts=starts, heights=heights, row_strips=row_strips, total_rows=row, width=width)
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def get_position_anchor(layout: BookLayout, scroll_y: int) -> tuple[int, float]:
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"""Mirrors app.js's getPositionAnchor(): the last block whose top row is at
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or above scroll_y, or the first block if none has scrolled that far yet."""
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n = len(layout.heights)
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if n == 0:
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return 0, 0.0
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best_index = 0
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found = False
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for i in range(n):
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if layout.heights[i] < 1:
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continue
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if layout.starts[i] > scroll_y:
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break
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best_index = i
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found = True
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if not found:
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best_index = next((i for i in range(n) if layout.heights[i] >= 1), 0)
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top = layout.starts[best_index]
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height = max(1, layout.heights[best_index])
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inner_fraction = max(0.0, min(1.0, (scroll_y - top) / height))
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return best_index, inner_fraction
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def scroll_y_for_anchor(layout: BookLayout, block_index: int, inner_fraction: float) -> int:
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"""Mirrors app.js's restoreFromAnchor()."""
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n = len(layout.heights)
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if n == 0:
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return 0
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idx = max(0, min(block_index, n - 1))
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top = layout.starts[idx]
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height = layout.heights[idx]
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return top + round(inner_fraction * height)
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