feat: Add placeholder cover generator for books without covers
Generate styled placeholder covers (title, author, book icon) when a book has no embedded cover image, instead of showing a blank rectangle. - Add PlaceholderCoverGenerator lib with 1-bit BMP rendering, scaled fonts, word-wrap, and a book icon bitmap - Integrate as fallback in Epub/Xtc/Txt reader activities and SleepActivity after format-specific cover generation fails - Add fallback in HomeActivity::loadRecentCovers() so the home screen also shows placeholder thumbnails when cache is cleared - Add Txt::getThumbBmpPath() for TXT thumbnail support - Add helper scripts for icon and layout preview generation Co-authored-by: Cursor <cursoragent@cursor.com>
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cottongin
179
scripts/preview_placeholder_cover.py
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179
scripts/preview_placeholder_cover.py
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#!/usr/bin/env python3
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"""Generate a preview of the placeholder cover layout at full cover size (480x800).
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This mirrors the C++ PlaceholderCoverGenerator layout logic for visual verification.
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"""
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from PIL import Image, ImageDraw, ImageFont
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import sys
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import os
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# Reuse the book icon generator
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sys.path.insert(0, os.path.dirname(__file__))
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from generate_book_icon import generate_book_icon
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def create_preview(width=480, height=800, title="The Great Gatsby", author="F. Scott Fitzgerald"):
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img = Image.new("1", (width, height), 1) # White
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draw = ImageDraw.Draw(img)
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# Proportional layout constants
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edge_padding = max(3, width // 48) # ~10px at 480w
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border_width = max(2, width // 96) # ~5px at 480w
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inner_padding = max(4, width // 32) # ~15px at 480w
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title_scale = 2 if height >= 600 else 1
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author_scale = 2 if height >= 600 else 1 # Author also larger on full covers
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icon_scale = 2 if height >= 600 else (1 if height >= 350 else 0)
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# Draw border inset from edge
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bx = edge_padding
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by = edge_padding
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bw = width - 2 * edge_padding
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bh = height - 2 * edge_padding
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for i in range(border_width):
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draw.rectangle([bx + i, by + i, bx + bw - 1 - i, by + bh - 1 - i], outline=0)
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# Content area
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content_x = edge_padding + border_width + inner_padding
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content_y = edge_padding + border_width + inner_padding
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content_w = width - 2 * content_x
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content_h = height - 2 * content_y
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# Zones
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title_zone_h = content_h * 2 // 3
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author_zone_h = content_h - title_zone_h
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author_zone_y = content_y + title_zone_h
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# Separator
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sep_w = content_w // 3
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sep_x = content_x + (content_w - sep_w) // 2
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draw.line([sep_x, author_zone_y, sep_x + sep_w, author_zone_y], fill=0)
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# Use a basic font for the preview (won't match exact Ubuntu metrics, but shows layout)
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try:
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title_font = ImageFont.truetype("/System/Library/Fonts/Helvetica.ttc", 12 * title_scale)
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author_font = ImageFont.truetype("/System/Library/Fonts/Helvetica.ttc", 10 * author_scale)
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except (OSError, IOError):
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title_font = ImageFont.load_default()
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author_font = ImageFont.load_default()
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# Icon dimensions (needed for title text wrapping)
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icon_w_px = 48 * icon_scale if icon_scale > 0 else 0
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icon_h_px = 48 * icon_scale if icon_scale > 0 else 0
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icon_gap = max(8, width // 40) if icon_scale > 0 else 0
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title_text_w = content_w - icon_w_px - icon_gap # Title wraps in narrower area beside icon
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# Wrap title (within the narrower area to the right of the icon)
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title_lines = []
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words = title.split()
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current_line = ""
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for word in words:
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test = f"{current_line} {word}".strip()
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bbox = draw.textbbox((0, 0), test, font=title_font)
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if bbox[2] - bbox[0] <= title_text_w:
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current_line = test
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else:
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if current_line:
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title_lines.append(current_line)
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current_line = word
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if current_line:
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title_lines.append(current_line)
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title_lines = title_lines[:5]
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# Line spacing: 75% of advanceY (tighter so 2-3 lines fit within icon height)
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title_line_h = 29 * title_scale * 3 // 4 # Based on C++ ubuntu_12_bold advanceY
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# Measure actual single-line height from the PIL font for accurate centering
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sample_bbox = draw.textbbox((0, 0), "Ag", font=title_font) # Tall + descender chars
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single_line_visual_h = sample_bbox[3] - sample_bbox[1]
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# Visual height: line spacing between lines + actual height of last line's glyphs
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num_title_lines = len(title_lines)
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title_visual_h = (num_title_lines - 1) * title_line_h + single_line_visual_h if num_title_lines > 0 else 0
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title_block_h = max(icon_h_px, title_visual_h)
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title_start_y = content_y + (title_zone_h - title_block_h) // 2
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if title_start_y < content_y:
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title_start_y = content_y
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# If title fits within icon height, center it vertically against the icon.
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# Otherwise top-align so extra lines overflow below.
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icon_y = title_start_y
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if icon_h_px > 0 and title_visual_h <= icon_h_px:
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title_text_y = title_start_y + (icon_h_px - title_visual_h) // 2
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else:
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title_text_y = title_start_y
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# Horizontal centering: measure widest title line, center icon+gap+text block
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max_title_line_w = 0
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for line in title_lines:
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bbox = draw.textbbox((0, 0), line, font=title_font)
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w = bbox[2] - bbox[0]
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if w > max_title_line_w:
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max_title_line_w = w
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title_block_w = icon_w_px + icon_gap + max_title_line_w
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title_block_x = content_x + (content_w - title_block_w) // 2
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# Draw icon
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if icon_scale > 0:
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icon_img = generate_book_icon(48)
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scaled_icon = icon_img.resize((icon_w_px, icon_h_px), Image.NEAREST)
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for iy in range(scaled_icon.height):
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for ix in range(scaled_icon.width):
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if not scaled_icon.getpixel((ix, iy)):
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img.putpixel((title_block_x + ix, icon_y + iy), 0)
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# Draw title (to the right of the icon)
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title_text_x = title_block_x + icon_w_px + icon_gap
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current_y = title_text_y
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for line in title_lines:
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draw.text((title_text_x, current_y), line, fill=0, font=title_font)
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current_y += title_line_h
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# Wrap author
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author_lines = []
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words = author.split()
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current_line = ""
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for word in words:
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test = f"{current_line} {word}".strip()
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bbox = draw.textbbox((0, 0), test, font=author_font)
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if bbox[2] - bbox[0] <= content_w:
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current_line = test
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else:
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if current_line:
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author_lines.append(current_line)
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current_line = word
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if current_line:
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author_lines.append(current_line)
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author_lines = author_lines[:3]
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# Draw author centered in bottom 1/3
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author_line_h = 24 * author_scale # Ubuntu 10 regular advanceY ~24
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author_block_h = len(author_lines) * author_line_h
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author_start_y = author_zone_y + (author_zone_h - author_block_h) // 2
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for line in author_lines:
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bbox = draw.textbbox((0, 0), line, font=author_font)
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line_w = bbox[2] - bbox[0]
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line_x = content_x + (content_w - line_w) // 2
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draw.text((line_x, author_start_y), line, fill=0, font=author_font)
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author_start_y += author_line_h
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return img
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if __name__ == "__main__":
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# Full cover
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img = create_preview(480, 800, "A Really Long Book Title That Should Wrap", "Jane Doe")
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img.save("mod/preview_cover_480x800.png")
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print("Saved mod/preview_cover_480x800.png", file=sys.stderr)
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# Medium thumbnail
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img2 = create_preview(240, 400, "A Really Long Book Title That Should Wrap", "Jane Doe")
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img2.save("mod/preview_thumb_240x400.png")
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print("Saved mod/preview_thumb_240x400.png", file=sys.stderr)
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# Small thumbnail
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img3 = create_preview(136, 226, "A Really Long Book Title", "Jane Doe")
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img3.save("mod/preview_thumb_136x226.png")
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print("Saved mod/preview_thumb_136x226.png", file=sys.stderr)
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