缩放PDF内容以适应打印
我需要打印文件，但发现内容周围的空白区域通常太大，浪费纸张并使文本显得比应有的小。这个脚本通过检测内容区域并将其放大以填充页面，同时保留较小的边距，从而自动缩放PDF内容以更好地适应页面。
import subprocess
import sys
import os
from PIL import Image
from pdf2image import convert_from_path
MARGIN_PERCENT = 0.005
DPI = 72
def convert_pixels_to_points(pixels, dpi):
"""将像素转换为点。"""
return pixels * 72 / dpi
def get_image_dimensions(image):
"""获取图像的像素和点尺寸。"""
width, height = image.size
dpi = image.info.get('dpi', (DPI, DPI))
width_points = convert_pixels_to_points(width, dpi[0])
height_points = convert_pixels_to_points(height, dpi[1])
return width, height, width_points, height_points, dpi
def analyze_whitespace(image, width, height):
"""分析空白区域以找到内容边界框。"""
left_margin_px = width
right_margin_px = 0
top_margin_px = height
bottom_margin_px = 0
found_content = False
for x in range(width):
for y in range(height):
pixel = image.getpixel((x, y))
if isinstance(pixel, tuple):
if any(c < 250 for c in pixel):
if not found_content:
left_margin_px = x
top_margin_px = y
found_content = True
right_margin_px = max(right_margin_px, x)
bottom_margin_px = max(bottom_margin_px, y)
elif pixel < 250:
if not found_content:
left_margin_px = x
top_margin_px = y
found_content = True
right_margin_px = max(right_margin_px, x)
bottom_margin_px = max(bottom_margin_px, y)
if not found_content:
return None, None, None, None
right_margin_px = width - right_margin_px
bottom_margin_px = height - bottom_margin_px
return left_margin_px, right_margin_px, top_margin_px, bottom_margin_px
def calculate_scale_factor(input_pdf):
"""
检测PDF第一页的尺寸，分析空白区域，
并根据PDF内容和目标A4尺寸（带边距）计算缩放因子。
返回缩放因子，如果发生错误则返回None。
"""
print(f"计算缩放因子：{input_pdf}")
try:
images = convert_from_path(input_pdf, first_page=1, last_page=1)
if not images:
print(" 无法将PDF转换为图像。")
return None
image = images[0]
width, height, width_points, height_points, dpi = get_image_dimensions(image)
margins = analyze_whitespace(image, width, height)
if margins[0] is None:
print(" 无法确定内容边界框。")
left_margin_points = 0
right_margin_points = 0
top_margin_points = 0
bottom_margin_points = 0
else:
left_margin_px, right_margin_px, top_margin_px, bottom_margin_px = margins
content_width_px = right_margin_px - left_margin_px
content_height_px = bottom_margin_px - top_margin_px
left_margin_points = convert_pixels_to_points(left_margin_px, dpi[0])
right_margin_points = convert_pixels_to_points(right_margin_px, dpi[0])
top_margin_points = convert_pixels_to_points(top_margin_px, dpi[1])
bottom_margin_points = convert_pixels_to_points(bottom_margin_px, dpi[1])
print(f" 内容框：左={left_margin_px}, 上={top_margin_px}, 右={right_margin_px}, 下={bottom_margin_px}")
print(f" 内容尺寸（像素）：宽度={content_width_px}, 高度={content_height_px}")
print(f" 边距（点）：左={left_margin_points}, 右={right_margin_points}, 上={top_margin_points}, 下={bottom_margin_points}")
print(f" 检测到的尺寸：宽度={width_points}, 高度={height_points}")
width_margin_points = min(left_margin_points, right_margin_points)
height_margin_points = min(top_margin_points, bottom_margin_points)
content_width = width_points - width_margin_points * 2
content_height = height_points - height_margin_points * 2
target_width = width_points * (1 - 2 * MARGIN_PERCENT)
target_height = height_points * (1- 2 * MARGIN_PERCENT)
width_scale = target_width / content_width
height_scale = target_height / content_height
print(f" 内容尺寸（点）：宽度={content_width}, 高度={content_height}")
if content_width <= 0 or content_height <= 0:
print("错误：无法确定内容尺寸。")
return None
print(f" 目标尺寸：宽度={target_width}, 高度={target_height}")
print(f" 计算出的宽度缩放：{width_scale}, 高度缩放：{height_scale}")
scale_factor = min(width_scale, height_scale)
print(f" 最终缩放因子：{scale_factor}")
return scale_factor
except Exception as e:
print(f"获取PDF尺寸或计算缩放因子时出错：{e}")
return None
def scale_pdf(input_pdf, output_pdf, scale_factor):
"""使用pdfjam缩放PDF。"""
print(f"将 {input_pdf} 缩放至 {output_pdf}，缩放因子：{scale_factor}")
try:
subprocess.run(
[
"pdfjam",
"--scale",
str(scale_factor),
input_pdf,
"--outfile",
output_pdf,
],
check=True,
)
print(f"成功将 {input_pdf} 缩放至 {output_pdf}")
except subprocess.CalledProcessError as e:
print(f"缩放PDF时出错：{e}")
except FileNotFoundError:
print("错误：未找到pdfjam命令。请确保已安装并将其添加到系统的PATH中。")
if __name__ == "__main__":
if len(sys.argv) != 3:
print("用法：python scale-pdf.py <input_pdf> <output_pdf>")
sys.exit(1)
input_pdf = sys.argv[1]
output_pdf = sys.argv[2]
print(f"输入PDF：{input_pdf}, 输出PDF：{output_pdf}")
if not os.path.exists(input_pdf):
print(f"错误：未找到输入PDF文件：{input_pdf}")
sys.exit(1)
scale_factor = calculate_scale_factor(input_pdf)
if scale_factor is None:
sys.exit(1)
scale_pdf(input_pdf, output_pdf, scale_factor)