建二維之構

以 SVG 之生、圖佈之算、影像之合、批處之流，程式化建二維之圖。涵向量圖之生、點陣圖之操、排印、圖表與信息圖之自動作。

用時

• 程式化生圖、流程、信息圖
• 建可重現之科學圖或刊圖
• 自動作徽、標、視資
• 合多影像或數據視
• 建標準庫無之自訂圖類
• 批生參變之圖
• 為網或印建 SVG 樣

入

法

一、設 Python 境

裝二維構所需諸庫：

# Core libraries
pip install svgwrite pillow cairosvg

# Optional: advanced features
pip install drawsvg reportlab pycairo

# For data-driven graphics
pip install matplotlib numpy pandas

得： 諸庫裝成 敗則： 察 Python 版（3.7+），用虛境避衝

二、建基本 SVG 圖

以 svgwrite 生 SVG：

import svgwrite
from svgwrite import cm, mm

def create_basic_svg(output_path):
    """Create a simple SVG graphic."""
    # Initialize drawing (use mm for precise dimensions)
    dwg = svgwrite.Drawing(output_path, size=('180mm', '120mm'), profile='full')

    # Add background rectangle
    dwg.add(dwg.rect(
        insert=(0, 0),
        size=('100%', '100%'),
        fill='white'
    ))

    # Add shapes
    dwg.add(dwg.circle(
        center=(90*mm, 60*mm),
        r=30*mm,
        fill='lightblue',
        stroke='navy',
        stroke_width=2
    ))

    dwg.add(dwg.rect(
        insert=(30*mm, 30*mm),
        size=(60*mm, 40*mm),
        fill='lightgreen',
        stroke='darkgreen',
        stroke_width=2,
        rx=5,  # Rounded corners
        ry=5
    ))

    # Add text
    dwg.add(dwg.text(
        'Example Graphic',
        insert=(90*mm, 20*mm),
        text_anchor='middle',
        font_size='18pt',
        font_family='Arial',
        fill='black'
    ))

    dwg.save()
    print(f"Saved: {output_path}")

得： SVG 文件生，含形字 敗則： 察 svgwrite 版，驗出目錄可書

三、以佈邏輯建圖

以算得位建構之圖：

def create_flowchart(steps, output_path):
    """Generate a flowchart from list of steps."""
    dwg = svgwrite.Drawing(output_path, size=('800px', '600px'))

    # Layout parameters
    box_width = 120
    box_height = 60
    spacing_y = 100
    start_x = 340
    start_y = 50

    for i, step in enumerate(steps):
        y_pos = start_y + i * spacing_y

        # Draw box
        box = dwg.add(dwg.g(id=f'step_{i}'))

        box.add(dwg.rect(
            insert=(start_x, y_pos),
            size=(box_width, box_height),
            fill='lightblue',
            stroke='navy',
            stroke_width=2,
            rx=5,
            ry=5
        ))

        # Add text (wrapped if needed)
        text_lines = wrap_text(step, max_width=16)
        text_y = y_pos + box_height/2 - (len(text_lines)-1) * 7

        for j, line in enumerate(text_lines):
            box.add(dwg.text(
                line,
                insert=(start_x + box_width/2, text_y + j*14),
                text_anchor='middle',
                font_size='12pt',
                font_family='Arial',
                fill='black'
            ))

        # Draw arrow to next step
        if i < len(steps) - 1:
            arrow_start_y = y_pos + box_height
            arrow_end_y = y_pos + spacing_y

            dwg.add(dwg.line(
                start=(start_x + box_width/2, arrow_start_y),
                end=(start_x + box_width/2, arrow_end_y),
                stroke='black',
                stroke_width=2,
                marker_end=dwg.marker(
                    id='arrow',
                    viewBox='0 0 10 10',
                    refX=5,
                    refY=5,
                    markerWidth=6,
                    markerHeight=6,
                    orient='auto'
                )
            ))

    dwg.save()

def wrap_text(text, max_width=20):
    """Simple text wrapping."""
    words = text.split()
    lines = []
    current_line = []

    for word in words:
        test_line = ' '.join(current_line + [word])
        if len(test_line) <= max_width:
            current_line.append(word)
        else:
            if current_line:
                lines.append(' '.join(current_line))
            current_line = [word]

    if current_line:
        lines.append(' '.join(current_line))

    return lines

得： 流程圖，盒相連而箭指 敗則： 調佈之算，驗箭標之定

四、合點陣之像

以 Pillow 合多像：

from PIL import Image, ImageDraw, ImageFont, ImageFilter
import os

def composite_images(image_paths, output_path, layout='grid'):
    """Composite multiple images into single output."""
    # Load images
    images = [Image.open(path) for path in image_paths]

    if layout == 'grid':
        # Calculate grid dimensions
        n = len(images)
        cols = int(n ** 0.5)
        rows = (n + cols - 1) // cols

        # Get max dimensions
        max_width = max(img.width for img in images)
        max_height = max(img.height for img in images)

        # Create composite canvas
        canvas_width = cols * max_width
        canvas_height = rows * max_height
        composite = Image.new('RGB', (canvas_width, canvas_height), 'white')

        # Paste images
        for i, img in enumerate(images):
            row = i // cols
            col = i % cols
            x = col * max_width
            y = row * max_height
            composite.paste(img, (x, y))

    elif layout == 'horizontal':
        # Horizontal concatenation
        total_width = sum(img.width for img in images)
        max_height = max(img.height for img in images)
        composite = Image.new('RGB', (total_width, max_height), 'white')

        x_offset = 0
        for img in images:
            composite.paste(img, (x_offset, 0))
            x_offset += img.width

    elif layout == 'vertical':
        # Vertical concatenation
        max_width = max(img.width for img in images)
        total_height = sum(img.height for img in images)
        composite = Image.new('RGB', (max_width, total_height), 'white')

        y_offset = 0
        for img in images:
            composite.paste(img, (0, y_offset))
            y_offset += img.height

    composite.save(output_path)
    print(f"Saved composite: {output_path}")

def add_annotations(image_path, annotations, output_path):
    """Add text annotations to image."""
    img = Image.open(image_path)
    draw = ImageDraw.Draw(img)

    # Load font
    try:
        font = ImageFont.truetype("Arial.ttf", 24)
    except:
        font = ImageFont.load_default()

    for annotation in annotations:
        text = annotation['text']
        position = annotation['position']
        color = annotation.get('color', 'black')

        # Add text shadow for readability
        shadow_offset = 2
        draw.text(
            (position[0] + shadow_offset, position[1] + shadow_offset),
            text,
            font=font,
            fill='white'
        )
        draw.text(position, text, font=font, fill=color)

    img.save(output_path)

得： 合像成，佈正 敗則： 察諸入像皆存，驗像模式相容

五、依數而生圖

由數建視：

import numpy as np

def create_bar_chart_svg(data, labels, output_path):
    """Generate SVG bar chart from data."""
    dwg = svgwrite.Drawing(output_path, size=('600px', '400px'))

    # Chart area
    margin = 50
    chart_width = 500
    chart_height = 300
    bar_spacing = 10

    # Calculate bar dimensions
    n_bars = len(data)
    bar_width = (chart_width - (n_bars - 1) * bar_spacing) / n_bars

    # Scale data to fit chart
    max_value = max(data)
    scale = chart_height / max_value

    # Draw axes
    dwg.add(dwg.line(
        start=(margin, margin),
        end=(margin, margin + chart_height),
        stroke='black',
        stroke_width=2
    ))
    dwg.add(dwg.line(
        start=(margin, margin + chart_height),
        end=(margin + chart_width, margin + chart_height),
        stroke='black',
        stroke_width=2
    ))

    # Draw bars
    for i, (value, label) in enumerate(zip(data, labels)):
        x = margin + i * (bar_width + bar_spacing)
        bar_height = value * scale
        y = margin + chart_height - bar_height

        # Bar
        dwg.add(dwg.rect(
            insert=(x, y),
            size=(bar_width, bar_height),
            fill='steelblue',
            stroke='navy',
            stroke_width=1
        ))

        # Value label
        dwg.add(dwg.text(
            f'{value:.1f}',
            insert=(x + bar_width/2, y - 5),
            text_anchor='middle',
            font_size='10pt',
            fill='black'
        ))

        # X-axis label
        dwg.add(dwg.text(
            label,
            insert=(x + bar_width/2, margin + chart_height + 20),
            text_anchor='middle',
            font_size='10pt',
            fill='black'
        ))

    dwg.save()

得： SVG 柱圖，數已縮 敗則： 處邊況（空數、負值），增驗

六、批生圖

自動作多圖：

def batch_generate_badges(users, template_path, output_dir):
    """Generate badge for each user."""
    os.makedirs(output_dir, exist_ok=True)

    for user in users:
        output_path = os.path.join(output_dir, f"{user['id']}_badge.svg")

        dwg = svgwrite.Drawing(output_path, size=('300px', '100px'))

        # Background
        dwg.add(dwg.rect(
            insert=(0, 0),
            size=('100%', '100%'),
            fill='#3366cc',
            rx=10,
            ry=10
        ))

        # User name
        dwg.add(dwg.text(
            user['name'],
            insert=(150, 40),
            text_anchor='middle',
            font_size='20pt',
            font_weight='bold',
            fill='white'
        ))

        # User role
        dwg.add(dwg.text(
            user['role'],
            insert=(150, 70),
            text_anchor='middle',
            font_size='14pt',
            fill='lightblue'
        ))

        dwg.save()
        print(f"Generated badge: {output_path}")

得： 每數項生單獨之圖 敗則： 察數構，缺域以默填

七、SVG 轉點陣

出 SVG 為 PNG／PDF 以供諸用：

import cairosvg

def svg_to_png(svg_path, png_path, dpi=300):
    """Convert SVG to PNG with specified DPI."""
    # Calculate pixel dimensions from DPI
    # Assuming A4 size as example
    width_inches = 8.27
    height_inches = 11.69

    width_px = int(width_inches * dpi)
    height_px = int(height_inches * dpi)

    cairosvg.svg2png(
        url=svg_path,
        write_to=png_path,
        output_width=width_px,
        output_height=height_px
    )
    print(f"Converted to PNG: {png_path}")

def svg_to_pdf(svg_path, pdf_path):
    """Convert SVG to PDF."""
    cairosvg.svg2pdf(url=svg_path, write_to=pdf_path)
    print(f"Converted to PDF: {pdf_path}")

得： 點陣出生於定之解析 敗則： 若缺則裝 cairo 系庫，驗 SVG 合法

驗

• 圖於目標程式正現，字可讀位正
• 色合說（察十六進位），尺合用
• SVG 合標準（若需）
• 點陣出有正 DPI
• 佈適數變
• 批處無訛而畢，出文件有序
• 碼含訛處

陷

1. 單位混：SVG 單（px、mm、cm）與屏素、印 DPI 異
2. 字溢：字越形界，宜包
3. 字型缺：系字或異，宜嵌或用網安字型
4. 坐標算：格佈之差一
5. 色式：SVG 用十六進位字串（#rrggbb），非元組
6. SVG 合法：察 XML 構，閉諸標
7. 路徑：處特字、空格於名中
8. 記憶：大批或需分塊
9. 比例與透：調像時守比；PNG 支 alpha，JPEG 不支

參

• render-publication-graphic：刊用出之需
• create-3d-scene：三維之程式法
• generate-quarto-report：圖入報告