Upload preview_generator.py

core/preview_generator.py

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+"""
+Preview Generator for Typography and Color Ramps
+
+Generates HTML previews for:
+1. Typography - Actual font rendering with detected styles
+2. Color Ramps - 11 shades (50-950) with AA compliance indicators
+"""
+
+from typing import Optional
+import colorsys
+import re
+
+
+# =============================================================================
+# TYPOGRAPHY PREVIEW
+# =============================================================================
+
+def generate_typography_preview_html(
+    typography_tokens: dict,
+    font_family: str = "Open Sans",
+    background: str = "#FAFAFA",
+    sample_text: str = "The quick brown fox jumps over the lazy dog"
+) -> str:
+    """
+    Generate HTML preview for typography tokens.
+    
+    Args:
+        typography_tokens: Dict of typography styles {name: {font_size, font_weight, line_height, letter_spacing}}
+        font_family: Primary font family detected
+        background: Background color (neutral)
+        sample_text: Text to render for preview
+    
+    Returns:
+        HTML string for Gradio HTML component
+    """
+    
+    # Sort tokens by font size (largest first)
+    sorted_tokens = []
+    for name, token in typography_tokens.items():
+        size_str = str(token.get("font_size", "16px"))
+        size_num = float(re.sub(r'[^0-9.]', '', size_str) or 16)
+        sorted_tokens.append((name, token, size_num))
+    
+    sorted_tokens.sort(key=lambda x: -x[2])  # Descending by size
+    
+    # Generate rows
+    rows_html = ""
+    for name, token, size_num in sorted_tokens[:15]:  # Limit to 15 styles
+        font_size = token.get("font_size", "16px")
+        font_weight = token.get("font_weight", "400")
+        line_height = token.get("line_height", "1.5")
+        letter_spacing = token.get("letter_spacing", "0")
+        
+        # Convert weight names to numbers
+        weight_map = {
+            "thin": 100, "extralight": 200, "light": 300, "regular": 400,
+            "medium": 500, "semibold": 600, "bold": 700, "extrabold": 800, "black": 900
+        }
+        if isinstance(font_weight, str) and font_weight.lower() in weight_map:
+            font_weight = weight_map[font_weight.lower()]
+        
+        # Weight label
+        weight_labels = {
+            100: "Thin", 200: "ExtraLight", 300: "Light", 400: "Regular",
+            500: "Medium", 600: "SemiBold", 700: "Bold", 800: "ExtraBold", 900: "Black"
+        }
+        weight_label = weight_labels.get(int(font_weight) if str(font_weight).isdigit() else 400, "Regular")
+        
+        # Clean up name for display
+        display_name = name.replace("_", " ").replace("-", " ").title()
+        if len(display_name) > 15:
+            display_name = display_name[:15] + "..."
+        
+        # Truncate sample text for large sizes
+        display_text = sample_text
+        if size_num > 48:
+            display_text = sample_text[:30] + "..."
+        elif size_num > 32:
+            display_text = sample_text[:40] + "..."
+        
+        rows_html += f'''
+        <tr>
+            <td class="scale-name">
+                <div class="scale-label">{display_name}</div>
+            </td>
+            <td class="meta">{font_family}</td>
+            <td class="meta">{weight_label}</td>
+            <td class="meta">{int(size_num)}</td>
+            <td class="meta">Sentence</td>
+            <td class="meta">{letter_spacing}</td>
+        </tr>
+        <tr>
+            <td colspan="6" class="preview-cell">
+                <div class="preview-text" style="
+                    font-family: '{font_family}', sans-serif;
+                    font-size: {font_size};
+                    font-weight: {font_weight};
+                    line-height: {line_height};
+                    letter-spacing: {letter_spacing}px;
+                ">{display_text}</div>
+            </td>
+        </tr>
+        '''
+    
+    html = f'''
+    <style>
+        @import url('https://fonts.googleapis.com/css2?family={font_family.replace(" ", "+")}:wght@100;200;300;400;500;600;700;800;900&display=swap');
+        
+        .typography-preview {{
+            font-family: system-ui, -apple-system, sans-serif;
+            background: {background};
+            border-radius: 12px;
+            padding: 20px;
+            overflow-x: auto;
+        }}
+        
+        .typography-preview table {{
+            width: 100%;
+            border-collapse: collapse;
+        }}
+        
+        .typography-preview th {{
+            text-align: left;
+            padding: 12px 16px;
+            font-size: 12px;
+            font-weight: 600;
+            color: #666;
+            text-transform: uppercase;
+            letter-spacing: 0.5px;
+            border-bottom: 2px solid #E0E0E0;
+        }}
+        
+        .typography-preview td {{
+            padding: 8px 16px;
+            vertical-align: middle;
+        }}
+        
+        .typography-preview .scale-name {{
+            font-weight: 600;
+            color: #333;
+            min-width: 100px;
+        }}
+        
+        .typography-preview .scale-label {{
+            font-size: 14px;
+        }}
+        
+        .typography-preview .meta {{
+            font-size: 13px;
+            color: #666;
+            white-space: nowrap;
+        }}
+        
+        .typography-preview .preview-cell {{
+            padding: 16px;
+            background: #FFFFFF;
+            border-bottom: 1px solid #E8E8E8;
+        }}
+        
+        .typography-preview .preview-text {{
+            color: #1A1A1A;
+            margin: 0;
+            word-break: break-word;
+        }}
+        
+        .typography-preview tr:hover .preview-cell {{
+            background: #F5F5F5;
+        }}
+    </style>
+    
+    <div class="typography-preview">
+        <table>
+            <thead>
+                <tr>
+                    <th>Scale Category</th>
+                    <th>Typeface</th>
+                    <th>Weight</th>
+                    <th>Size</th>
+                    <th>Case</th>
+                    <th>Letter Spacing</th>
+                </tr>
+            </thead>
+            <tbody>
+                {rows_html}
+            </tbody>
+        </table>
+    </div>
+    '''
+    
+    return html
+
+
+# =============================================================================
+# COLOR RAMP PREVIEW
+# =============================================================================
+
+def hex_to_rgb(hex_color: str) -> tuple:
+    """Convert hex color to RGB tuple."""
+    hex_color = hex_color.lstrip('#')
+    if len(hex_color) == 3:
+        hex_color = ''.join([c*2 for c in hex_color])
+    return tuple(int(hex_color[i:i+2], 16) for i in (0, 2, 4))
+
+
+def rgb_to_hex(rgb: tuple) -> str:
+    """Convert RGB tuple to hex string."""
+    return '#{:02x}{:02x}{:02x}'.format(int(rgb[0]), int(rgb[1]), int(rgb[2]))
+
+
+def get_luminance(rgb: tuple) -> float:
+    """Calculate relative luminance for contrast ratio."""
+    def adjust(c):
+        c = c / 255
+        return c / 12.92 if c <= 0.03928 else ((c + 0.055) / 1.055) ** 2.4
+    
+    r, g, b = rgb
+    return 0.2126 * adjust(r) + 0.7152 * adjust(g) + 0.0722 * adjust(b)
+
+
+def get_contrast_ratio(color1: tuple, color2: tuple) -> float:
+    """Calculate contrast ratio between two colors."""
+    l1 = get_luminance(color1)
+    l2 = get_luminance(color2)
+    lighter = max(l1, l2)
+    darker = min(l1, l2)
+    return (lighter + 0.05) / (darker + 0.05)
+
+
+def generate_color_ramp(base_hex: str) -> list[dict]:
+    """
+    Generate 11 shades (50-950) from a base color.
+    
+    Uses OKLCH-like approach for perceptually uniform steps.
+    """
+    try:
+        rgb = hex_to_rgb(base_hex)
+    except:
+        return []
+    
+    # Convert to HLS for easier manipulation
+    r, g, b = [x / 255 for x in rgb]
+    h, l, s = colorsys.rgb_to_hls(r, g, b)
+    
+    # Define lightness levels for each shade
+    # 50 = very light (0.95), 500 = base, 950 = very dark (0.05)
+    shade_lightness = {
+        50: 0.95,
+        100: 0.90,
+        200: 0.80,
+        300: 0.70,
+        400: 0.60,
+        500: l,  # Keep original lightness for 500
+        600: 0.45,
+        700: 0.35,
+        800: 0.25,
+        900: 0.15,
+        950: 0.08,
+    }
+    
+    # Adjust saturation for light/dark shades
+    ramp = []
+    for shade, target_l in shade_lightness.items():
+        # Reduce saturation for very light colors
+        if target_l > 0.8:
+            adjusted_s = s * 0.6
+        elif target_l < 0.2:
+            adjusted_s = s * 0.8
+        else:
+            adjusted_s = s
+        
+        # Generate new RGB
+        new_r, new_g, new_b = colorsys.hls_to_rgb(h, target_l, adjusted_s)
+        new_rgb = (int(new_r * 255), int(new_g * 255), int(new_b * 255))
+        new_hex = rgb_to_hex(new_rgb)
+        
+        # Check AA compliance
+        white = (255, 255, 255)
+        black = (0, 0, 0)
+        contrast_white = get_contrast_ratio(new_rgb, white)
+        contrast_black = get_contrast_ratio(new_rgb, black)
+        
+        # AA requires 4.5:1 for normal text
+        aa_on_white = contrast_white >= 4.5
+        aa_on_black = contrast_black >= 4.5
+        
+        ramp.append({
+            "shade": shade,
+            "hex": new_hex,
+            "rgb": new_rgb,
+            "contrast_white": round(contrast_white, 2),
+            "contrast_black": round(contrast_black, 2),
+            "aa_on_white": aa_on_white,
+            "aa_on_black": aa_on_black,
+        })
+    
+    return ramp
+
+
+def generate_color_ramps_preview_html(
+    color_tokens: dict,
+    background: str = "#FAFAFA"
+) -> str:
+    """
+    Generate HTML preview for color ramps.
+    
+    Args:
+        color_tokens: Dict of colors {name: {value: "#hex", ...}}
+        background: Background color
+    
+    Returns:
+        HTML string for Gradio HTML component
+    """
+    
+    rows_html = ""
+    
+    for name, token in list(color_tokens.items())[:10]:  # Limit to 10 colors
+        # Get hex value
+        if isinstance(token, dict):
+            hex_val = token.get("value", "#888888")
+        else:
+            hex_val = str(token)
+        
+        # Clean up hex
+        if not hex_val.startswith("#"):
+            hex_val = f"#{hex_val}"
+        
+        # Generate ramp
+        ramp = generate_color_ramp(hex_val)
+        if not ramp:
+            continue
+        
+        # Clean name
+        display_name = name.replace("_", " ").replace("-", " ").title()
+        if len(display_name) > 15:
+            display_name = display_name[:12] + "..."
+        
+        # Generate shade cells
+        shades_html = ""
+        for shade_info in ramp:
+            shade = shade_info["shade"]
+            hex_color = shade_info["hex"]
+            aa_white = shade_info["aa_on_white"]
+            aa_black = shade_info["aa_on_black"]
+            
+            # Determine text color for label
+            text_color = "#000" if shade < 500 else "#FFF"
+            
+            # AA indicator
+            if aa_white or aa_black:
+                aa_indicator = "✓"
+                aa_class = "aa-pass"
+            else:
+                aa_indicator = "✗"
+                aa_class = "aa-fail"
+            
+            shades_html += f'''
+            <div class="shade-cell" style="background-color: {hex_color};" title="{hex_color} | AA: {'Pass' if aa_white or aa_black else 'Fail'}">
+                <span class="shade-label" style="color: {text_color};">{shade}</span>
+                <span class="aa-badge {aa_class}">{aa_indicator}</span>
+            </div>
+            '''
+        
+        rows_html += f'''
+        <div class="color-row">
+            <div class="color-info">
+                <div class="color-swatch" style="background-color: {hex_val};"></div>
+                <div class="color-meta">
+                    <div class="color-name">{display_name}</div>
+                    <div class="color-hex">{hex_val}</div>
+                </div>
+            </div>
+            <div class="color-ramp">
+                {shades_html}
+            </div>
+        </div>
+        '''
+    
+    html = f'''
+    <style>
+        .color-ramps-preview {{
+            font-family: system-ui, -apple-system, sans-serif;
+            background: {background};
+            border-radius: 12px;
+            padding: 20px;
+            overflow-x: auto;
+        }}
+        
+        .color-row {{
+            display: flex;
+            align-items: center;
+            margin-bottom: 16px;
+            padding-bottom: 16px;
+            border-bottom: 1px solid #E8E8E8;
+        }}
+        
+        .color-row:last-child {{
+            border-bottom: none;
+            margin-bottom: 0;
+            padding-bottom: 0;
+        }}
+        
+        .color-info {{
+            display: flex;
+            align-items: center;
+            min-width: 140px;
+            margin-right: 20px;
+        }}
+        
+        .color-swatch {{
+            width: 40px;
+            height: 40px;
+            border-radius: 50%;
+            border: 2px solid rgba(0,0,0,0.1);
+            margin-right: 12px;
+            flex-shrink: 0;
+        }}
+        
+        .color-meta {{
+            flex: 1;
+        }}
+        
+        .color-name {{
+            font-weight: 600;
+            font-size: 14px;
+            color: #333;
+            margin-bottom: 2px;
+        }}
+        
+        .color-hex {{
+            font-size: 12px;
+            color: #666;
+            font-family: monospace;
+        }}
+        
+        .color-ramp {{
+            display: flex;
+            gap: 4px;
+            flex: 1;
+        }}
+        
+        .shade-cell {{
+            width: 48px;
+            height: 48px;
+            border-radius: 6px;
+            display: flex;
+            flex-direction: column;
+            align-items: center;
+            justify-content: center;
+            position: relative;
+            cursor: pointer;
+            transition: transform 0.15s;
+        }}
+        
+        .shade-cell:hover {{
+            transform: scale(1.1);
+            z-index: 10;
+            box-shadow: 0 4px 12px rgba(0,0,0,0.2);
+        }}
+        
+        .shade-label {{
+            font-size: 10px;
+            font-weight: 600;
+            opacity: 0.9;
+        }}
+        
+        .aa-badge {{
+            font-size: 9px;
+            margin-top: 2px;
+        }}
+        
+        .aa-pass {{
+            color: #22C55E;
+        }}
+        
+        .aa-fail {{
+            color: #EF4444;
+        }}
+        
+        .shade-cell:hover .shade-label,
+        .shade-cell:hover .aa-badge {{
+            opacity: 1;
+        }}
+        
+        /* Header row */
+        .ramp-header {{
+            display: flex;
+            margin-bottom: 12px;
+            padding-left: 160px;
+        }}
+        
+        .ramp-header-label {{
+            width: 48px;
+            text-align: center;
+            font-size: 11px;
+            font-weight: 600;
+            color: #666;
+            margin-right: 4px;
+        }}
+    </style>
+    
+    <div class="color-ramps-preview">
+        <div class="ramp-header">
+            <span class="ramp-header-label">50</span>
+            <span class="ramp-header-label">100</span>
+            <span class="ramp-header-label">200</span>
+            <span class="ramp-header-label">300</span>
+            <span class="ramp-header-label">400</span>
+            <span class="ramp-header-label">500</span>
+            <span class="ramp-header-label">600</span>
+            <span class="ramp-header-label">700</span>
+            <span class="ramp-header-label">800</span>
+            <span class="ramp-header-label">900</span>
+            <span class="ramp-header-label">950</span>
+        </div>
+        {rows_html}
+    </div>
+    '''
+    
+    return html
+
+
+# =============================================================================
+# COMBINED PREVIEW
+# =============================================================================
+
+def generate_design_system_preview_html(
+    typography_tokens: dict,
+    color_tokens: dict,
+    font_family: str = "Open Sans",
+    sample_text: str = "The quick brown fox jumps over the lazy dog"
+) -> tuple[str, str]:
+    """
+    Generate both typography and color ramp previews.
+    
+    Returns:
+        Tuple of (typography_html, color_ramps_html)
+    """
+    typography_html = generate_typography_preview_html(
+        typography_tokens=typography_tokens,
+        font_family=font_family,
+        sample_text=sample_text,
+    )
+    
+    color_ramps_html = generate_color_ramps_preview_html(
+        color_tokens=color_tokens,
+    )
+    
+    return typography_html, color_ramps_html