feat(watermark): add automatic responsive watermarking on image uploads

- Create reusable watermark utility in utils/watermark.py supporting PIL, UploadedFile, bytes, and DRF serializer fields
- Default position set to bottom-left with responsive 32% width scaling and alpha blending
- Auto-resolve SVG watermark to high-resolution PNG
- Integrate automatic watermarking into Article thumbnails, Hadith/Book Reference images, Corrections, Original Texts, and Interpretations

apps/article/serializers_admin.py

@@ -9,14 +9,21 @@ from .models import Article, ArticleCategory, ArticleCollection, ArticleContent,
 class AbsoluteImageField(serializers.ImageField):
     def to_internal_value(self, data):
         uploaded = super().to_internal_value(data)
-        compressed_bytes = maybe_compress_uploaded_file(uploaded)
-        if compressed_bytes is None:
+        if not uploaded:
             return uploaded
 
+        from utils.watermark import apply_watermark_to_upload
+        watermarked = apply_watermark_to_upload(uploaded, position="bottom_left")
+        target_file = watermarked or uploaded
+
+        compressed_bytes = maybe_compress_uploaded_file(target_file)
+        if compressed_bytes is None:
+            return target_file
+
         return SimpleUploadedFile(
-            name=getattr(uploaded, "name", "image"),
+            name=getattr(target_file, "name", "image"),
             content=compressed_bytes,
-            content_type=getattr(uploaded, "content_type", None),
+            content_type=getattr(target_file, "content_type", None),
         )
 
     def to_representation(self, value):

apps/hadis/models/hadis.py

@@ -367,6 +367,9 @@ class ReferenceImage(models.Model):
         return f'{self.reference}-{self.id}'
     
     def save(self, *args, **kwargs):
+        from utils.watermark import apply_watermark_to_field_file
+        apply_watermark_to_field_file(self.thumbnail, position="bottom_left")
+
         if ReferenceImage.objects.filter(reference=self.reference, priority=self.priority).exists():
             ReferenceImage.objects.filter(
                 reference=self.reference,
@@ -480,6 +483,11 @@ class CorrectionReferenceImage(models.Model):
     image = models.ImageField(upload_to='hadis/correction_images/')
     priority = models.IntegerField(default=0)
 
+    def save(self, *args, **kwargs):
+        from utils.watermark import apply_watermark_to_field_file
+        apply_watermark_to_field_file(self.image, position="bottom_left")
+        super().save(*args, **kwargs)
+
 
 # --- FOR INTERPRETATIONS ---
 class InterpretationReference(models.Model):
@@ -499,4 +507,9 @@ class InterpretationReference(models.Model):
 class InterpretationReferenceImage(models.Model):
     reference = models.ForeignKey(InterpretationReference, related_name='images', on_delete=models.CASCADE)
     image = models.ImageField(upload_to='hadis/interpretation_images/')
-    priority = models.IntegerField(default=0)
+    priority = models.IntegerField(default=0)
+
+    def save(self, *args, **kwargs):
+        from utils.watermark import apply_watermark_to_field_file
+        apply_watermark_to_field_file(self.image, position="bottom_left")
+        super().save(*args, **kwargs)

apps/hadis/models/reference.py

@@ -307,6 +307,11 @@ class BookReferenceImage(models.Model):
         verbose_name_plural = _('Book Reference Images')
         ordering = ['order', '-created_at']
 
+    def save(self, *args, **kwargs):
+        from utils.watermark import apply_watermark_to_field_file
+        apply_watermark_to_field_file(self.image, position="bottom_left")
+        super().save(*args, **kwargs)
+
     def get_description(self,lang):
         """
             Get title for a specific language

apps/hadis/models/transmitter.py

@@ -599,6 +599,11 @@ class OriginalTextReferenceImage(models.Model):
     image = models.ImageField(upload_to='hadis/original_text_images/')
     priority = models.IntegerField(default=0)
 
+    def save(self, *args, **kwargs):
+        from utils.watermark import apply_watermark_to_field_file
+        apply_watermark_to_field_file(self.image, position="bottom_left")
+        super().save(*args, **kwargs)
+
 
 RELATION_TYPE_MAP = {
     'stepfather': [{'language_code': 'ru', 'text': 'Отчим'}, {'language_code': 'ar', 'text': 'زوج الأم'}, {'language_code': 'en', 'text': 'Stepfather'}],

apps/hadis/serializers/serializers_admin.py

@@ -34,6 +34,25 @@ def safe_copy_data(data):
 
 
 class AbsoluteImageField(serializers.ImageField):
+    def to_internal_value(self, data):
+        uploaded = super().to_internal_value(data)
+        if not uploaded:
+            return uploaded
+
+        from utils.watermark import apply_watermark_to_upload
+        watermarked = apply_watermark_to_upload(uploaded, position="bottom_left")
+        target_file = watermarked or uploaded
+
+        compressed_bytes = maybe_compress_uploaded_file(target_file)
+        if compressed_bytes is None:
+            return target_file
+
+        return SimpleUploadedFile(
+            name=getattr(target_file, "name", "image"),
+            content=compressed_bytes,
+            content_type=getattr(target_file, "content_type", None),
+        )
+
     def to_representation(self, value):
         if not value:
             return None

utils/watermark.py

@@ -0,0 +1,349 @@
+"""
+Watermark utility for applying logo/watermark overlays onto uploaded images.
+Supports Django UploadedFile, file paths, raw bytes, and PIL Image instances.
+Default position is bottom-left.
+"""
+import io
+import os
+import logging
+from pathlib import Path
+from typing import Optional, Union, Tuple
+from PIL import Image, ImageEnhance
+from django.conf import settings
+from django.core.files.uploadedfile import SimpleUploadedFile, UploadedFile
+
+logger = logging.getLogger(__name__)
+
+# Default watermark search paths
+DEFAULT_WATERMARK_PATHS = [
+    getattr(settings, "WATERMARK_IMAGE_PATH", None),
+    os.path.join(settings.BASE_DIR, "static", "images", "watermark.png"),
+    os.path.join(settings.BASE_DIR, "static", "images", "watermark.svg"),
+    os.path.join(settings.BASE_DIR, "static", "images", "Frame.svg"),
+]
+
+
+def _get_default_watermark_path() -> Optional[str]:
+    for p in DEFAULT_WATERMARK_PATHS:
+        if p and os.path.exists(p):
+            return p
+    return None
+
+
+def is_watermarkable_image(filename: str, content_type: Optional[str] = None) -> bool:
+    """
+    Check if a file is an image format that supports watermarking.
+    Excludes SVG and GIF animations.
+    """
+    name = (filename or "").lower()
+    ctype = (content_type or "").lower()
+
+    if name.endswith(".gif") or name.endswith(".svg"):
+        return False
+    if ctype in {"image/gif", "image/svg+xml"}:
+        return False
+
+    valid_exts = (".jpg", ".jpeg", ".png", ".webp", ".bmp", ".tif", ".tiff", ".avif")
+    return name.endswith(valid_exts) or ctype.startswith("image/")
+
+
+def apply_watermark_to_image(
+    base_img: Image.Image,
+    watermark_source: Optional[Union[str, Path, Image.Image]] = None,
+    position: str = "bottom_left",
+    opacity: float = 0.85,
+    scale_ratio: float = 0.32,
+    padding: int = 24,
+) -> Image.Image:
+    """
+    Apply a watermark image onto a base PIL Image.
+
+    Args:
+        base_img: PIL Image to watermark.
+        watermark_source: Path to watermark image or PIL Image object.
+        position: 'bottom_left' (default) | 'bottom_right' | 'top_right' | 'top_left' | 'center'.
+        opacity: Float 0.0 to 1.0.
+        scale_ratio: Watermark width relative to base image width (default 0.32).
+        padding: Pixel padding from borders.
+
+    Returns:
+        New PIL Image with watermark blended.
+    """
+    if watermark_source is None:
+        watermark_source = _get_default_watermark_path()
+
+    if not watermark_source:
+        logger.debug("[Watermark] No watermark image found; skipping watermarking.")
+        return base_img
+
+    try:
+        if isinstance(watermark_source, (str, Path)):
+            src_str = str(watermark_source)
+            if not os.path.exists(src_str):
+                logger.warning("[Watermark] File not found: %s", src_str)
+                return base_img
+
+            # Pillow cannot open SVG directly; resolve to raster PNG if SVG given
+            if src_str.lower().endswith(".svg"):
+                png_candidate = os.path.splitext(src_str)[0] + ".png"
+                if os.path.exists(png_candidate):
+                    src_str = png_candidate
+                else:
+                    default_png = os.path.join(settings.BASE_DIR, "static", "images", "watermark.png")
+                    if os.path.exists(default_png):
+                        src_str = default_png
+                    else:
+                        logger.warning("[Watermark] Cannot open SVG without raster version: %s", src_str)
+                        return base_img
+
+            wm_img = Image.open(src_str).convert("RGBA")
+        elif isinstance(watermark_source, Image.Image):
+            wm_img = watermark_source.convert("RGBA")
+        else:
+            return base_img
+
+        # Ensure base image is in RGBA for clean alpha blending
+        original_mode = base_img.mode
+        original_format = getattr(base_img, "format", None)
+        base_rgba = base_img.convert("RGBA")
+        base_w, base_h = base_rgba.size
+
+        # Compute responsive dimensions for watermark (clear and prominent)
+        target_wm_w = max(int(base_w * scale_ratio), 120)
+        wm_aspect = wm_img.height / wm_img.width
+        target_wm_h = max(int(target_wm_w * wm_aspect), 35)
+
+        # Scale down if height exceeds 45% of base image height
+        if target_wm_h > int(base_h * 0.45):
+            target_wm_h = int(base_h * 0.45)
+            target_wm_w = int(target_wm_h / wm_aspect)
+
+        wm_resized = wm_img.resize((target_wm_w, target_wm_h), Image.Resampling.LANCZOS)
+
+        # Adjust watermark opacity
+        if opacity < 1.0:
+            alpha = wm_resized.split()[3]
+            alpha = ImageEnhance.Brightness(alpha).enhance(max(0.0, min(1.0, opacity)))
+            wm_resized.putalpha(alpha)
+
+        # Determine coordinates
+        pos = position.lower()
+        if pos == "bottom_left":
+            x = padding
+            y = base_h - target_wm_h - padding
+        elif pos == "bottom_right":
+            x = base_w - target_wm_w - padding
+            y = base_h - target_wm_h - padding
+        elif pos == "top_right":
+            x = base_w - target_wm_w - padding
+            y = padding
+        elif pos == "top_left":
+            x = padding
+            y = padding
+        elif pos == "center":
+            x = (base_w - target_wm_w) // 2
+            y = (base_h - target_wm_h) // 2
+        else:
+            x = padding
+            y = base_h - target_wm_h - padding
+
+        # Keep inside image boundaries
+        x = max(0, min(x, base_w - target_wm_w))
+        y = max(0, min(y, base_h - target_wm_h))
+
+        # Composite watermark onto base image
+        transparent_layer = Image.new("RGBA", (base_w, base_h), (0, 0, 0, 0))
+        transparent_layer.paste(wm_resized, (x, y), mask=wm_resized)
+        watermarked_rgba = Image.alpha_composite(base_rgba, transparent_layer)
+
+        # Restore original color mode if needed (e.g. RGB for JPEG)
+        if original_mode in ("RGB", "L"):
+            result = watermarked_rgba.convert(original_mode)
+        else:
+            result = watermarked_rgba
+
+        result.format = original_format or "PNG"
+        return result
+
+    except Exception as exc:
+        logger.error("[Watermark] Failed to apply watermark: %s", exc)
+        return base_img
+
+
+def apply_watermark_to_bytes(
+    image_bytes: bytes,
+    filename: str = "image.png",
+    watermark_source: Optional[Union[str, Path, Image.Image]] = None,
+    position: str = "bottom_left",
+    opacity: float = 0.85,
+    scale_ratio: float = 0.32,
+    padding: int = 24,
+    quality: int = 90,
+) -> bytes:
+    """
+    Apply watermark to raw image bytes and return watermarked image bytes.
+    """
+    if not image_bytes:
+        return image_bytes
+
+    try:
+        with Image.open(io.BytesIO(image_bytes)) as img:
+            format_name = img.format or "JPEG"
+            watermarked_img = apply_watermark_to_image(
+                base_img=img,
+                watermark_source=watermark_source,
+                position=position,
+                opacity=opacity,
+                scale_ratio=scale_ratio,
+                padding=padding,
+            )
+
+            out_io = io.BytesIO()
+            if format_name.upper() in ("JPEG", "JPG"):
+                if watermarked_img.mode != "RGB":
+                    watermarked_img = watermarked_img.convert("RGB")
+                watermarked_img.save(out_io, format="JPEG", quality=quality, optimize=True)
+            elif format_name.upper() == "WEBP":
+                watermarked_img.save(out_io, format="WEBP", quality=quality, method=6)
+            else:
+                watermarked_img.save(out_io, format="PNG", optimize=True)
+
+            return out_io.getvalue()
+
+    except Exception as exc:
+        logger.error("[Watermark] Error processing image bytes: %s", exc)
+        return image_bytes
+
+
+def apply_watermark_to_upload(
+    file_obj,
+    watermark_source: Optional[Union[str, Path, Image.Image]] = None,
+    position: str = "bottom_left",
+    opacity: float = 0.85,
+    scale_ratio: float = 0.32,
+    padding: int = 24,
+    quality: int = 90,
+) -> Optional[SimpleUploadedFile]:
+    """
+    Takes an uploaded file object (e.g. from request.FILES), applies watermark,
+    and returns a new SimpleUploadedFile ready to be saved to an ImageField.
+    """
+    if not file_obj:
+        return file_obj
+
+    filename = getattr(file_obj, "name", "upload.jpg")
+    content_type = getattr(file_obj, "content_type", "image/jpeg")
+
+    if not is_watermarkable_image(filename, content_type):
+        return file_obj
+
+    try:
+        raw_bytes = file_obj.read()
+        if hasattr(file_obj, "seek"):
+            file_obj.seek(0)
+
+        if not raw_bytes:
+            return file_obj
+
+        watermarked_bytes = apply_watermark_to_bytes(
+            image_bytes=raw_bytes,
+            filename=filename,
+            watermark_source=watermark_source,
+            position=position,
+            opacity=opacity,
+            scale_ratio=scale_ratio,
+            padding=padding,
+            quality=quality,
+        )
+
+        return SimpleUploadedFile(
+            name=filename,
+            content=watermarked_bytes,
+            content_type=content_type,
+        )
+
+    except Exception as exc:
+        logger.error("[Watermark] Failed to process upload %s: %s", filename, exc)
+        if hasattr(file_obj, "seek"):
+            file_obj.seek(0)
+        return file_obj
+
+
+def apply_watermark_to_field_file(
+    field_file,
+    position: str = "bottom_left",
+    opacity: float = 0.85,
+    scale_ratio: float = 0.32,
+    padding: int = 24,
+    quality: int = 90,
+):
+    """
+    Applies watermark to a Django FieldFile instance inside a model's save() method
+    if a new or uncommitted file is present.
+    """
+    if not field_file or not hasattr(field_file, "file"):
+        return
+
+    try:
+        file_obj = field_file.file
+        # Check if it's an UploadedFile instance or not yet saved to storage
+        if isinstance(file_obj, UploadedFile) or not getattr(field_file, "_committed", True):
+            watermarked = apply_watermark_to_upload(
+                file_obj=file_obj,
+                position=position,
+                opacity=opacity,
+                scale_ratio=scale_ratio,
+                padding=padding,
+                quality=quality,
+            )
+            if watermarked:
+                field_file.save(field_file.name, watermarked, save=False)
+    except Exception as exc:
+        logger.error("[Watermark] Failed to watermark field file: %s", exc)
+
+
+# DRF Serializer Field Integration
+try:
+    from rest_framework import serializers
+
+    class WatermarkedImageField(serializers.ImageField):
+        """
+        DRF ImageField that automatically applies a watermark to uploaded image files.
+        """
+        def __init__(
+            self,
+            *args,
+            watermark_source=None,
+            position="bottom_left",
+            opacity=0.85,
+            scale_ratio=0.32,
+            padding=24,
+            quality=90,
+            **kwargs,
+        ):
+            self.watermark_source = watermark_source
+            self.position = position
+            self.opacity = opacity
+            self.scale_ratio = scale_ratio
+            self.padding = padding
+            self.quality = quality
+            super().__init__(*args, **kwargs)
+
+        def to_internal_value(self, data):
+            uploaded = super().to_internal_value(data)
+            if not uploaded:
+                return uploaded
+
+            watermarked = apply_watermark_to_upload(
+                file_obj=uploaded,
+                watermark_source=self.watermark_source,
+                position=self.position,
+                opacity=self.opacity,
+                scale_ratio=self.scale_ratio,
+                padding=self.padding,
+                quality=self.quality,
+            )
+            return watermarked or uploaded
+
+except ImportError:
+    pass