2nd/10_Wiki/Topic_CSS/CSS_Masking_SVG.md

id, title, category, status, verification_status, canonical_id, aliases, duplicate_of, source_trust_level, confidence_score, created_at, updated_at, review_reason, merge_history, tags, raw_sources, applied_in, github_commit

id	title	category	status	verification_status	canonical_id	aliases	duplicate_of	source_trust_level	confidence_score	created_at	updated_at	review_reason	merge_history	tags	raw_sources	applied_in	github_commit
css-masking-with-svg	CSS Masking with SVG	Frontend	draft	conceptual		SVG mask svg mask element mask-image svg CSS masking SVG svg clip shapes		B	0.87	2026-06-23	2026-06-23			css web frontend w3schools masking svg mask-image	https://www.w3schools.com/css/css3_masking_svg.asp

CSS Masking with SVG

🎯 한 줄 통찰 (One-line insight)

An SVG <mask> element can act as a mask layer for an image, using SVG shapes (circle, ellipse, polygon) to define which parts of the image are revealed. [S1]

🧠 핵심 개념 (Core concepts)

• SVG mask layer — an SVG <mask> element can serve as the mask layer applied to an image. [S1]
• Shape-driven — the visible region is defined by SVG shapes (<circle>, <ellipse>, <polygon>) filled with #ffffff inside the mask. [S1]
• Wiring — the image references the mask via mask="url(#svgmask1)", where the id matches the <mask> element's id. [S1]

🧩 추출된 패턴 (Extracted patterns)

• Define-then-reference — declare a <mask id="..."> containing white-filled shapes, then point the <image>'s mask attribute at url(#id). [S1]
• Composite masks — multiple shapes (e.g. several <circle>s) inside one <mask> reveal multiple regions at once. [S1]

📖 세부 내용 (Details)

This page demonstrates how to apply SVG mask layers to images using various SVG shapes. Each example defines an SVG <mask> with one or more white-filled (#ffffff) shapes, then applies it to an <image> via mask="url(#svgmask1)". [S1]

Circle mask [S1]

<svg width="600" height="400" xmlns="http://www.w3.org/2000/svg">
  <mask id="svgmask1">
    <circle r="150" cx="200" cy="200" fill="#ffffff" />
  </mask>
  <image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="img_5terre.jpg" mask="url(#svgmask1)"></image>
</svg>

Ellipse mask [S1]

<svg width="600" height="400" xmlns="http://www.w3.org/2000/svg">
  <mask id="svgmask1">
    <ellipse cx="220" cy="150" rx="200" ry="100" fill="#ffffff" />
  </mask>
  <image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="img_5terre.jpg" mask="url(#svgmask1)"></image>
</svg>

Triangle mask [S1]

<svg width="600" height="400" xmlns="http://www.w3.org/2000/svg">
  <mask id="svgmask1">
    <polygon fill="#ffffff" points="200 0, 400 400, 0 400"></polygon>
  </mask>
  <image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="img_5terre.jpg" mask="url(#svgmask1)"></image>
</svg>

Star mask [S1]

<svg width="600" height="400" xmlns="http://www.w3.org/2000/svg">
  <mask id="svgmask1">
    <polygon fill="#ffffff" points="100,10 40,198 190,78 10,78 160,198"></polygon>
  </mask>
  <image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="img_5terre.jpg" mask="url(#svgmask1)"></image>
</svg>

Multiple circles mask [S1]

<svg width="600" height="400" xmlns="http://www.w3.org/2000/svg">
  <mask id="svgmask1">
    <circle fill="#ffffff" cx="75" cy="75" r="75"></circle>
    <circle fill="#ffffff" cx="80" cy="260" r="75"></circle>
    <circle fill="#ffffff" cx="270" cy="160" r="75"></circle>
  </mask>
  <image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="img_5terre.jpg" mask="url(#svgmask1)"></image>
</svg>

CSS masking properties reference [S1]

Property	Description
mask-clip	Specifies which area is affected by a mask image
mask-composite	Specifies a compositing operation used on the current mask layer with the mask layers below it
mask-image	Specifies an image to be used as a mask layer for an element
mask-mode	Specifies whether the mask layer image is treated as a luminance mask or as an alpha mask
mask-origin	Specifies the origin position (the mask position area) of a mask layer image
mask-position	Sets the starting position of a mask layer image (relative to the mask position area)
mask-repeat	Specifies how the mask layer image is repeated
mask-size	Specifies the size of a mask layer image
mask-type	Specifies whether an SVG <mask> element is treated as a luminance mask or as an alpha mask

🛠️ 적용 사례 (Applied in summary)

The page's own examples are the applied cases: SVG <mask> layers (circle, ellipse, triangle, star, multiple circles) applied to the img_5terre.jpg image. No external project/commit applications found in the source.

💻 코드 패턴 (Code patterns)

Reveal a circular region of an image with an SVG mask (language: HTML/SVG):

<svg width="600" height="400" xmlns="http://www.w3.org/2000/svg">
  <mask id="svgmask1">
    <circle r="150" cx="200" cy="200" fill="#ffffff" />
  </mask>
  <image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="img_5terre.jpg" mask="url(#svgmask1)"></image>
</svg>

⚖️ 모순 및 업데이트 (Contradictions & updates)

No contradictions found in the source.

✅ 검증 상태 및 신뢰도

• 상태: draft
• 검증 단계: conceptual (실제 적용 사례 발견 시 applied/validated로 승격 가능)
• 출처 신뢰도: B (W3Schools — widely used educational reference, not a primary standards body)
• 신뢰 점수: 0.87
• 중복 검사 결과: 신규 생성 (New discovery)

🔗 지식 그래프 (Knowledge Graph)

• 상위/루트: CSS Tutorial
• 관련 개념: CSS Masking PNG, CSS Masking Gradients, CSS Image Shapes
• 참조 맥락: Referenced when masking an image to arbitrary shapes defined by SVG geometry.

📚 출처 (Sources)

• [S1] W3Schools — CSS Masking with SVG — https://www.w3schools.com/css/css3_masking_svg.asp

📝 변경 이력 (Change history)

• 2026-06-23: Initial draft synthesized from the W3Schools "CSS Masking with SVG" page (Astra wiki-curation, P-Reinforce v3.1 format).