CSS Masking
With CSS masking you create a mask layer to place over an element to partially or fully hide portions of the element.
The CSS mask-image Property
The CSS mask-image
property specifies a mask layer image.
The mask layer image can be a PNG image, an SVG image, a CSS gradient, or an SVG <mask> element.
Browser Support
Note: Most browsers only have partial support for CSS masking. You will need to use the -webkit- prefix in addition to the standard property in most browsers.
The numbers in the table below specify the first browser version that fully supports the property. Numbers followed by -webkit- specify the first version that worked with a prefix.
Property | |||||
---|---|---|---|---|---|
mask-image | 4.0 -webkit- | 79.0 -webkit- | 53.0 | 4.0 -webkit- | 15.0 -webkit- |
Use an Image as the Mask Layer
To use a PNG or an SVG image as the mask layer, use a url() value to pass in the mask layer image.
The mask image needs to have a transparent or semi-transparent area. Black indicates fully transparent.
Here is the mask image (a PNG image) we will use:
Here is an image from Cinque Terre, in Italy:
Now, we apply the mask image (the PNG image above) as the mask layer for the image from Cinque Terre, Italy:
Example
Here is the source code:
.mask1 { -webkit-mask-image: url(/cdn/articles/logo.png); mask-image: url(/cdn/articles/logo.png); -webkit-mask-repeat: no-repeat; mask-repeat: no-repeat; }
Example Explained
The mask-image
property specifies the image to be used as a mask layer for an element.
The mask-repeat
property specifies if or how a mask image will be repeated. The no-repeat
value indicates that the mask image will not be repeated (the mask image will only be shown once).
Another Example
If we omit the mask-repeat
property, the mask image will be repeated all over the image from Cinque Terre, Italy:
Example
Here is the source code:
.mask1 { -webkit-mask-image: url(/cdn/articles/logo.png); mask-image: url(/cdn/articles/logo.png); }
Use Gradients as the Mask Layer
CSS linear and radial gradients can also be used as mask images.
Linear Gradient Examples
Here, we use a linear-gradient as the mask layer for our image. This linear gradient goes from top (black) to bottom (transparent):
Example
Use a linear gradient as a mask layer:
.mask1 { -webkit-mask-image: linear-gradient(black, transparent); mask-image: linear-gradient(black, transparent); }
Here, we use a linear-gradient along with text masking as the mask layer for our image:
The Cinque Terre is a coastal area within Liguria, in the northwest of Italy. It lies in the west of La Spezia Province, and comprises five villages: Monterosso al Mare, Vernazza, Corniglia, Manarola, and Riomaggiore.
The Cinque Terre is a coastal area within Liguria, in the northwest of Italy. It lies in the west of La Spezia Province, and comprises five villages: Monterosso al Mare, Vernazza, Corniglia, Manarola, and Riomaggiore.
The Cinque Terre is a coastal area within Liguria, in the northwest of Italy. It lies in the west of La Spezia Province, and comprises five villages: Monterosso al Mare, Vernazza, Corniglia, Manarola, and Riomaggiore.
The Cinque Terre is a coastal area within Liguria, in the northwest of Italy. It lies in the west of La Spezia Province, and comprises five villages: Monterosso al Mare, Vernazza, Corniglia, Manarola, and Riomaggiore.
The Cinque Terre is a coastal area within Liguria, in the northwest of Italy. It lies in the west of La Spezia Province, and comprises five villages: Monterosso al Mare, Vernazza, Corniglia, Manarola, and Riomaggiore.
The Cinque Terre is a coastal area within Liguria, in the northwest of Italy. It lies in the west of La Spezia Province, and comprises five villages: Monterosso al Mare, Vernazza, Corniglia, Manarola, and Riomaggiore.
Example
Use a linear gradient along with text masking as a mask layer:
.mask1 { max-width: 600px; height: 350px; overflow-y: scroll; background: url(/cdn/articles/img_5terre.jpg) no-repeat; -webkit-mask-image: linear-gradient(black, transparent); mask-image: linear-gradient (black, transparent); }
Radial Gradient Examples
Here, we use a radial-gradient (shaped as a circle) as the mask layer for our image:
A radial gradient as a mask layer (a circle):
Example
Use a radial gradient as a mask layer (a circle):
.mask2 { -webkit-mask-image: radial-gradient(circle, black 50%, rgba(0, 0, 0, 0.5) 50%); mask-image: radial-gradient(circle, black 50%, rgba(0, 0, 0, 0.5) 50%); }
Here, we use a radial-gradient (shaped as an ellipse) as the mask layer for our image:
Example
Use another radial gradient as a mask layer (an ellipse):
.mask3 { -webkit-mask-image: radial-gradient(ellipse, black 50%, rgba(0, 0, 0, 0.5) 50%); mask-image: radial-gradient(ellipse, black 50%, rgba(0, 0, 0, 0.5)); }
Use SVG as the Mask Layer
The SVG <mask>
element can be used inside an SVG graphic to create masking effects.
Here, we use the SVG <mask>
element to create different mask layers for our image:
Example
An SVG mask layer (formed as a triangle):
<svg width="600" height="400"> <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="/cdn/articles/img_5terre.jpg" mask="url(#svgmask1)"></image> </svg>
Example
An SVG mask layer (formed as a star):
<svg width="600" height="210"> <mask id="svgmask2"> <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="/cdn/articles/img_5terre.jpg" mask="url(#svgmask2)"></image> </svg>
Example
An SVG mask layer (formed as circles):
<svg width="600" height="400"> <mask id="svgmask3"> <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="/cdn/articles/img_5terre.jpg" mask="url(#svgmask3)"></image> </svg>
CSS Masking Properties
The following table lists all the CSS masking properties:
Property | Description |
---|---|
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 |