Class: LayerMaskedImage

LayerMaskedImage

LayerMaskedImage provides specialized handling for masked scalar images with bilinear interpolation. It implements custom texture sampling and masking operations through WebGL shaders.

Features:

  • Custom scalar image handling
  • Bilinear interpolation with masking
  • WebGL shader-based processing
  • Support for both WebGL 1 and 2
  • Nearest-neighbor texture filtering
  • Masked value visualization

Technical Details:

  • Uses LUMINANCE format for single-channel data
  • Implements custom bilinear sampling in shader
  • Handles mask values through alpha channel
  • Supports value rescaling (255.0/254.0 scale with -1.0/254.0 bias)
  • Uses custom texture parameters for proper sampling

Shader Implementation:

  • Performs bilinear interpolation in shader
  • Handles masked values (0 = masked)
  • Implements value rescaling
  • Provides visualization of masked areas (in red)
  • Uses texelFetch for precise sampling

new LayerMaskedImage(options)

Creates a new LayerMaskedImage instance

Parameters:
Name Type Description
options LayerMaskedImageOptions

Configuration options

Source:
Throws:
  • If rasters options is not empty

    Type
    Error
  • If url is not provided and layout has no URLs

    Type
    Error
Example
```javascript
// Create masked image layer
const maskedLayer = new OpenLIME.Layer({
  type: 'maskedimage',
  url: 'masked-data.png',
  format: 'vec4'
});

// Add to viewer
viewer.addLayer('masked', maskedLayer);
```

Extends

Methods


addControl(name, value)

Adds a shader parameter control

Parameters:
Name Type Description
name string

Control identifier

value *

Initial value

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Overrides:
Source:
Throws:

If control already exists

Type
Error

addShader(id, shader)

Adds a shader to the layer's available shaders

Parameters:
Name Type Description
id string

Unique identifier for the shader

shader Shader

Shader instance to add

Inherited From:
Overrides:
Source:
Throws:

If shader with the same id already exists

Type
Error
Returns:

This layer instance for method chaining

Type
Layer
Example
```javascript
const customShader = new OpenLIME.Shader({...});
layer.addShader('custom', customShader);
layer.setShader('custom');
```

addShaderFilter(filter)

Adds a filter to the current shader

Parameters:
Name Type Description
filter Object

Filter specification

Inherited From:
Overrides:
Source:
Throws:

If no shader is set

Type
Error

boundingBox()

Gets layer bounding box in scene coordinates

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Returns:

Bounding box

Type
BoundingBox

clearShaderFilters(name)

Removes all filters from the current shader

Parameters:
Name Type Description
name Object

Filter name

Inherited From:
Overrides:
Source:
Throws:

If no shader is set

Type
Error

derive( [options])

Creates a new Layer that shares tiles with this layer but uses a different shader. This method allows efficient creation of derivative layers that share the same source textures, which is useful for applying different visual effects to the same image data without duplicating resources.

Parameters:
Name Type Argument Default Description
options Object <optional>
{}

Options for the new layer

Properties
Name Type Argument Description
shaders Object <optional>

Map of shaders for the new layer

defaultShader string <optional>

ID of shader to set as active

label string <optional>

Label for the new layer (defaults to original label)

zindex number <optional>

Z-index for the new layer (defaults to original + 1)

visible boolean <optional>

Layer visibility (defaults to same as original)

transform Transform <optional>

Custom transform (defaults to copy of original)

mipmapBias number <optional>

Custom mipmap bias (defaults to original value)

pixelSize number <optional>

Custom pixel size (defaults to original value)

debug boolean <optional>

Debug mode flag (defaults to original value)

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Returns:

A new layer sharing textures with this one

Type
Layer
Example
```javascript
// Create a derived layer with edge detection shader
const enhancedShader = new OpenLIME.ShaderEdgeDetection();
const derivedLayer = originalLayer.derive({
    label: 'Edge Detection',
    shaders: { 'edge': enhancedShader },
    defaultShader: 'edge',
    zindex: 10
});
viewer.addLayer('edges', derivedLayer);
```
or
```javascript
const enhancedShader = new OpenLIME.ShaderEdgeDetection();
const derivedLayer = layer.derive({
    label: 'Enhanced Image'
});
derivedLayer.addShader('enhanced', enhancedShader);
derivedLayer.setShader('enhanced');
viewer.addLayer('Enhanced Image', derivedLayer);
```

getControl(name)

Gets the shader parameter control corresponding to name

Parameters:
Name Type Description
name *

The name of the control. return {*} The control

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Overrides:
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getMode()

Gets the current shader visualization mode

Inherited From:
Overrides:
Source:
Returns:

Current mode or null if no shader

Type
string | null

getModes()

Gets available shader modes

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Overrides:
Source:
Returns:

Array of available modes

Type
Array.<string>

getPixelValues(x, y)

Gets pixel values for a specific pixel location Works with both single images and tiled formats

Parameters:
Name Type Description
x number

X coordinate in image space (0,0 at top-left)

y number

Y coordinate in image space (0,0 at top-left)

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Overrides:
Source:
Returns:

Array containing RGBA values for each raster at the specified pixel

Type
Array.<Uint8Array>

getState( [stateMask])

Gets the current layer state

Parameters:
Name Type Argument Default Description
stateMask Object <optional>
null

Optional mask to filter returned state properties

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Overrides:
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Returns:

Current state object

Type
Object

interpolateControls()

Updates control interpolation

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Overrides:
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Returns:

Whether all interpolations are complete

Type
boolean

loadTexture(gl, img)

Loads a texture supporting WebGL 2.0+

Parameters:
Name Type Description
gl WebGLRenderingContext | WebGL2RenderingContext

The WebGL context

img HTMLImageElement

The image to load as a texture

Source:
Returns:
  • The created texture
Type
WebGLTexture

<async> loadTile(tile, callback)

Loads and processes a single image tile with optimized resource management. Implements request batching, concurrent loading, and proper error handling.

Parameters:
Name Type Description
tile Object

Tile specification object

Properties
Name Type Argument Description
index string

Unique tile identifier

url string

Base URL for tile resource

start number <optional>

Start byte for partial content (for tarzoom)

end number <optional>

End byte for partial content (for tarzoom)

offsets Array.<Object> <optional>

Byte offsets for interleaved formats

callback function

Completion callback(error, size)

Inherited From:
Overrides:
Source:
Throws:

If tile is already in processing queue

Type
Error
Returns:
Type
Promise.<void>

pixelSizePerMM()

Gets pixel size in millimeters

Inherited From:
Overrides:
Source:
Returns:

Size of one pixel in mm

Type
number

removeShader(id)

Removes a shader from the layer's available shaders

Parameters:
Name Type Description
id string

Identifier of the shader to remove

Inherited From:
Overrides:
Source:
Throws:

If shader with the specified id doesn't exist

Type
Error
Returns:

This layer instance for method chaining

Type
Layer
Example
```javascript
// Remove a shader that's no longer needed
layer.removeShader('oldEffect');
```

removeShaderFilter(name)

Removes a filter from the current shader

Parameters:
Name Type Description
name Object

Filter name

Inherited From:
Overrides:
Source:
Throws:

If no shader is set

Type
Error

scale()

Gets layer scale

Inherited From:
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Source:
Returns:

Current scale value

Type
number

setControl(name, value [, dt] [, easing])

Sets a shader control value with optional animation

Parameters:
Name Type Argument Default Description
name string

Control identifier

value *

New value

dt number <optional>

Animation duration in ms

easing string <optional>
'linear'

Easing function

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Fires:

setMode(mode)

Sets shader visualization mode

Parameters:
Name Type Description
mode string

Mode to set

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Fires:

setShader(id)

Sets the active shader

Parameters:
Name Type Description
id string

Shader identifier from registered shaders

Inherited From:
Overrides:
Source:
Fires:
Throws:

If shader ID is not found

Type
Error

setState(state [, dt] [, easing])

Sets the layer state with optional animation

Parameters:
Name Type Argument Default Description
state Object

State object with controls and mode

dt number <optional>

Animation duration in ms

easing string <optional>
'linear'

Easing function ('linear'|'ease-out'|'ease-in-out')

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Overrides:
Source:

setTransform(tx)

Sets the layer's transform

Parameters:
Name Type Description
tx Transform

New transform

Inherited From:
Overrides:
Source:
Fires:
  • Layer#event:updateSize

setViewport(view)

Sets the layer's viewport

Parameters:
Name Type Description
view Object

Viewport specification

Properties
Name Type Description
x number

X position

y number

Y position

dx number

Width

dy number

Height

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setVisible(visible)

Sets layer visibility

Parameters:
Name Type Description
visible boolean

Whether layer should be visible

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setZindex(zindex)

Sets layer rendering order

Parameters:
Name Type Description
zindex number

Stack order value

Inherited From:
Overrides:
Source:
Fires:

Events


ready

The event is fired when a layer is initialized.

Inherited From:
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Source:

update

The event is fired if a redraw is needed.

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Overrides:
Source: