Interface: Image
ImageModule.Image
An image is a high-level data type, which can be used for model inference with MobileModel.execute or it can be drawn on a [[Canvas.drawImage]].
An Image object in JavaScript is a reference to a native image object
wrapped in NativeJSRef. The image data is not transferred over the React
Native Bridge, but it offers functions to manipulate the image. All
functions are executed async in native.
Eventually, this will change with the introduction of the new React Native architecture including JSI, Fabric, and TurboModules.
Hierarchy
↳ Image
Properties
ID
• ID: string
The internal ID for the object instance in native. Instead of serializing the object in native and sending it via the React Native Bridge, each native object will be assigned an ID which is sent to JavaScript instead. The ID will be used to reference the native object instance when calling functions on the JavaScript object.
Inherited from
Defined in
NativeJSRef.ts:64
Methods
getHeight
▸ getHeight(): number
Get the height of an image (in pixel).
Returns
number
Defined in
ImageModule.ts:44
getNaturalHeight
▸ getNaturalHeight(): number
Get the natural height of an image (in pixel).
Returns
number
Defined in
ImageModule.ts:54
getNaturalWidth
▸ getNaturalWidth(): number
Get the natural width of an image (in pixel).
Returns
number
Defined in
ImageModule.ts:59
getPixelDensity
▸ getPixelDensity(): number
Get the pixel density for this image. The width and height multiplied
by the pixelDensity is naturalWidth and naturalHeight.
Returns
number
Defined in
ImageModule.ts:65
getWidth
▸ getWidth(): number
Get the width of an image (in pixel).
Returns
number
Defined in
ImageModule.ts:49
release
▸ release(): Promise<void>
Until explicitly released, an Image will have a reference in memory.
Not calling Image.release can eventually result in an
OutOfMemoryException.
While this is an async function, it does not need to be awaited. For
example, the GC on Android will eventually free the allocated memory.
Returns
Promise<void>
Defined in
ImageModule.ts:79
scale
▸ scale(sx, sy): Promise<Image>
The Image.scale method of the Image API adds a scaling
transformation horizontally and/or vertically. For instance, a scaling
factor of 0.5 results in a unit size of 0.5 pixels; the image is thus
at half the normal size. Similarly, a scaling factor of 2.0 increases
the unit size so that one unit becomes two pixels; images are thus at
twice the normal size.
The method will apply the scaling on a copy of the Image and return the scaled Image asynchronously.
Parameters
| Name | Type | Description |
|---|---|---|
sx | number | Scaling factor in the horizontal direction. A negative value flips pixels across the vertical axis. A value of 1 results in no horizontal scaling. |
sy | number | Scaling factor in the vertical direction. A negative value flips pixels across the horizontal axis. A value of 1 results in no vertical scaling. |
Returns
Promise<Image>
Defined in
ImageModule.ts:95