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Builder

class Builder : Builder<Preview!, PreviewConfig!, Preview.Builder!>, Builder<Preview.Builder!>, Builder<Preview.Builder!>
kotlin.Any
   ↳ androidx.camera.core.Preview.Builder

Builder for a Preview.

Summary

Public constructors

Creates a new Builder object.
Public methods
Preview

Builds an immutable Preview from the current state.
Preview.Builder
setTargetAspectRatio(aspectRatio: Int)

Sets the aspect ratio of the intended target for images from this configuration.
Preview.Builder
setTargetName(@NonNull targetName: String)

Sets the name of the target object being configured, used only for debug logging.
Preview.Builder
setTargetResolution(@NonNull resolution: Size)

Sets the resolution of the intended target from this configuration.
Preview.Builder

Sets the rotation that the intended target resolution is expressed in.

Public constructors

<init>

Builder()

Creates a new Builder object.

Public methods

build

@NonNull fun build(): Preview

Builds an immutable Preview from the current state.

Return
Preview A Preview populated with the current state.
Exceptions
IllegalArgumentException if attempting to set both target aspect ratio and target resolution.

setTargetAspectRatio

@NonNull fun setTargetAspectRatio(aspectRatio: Int): Preview.Builder

Sets the aspect ratio of the intended target for images from this configuration.

The aspect ratio is the ratio of width to height in the sensor orientation.

It is not allowed to set both target aspect ratio and target resolution on the same use case. Attempting so will throw an IllegalArgumentException when building the Config.

The target aspect ratio is used as a hint when determining the resulting output aspect ratio which may differ from the request, possibly due to device constraints. Application code should check the resulting output's resolution and the resulting aspect ratio may not be exactly as requested.

For Preview, the value will be used to calculate the suggested resolution size in SurfaceRequest#getResolution().

If not set, resolutions with aspect ratio 4:3 will be considered in higher priority.

For the following devices, the aspect ratio will be forced to AspectRatio#RATIO_16_9 regardless of the config. On these devices, the camera HAL produces a preview with a 16:9 aspect ratio regardless of the aspect ratio of the preview surface.

  • SM-J710MN, Samsung Galaxy J7 (2016)
  • SM-T580, Samsung Galaxy Tab A J7 (2016)
Parameters
aspectRatio Int: The desired Preview AspectRatio
Return
Preview.Builder The current Builder.

setTargetName

@NonNull fun setTargetName(@NonNull targetName: String): Preview.Builder

Sets the name of the target object being configured, used only for debug logging.

The name should be a value that can uniquely identify an instance of the object being configured.

If not set, the target name will default to an unique name automatically generated with the class canonical name and random UUID.

Parameters
targetName String: A unique string identifier for the instance of the class being configured.
Return
Preview.Builder the current Builder.

setTargetResolution

@NonNull fun setTargetResolution(@NonNull resolution: Size): Preview.Builder

Sets the resolution of the intended target from this configuration.

The target resolution attempts to establish a minimum bound for the preview resolution. The actual preview resolution will be the closest available resolution in size that is not smaller than the target resolution, as determined by the Camera implementation. However, if no resolution exists that is equal to or larger than the target resolution, the nearest available resolution smaller than the target resolution will be chosen. Resolutions with the same aspect ratio of the provided Size will be considered in higher priority before resolutions of different aspect ratios.

It is not allowed to set both target aspect ratio and target resolution on the same use case. Attempting so will throw an IllegalArgumentException when building the Config.

The resolution Size should be expressed in the coordinate frame after rotating the supported sizes by the target rotation. For example, a device with portrait natural orientation in natural target rotation requesting a portrait image may specify 480x640, and the same device, rotated 90 degrees and targeting landscape orientation may specify 640x480.

The maximum available resolution that could be selected for a Preview is limited to be under 1080p. The limitation of 1080p for Preview has considered both performance and quality factors that users can obtain reasonable quality and smooth output stream under 1080p.

If not set, the default selected resolution will be the best size match to the device's screen resolution, or to 1080p (1920x1080), whichever is smaller.

Parameters
resolution Size: The target resolution to choose from supported output sizes list.
Return
Preview.Builder The current Builder.

setTargetRotation

@NonNull fun setTargetRotation(rotation: Int): Preview.Builder

Sets the rotation that the intended target resolution is expressed in.

This sets the rotation that is used when specifying a target resolution using setTargetResolution(Size), which accepts a resolution at the target orientation.

rotation is one of four valid values: Surface#ROTATION_0, , Surface#ROTATION_180, Surface#ROTATION_270. Rotation values are relative to the "natural" rotation, Surface#ROTATION_0.

For example a portrait natural device may specify a portrait image target resolution as 480x640, and the same device rotated to and displaying in landscape (i.e. as returned by Display#getRotation()) may set the target rotation to Surface#ROTATION_90 and resolution to 640x480.

If not set, the target rotation will default to the value of Display#getRotation() of the default display at the time the use case is created. The use case is fully created once it has been attached to a camera.

Note that SurfaceView does not support non-display rotation. If the target rotation is different than the value of Display#getRotation(), SurfaceView should not be used to provide the Surface in SurfaceRequest#provideSurface(Surface, Executor, Consumer)

Parameters
rotation Int: The rotation of the intended target.
Return
Preview.Builder The current Builder.