Transaction

Transaction

Transaction()

Open a new transaction object. The transaction may be filed with commands to manipulate SurfaceControl instances, and then applied atomically with apply. Eventually the user should invoke #close, when the object is no longer required. Note however that re-using a transaction after a call to apply is allowed as a convenience.

addTransactionCommittedListener

open fun addTransactionCommittedListener(
    executor: Executor, 
    listener: SurfaceControl.TransactionCommittedListener
): SurfaceControl.Transaction

Request to add a TransactionCommittedListener. The callback is invoked when transaction is applied and the updates are ready to be presented. This callback does not mean buffers have been released! It simply means that any new transactions applied will not overwrite the transaction for which we are receiving a callback and instead will be included in the next frame. If you are trying to avoid dropping frames (overwriting transactions), and unable to use timestamps (Which provide a more efficient solution), then this method provides a method to pace your transaction application. The listener is invoked once the transaction is applied, and never again. Multiple listeners can be added to the same transaction, however the order the listeners will be called is not guaranteed.

apply

open fun apply(): Unit

Apply the transaction, clearing it's state, and making it usable as a new transaction.

clearFrameRate

open fun clearFrameRate(sc: SurfaceControl): SurfaceControl.Transaction

Clears the frame rate which was set for the surface SurfaceControl.

This is equivalent to calling setFrameRate(android.view.SurfaceControl,float,int,int) using 0 for frameRate.

Note that this only has an effect for surfaces presented on the display. If this surface is consumed by something other than the system compositor, e.g. a media codec, this call has no effect.

clearTrustedPresentationCallback

open fun clearTrustedPresentationCallback(sc: SurfaceControl): SurfaceControl.Transaction

Deprecated: Use WindowManager#unregisterTrustedPresentationListener(Consumer) instead.

Clears the callback for a specific SurfaceControl

close

open fun close(): Unit

Release the native transaction object, without applying it.

describeContents

open fun describeContents(): Int

merge

open fun merge(other: SurfaceControl.Transaction): SurfaceControl.Transaction

Merge the other transaction into this transaction, clearing the other transaction as if it had been applied.

reparent

open fun reparent(
    sc: SurfaceControl, 
    newParent: SurfaceControl?
): SurfaceControl.Transaction

Re-parents a given layer to a new parent. Children inherit transform (position, scaling) crop, visibility, and Z-ordering from their parents, as if the children were pixels within the parent Surface.

setAlpha

open fun setAlpha(
    sc: SurfaceControl, 
    alpha: Float
): SurfaceControl.Transaction

Set the alpha for a given surface. If the alpha is non-zero the SurfaceControl will be blended with the Surfaces under it according to the specified ratio.

setBuffer

open fun setBuffer(
    sc: SurfaceControl, 
    buffer: HardwareBuffer?
): SurfaceControl.Transaction

Updates the HardwareBuffer displayed for the SurfaceControl. Note that the buffer must be allocated with HardwareBuffer#USAGE_COMPOSER_OVERLAY as well as HardwareBuffer#USAGE_GPU_SAMPLED_IMAGE as the surface control might be composited using either an overlay or using the GPU.

setBuffer

open fun setBuffer(
    sc: SurfaceControl, 
    buffer: HardwareBuffer?, 
    fence: SyncFence?
): SurfaceControl.Transaction

Updates the HardwareBuffer displayed for the SurfaceControl. Note that the buffer must be allocated with HardwareBuffer#USAGE_COMPOSER_OVERLAY as well as HardwareBuffer#USAGE_GPU_SAMPLED_IMAGE as the surface control might be composited using either an overlay or using the GPU. A presentation fence may be passed to improve performance by allowing the buffer to complete rendering while it is waiting for the transaction to be applied. For example, if the buffer is being produced by rendering with OpenGL ES then a fence created with android.opengl.EGLExt#eglDupNativeFenceFDANDROID(EGLDisplay, EGLSync) can be used to allow the GPU rendering to be concurrent with the transaction. The compositor will wait for the fence to be signaled before the buffer is displayed. If multiple buffers are set as part of the same transaction, the presentation fences of all of them must signal before any buffer is displayed. That is, the entire transaction is delayed until all presentation fences have signaled, ensuring the transaction remains consistent.

setBuffer

open fun setBuffer(
    sc: SurfaceControl, 
    buffer: HardwareBuffer?, 
    fence: SyncFence?, 
    releaseCallback: Consumer<SyncFence!>?
): SurfaceControl.Transaction

Updates the HardwareBuffer displayed for the SurfaceControl. Note that the buffer must be allocated with HardwareBuffer#USAGE_COMPOSER_OVERLAY as well as HardwareBuffer#USAGE_GPU_SAMPLED_IMAGE as the surface control might be composited using either an overlay or using the GPU. A presentation fence may be passed to improve performance by allowing the buffer to complete rendering while it is waiting for the transaction to be applied. For example, if the buffer is being produced by rendering with OpenGL ES then a fence created with android.opengl.EGLExt#eglDupNativeFenceFDANDROID(EGLDisplay, EGLSync) can be used to allow the GPU rendering to be concurrent with the transaction. The compositor will wait for the fence to be signaled before the buffer is displayed. If multiple buffers are set as part of the same transaction, the presentation fences of all of them must signal before any buffer is displayed. That is, the entire transaction is delayed until all presentation fences have signaled, ensuring the transaction remains consistent. A releaseCallback may be passed to know when the buffer is safe to be reused. This is recommended when attempting to render continuously using SurfaceControl transactions instead of through Surface, as it provides a safe & reliable way to know when a buffer can be re-used. The callback will be invoked with a SyncFence which, if valid, must be waited on prior to using the buffer. This can either be done directly with SyncFence#awaitForever() or it may be done indirectly such as passing it as a release fence to android.media.Image#setFence(SyncFence) when using android.media.ImageReader.

setBufferSize

open fun setBufferSize(
    sc: SurfaceControl, 
    w: Int, 
    h: Int
): SurfaceControl.Transaction

Set the default buffer size for the SurfaceControl, if there is a Surface associated with the control, then this will be the default size for buffers dequeued from it.

setBufferTransform

open fun setBufferTransform(
    sc: SurfaceControl, 
    transform: Int
): SurfaceControl.Transaction

Sets the buffer transform that should be applied to the current buffer. This can be used in combination with AttachedSurfaceControl#addOnBufferTransformHintChangedListener(AttachedSurfaceControl.OnBufferTransformHintChangedListener) to pre-rotate the buffer for the current display orientation. This can improve the performance of displaying the associated buffer.

setCrop

open fun setCrop(
    sc: SurfaceControl, 
    crop: Rect?
): SurfaceControl.Transaction

Bounds the surface and its children to the bounds specified. Size of the surface will be ignored and only the crop and buffer size will be used to determine the bounds of the surface. If no crop is specified and the surface has no buffer, the surface bounds is only constrained by the size of its parent bounds.

setDamageRegion

open fun setDamageRegion(
    sc: SurfaceControl, 
    region: Region?
): SurfaceControl.Transaction

Updates the region for the content on this surface updated in this transaction. The damage region is the area of the buffer that has changed since the previously sent buffer. This can be used to reduce the amount of recomposition that needs to happen when only a small region of the buffer is being updated, such as for a small blinking cursor or a loading indicator.

setDataSpace

open fun setDataSpace(
    sc: SurfaceControl, 
    dataspace: Int
): SurfaceControl.Transaction

Set the dataspace for the SurfaceControl. This will control how the buffer set with setBuffer(android.view.SurfaceControl,android.hardware.HardwareBuffer) is displayed.

setExtendedRangeBrightness

open fun setExtendedRangeBrightness(
    sc: SurfaceControl, 
    currentBufferRatio: Float, 
    desiredRatio: Float
): SurfaceControl.Transaction

Sets the desired extended range brightness for the layer. This only applies for layers whose dataspace has RANGE_EXTENDED.

setFrameRate

open fun setFrameRate(
    sc: SurfaceControl, 
    frameRate: Float, 
    compatibility: Int
): SurfaceControl.Transaction

Sets the intended frame rate for this surface. Any switching of refresh rates is most probably going to be seamless.

setFrameRate

open fun setFrameRate(
    sc: SurfaceControl, 
    frameRate: Float, 
    compatibility: Int, 
    changeFrameRateStrategy: Int
): SurfaceControl.Transaction

Sets the intended frame rate for the surface SurfaceControl.

On devices that are capable of running the display at different refresh rates, the system may choose a display refresh rate to better match this surface's frame rate. Usage of this API won't directly affect the application's frame production pipeline. However, because the system may change the display refresh rate, calls to this function may result in changes to Choreographer callback timings, and changes to the time interval at which the system releases buffers back to the application.

Note that this only has an effect for surfaces presented on the display. If this surface is consumed by something other than the system compositor, e.g. a media codec, this call has no effect.

setGeometry

open fun setGeometry(
    sc: SurfaceControl, 
    sourceCrop: Rect?, 
    destFrame: Rect?, 
    orientation: Int
): SurfaceControl.Transaction

Deprecated: Use setCrop(android.view.SurfaceControl,android.graphics.Rect), setBufferTransform(android.view.SurfaceControl,int), setPosition(android.view.SurfaceControl,float,float) and setScale(android.view.SurfaceControl,float,float) instead.

Specify how the buffer associated with this Surface is mapped in to the parent coordinate space. The source frame will be scaled to fit the destination frame, after being rotated according to the orientation parameter.

setLayer

open fun setLayer(
    sc: SurfaceControl, 
    z: Int
): SurfaceControl.Transaction

Set the Z-order for a given SurfaceControl, relative to it's siblings. If two siblings share the same Z order the ordering is undefined. Surfaces with a negative Z will be placed below the parent surface.

setOpaque

open fun setOpaque(
    sc: SurfaceControl, 
    isOpaque: Boolean
): SurfaceControl.Transaction

Indicates whether the surface must be considered opaque, even if its pixel format is set to translucent. This can be useful if an application needs full RGBA 8888 support for instance but will still draw every pixel opaque.

This flag only determines whether opacity will be sampled from the alpha channel. Plane-alpha from calls to setAlpha() can still result in blended composition regardless of the opaque setting. Combined effects are (assuming a buffer format with an alpha channel):

• OPAQUE + alpha(1.0) == opaque composition
• OPAQUE + alpha(0.x) == blended composition
• OPAQUE + alpha(0.0) == no composition
• !OPAQUE + alpha(1.0) == blended composition
• !OPAQUE + alpha(0.x) == blended composition
• !OPAQUE + alpha(0.0) == no composition

setPosition

open fun setPosition(
    sc: SurfaceControl, 
    x: Float, 
    y: Float
): SurfaceControl.Transaction

Sets the SurfaceControl to the specified position relative to the parent SurfaceControl

setScale

open fun setScale(
    sc: SurfaceControl, 
    scaleX: Float, 
    scaleY: Float
): SurfaceControl.Transaction

Sets the SurfaceControl to the specified scale with (0, 0) as the center point of the scale.

setTrustedPresentationCallback

open fun setTrustedPresentationCallback(
    sc: SurfaceControl, 
    thresholds: SurfaceControl.TrustedPresentationThresholds, 
    executor: Executor, 
    listener: Consumer<Boolean!>
): SurfaceControl.Transaction

Deprecated: Use WindowManager#registerTrustedPresentationListener(IBinder, instead.

Sets a callback to receive feedback about the presentation of a SurfaceControl. When the SurfaceControl is presented according to the passed in TrustedPresentationThresholds, it is said to "enter the state", and receives the callback with true. When the conditions fall out of thresholds, it is then said to leave the state.

There are a few simple thresholds:

• minAlpha: Lower bound on computed alpha
• minFractionRendered: Lower bounds on fraction of pixels that were rendered
• stabilityThresholdMs: A time that alpha and fraction rendered must remain within bounds before we can "enter the state"

The fraction of pixels rendered is a computation based on scale, crop and occlusion. The calculation may be somewhat counterintuitive, so we can work through an example. Imagine we have a SurfaceControl with a 100x100 buffer which is occluded by (10x100) pixels on the left, and cropped by (100x10) pixels on the top. Furthermore imagine this SurfaceControl is scaled by 0.9 in both dimensions. (c=crop,o=occluded,b=both,x=none)

We first start by computing fr=xscale*yscale=0.9*0.9=0.81, indicating that "81%" of the pixels were rendered. This corresponds to what was 100 pixels being displayed in 81 pixels. This is somewhat of an abuse of language, as the information of merged pixels isn't totally lost, but we err on the conservative side.

We then repeat a similar process for the crop and covered regions and accumulate the results: fr = fr * (fractionNotCropped) * (fractionNotCovered) So for this example we would get 0.9*0.9*0.9*0.9=0.65...

Notice that this is not completely accurate, as we have double counted the region marked as b. However we only wanted a "lower bound" and so it is ok to err in this direction. Selection of the threshold will ultimately be somewhat arbitrary, and so there are some somewhat arbitrary decisions in this API as well.

setVisibility

open fun setVisibility(
    sc: SurfaceControl, 
    visible: Boolean
): SurfaceControl.Transaction

Toggle the visibility of a given Layer and it's sub-tree.

writeToParcel

open fun writeToParcel(
    dest: Parcel, 
    flags: Int
): Unit

Writes the transaction to parcel, clearing the transaction as if it had been applied so it can be used to store future transactions. It's the responsibility of the parcel reader to apply the original transaction.

CREATOR

static val CREATOR: Parcelable.Creator<SurfaceControl.Transaction!>