InProgressStroke

class InProgressStroke

Use an InProgressStroke to efficiently build a stroke over multiple rendering frames with incremental inputs.

To use an InProgressStroke, you would typically:

  1. Begin a stroke by calling start with a chosen Brush.

  2. Repeatedly update the stroke:

    1. Call enqueueInputs with any new real and predicted stroke inputs.

    2. Call updateShape when needsUpdate is true and new geometry is needed for rendering.

    3. Render the current stroke mesh or outlines, either via a provided renderer that accepts an InProgressStroke or by using the various getters on this type with a custom renderer.

  3. Call finishInput once there are no more inputs for this stroke (e.g. the user lifts the stylus from the screen).

  4. Continue to call updateShape and render after finishInput until getNeedsUpdate returns false (to allow any lingering brush animations to complete).

  5. Extract the completed stroke by calling toImmutable.

  6. For best performance, reuse this object and go back to step 1 rather than allocating a new instance.

Summary

Public constructors

Public functions
Result<Unit>
enqueueInputs(
    realInputs: StrokeInputBatch,
    predictedInputs: StrokeInputBatch
)

Enqueues the incremental realInputs and sets the prediction to predictedInputs, overwriting any previous prediction.
Unit
enqueueInputsOrThrow(
    realInputs: StrokeInputBatch,
    predictedInputs: StrokeInputBatch
)
Unit

Indicates that the inputs for the current stroke are finished.
@IntRange(from = 0) Int

Returns the number of BrushCoats for the current brush, or zero if start has not been called.
@IntRange(from = 0) Int

Returns the number of StrokeInputs in the stroke so far.
Boolean

Returns true if calling updateShape would have any effect on the stroke (and should thus be called before the next render), or false if no calls to updateShape are currently needed.
@IntRange(from = 0) Int
getOutlineCount(coatIndex: @IntRange(from = 0) Int)

Returns the number of outlines for the specified brush coat.
@IntRange(from = 0) Int
getOutlineVertexCount(
    coatIndex: @IntRange(from = 0) Int,
    outlineIndex: @IntRange(from = 0) Int
)

Returns the number of outline points for the specified outline and brush coat.
@IntRange(from = 0) Int

Returns the number of inputs in the current stroke prediction.
@IntRange(from = 0) Int
Boolean

Returns true if finishInput has been called since the last call to start, or if start hasn't been called yet.
StrokeInput
populateInput(out: StrokeInput, index: @IntRange(from = 0) Int)

Gets the value of the i-th input and overwrites out.
MutableStrokeInputBatch
populateInputs(
    out: MutableStrokeInputBatch,
    from: @IntRange(from = 0) Int,
    to: @IntRange(from = 0) Int
)

Add the specified range of inputs from this stroke to the output MutableStrokeInputBatch.
BoxAccumulator
populateMeshBounds(
    coatIndex: @IntRange(from = 0) Int,
    outBoxAccumulator: BoxAccumulator
)

Writes to outBoxAccumulator the bounding box of the vertex positions of the mesh for brush coat coatIndex.
Unit
populateOutlinePosition(
    coatIndex: @IntRange(from = 0) Int,
    outlineIndex: @IntRange(from = 0) Int,
    outlineVertexIndex: @IntRange(from = 0) Int,
    outPosition: MutableVec
)

Fills outPosition with the x- and y- coordinates of the specified outline vertex.
BoxAccumulator

Returns the bounding rectangle of mesh positions added, modified, or removed by calls to updateShape since the most recent call to start or resetUpdatedRegion.
Unit

Call after making use of a value from populateUpdatedRegion to reset the accumulation.
Unit
start(brush: Brush)

Clears and starts a new stroke with the given brush.
Stroke

Copies the current input, brush, and geometry as of the last call to start or updateShape to a new Stroke.
Result<Unit>
updateShape(currentElapsedTimeMillis: Long)

Updates the stroke geometry up to the given duration since the start of the stroke.
Unit
updateShapeOrThrow(currentElapsedTimeMillis: Long)

Protected functions
Unit

Public properties
Brush?

The Brush currently being used to generate the stroke content.

Public constructors

InProgressStroke

Added in 1.0.0-alpha01
InProgressStroke()

Public functions

enqueueInputs

Added in 1.0.0-alpha01
fun enqueueInputs(
    realInputs: StrokeInputBatch,
    predictedInputs: StrokeInputBatch
): Result<Unit>

Enqueues the incremental realInputs and sets the prediction to predictedInputs, overwriting any previous prediction. Queued inputs will be processed on the next call to updateShape.

This method requires that:

If the above requirements are not satisfied, the Result will be a failure and this object is left in the state it had prior to the call.

Either one or both of realInputs and predictedInputs may be empty.

enqueueInputsOrThrow

Added in 1.0.0-alpha01
fun enqueueInputsOrThrow(
    realInputs: StrokeInputBatch,
    predictedInputs: StrokeInputBatch
): Unit
See also
enqueueInputs

finishInput

Added in 1.0.0-alpha01
fun finishInput(): Unit

Indicates that the inputs for the current stroke are finished. After calling this, it is an error to call enqueueInputs until start is called again to start a new stroke. This method is idempotent; it has no effect if start was never called, or if this method has already been called since the last call to start.

getBrushCoatCount

Added in 1.0.0-alpha01
fun getBrushCoatCount(): @IntRange(from = 0) Int

Returns the number of BrushCoats for the current brush, or zero if start has not been called.

getInputCount

Added in 1.0.0-alpha01
fun getInputCount(): @IntRange(from = 0) Int

Returns the number of StrokeInputs in the stroke so far. This counts all of the real inputs and the most-recently-processed sequence of predicted inputs.

getNeedsUpdate

Added in 1.0.0-alpha01
fun getNeedsUpdate(): Boolean

Returns true if calling updateShape would have any effect on the stroke (and should thus be called before the next render), or false if no calls to updateShape are currently needed. Specifically:

  • If the brush has one or more timed animation behavior that are still active (which can be true even after inputs are finished), returns true.

  • If there are no active animation behaviors, but there are pending inputs from an enqueueInputs call that have not yet been consumed by a call to updateShape, returns true.

  • Otherwise, returns false.

Once isInputFinished returns true and this method returns false, the stroke is considered "dry", and will not change any further until the next call to start.

getOutlineCount

Added in 1.0.0-alpha01
fun getOutlineCount(coatIndex: @IntRange(from = 0) Int): @IntRange(from = 0) Int

Returns the number of outlines for the specified brush coat. Calls to functions that accept an outlineIndex must treat the result of this function as an upper bound.

Parameters
coatIndex: @IntRange(from = 0) Int

Must be between 0 (inclusive) and the result of getBrushCoatCount (exclusive).

getOutlineVertexCount

Added in 1.0.0-alpha01
fun getOutlineVertexCount(
    coatIndex: @IntRange(from = 0) Int,
    outlineIndex: @IntRange(from = 0) Int
): @IntRange(from = 0) Int

Returns the number of outline points for the specified outline and brush coat. populateOutlinePosition must treat the result of this as the upper bound of its outlineVertexIndex parameter.

Parameters
coatIndex: @IntRange(from = 0) Int

Must be between 0 (inclusive) and the result of getBrushCoatCount (exclusive).
outlineIndex: @IntRange(from = 0) Int

Must be between 0 (inclusive) and the result of getOutlineCount for the same coatIndex (exclusive).

getPredictedInputCount

Added in 1.0.0-alpha01
fun getPredictedInputCount(): @IntRange(from = 0) Int

Returns the number of inputs in the current stroke prediction.

getRealInputCount

Added in 1.0.0-alpha01
fun getRealInputCount(): @IntRange(from = 0) Int

isInputFinished

Added in 1.0.0-alpha01
fun isInputFinished(): Boolean

Returns true if finishInput has been called since the last call to start, or if start hasn't been called yet. If this returns true, it is an error to call enqueueInputs.

populateInput

Added in 1.0.0-alpha01
fun populateInput(out: StrokeInput, index: @IntRange(from = 0) Int): StrokeInput

Gets the value of the i-th input and overwrites out. Requires that index is positive and less than getInputCount.

Returns
StrokeInput

out

populateInputs

Added in 1.0.0-alpha01
fun populateInputs(
    out: MutableStrokeInputBatch,
    from: @IntRange(from = 0) Int = 0,
    to: @IntRange(from = 0) Int = getInputCount()
): MutableStrokeInputBatch

Add the specified range of inputs from this stroke to the output MutableStrokeInputBatch.

Returns
MutableStrokeInputBatch

out

populateMeshBounds

Added in 1.0.0-alpha01
fun populateMeshBounds(
    coatIndex: @IntRange(from = 0) Int,
    outBoxAccumulator: BoxAccumulator
): BoxAccumulator

Writes to outBoxAccumulator the bounding box of the vertex positions of the mesh for brush coat coatIndex.

Parameters
coatIndex: @IntRange(from = 0) Int

The index of the coat to obtain the bounding box from.
outBoxAccumulator: BoxAccumulator

The pre-allocated BoxAccumulator to be filled with the result.
Returns
BoxAccumulator

outBoxAccumulator

populateOutlinePosition

Added in 1.0.0-alpha01
fun populateOutlinePosition(
    coatIndex: @IntRange(from = 0) Int,
    outlineIndex: @IntRange(from = 0) Int,
    outlineVertexIndex: @IntRange(from = 0) Int,
    outPosition: MutableVec
): Unit

Fills outPosition with the x- and y- coordinates of the specified outline vertex.

Parameters
coatIndex: @IntRange(from = 0) Int

Must be between 0 (inclusive) and the result of getBrushCoatCount (exclusive).
outlineIndex: @IntRange(from = 0) Int

Must be between 0 (inclusive) and the result of getOutlineCount (exclusive) for the same coatIndex.
outlineVertexIndex: @IntRange(from = 0) Int

Must be between 0 (inclusive) and the result of getOutlineVertexCount (exclusive) for the same coatIndex and outlineIndex.
outPosition: MutableVec

the pre-allocated MutableVec to be filled with the result.

populateUpdatedRegion

Added in 1.0.0-alpha01
fun populateUpdatedRegion(outBoxAccumulator: BoxAccumulator): BoxAccumulator

Returns the bounding rectangle of mesh positions added, modified, or removed by calls to updateShape since the most recent call to start or resetUpdatedRegion.

Parameters
outBoxAccumulator: BoxAccumulator

The pre-allocated BoxAccumulator to be filled with the result.
Returns
BoxAccumulator

outBoxAccumulator

resetUpdatedRegion

Added in 1.0.0-alpha01
fun resetUpdatedRegion(): Unit

Call after making use of a value from populateUpdatedRegion to reset the accumulation.

start

Added in 1.0.0-alpha01
fun start(brush: Brush): Unit

Clears and starts a new stroke with the given brush.

This includes clearing or resetting any existing inputs, mesh data, and updated region. This method must be called at least once after construction before starting to call enqueueInputs or updateShape.

toImmutable

Added in 1.0.0-alpha01
fun toImmutable(): Stroke

Copies the current input, brush, and geometry as of the last call to start or updateShape to a new Stroke.

The resulting Stroke will not be modified if further inputs are added to this InProgressStroke, and a Stroke created by another call to this method will not modify or be connected in any way to the prior Stroke.

updateShape

Added in 1.0.0-alpha01
fun updateShape(currentElapsedTimeMillis: Long = Long.MAX_VALUE): Result<Unit>

Updates the stroke geometry up to the given duration since the start of the stroke. This will will consume any inputs queued up by calls to enqueueInputs, and cause brush animations (if any) to progress up to the specified time. Any stroke geometry resulting from previously-predicted input from before the previous call to this method will be cleared.

This method requires that:

  • start has been previously called to set the current brush.

  • The value of currentElapsedTimeMillis passed into this method over the course of a single stroke must be non-decreasing and non-negative. Its default value causes all ongoing stroke animations to be completed immediately. To have animations progress at their intended rate, pass in values for this field that are in the same time base as the StrokeInput.elapsedTimeMillis values being passed to enqueueInputs, repeatedly until isInputFinished returns true.

If the above requirements are not satisfied, the Result will be a failure and this object is left in the state it had prior to the call.

updateShapeOrThrow

Added in 1.0.0-alpha01
fun updateShapeOrThrow(currentElapsedTimeMillis: Long = Long.MAX_VALUE): Unit
See also
updateShape

Protected functions

finalize

Added in 1.0.0-alpha01
protected fun finalize(): Unit

Public properties

brush

Added in 1.0.0-alpha01
val brush: Brush?

The Brush currently being used to generate the stroke content. To set this, call start.