InProgressStroke


public final 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 isUpdateNeeded 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 isUpdateNeeded returns false (to allow any lingering brush shape 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 methods

final void
enqueueInputs(
    @NonNull StrokeInputBatch realInputs,
    @NonNull StrokeInputBatch predictedInputs
)

Enqueues the incremental realInputs and sets the prediction to predictedInputs, overwriting any previous prediction.

final void

Indicates that the inputs for the current stroke are finished.

final Brush

The Brush currently being used to generate the stroke content.

final @IntRange(from = 0) int

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

final @IntRange(from = 0) int

Returns the number of StrokeInputs in the stroke so far.

final @IntRange(from = 0) int
getOutlineCount(@IntRange(from = 0) int coatIndex)

Returns the number of outlines for the specified brush coat.

final @IntRange(from = 0) int
getOutlineVertexCount(
    @IntRange(from = 0) int coatIndex,
    @IntRange(from = 0) int outlineIndex
)

Returns the number of outline points for the specified outline and brush coat.

final @IntRange(from = 0) int

Returns the number of inputs in the current stroke prediction.

final @IntRange(from = 0) int
final boolean

Returns true if finishInput has been called since the last call to start, or if start hasn't been called yet.

final 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.

final @NonNull StrokeInput
populateInput(@NonNull StrokeInput out, @IntRange(from = 0) int index)

Gets the value of the i-th input and overwrites out.

final @NonNull MutableStrokeInputBatch
populateInputs(
    @NonNull MutableStrokeInputBatch out,
    @IntRange(from = 0) int from,
    @IntRange(from = 0) int to
)

Replace the contents of the MutableStrokeInputBatch with the specified range of inputs from the this InProgressStroke.

final @NonNull BoxAccumulator
populateMeshBounds(
    @IntRange(from = 0) int coatIndex,
    @NonNull BoxAccumulator outMeshBounds
)

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

final @NonNull MutableVec
populateOutlinePosition(
    @IntRange(from = 0) int coatIndex,
    @IntRange(from = 0) int outlineIndex,
    @IntRange(from = 0) int outlineVertexIndex,
    @NonNull MutableVec outPosition
)

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

final @NonNull 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.

final void

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

final void

Clears and starts a new stroke with the given brush.

final @NonNull Stroke

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

final void
updateShape(long currentElapsedTimeMillis)

Updates the stroke geometry up to the given duration since the start of the stroke.

Protected methods

final void

Public constructors

InProgressStroke

Added in 1.0.0-alpha05
public InProgressStroke()

Public methods

enqueueInputs

Added in 1.0.0-alpha05
public final void enqueueInputs(
    @NonNull StrokeInputBatch realInputs,
    @NonNull StrokeInputBatch predictedInputs
)

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:

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

Throws
kotlin.IllegalStateException

If start has not been called since construction or the last call to finishInput.

kotlin.IllegalArgumentException

If the input is not valid. Note that this can be a common occurrence with real user input on certain devices, in particular due to duplicate or out-of-order inputs. Therefore, users should either catch and handle this exception or sanitize the input to avoid ensure validity before passing it to this function.

finishInput

Added in 1.0.0-alpha05
public final void finishInput()

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. This method is synchronous, but the stroke may not be fully finished changing shape due to brush shape animations until isUpdateNeeded returns false. Until that condition is met, keep calling updateShape periodically and rendering the result.

getBrush

Added in 1.0.0-alpha05
public final Brush getBrush()

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

getBrushCoatCount

Added in 1.0.0-alpha05
public final @IntRange(from = 0) int getBrushCoatCount()

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

getInputCount

Added in 1.0.0-alpha05
public final @IntRange(from = 0) int getInputCount()

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.

getOutlineCount

Added in 1.0.0-alpha05
public final @IntRange(from = 0) int getOutlineCount(@IntRange(from = 0) int coatIndex)

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. Coats with discontinuous geometry will always have multiple outlines, but even continuous geometry may be drawn with multiple overlapping outlines when this improves rendering quality or performance.

Parameters
@IntRange(from = 0) int coatIndex

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

getOutlineVertexCount

Added in 1.0.0-alpha05
public final @IntRange(from = 0) int getOutlineVertexCount(
    @IntRange(from = 0) int coatIndex,
    @IntRange(from = 0) int outlineIndex
)

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
@IntRange(from = 0) int coatIndex

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

@IntRange(from = 0) int outlineIndex

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

getPredictedInputCount

Added in 1.0.0-alpha05
public final @IntRange(from = 0) int getPredictedInputCount()

Returns the number of inputs in the current stroke prediction.

getRealInputCount

Added in 1.0.0-alpha05
public final @IntRange(from = 0) int getRealInputCount()

isInputFinished

Added in 1.0.0-alpha05
public final boolean isInputFinished()

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.

isUpdateNeeded

Added in 1.0.0-alpha05
public final boolean isUpdateNeeded()

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 shape animation behavior that are still active (which can be true even after inputs are finished), returns true.

  • If there are no active shape 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.

populateInput

Added in 1.0.0-alpha05
public final @NonNull StrokeInput populateInput(@NonNull StrokeInput out, @IntRange(from = 0) int index)

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

Returns the passed-in StrokeInput to make it easier to chain calls.

populateInputs

Added in 1.0.0-alpha05
public final @NonNull MutableStrokeInputBatch populateInputs(
    @NonNull MutableStrokeInputBatch out,
    @IntRange(from = 0) int from,
    @IntRange(from = 0) int to
)

Replace the contents of the MutableStrokeInputBatch with the specified range of inputs from the this InProgressStroke. By default, all inputs are copied.

Returns the passed-in MutableStrokeInputBatch to make it easier to chain calls.

populateMeshBounds

Added in 1.0.0-alpha05
public final @NonNull BoxAccumulator populateMeshBounds(
    @IntRange(from = 0) int coatIndex,
    @NonNull BoxAccumulator outMeshBounds
)

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

Returns the passed in BoxAccumulator to make it easier to chain calls.

Parameters
@IntRange(from = 0) int coatIndex

The index of the coat to obtain the bounding box from.

@NonNull BoxAccumulator outMeshBounds

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

populateOutlinePosition

Added in 1.0.0-alpha05
public final @NonNull MutableVec populateOutlinePosition(
    @IntRange(from = 0) int coatIndex,
    @IntRange(from = 0) int outlineIndex,
    @IntRange(from = 0) int outlineVertexIndex,
    @NonNull MutableVec outPosition
)

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

Returns the passed-in MutableVec to make it easier to chain calls.

Parameters
@IntRange(from = 0) int coatIndex

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

@IntRange(from = 0) int outlineIndex

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

@IntRange(from = 0) int outlineVertexIndex

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

@NonNull MutableVec outPosition

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

populateUpdatedRegion

Added in 1.0.0-alpha05
public final @NonNull BoxAccumulator populateUpdatedRegion(@NonNull BoxAccumulator outUpdatedRegion)

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

Returns the passed in BoxAccumulator to make it easier to chain calls.

Parameters
@NonNull BoxAccumulator outUpdatedRegion

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

resetUpdatedRegion

Added in 1.0.0-alpha05
public final void resetUpdatedRegion()

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

start

Added in 1.0.0-alpha05
public final void start(@NonNull Brush brush)

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 making any calls to enqueueInputs or updateShape.

toImmutable

Added in 1.0.0-alpha05
public final @NonNull Stroke toImmutable()

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-alpha05
public final void updateShape(long currentElapsedTimeMillis)

Updates the stroke geometry up to the given duration since the start of the stroke. This will consume any inputs queued up by calls to enqueueInputs, and cause brush shape 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:

Clients that do not use brushes with shape animation behaviors can omit currentElapsedTimeMillis. Doing so when using brushes with shape animation beaviors will cause the animation to be completed immediately.

Throws
kotlin.IllegalStateException

If start has not been called.

kotlin.IllegalArgumentException

If currentElapsedTimeMillis is negative or decreased from a previous call to this method for the same in-progress stroke.

Protected methods

finalize

Added in 1.0.0-alpha05
protected final void finalize()