LowLatencyCanvasView


@RequiresApi(value = 29)
public final class LowLatencyCanvasView extends ViewGroup


View implementation that leverages a "front buffered" rendering system. This allows for lower latency graphics by leveraging a combination of front buffered alongside multi-buffered content layers. This class provides similar functionality to CanvasFrontBufferedRenderer, however, leverages the traditional View system for implementing the multi buffered content instead of a separate SurfaceControlCompat instance and entirely abstracts all SurfaceView usage for simplicity.

Drawing of this View's content is handled by a consumer specified LowLatencyCanvasView.Callback implementation instead of View.onDraw. Rendering here is done with a Canvas into a single buffer that is presented on screen above the rest of the View hierarchy content. This overlay is transient and will only be visible after LowLatencyCanvasView.renderFrontBufferedLayer is called and hidden after LowLatencyCanvasView.commit is invoked. After LowLatencyCanvasView.commit is invoked, this same buffer is wrapped into a bitmap and drawn within this View's View.onDraw implementation.

Calls to LowLatencyCanvasView.renderFrontBufferedLayer will trigger LowLatencyCanvasView.Callback.onDrawFrontBufferedLayer to be invoked to handle drawing of content with the provided Canvas.

After LowLatencyCanvasView.commit is called, the overlay is hidden and the buffer is drawn within the View hierarchy, similar to traditional View implementations.

A common use case would be a drawing application that intends to minimize the amount of latency when content is drawn with a stylus. In this case, touch events between MotionEvent.ACTION_DOWN and MotionEvent.ACTION_MOVE can trigger calls to LowLatencyCanvasView.renderFrontBufferedLayer which will minimize the delay between then the content is visible on screen. Finally when the gesture is complete on MotionEvent.ACTION_UP, a call to LowLatencyCanvasView.commit would be invoked to hide the transient overlay and render the scene within the View hierarchy like a traditional View. This helps provide a balance of low latency guarantees while mitigating potential tearing artifacts.

This helps support low latency rendering for simpler use cases at the expensive of configuration customization of the multi buffered layer content.

import androidx.annotation.WorkerThread
import androidx.graphics.lowlatency.LowLatencyCanvasView

LowLatencyCanvasView(context).apply {
    setBackgroundColor(Color.WHITE)

    data class Line(
        val x1: Float,
        val y1: Float,
        val x2: Float,
        val y2: Float,
    )
    // Thread safe collection to support creation of new lines from the UI thread as well as
    // consumption of lines from the background drawing thread
    val lines = Collections.synchronizedList(ArrayList<Line>())
    setRenderCallback(object : LowLatencyCanvasView.Callback {

        val mAllLines = ArrayList<Line>()

        private val mPaint = Paint(Paint.ANTI_ALIAS_FLAG).apply {
            strokeWidth = 15f
            color = Color.CYAN
            alpha = 128
        }

        @WorkerThread
        override fun onRedrawRequested(
            canvas: Canvas,
            width: Int,
            height: Int
        ) {
            for (line in mAllLines) {
                canvas.drawLine(line.x1, line.y1, line.x2, line.y2, mPaint)
            }
        }

        @WorkerThread
        override fun onDrawFrontBufferedLayer(
            canvas: Canvas,
            width: Int,
            height: Int
        ) {
            lines.removeFirstOrNull()?.let { line ->
                mAllLines.add(line)
                canvas.drawLine(line.x1, line.y1, line.x2, line.y2, mPaint)
            }
        }
    })
    setOnTouchListener(object : View.OnTouchListener {

        var mCurrentX = -1f
        var mCurrentY = -1f
        var mPreviousX = -1f
        var mPreviousY = -1f

        override fun onTouch(v: View?, event: MotionEvent?): Boolean {
            if (event == null) return false
            when (event.action) {
                MotionEvent.ACTION_DOWN -> {
                    requestUnbufferedDispatch(event)
                    mCurrentX = event.x
                    mCurrentY = event.y
                }
                MotionEvent.ACTION_MOVE -> {
                    mPreviousX = mCurrentX
                    mPreviousY = mCurrentY
                    mCurrentX = event.x
                    mCurrentY = event.y

                    val line = Line(mPreviousX, mPreviousY, mCurrentX, mCurrentY)
                    lines.add(line)
                    renderFrontBufferedLayer()
                }
                MotionEvent.ACTION_CANCEL -> {
                    cancel()
                }
                MotionEvent.ACTION_UP -> {
                    commit()
                }
            }
            return true
        }
    })
}

Summary

Nested types

Provides callbacks for consumers to draw into the front buffered overlay as well as provide opportunities to synchronize SurfaceControlCompat.Transactions to submit the layers to the hardware compositor

Public constructors

LowLatencyCanvasView(
    @NonNull Context context,
    AttributeSet attrs,
    int defStyle
)

Public methods

void
addView(View child)
void
addView(View child, int index)
void
void
addView(View child, int index, ViewGroup.LayoutParams params)
void
addView(View child, int width, int height)
final void

Cancels any in progress request to render to the front buffer and hides the front buffered overlay.

final void

Clears the content of the buffer and hides the front buffered overlay.

final void

Invalidates this View and draws the buffer within View#onDraw.

final void

Dispatches a runnable to be executed on the background rendering thread.

final void

Render content to the front buffered layer.

final void

Configures the Callback used to render contents to the front buffered overlay as well as optionally configuring the SurfaceControlCompat.Transaction used to update contents on screen.

Protected methods

void
void
void
onLayout(boolean changed, int l, int t, int r, int b)

Inherited methods

From android.view.View
void
void
void
void
@NonNull ViewPropertyAnimator
void
void
void
boolean
boolean
boolean
awakenScrollBars(int p0, boolean p1)
void
void

This method is deprecated. Deprecated in Java

void
buildDrawingCache(boolean p0)

This method is deprecated. Deprecated in Java

void
boolean
boolean
boolean
boolean
boolean
boolean
final void
void
final void
boolean
void
void
int
int
int
void
@NonNull WindowInsets
int
int
int
@NonNull AccessibilityNodeInfo
void
void

This method is deprecated. Deprecated in Java

boolean
boolean
dispatchNestedFling(float p0, float p1, boolean p2)
boolean
dispatchNestedPreFling(float p0, float p1)
boolean
boolean
dispatchNestedPreScroll(
    int p0,
    int p1,
    @Nullable int[] p2,
    @Nullable int[] p3
)
boolean
dispatchNestedScroll(int p0, int p1, int p2, int p3, @Nullable int[] p4)
boolean
void
void
drawableHotspotChanged(float p0, float p1)
final @Nullable OnBackInvokedDispatcher
final @NonNull T
<T extends View> findViewById(int p0)
final @NonNull T
<T extends View> findViewWithTag(@NonNull Object p0)
boolean

This method is deprecated. Deprecated in Java

@NonNull View
focusSearch(int p0)
void
void
void
generateDisplayHash(
    @NonNull String p0,
    @Nullable Rect p1,
    @NonNull Executor p2,
    @NonNull DisplayHashResultCallback p3
)
@NonNull View.AccessibilityDelegate
int
@NonNull AccessibilityNodeProvider
@Nullable CharSequence
int
int
@Nullable String
@Nullable String
float
@ViewDebug.ExportedProperty(category = "drawing")
getAlpha()
@NonNull Animation
@Nullable Matrix
@NonNull IBinder
@NonNull int[]
@NonNull Map<@NonNull Integer, @NonNull Integer>
@Nullable String[]
final @NonNull AutofillId
int
@Nullable AutofillValue
@NonNull Drawable
@Nullable BlendMode
@Nullable ColorStateList
@Nullable PorterDuff.Mode
int
@ViewDebug.ExportedProperty(category = "layout")
getBaseline()
final int
float
int
float
@NonNull Rect
boolean
final boolean
final @Nullable ContentCaptureSession
@NonNull CharSequence
@ViewDebug.ExportedProperty(category = "accessibility")
getContentDescription()
final @NonNull Context
@NonNull ContextMenu.ContextMenuInfo
final boolean
@NonNull Display
final @NonNull int[]
@NonNull Bitmap

This method is deprecated. Deprecated in Java

@NonNull Bitmap
getDrawingCache(boolean p0)

This method is deprecated. Deprecated in Java

int

This method is deprecated. Deprecated in Java

int

This method is deprecated. Deprecated in Java

void
long
float
@ViewDebug.ExportedProperty(category = "drawing")
getElevation()
int
boolean
boolean
int
@ViewDebug.ExportedProperty(mapping = [@ViewDebug.IntToString(from = 0, to = "NOT_FOCUSABLE"), @ViewDebug.IntToString(from = 1, to = "FOCUSABLE"), @ViewDebug.IntToString(from = 16, to = "FOCUSABLE_AUTO")], category = "focus")
getFocusable()
@NonNull ArrayList<@NonNull View>
getFocusables(int p0)
void
@NonNull Drawable
int
@Nullable BlendMode
@Nullable ColorStateList
@Nullable PorterDuff.Mode
final boolean
boolean
@NonNull Handler
float
float
float
float
@Nullable Runnable
final boolean
final int
@ViewDebug.ExportedProperty(category = "layout")
getHeight()
void
int
int
@Nullable Drawable
@Nullable Drawable
int
int
@ViewDebug.ExportedProperty(category = "accessibility", mapping = [@ViewDebug.IntToString(from = 0, to = "auto"), @ViewDebug.IntToString(from = 1, to = "yes"), @ViewDebug.IntToString(from = 2, to = "no"), @ViewDebug.IntToString(from = 4, to = "noHideDescendants")])
getImportantForAccessibility()
int
@ViewDebug.ExportedProperty(mapping = [@ViewDebug.IntToString(from = 0, to = "auto"), @ViewDebug.IntToString(from = 1, to = "yes"), @ViewDebug.IntToString(from = 2, to = "no"), @ViewDebug.IntToString(from = 4, to = "yesExcludeDescendants"), @ViewDebug.IntToString(from = 8, to = "noExcludeDescendants")])
getImportantForAutofill()
int
@ViewDebug.ExportedProperty(mapping = [@ViewDebug.IntToString(from = 0, to = "auto"), @ViewDebug.IntToString(from = 1, to = "yes"), @ViewDebug.IntToString(from = 2, to = "no"), @ViewDebug.IntToString(from = 4, to = "yesExcludeDescendants"), @ViewDebug.IntToString(from = 8, to = "noExcludeDescendants")])
getImportantForContentCapture()
boolean
@NonNull KeyEvent.DispatcherState
int
@ViewDebug.ExportedProperty(category = "accessibility")
getLabelFor()
int
int
@ViewDebug.ExportedProperty(category = "layout", mapping = [@ViewDebug.IntToString(from = 0, to = "RESOLVED_DIRECTION_LTR"), @ViewDebug.IntToString(from = 1, to = "RESOLVED_DIRECTION_RTL")])
getLayoutDirection()
@NonNull ViewGroup.LayoutParams
@ViewDebug.ExportedProperty(deepExport = true, prefix = "layout_")
getLayoutParams()
final int
float
int
final boolean
void
void
void
@NonNull Matrix
final int
final int
@ViewDebug.ExportedProperty(category = "measurement", flagMapping = [@ViewDebug.FlagToString(mask = -16777216, equals = 16777216, name = "MEASURED_STATE_TOO_SMALL")])
getMeasuredHeightAndState()
final int
final int
final int
@ViewDebug.ExportedProperty(category = "measurement", flagMapping = [@ViewDebug.FlagToString(mask = -16777216, equals = 16777216, name = "MEASURED_STATE_TOO_SMALL")])
getMeasuredWidthAndState()
int
int
int
int
int
int
int
int
@NonNull View.OnFocusChangeListener
int
@NonNull ViewOutlineProvider
int
int
int
int
int
int
int
int
final @NonNull ViewParent
@NonNull ViewParent
float
@ViewDebug.ExportedProperty(category = "drawing")
getPivotX()
float
@ViewDebug.ExportedProperty(category = "drawing")
getPivotY()
@NonNull PointerIcon
final @NonNull List<@NonNull Rect>
@Nullable String[]
@NonNull Resources
final boolean
final int
float
int
@Nullable AttachedSurfaceControl
@NonNull View
@NonNull WindowInsets
float
@ViewDebug.ExportedProperty(category = "drawing")
getRotation()
float
@ViewDebug.ExportedProperty(category = "drawing")
getRotationX()
float
@ViewDebug.ExportedProperty(category = "drawing")
getRotationY()
float
@ViewDebug.ExportedProperty(category = "drawing")
getScaleX()
float
@ViewDebug.ExportedProperty(category = "drawing")
getScaleY()
int
int
int
int
@ViewDebug.ExportedProperty(mapping = [@ViewDebug.IntToString(from = 0, to = "INSIDE_OVERLAY"), @ViewDebug.IntToString(from = 16777216, to = "INSIDE_INSET"), @ViewDebug.IntToString(from = 33554432, to = "OUTSIDE_OVERLAY"), @ViewDebug.IntToString(from = 50331648, to = "OUTSIDE_INSET")])
getScrollBarStyle()
int
int
final int
final int
int
@ViewDebug.ExportedProperty(category = "drawing")
getSolidColor()
int
final @Nullable CharSequence
@ViewDebug.ExportedProperty(category = "accessibility")
getStateDescription()
@NonNull StateListAnimator
int
int
@NonNull List<@NonNull Rect>
int

This method is deprecated. Deprecated in Java

@NonNull Object
@NonNull Object
getTag(int p0)
int
@ViewDebug.ExportedProperty(category = "text", mapping = [@ViewDebug.IntToString(from = 0, to = "INHERIT"), @ViewDebug.IntToString(from = 1, to = "GRAVITY"), @ViewDebug.IntToString(from = 2, to = "TEXT_START"), @ViewDebug.IntToString(from = 3, to = "TEXT_END"), @ViewDebug.IntToString(from = 4, to = "CENTER"), @ViewDebug.IntToString(from = 5, to = "VIEW_START"), @ViewDebug.IntToString(from = 6, to = "VIEW_END")])
getTextAlignment()
int
@ViewDebug.ExportedProperty(category = "text", mapping = [@ViewDebug.IntToString(from = 0, to = "INHERIT"), @ViewDebug.IntToString(from = 1, to = "FIRST_STRONG"), @ViewDebug.IntToString(from = 2, to = "ANY_RTL"), @ViewDebug.IntToString(from = 3, to = "LTR"), @ViewDebug.IntToString(from = 4, to = "RTL"), @ViewDebug.IntToString(from = 5, to = "LOCALE"), @ViewDebug.IntToString(from = 6, to = "FIRST_STRONG_LTR"), @ViewDebug.IntToString(from = 7, to = "FIRST_STRONG_RTL")])
getTextDirection()
@Nullable CharSequence
final int
float
int
@NonNull TouchDelegate
@NonNull ArrayList<@NonNull View>
float
@NonNull String
float
float
float
long
int
int
@Nullable Drawable
@Nullable Drawable
int
@Nullable ViewTranslationResponse
@NonNull ViewTreeObserver
int
@ViewDebug.ExportedProperty(mapping = [@ViewDebug.IntToString(from = 0, to = "VISIBLE"), @ViewDebug.IntToString(from = 4, to = "INVISIBLE"), @ViewDebug.IntToString(from = 8, to = "GONE")])
getVisibility()
final int
@ViewDebug.ExportedProperty(category = "layout")
getWidth()
int
@NonNull WindowId
@Nullable WindowInsetsController
int

This method is deprecated. Deprecated in Java

@NonNull IBinder
int
void
float
@ViewDebug.ExportedProperty(category = "drawing")
getX()
float
@ViewDebug.ExportedProperty(category = "drawing")
getY()
float
@ViewDebug.ExportedProperty(category = "drawing")
getZ()
boolean
boolean
boolean
boolean
boolean
boolean
boolean
boolean
void
void

This method is deprecated. Deprecated in Java

void
invalidate(int p0, int p1, int p2, int p3)

This method is deprecated. Deprecated in Java

void
void
boolean
boolean
boolean
boolean
boolean
boolean
boolean
boolean
boolean
boolean
boolean

This method is deprecated. Deprecated in Java

boolean
boolean
final boolean
@ViewDebug.ExportedProperty(category = "focus")
isFocusable()
final boolean
boolean
@ViewDebug.ExportedProperty(category = "focus")
isFocused()
final boolean
boolean
boolean
boolean
boolean
boolean
boolean
boolean
boolean
final boolean
final boolean
boolean
boolean
boolean
final boolean
boolean
boolean
boolean
boolean
boolean
boolean
@ViewDebug.ExportedProperty(category = "drawing")
isOpaque()
boolean
boolean
boolean
final boolean
boolean
boolean
boolean
boolean
boolean
boolean
boolean
final boolean
boolean
boolean
final boolean
boolean
boolean
boolean
boolean
boolean
@NonNull View
final void
measure(int p0, int p1)
void
void
void
void
@NonNull WindowInsets
void
boolean
boolean
void
void
@NonNull InputConnection
void
void
void
onDisplayHint(int p0)
boolean
void
final void
boolean
void
void
void
onFocusChanged(boolean p0, int p1, @Nullable Rect p2)
boolean
void
onHoverChanged(boolean p0)
boolean
void
void
boolean
onKeyDown(int p0, @NonNull KeyEvent p1)
boolean
boolean
onKeyMultiple(int p0, int p1, @NonNull KeyEvent p2)
boolean
onKeyPreIme(int p0, @NonNull KeyEvent p1)
boolean
boolean
onKeyUp(int p0, @NonNull KeyEvent p1)
void
onMeasure(int p0, int p1)
void
onOverScrolled(int p0, int p1, boolean p2, boolean p3)
void
void
void
void
void
void
void
@Nullable ContentInfo
void
void
@Nullable Parcelable
void
void
void
onScrollChanged(int p0, int p1, int p2, int p3)
boolean
onSetAlpha(int p0)
void
onSizeChanged(int p0, int p1, int p2, int p3)
void
boolean
boolean
void
void
void
void
void
void

This method is deprecated. Deprecated in Java

void
boolean
overScrollBy(
    int p0,
    int p1,
    int p2,
    int p3,
    int p4,
    int p5,
    int p6,
    int p7,
    boolean p8
)
boolean
boolean
boolean
boolean
performContextClick(float p0, float p1)
boolean
boolean
performHapticFeedback(int p0, int p1)
boolean
boolean
performLongClick(float p0, float p1)
@Nullable ContentInfo
void
boolean
boolean
postDelayed(@NonNull Runnable p0, long p1)
void
void
postInvalidate(int p0, int p1, int p2, int p3)
void
void
postInvalidateDelayed(long p0, int p1, int p2, int p3, int p4)
void
void
postInvalidateOnAnimation(int p0, int p1, int p2, int p3)
void
void
void
void
boolean
void
void
void
void
void

This method is deprecated. Deprecated in Java

final boolean
final boolean
requestFocus(int p0)
final boolean
void
void
boolean
boolean
final void
final void
final @NonNull T
<T extends View> requireViewById(int p0)
void
void
final void
saveAttributeDataForStyleable(
    @NonNull Context p0,
    @NonNull int[] p1,
    @Nullable AttributeSet p2,
    @NonNull TypedArray p3,
    int p4,
    int p5
)
void
void
void
scrollBy(int p0, int p1)
void
scrollTo(int p0, int p1)
void
void
void
void
void
void
void
void
void
void
setActivated(boolean p0)
void
void
void
void
setAlpha(float p0)
void
void
void
void
void
void
void
void

This method is deprecated. Deprecated in Java

void
void
void
void
final void
setBottom(int p0)
void
void
setClickable(boolean p0)
void
void
setClipToOutline(boolean p0)
void
void
void
setContextClickable(boolean p0)
void
void

This method is deprecated. Deprecated in Java

void

This method is deprecated. Deprecated in Java

void

This method is deprecated. Deprecated in Java

void
void
setElevation(float p0)
void
setEnabled(boolean p0)
void
void
void
void
setFocusable(boolean p0)
void
setFocusable(int p0)
void
void
setFocusedByDefault(boolean p0)
void
setForceDarkAllowed(boolean p0)
void
void
void
void
void
void
setHandwritingBoundsOffsets(float p0, float p1, float p2, float p3)
void
void
void
void
void
void
void
void
setHovered(boolean p0)
void
setId(int p0)
void
void
void
void
setIsCredential(boolean p0)
void
void
setKeepScreenOn(boolean p0)
void
void
setLabelFor(int p0)
void
void
setLayerType(int p0, @Nullable Paint p1)
void
void
final void
setLeft(int p0)
final void
setLeftTopRightBottom(int p0, int p1, int p2, int p3)
void
setLongClickable(boolean p0)
final void
setMeasuredDimension(int p0, int p1)
void
void
void
void
void
void
void
void
void
void
void
void
void
void
void
void
void
void
void
void
void
void
void

This method is deprecated. Deprecated in Java

void
void
void
void
void
void
setPadding(int p0, int p1, int p2, int p3)
void
setPaddingRelative(int p0, int p1, int p2, int p3)
void
setPivotX(float p0)
void
setPivotY(float p0)
void
final void
setPreferKeepClear(boolean p0)
final void
void
setPressed(boolean p0)
void
final void
final void
setRight(int p0)
void
setRotation(float p0)
void
setRotationX(float p0)
void
setRotationY(float p0)
void
setSaveEnabled(boolean p0)
void
void
setScaleX(float p0)
void
setScaleY(float p0)
void
void
void
void
void
final void
void
void
setScrollContainer(boolean p0)
void
void
setScrollIndicators(int p0, int p1)
void
setScrollX(int p0)
void
setScrollY(int p0)
void
void
setSelected(boolean p0)
void
void
void
void
void

This method is deprecated. Deprecated in Java

void
void
setTag(int p0, @NonNull Object p1)
void
void
void
final void
setTop(int p0)
void
void
final void
void
void
setTranslationX(float p0)
void
setTranslationY(float p0)
void
setTranslationZ(float p0)
void
void
void
void
void
void
void
setVisibility(int p0)
void

This method is deprecated. Deprecated in Java

void
setWillNotDraw(boolean p0)
void
setX(float p0)
void
setY(float p0)
void
setZ(float p0)
boolean
boolean
showContextMenu(float p0, float p1)
@NonNull ActionMode
@NonNull ActionMode
void
final boolean
startDrag(
    @NonNull ClipData p0,
    @NonNull View.DragShadowBuilder p1,
    @NonNull Object p2,
    int p3
)

This method is deprecated. Deprecated in Java

final boolean
startDragAndDrop(
    @NonNull ClipData p0,
    @NonNull View.DragShadowBuilder p1,
    @NonNull Object p2,
    int p3
)
boolean
void
@NonNull String
void
void
void
void
final void
boolean
boolean

This method is deprecated. Deprecated in Java

boolean
@ViewDebug.ExportedProperty(category = "drawing")
willNotDraw()
From android.view.ViewGroup
void
void
void
addFocusables(@NonNull ArrayList<@NonNull View> p0, int p1, int p2)
void
boolean
void
boolean
addViewInLayout(
    @NonNull View p0,
    int p1,
    @NonNull ViewGroup.LayoutParams p2
)
boolean
addViewInLayout(
    @NonNull View p0,
    int p1,
    @NonNull ViewGroup.LayoutParams p2,
    boolean p3
)
void
attachLayoutAnimationParameters(
    @NonNull View p0,
    @NonNull ViewGroup.LayoutParams p1,
    int p2,
    int p3
)
void
attachViewToParent(
    @NonNull View p0,
    int p1,
    @NonNull ViewGroup.LayoutParams p2
)
void
boolean
boolean
void
void
void
void
void
void
void
debug(int p0)
void
void
void
void
detachViewsFromParent(int p0, int p1)
@NonNull WindowInsets
boolean
void
void
void
boolean
void
void
dispatchDrawableHotspotChanged(float p0, float p1)
void
void
boolean
boolean
boolean
boolean
boolean
boolean
void
void
void
void
void
void
void
void
dispatchSetPressed(boolean p0)
void
dispatchSetSelected(boolean p0)
void
void

This method is deprecated. Deprecated in Java

void
boolean
boolean
boolean
void
void
void
void
@NonNull WindowInsets
@NonNull WindowInsetsAnimation.Bounds
void

This method is deprecated. Deprecated in Java

void
boolean
drawChild(@NonNull Canvas p0, @NonNull View p1, long p2)
void
void
@NonNull View
@Nullable OnBackInvokedDispatcher
void
findViewsWithText(
    @NonNull ArrayList<@NonNull View> p0,
    @NonNull CharSequence p1,
    int p2
)
@NonNull View
focusSearch(@NonNull View p0, int p1)
void
boolean
@NonNull ViewGroup.LayoutParams
@NonNull ViewGroup.LayoutParams
@NonNull ViewGroup.LayoutParams
@NonNull CharSequence
@NonNull View
getChildAt(int p0)
int
final int
int
getChildDrawingOrder(int p0, int p1)
boolean
boolean
boolean
boolean
int
@ViewDebug.ExportedProperty(category = "focus", mapping = [@ViewDebug.IntToString(from = 131072, to = "FOCUS_BEFORE_DESCENDANTS"), @ViewDebug.IntToString(from = 262144, to = "FOCUS_AFTER_DESCENDANTS"), @ViewDebug.IntToString(from = 393216, to = "FOCUS_BLOCK_DESCENDANTS")])
getDescendantFocusability()
@NonNull View
@NonNull LayoutAnimationController
@NonNull Animation.AnimationListener
int
@NonNull LayoutTransition
int
@NonNull ViewGroupOverlay
int
@ViewDebug.ExportedProperty(category = "drawing", mapping = [@ViewDebug.IntToString(from = 0, to = "NONE"), @ViewDebug.IntToString(from = 1, to = "ANIMATION"), @ViewDebug.IntToString(from = 2, to = "SCROLLING"), @ViewDebug.IntToString(from = 3, to = "ALL")])
getPersistentDrawingCache()

This method is deprecated. Deprecated in Java

boolean
boolean
boolean
int
final void

This method is deprecated. Deprecated in Java

@NonNull ViewParent

This method is deprecated. Deprecated in Java

boolean

This method is deprecated. Deprecated in Java

boolean

This method is deprecated. Deprecated in Java

boolean
boolean

This method is deprecated. Deprecated in Java

boolean
boolean
boolean
void
final void
layout(int p0, int p1, int p2, int p3)
void
measureChild(@NonNull View p0, int p1, int p2)
void
measureChildWithMargins(@NonNull View p0, int p1, int p2, int p3, int p4)
void
measureChildren(int p0, int p1)
void
notifySubtreeAccessibilityStateChanged(
    @NonNull View p0,
    @NonNull View p1,
    int p2
)
final void
final void
@NonNull int[]
void
void
boolean
boolean
boolean
onNestedFling(@NonNull View p0, float p1, float p2, boolean p3)
boolean
onNestedPreFling(@NonNull View p0, float p1, float p2)
boolean
void
onNestedPreScroll(@NonNull View p0, int p1, int p2, @NonNull int[] p3)
void
onNestedScroll(@NonNull View p0, int p1, int p2, int p3, int p4)
void
boolean
boolean
@NonNull PointerIcon
boolean
void
void
void
void
void
void
void
removeDetachedView(@NonNull View p0, boolean p1)
void
void
removeViewAt(int p0)
void
void
removeViews(int p0, int p1)
void
removeViewsInLayout(int p0, int p1)
void
boolean
requestChildRectangleOnScreen(
    @NonNull View p0,
    @NonNull Rect p1,
    boolean p2
)
void
boolean
requestFocus(int p0, @NonNull Rect p1)
boolean
void
boolean
void
void
void

This method is deprecated. Deprecated in Java

void

This method is deprecated. Deprecated in Java

void

This method is deprecated. Deprecated in Java

void
void

This method is deprecated. Deprecated in Java

void
setClipChildren(boolean p0)
void
setClipToPadding(boolean p0)
void
void
void
void
setLayoutMode(int p0)
void
void
void
void

This method is deprecated. Deprecated in Java

void
void
void
setTransitionGroup(boolean p0)
void
boolean
boolean
boolean
showContextMenuForChild(@NonNull View p0, float p1, float p2)
@NonNull ActionMode
@NonNull ActionMode
startActionModeForChild(
    @NonNull View p0,
    @NonNull ActionMode.Callback p1,
    int p2
)
void
void
void
suppressLayout(boolean p0)
void

Public constructors

LowLatencyCanvasView

Added in 1.0.2
public LowLatencyCanvasView(
    @NonNull Context context,
    AttributeSet attrs,
    int defStyle
)

Public methods

addView

public void addView(View child)

addView

public void addView(View child, int index)

addView

public void addView(View child, ViewGroup.LayoutParams params)

addView

public void addView(View child, int index, ViewGroup.LayoutParams params)

addView

public void addView(View child, int width, int height)

cancel

Added in 1.0.2
public final void cancel()

Cancels any in progress request to render to the front buffer and hides the front buffered overlay. Cancellation is a "best-effort" approach and any in progress rendering will still be applied.

clear

Added in 1.0.2
public final void clear()

Clears the content of the buffer and hides the front buffered overlay. This will cancel all pending requests to render. This is similar to cancel, however in addition to cancelling the pending render requests, this also clears the contents of the buffer. Similar to commit this will also hide the front buffered overlay.

commit

Added in 1.0.2
public final void commit()

Invalidates this View and draws the buffer within View#onDraw. This will synchronously hide the front buffered overlay when drawing the buffer to this View. Consumers are encouraged to invoke this method when a user gesture that requires low latency rendering is complete. For example in response to a MotionEvent.ACTION_UP event in an implementation of View.onTouchEvent.

execute

Added in 1.0.2
public final void execute(@NonNull Runnable runnable)

Dispatches a runnable to be executed on the background rendering thread. This is useful for updating data structures used to issue drawing instructions on the same thread that Callback.onDrawFrontBufferedLayer is invoked on.

renderFrontBufferedLayer

Added in 1.0.2
public final void renderFrontBufferedLayer()

Render content to the front buffered layer. This triggers a call to Callback.onDrawFrontBufferedLayer. Callback implementations can also configure the corresponding SurfaceControlCompat.Transaction that updates the contents on screen by implementing the optional Callback.onFrontBufferedLayerRenderComplete callback

setRenderCallback

Added in 1.0.2
public final void setRenderCallback(LowLatencyCanvasView.Callback callback)

Configures the Callback used to render contents to the front buffered overlay as well as optionally configuring the SurfaceControlCompat.Transaction used to update contents on screen.

Protected methods

onAttachedToWindow

protected void onAttachedToWindow()

onDraw

protected void onDraw(@NonNull Canvas canvas)

onLayout

protected void onLayout(boolean changed, int l, int t, int r, int b)