HardwareRenderer
public
class
HardwareRenderer
extends Object
| java.lang.Object | |
| ↳ | android.graphics.HardwareRenderer |
Creates an instance of a hardware-accelerated renderer. This is used to render a scene built
from RenderNode's to an output Surface. There can be as many
HardwareRenderer instances as desired.
Resources & lifecycle
All HardwareRenderer instances share a common render thread. The render thread contains
the GPU context & resources necessary to do GPU-accelerated rendering. As such, the first
HardwareRenderer created comes with the cost of also creating the associated GPU contexts,
however each incremental HardwareRenderer thereafter is fairly cheap. The expected usage
is to have a HardwareRenderer instance for every active Surface. For example
when an Activity shows a Dialog the system internally will use 2 hardware renderers, both
of which may be drawing at the same time.
NOTE: Due to the shared, cooperative nature of the render thread it is critical that
any Surface used must have a prompt, reliable consuming side. System-provided
consumers such as SurfaceView,
Window.takeSurface(SurfaceHolder.Callback2),
or TextureView all fit this requirement. However if custom consumers
are used such as when using SurfaceTexture or ImageReader
it is the app's responsibility to ensure that they consume updates promptly and rapidly.
Failure to do so will cause the render thread to stall on that surface, blocking all
HardwareRenderer instances.
Summary
Nested classes | |
|---|---|
class |
HardwareRenderer.FrameRenderRequest
Sets the parameters that can be used to control a render request for a
|
Constants | |
|---|---|
int |
SYNC_CONTEXT_IS_STOPPED
The hardware renderer has been set to a "stopped" state. |
int |
SYNC_FRAME_DROPPED
The content was synced but the renderer has declined to produce a frame in this vsync interval. |
int |
SYNC_LOST_SURFACE_REWARD_IF_FOUND
The hardware renderer no longer has a valid |
int |
SYNC_OK
Nothing interesting to report. |
int |
SYNC_REDRAW_REQUESTED
The renderer is requesting a redraw. |
Public constructors | |
|---|---|
HardwareRenderer()
Creates a new instance of a HardwareRenderer. |
|
Public methods | |
|---|---|
void
|
clearContent()
Destroys all the display lists associated with the current rendering content. |
HardwareRenderer.FrameRenderRequest
|
createRenderRequest()
Returns a |
void
|
destroy()
Destroys the rendering context of this HardwareRenderer. |
static
boolean
|
isDrawingEnabled()
Returns true if HardwareRender will produce output. |
boolean
|
isOpaque()
Whether or not the renderer is set to be opaque. |
void
|
notifyFramePending()
Notifies the hardware renderer that a call to |
void
|
setContentRoot(RenderNode content)
Sets the content root to render. |
static
void
|
setDrawingEnabled(boolean drawingEnabled)
Toggles whether or not HardwareRenderer will produce drawing output globally in the current process. |
void
|
setLightSourceAlpha(float ambientShadowAlpha, float spotShadowAlpha)
Configures the ambient & spot shadow alphas. |
void
|
setLightSourceGeometry(float lightX, float lightY, float lightZ, float lightRadius)
Sets the center of the light source. |
void
|
setName(String name)
Sets a name for this renderer. |
void
|
setOpaque(boolean opaque)
Change the HardwareRenderer's opacity. |
void
|
setSurface(Surface surface)
The surface to render into. |
void
|
start()
Resumes rendering into the surface. |
void
|
stop()
Hard stops rendering into the surface. |
Inherited methods | |
|---|---|
Constants
SYNC_CONTEXT_IS_STOPPED
public static final int SYNC_CONTEXT_IS_STOPPED
The hardware renderer has been set to a "stopped" state. If this is returned then the rendering content has been synced, however a frame was not produced.
Constant Value: 4 (0x00000004)
SYNC_FRAME_DROPPED
public static final int SYNC_FRAME_DROPPED
The content was synced but the renderer has declined to produce a frame in this vsync interval. This can happen if a frame was already drawn in this vsync or if the renderer is outrunning the frame consumer. The renderer will internally re-schedule itself to render a frame in the next vsync signal, so the caller does not need to do anything in response to this signal.
Constant Value: 8 (0x00000008)
SYNC_LOST_SURFACE_REWARD_IF_FOUND
public static final int SYNC_LOST_SURFACE_REWARD_IF_FOUND
The hardware renderer no longer has a valid Surface to render to.
This can happen if Surface#release() was called. The user should no longer
attempt to call syncAndDraw until a new surface has been provided by calling
setSurface.
Spoiler: the reward is GPU-accelerated drawing, better find that Surface!
Constant Value: 2 (0x00000002)
SYNC_OK
public static final int SYNC_OK
Nothing interesting to report. Sync & draw kicked off
Constant Value: 0 (0x00000000)
SYNC_REDRAW_REQUESTED
public static final int SYNC_REDRAW_REQUESTED
The renderer is requesting a redraw. This can occur if there's an animation that's running in the RenderNode tree and the hardware renderer is unable to self-animate.
If this is returned from syncAndDraw the expectation is that syncAndDraw will be called again on the next vsync signal.
Constant Value: 1 (0x00000001)
Public constructors
HardwareRenderer
public HardwareRenderer ()
Creates a new instance of a HardwareRenderer. The HardwareRenderer will default to opaque with no light source configured.
Public methods
clearContent
public void clearContent ()
Destroys all the display lists associated with the current rendering content.
This includes releasing a reference to the current content root RenderNode. It will
therefore be necessary to call setContentRoot(android.graphics.RenderNode) in order to resume
rendering after calling this, along with re-recording the display lists for the
RenderNode tree.
It is recommended, but not necessary, to use this in combination with lifecycle events
such as Activity#onStop() and Activity#onStart() or in response to
ComponentCallbacks2.onTrimMemory(int) signals such as
ComponentCallbacks2.TRIM_MEMORY_UI_HIDDEN
See also stop().
createRenderRequest
public HardwareRenderer.FrameRenderRequest createRenderRequest ()
Returns a FrameRenderRequest that can be used to render a new frame. This is used
to synchronize the RenderNode content provided by setContentRoot(android.graphics.RenderNode) with
the RenderThread and then renders a single frame to the Surface set with
setSurface(android.view.Surface).
| Returns | |
|---|---|
HardwareRenderer.FrameRenderRequest |
An instance of FrameRenderRequest. The instance may be reused for every
frame, so the caller should not hold onto it for longer than a single render request.
This value cannot be null. |
destroy
public void destroy ()
Destroys the rendering context of this HardwareRenderer. This destroys the resources
associated with this renderer and releases the currently set Surface. This must
be called when this HardwareRenderer is no longer needed.
The renderer may be restored from this state by setting a new Surface, setting
new rendering content with setContentRoot(android.graphics.RenderNode), and resuming
rendering by issuing a new FrameRenderRequest.
It is recommended to call this in response to callbacks such as
SurfaceHolder.Callback.surfaceDestroyed(SurfaceHolder).
Note that if there are any outstanding frame commit callbacks they may never being invoked if the frame was deferred to a later vsync.
isDrawingEnabled
public static boolean isDrawingEnabled ()
Returns true if HardwareRender will produce output.
This value is global to the process and affects all uses of HardwareRenderer,
including
those created by the system such as those used by the View tree when using hardware
accelerated rendering.
Default is true in all production environments, but may be false in testing-focused
emulators or if setDrawingEnabled(boolean) is used.
| Returns | |
|---|---|
boolean |
|
isOpaque
public boolean isOpaque ()
Whether or not the renderer is set to be opaque. See setOpaque(boolean)
| Returns | |
|---|---|
boolean |
true if the renderer is opaque, false otherwise |
notifyFramePending
public void notifyFramePending ()
Notifies the hardware renderer that a call to FrameRenderRequest#syncAndDraw() will
be coming soon. This is used to help schedule when RenderThread-driven animations will
happen as the renderer wants to avoid producing more than one frame per vsync signal.
setContentRoot
public void setContentRoot (RenderNode content)
Sets the content root to render. It is not necessary to call this whenever the content
recording changes. Any mutations to the RenderNode content, or any of the RenderNode's
contained within the content node, will be applied whenever a new FrameRenderRequest
is issued via createRenderRequest() and FrameRenderRequest#syncAndDraw().
| Parameters | |
|---|---|
content |
RenderNode: The content to set as the root RenderNode. If null the content root is removed
and the renderer will draw nothing. |
setDrawingEnabled
public static void setDrawingEnabled (boolean drawingEnabled)
Toggles whether or not HardwareRenderer will produce drawing output globally in the current process. This applies to all HardwareRenderer instances, including those created by the platform such as those used by the system for hardware accelerated View rendering. The capability to disable drawing output is intended for test environments, primarily headless ones. By setting this to false, tests that launch activities or interact with Views can be quicker with less RAM usage by skipping the final step of View drawing. All View lifecycle events will occur as normal, only the final step of rendering on the GPU to the display will be skipped. This can be toggled on and off at will, so screenshot tests can also run in this same environment by toggling drawing back on and forcing a frame to be drawn such as by calling view#invalidate(). Once drawn and the screenshot captured, this can then be turned back off.
| Parameters | |
|---|---|
drawingEnabled |
boolean |
setLightSourceAlpha
public void setLightSourceAlpha (float ambientShadowAlpha,
float spotShadowAlpha)Configures the ambient & spot shadow alphas. This is the alpha used when the shadow has max alpha, and ramps down from the values provided to zero.
These values are typically provided by the current theme, see
R.attr.spotShadowAlpha and R.attr.ambientShadowAlpha.
This must be set at least once along with
setLightSourceGeometry(float, float, float, float) before shadows will work.
| Parameters | |
|---|---|
ambientShadowAlpha |
float: The alpha for the ambient shadow. If unsure, a reasonable default
is 0.039f.
Value is between 0.0f and 1.0f inclusive |
spotShadowAlpha |
float: The alpha for the spot shadow. If unsure, a reasonable default is
0.19f.
Value is between 0.0f and 1.0f inclusive |
setLightSourceGeometry
public void setLightSourceGeometry (float lightX,
float lightY,
float lightZ,
float lightRadius)Sets the center of the light source. The light source point controls the directionality and shape of shadows rendered by RenderNode Z & elevation.
The platform's recommendation is to set lightX to 'displayWidth / 2f - windowLeft', set lightY to 0 - windowTop, lightZ set to 600dp, and lightRadius to 800dp.
The light source should be setup both as part of initial configuration, and whenever the window moves to ensure the light source stays anchored in display space instead of in window space.
This must be set at least once along with setLightSourceAlpha(float, float)
before shadows will work.
| Parameters | |
|---|---|
lightX |
float: The X position of the light source |
lightY |
float: The Y position of the light source |
lightZ |
float: The Z position of the light source. Must be >= 0. |
lightRadius |
float: The radius of the light source. Smaller radius will have sharper edges,
larger radius will have softer shadows. |
setName
public void setName (String name)
Sets a name for this renderer. This is used to identify this renderer instance when reporting debug information such as the per-window frame time metrics reported by 'adb shell dumpsys gfxinfo [package] framestats'
| Parameters | |
|---|---|
name |
String: The debug name to use for this HardwareRenderer instance
This value cannot be null. |
setOpaque
public void setOpaque (boolean opaque)
Change the HardwareRenderer's opacity. Will take effect on the next frame produced.
If the renderer is set to opaque it is the app's responsibility to ensure that the content renders to every pixel of the Surface, otherwise corruption may result. Note that this includes ensuring that the first draw of any given pixel does not attempt to blend against the destination. If this is false then the hardware renderer will clear to transparent at the start of every frame.
| Parameters | |
|---|---|
opaque |
boolean: true if the content rendered is opaque, false if the renderer should clear
to transparent before rendering |
setSurface
public void setSurface (Surface surface)
The surface to render into. The surface is assumed to be associated with the display and
as such is still driven by vsync signals such as those from
Choreographer and that it has a native refresh rate matching that of
the display's (typically 60hz).
NOTE: Due to the shared, cooperative nature of the render thread it is critical that
any Surface used must have a prompt, reliable consuming side. System-provided
consumers such as SurfaceView,
Window.takeSurface(SurfaceHolder.Callback2),
or TextureView all fit this requirement. However if custom consumers
are used such as when using SurfaceTexture or ImageReader
it is the app's responsibility to ensure that they consume updates promptly and rapidly.
Failure to do so will cause the render thread to stall on that surface, blocking all
HardwareRenderer instances.
| Parameters | |
|---|---|
surface |
Surface: The surface to render into. If null then rendering will be stopped. If
non-null then Surface#isValid() must be true. |
start
public void start ()
Resumes rendering into the surface. Any pending rendering requests will produce a new frame at the next vsync signal.
This is useful in combination with lifecycle events such as Activity#onStart().
See stop() for stopping rendering.
stop
public void stop ()
Hard stops rendering into the surface. If the renderer is stopped it will
block any attempt to render. Calls to FrameRenderRequest#syncAndDraw() will
still sync over the latest rendering content, however they will not render and instead
SYNC_CONTEXT_IS_STOPPED will be returned.
This is useful in combination with lifecycle events such as Activity#onStop().
See start() for resuming rendering.
Content and code samples on this page are subject to the licenses described in the Content License. Java and OpenJDK are trademarks or registered trademarks of Oracle and/or its affiliates.
Last updated 2024-04-11 UTC.