gui: Update header docs for IGraphicBufferConsumer/Producer/BufferQueue
Also fix compiler warnings for libgui
Change-Id: I0ee38d9ad5eaa82d55bf812d291da8c433581cef
diff --git a/include/gui/IGraphicBufferConsumer.h b/include/gui/IGraphicBufferConsumer.h
index 0e35f13..9a6645c 100644
--- a/include/gui/IGraphicBufferConsumer.h
+++ b/include/gui/IGraphicBufferConsumer.h
@@ -48,6 +48,7 @@
status_t unflatten(void const*& buffer, size_t& size, int const*& fds, size_t& count);
public:
+ // The default value of mBuf, used to indicate this doesn't correspond to a slot.
enum { INVALID_BUFFER_SLOT = -1 };
BufferItem();
@@ -63,13 +64,17 @@
Rect mCrop;
// mTransform is the current transform flags for this buffer slot.
+ // refer to NATIVE_WINDOW_TRANSFORM_* in <window.h>
uint32_t mTransform;
// mScalingMode is the current scaling mode for this buffer slot.
+ // refer to NATIVE_WINDOW_SCALING_* in <window.h>
uint32_t mScalingMode;
// mTimestamp is the current timestamp for this buffer slot. This gets
- // to set by queueBuffer each time this slot is queued.
+ // to set by queueBuffer each time this slot is queued. This value
+ // is guaranteed to be monotonically increasing for each newly
+ // acquired buffer.
int64_t mTimestamp;
// mIsAutoTimestamp indicates whether mTimestamp was generated
@@ -79,7 +84,7 @@
// mFrameNumber is the number of the queued frame for this slot.
uint64_t mFrameNumber;
- // mBuf is the slot index of this buffer
+ // mBuf is the slot index of this buffer (default INVALID_BUFFER_SLOT).
int mBuf;
// mIsDroppable whether this buffer was queued with the
@@ -97,21 +102,42 @@
bool mTransformToDisplayInverse;
};
+ enum {
+ // Returned by releaseBuffer, after which the consumer must
+ // free any references to the just-released buffer that it might have.
+ STALE_BUFFER_SLOT = 1,
+ // Returned by dequeueBuffer if there are no pending buffers available.
+ NO_BUFFER_AVAILABLE,
+ // Returned by dequeueBuffer if it's too early for the buffer to be acquired.
+ PRESENT_LATER,
+ };
// acquireBuffer attempts to acquire ownership of the next pending buffer in
- // the BufferQueue. If no buffer is pending then it returns -EINVAL. If a
- // buffer is successfully acquired, the information about the buffer is
- // returned in BufferItem. If the buffer returned had previously been
+ // the BufferQueue. If no buffer is pending then it returns
+ // NO_BUFFER_AVAILABLE. If a buffer is successfully acquired, the
+ // information about the buffer is returned in BufferItem.
+ //
+ // If the buffer returned had previously been
// acquired then the BufferItem::mGraphicBuffer field of buffer is set to
// NULL and it is assumed that the consumer still holds a reference to the
// buffer.
//
- // If presentWhen is nonzero, it indicates the time when the buffer will
+ // If presentWhen is non-zero, it indicates the time when the buffer will
// be displayed on screen. If the buffer's timestamp is farther in the
// future, the buffer won't be acquired, and PRESENT_LATER will be
// returned. The presentation time is in nanoseconds, and the time base
// is CLOCK_MONOTONIC.
- virtual status_t acquireBuffer(BufferItem *buffer, nsecs_t presentWhen) = 0;
+ //
+ // Return of NO_ERROR means the operation completed as normal.
+ //
+ // Return of a positive value means the operation could not be completed
+ // at this time, but the user should try again later:
+ // * NO_BUFFER_AVAILABLE - no buffer is pending (nothing queued by producer)
+ // * PRESENT_LATER - the buffer's timestamp is farther in the future
+ //
+ // Return of a negative value means an error has occurred:
+ // * INVALID_OPERATION - too many buffers have been acquired
+ virtual status_t acquireBuffer(BufferItem* buffer, nsecs_t presentWhen) = 0;
// releaseBuffer releases a buffer slot from the consumer back to the
// BufferQueue. This may be done while the buffer's contents are still
@@ -125,6 +151,18 @@
//
// Note that the dependencies on EGL will be removed once we switch to using
// the Android HW Sync HAL.
+ //
+ // Return of NO_ERROR means the operation completed as normal.
+ //
+ // Return of a positive value means the operation could not be completed
+ // at this time, but the user should try again later:
+ // * STALE_BUFFER_SLOT - see above (second paragraph)
+ //
+ // Return of a negative value means an error has occurred:
+ // * BAD_VALUE - one of the following could've happened:
+ // * the buffer slot was invalid
+ // * the fence was NULL
+ // * the buffer slot specified is not in the acquired state
virtual status_t releaseBuffer(int buf, uint64_t frameNumber,
EGLDisplay display, EGLSyncKHR fence,
const sp<Fence>& releaseFence) = 0;
@@ -137,24 +175,38 @@
// the application.
//
// consumer may not be NULL.
+ //
+ // Return of a value other than NO_ERROR means an error has occurred:
+ // * NO_INIT - the buffer queue has been abandoned
+ // * BAD_VALUE - a NULL consumer was provided
virtual status_t consumerConnect(const sp<IConsumerListener>& consumer, bool controlledByApp) = 0;
// consumerDisconnect disconnects a consumer from the BufferQueue. All
// buffers will be freed and the BufferQueue is placed in the "abandoned"
// state, causing most interactions with the BufferQueue by the producer to
// fail.
+ //
+ // Return of a value other than NO_ERROR means an error has occurred:
+ // * BAD_VALUE - no consumer is currently connected
virtual status_t consumerDisconnect() = 0;
- // getReleasedBuffers sets the value pointed to by slotMask to a bit mask
- // indicating which buffer slots have been released by the BufferQueue
- // but have not yet been released by the consumer.
+ // getReleasedBuffers sets the value pointed to by slotMask to a bit set.
+ // Each bit index with a 1 corresponds to a released buffer slot with that
+ // index value. In particular, a released buffer is one that has
+ // been released by the BufferQueue but have not yet been released by the consumer.
//
// This should be called from the onBuffersReleased() callback.
+ //
+ // Return of a value other than NO_ERROR means an error has occurred:
+ // * NO_INIT - the buffer queue has been abandoned.
virtual status_t getReleasedBuffers(uint32_t* slotMask) = 0;
// setDefaultBufferSize is used to set the size of buffers returned by
// dequeueBuffer when a width and height of zero is requested. Default
// is 1x1.
+ //
+ // Return of a value other than NO_ERROR means an error has occurred:
+ // * BAD_VALUE - either w or h was zero
virtual status_t setDefaultBufferSize(uint32_t w, uint32_t h) = 0;
// setDefaultMaxBufferCount sets the default value for the maximum buffer
@@ -163,6 +215,9 @@
// take effect if the producer sets the count back to zero.
//
// The count must be between 2 and NUM_BUFFER_SLOTS, inclusive.
+ //
+ // Return of a value other than NO_ERROR means an error has occurred:
+ // * BAD_VALUE - bufferCount was out of range (see above).
virtual status_t setDefaultMaxBufferCount(int bufferCount) = 0;
// disableAsyncBuffer disables the extra buffer used in async mode
@@ -170,11 +225,20 @@
// flag) and has dequeueBuffer() return WOULD_BLOCK instead.
//
// This can only be called before consumerConnect().
+ //
+ // Return of a value other than NO_ERROR means an error has occurred:
+ // * INVALID_OPERATION - attempting to call this after consumerConnect.
virtual status_t disableAsyncBuffer() = 0;
// setMaxAcquiredBufferCount sets the maximum number of buffers that can
// be acquired by the consumer at one time (default 1). This call will
// fail if a producer is connected to the BufferQueue.
+ //
+ // maxAcquiredBuffers must be (inclusive) between 1 and MAX_MAX_ACQUIRED_BUFFERS.
+ //
+ // Return of a value other than NO_ERROR means an error has occurred:
+ // * BAD_VALUE - maxAcquiredBuffers was out of range (see above).
+ // * INVALID_OPERATION - attempting to call this after a producer connected.
virtual status_t setMaxAcquiredBufferCount(int maxAcquiredBuffers) = 0;
// setConsumerName sets the name used in logging
@@ -184,16 +248,22 @@
// GraphicBuffers of a defaultFormat if no format is specified
// in dequeueBuffer. Formats are enumerated in graphics.h; the
// initial default is HAL_PIXEL_FORMAT_RGBA_8888.
+ //
+ // Return of a value other than NO_ERROR means an unknown error has occurred.
virtual status_t setDefaultBufferFormat(uint32_t defaultFormat) = 0;
// setConsumerUsageBits will turn on additional usage bits for dequeueBuffer.
// These are merged with the bits passed to dequeueBuffer. The values are
// enumerated in gralloc.h, e.g. GRALLOC_USAGE_HW_RENDER; the default is 0.
+ //
+ // Return of a value other than NO_ERROR means an unknown error has occurred.
virtual status_t setConsumerUsageBits(uint32_t usage) = 0;
// setTransformHint bakes in rotation to buffers so overlays can be used.
// The values are enumerated in window.h, e.g.
// NATIVE_WINDOW_TRANSFORM_ROT_90. The default is 0 (no transform).
+ //
+ // Return of a value other than NO_ERROR means an unknown error has occurred.
virtual status_t setTransformHint(uint32_t hint) = 0;
// dump state into a string