Screen usage flag types

Types of usage flags.

Synopsis:

#include <screen/screen.h>
 
 enum {
      SCREEN_USAGE_DISPLAY = (1 << 0)   
      SCREEN_USAGE_READ = (1 << 1)   
      SCREEN_USAGE_WRITE = (1 << 2)   
      SCREEN_USAGE_NATIVE = (1 << 3)   
      SCREEN_USAGE_OPENGL_ES1 = (1 << 4)   
      SCREEN_USAGE_OPENGL_ES2 = (1 << 5)   
      SCREEN_USAGE_OPENGL_ES3 = (1 << 11)   
      SCREEN_USAGE_OPENVG = (1 << 6)   
      SCREEN_USAGE_VIDEO = (1 << 7)   
      SCREEN_USAGE_CAPTURE = (1 << 8)   
      SCREEN_USAGE_ROTATION = (1 << 9)   
      SCREEN_USAGE_OVERLAY = (1 << 10)   
};

Data:

SCREEN_USAGE_DISPLAY
Reserved, cannot be used by applications.
SCREEN_USAGE_READ
Flag to indicate that buffer(s) associated with the API object can be read from.
SCREEN_USAGE_WRITE
Flag to indicate that buffer(s) associated with the API object can be written to.
SCREEN_USAGE_NATIVE
Flag to indicate that buffer(s) associated with the API object can be used for native API operations.

If using blits or fills, this flag must be set on the API object.

SCREEN_USAGE_OPENGL_ES1
Flag to indicate that OpenGL ES 1.X is used for rendering the buffer associated with the API object.
SCREEN_USAGE_OPENGL_ES2
Flag to indicate that OpenGL ES 2.X is used for rendering the buffer associated with the API object.
SCREEN_USAGE_OPENGL_ES3
Flag to indicate that OpenGL ES 3.X is used for rendering the buffer associated with the API object.
SCREEN_USAGE_OPENVG
Flag to indicate that OpenVG is used for rendering the buffer associated with the API object.
SCREEN_USAGE_VIDEO
Flag to indicate that the buffer can be written to by a video decoder.
SCREEN_USAGE_CAPTURE
Flag to indicate that the buffer can be written to by capture devices (such as cameras, analog-to-digital-converters, ...), and read by a hardware video encoder.
SCREEN_USAGE_ROTATION
Flag to indicate that the buffer can be re-configured from landscape to portrait orientation without reallocation.

Rotation

SCREEN_USAGE_OVERLAY
Flag to indicate the use of a non-composited layer.

The Screen API uses a composited layer by default. The SCREEN_USAGE_OVERLAY flag is used to override this default behaviour to use a non-composited layer instead. Note that when the overlay usage bit is added or removed, then changing SCREEN_PROPERTY_USAGE affects the pipeline. Use the SCREEN_USAGE_OVERLAY flag in favor of the SCREEN_PROPERTY_PIPELINE property to specify whether to use a composited or a non-composited layer.

Library:

libscreen

Description:

Usage flags are used when allocating buffers. Depending on the usage, different constraints such as width, height, stride granularity or special alignment must be observed. The usage is also valuable in determining the amount of caching that can be set on a particular buffer.

Last modified: 2013-12-23

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