android 使用etc1,ETC1 - Android SDK | Android Developers
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android.opengl.ETC1
Class Overview
Methods for encoding and decoding ETC1 textures.
The standard for the ETC1 texture format can be found at
http://www.khronos.org/registry/gles/extensions/OES/OES_compressed_ETC1_RGB8_texture.txt
The PKM file format is of a 16-byte header that describes the image bounds
followed by the encoded ETC1 texture data.
See Also
Summary
Constants
int
Size in bytes of a decoded block.
int
Size in bytes of an encoded block.
int
Accepted by the internalformat parameter of glCompressedTexImage2D.
int
Size of a PKM file header, in bytes.
Public Constructors
Public Methods
static
void
Decode a block of pixels.
static
void
Buffer in, Buffer out, int width, int height, int pixelSize, int stride)
Decode an entire image.
static
void
Buffer in, int validPixelMask, Buffer out)
Encode a block of pixels.
static
void
Buffer in, int width, int height, int pixelSize, int stride, Buffer out)
Encode an entire image.
static
void
Buffer header, int width, int height)
Format a PKM header
static
int
Return the size of the encoded image data (does not include size of PKM header).
static
int
Read the image height from a PKM header
static
int
Read the image width from a PKM header
static
boolean
Check if a PKM header is correctly formatted.
[Expand]
Inherited Methods
From class
java.lang.Object
Creates and returns a copy of this Object.
boolean
Compares this instance with the specified object and indicates if they
are equal.
void
Invoked when the garbage collector has detected that this instance is no longer reachable.
final
Class>
Returns the unique instance of
int
Returns an integer hash code for this object.
final
void
Causes a thread which is waiting on this object's monitor (by means of
calling one of the wait() methods) to be woken up.
final
void
Causes all threads which are waiting on this object's monitor (by means
of calling one of the wait() methods) to be woken up.
Returns a string containing a concise, human-readable description of this
object.
final
void
Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object.
final
void
Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the
specified timeout expires.
final
void
Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the
specified timeout expires.
Constants
public
static
final
int
DECODED_BLOCK_SIZE
Size in bytes of a decoded block.
Constant Value:
48
(0x00000030)
public
static
final
int
ENCODED_BLOCK_SIZE
Size in bytes of an encoded block.
Constant Value:
8
(0x00000008)
public
static
final
int
ETC1_RGB8_OES
Accepted by the internalformat parameter of glCompressedTexImage2D.
Constant Value:
36196
(0x00008d64)
public
static
final
int
ETC_PKM_HEADER_SIZE
Size of a PKM file header, in bytes.
Constant Value:
16
(0x00000010)
Public Constructors
public
ETC1
()
Public Methods
public
static
void
decodeBlock
Decode a block of pixels.
Parameters
ina native order direct buffer of size ENCODED_BLOCK_SIZE that contains the
ETC1 compressed version of the data.
outa native order direct buffer of size DECODED_BLOCK_SIZE that will receive
the decoded data. The data represents a
4 x 4 square of 3-byte pixels in form R, G, B. Byte (3 * (x + 4 * y) is the R
value of pixel (x, y).
public
static
void
decodeImage
(Buffer in, Buffer out, int width, int height, int pixelSize, int stride)
Decode an entire image.
Parameters
innative order direct buffer of the encoded data.
outnative order direct buffer of the image data. Will be written such that
pixel (x,y) is at pIn + pixelSize * x + stride * y. Must be
large enough to store entire image.
pixelSizemust be 2 or 3. 2 is an GL_UNSIGNED_SHORT_5_6_5 image,
3 is a GL_BYTE RGB image.
public
static
void
encodeBlock
(Buffer in, int validPixelMask, Buffer out)
Encode a block of pixels.
Parameters
ina native order direct buffer of size DECODED_BLOCK_SIZE that represent a
4 x 4 square of 3-byte pixels in form R, G, B. Byte (3 * (x + 4 * y) is the R
value of pixel (x, y).
validPixelMaskis a 16-bit mask where bit (1 << (x + y * 4)) indicates whether
the corresponding (x,y) pixel is valid. Invalid pixel color values are ignored when compressing.
outa native order direct buffer of size ENCODED_BLOCK_SIZE that receives the
ETC1 compressed version of the data.
public
static
void
encodeImage
(Buffer in, int width, int height, int pixelSize, int stride, Buffer out)
Encode an entire image.
Parameters
ina native order direct buffer of the image data. Formatted such that
pixel (x,y) is at pIn + pixelSize * x + stride * y;
pixelSizemust be 2 or 3. 2 is an GL_UNSIGNED_SHORT_5_6_5 image,
3 is a GL_BYTE RGB image.
outa native order direct buffer of the encoded data.
Must be large enough to store entire encoded image.
public
static
void
formatHeader
(Buffer header, int width, int height)
Format a PKM header
Parameters
headernative order direct buffer of the header.
widththe width of the image in pixels.
heightthe height of the image in pixels.
public
static
int
getEncodedDataSize
(int width, int height)
Return the size of the encoded image data (does not include size of PKM header).
public
static
int
getHeight
(Buffer header)
Read the image height from a PKM header
Parameters
headernative order direct buffer of the header.
public
static
int
getWidth
(Buffer header)
Read the image width from a PKM header
Parameters
headernative order direct buffer of the header.
public
static
boolean
isValid
(Buffer header)
Check if a PKM header is correctly formatted.
Parameters
headernative order direct buffer of the header.
Except as noted, this content is licensed under Apache 2.0.
For details and restrictions, see the Content License.
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