ETC1

public class ETC1
extends Object

java.lang.Object
   ↳ android.opengl.ETC1

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 DECODED_BLOCK_SIZE

Size in bytes of a decoded block.

int ENCODED_BLOCK_SIZE

Size in bytes of an encoded block.

int ETC1_RGB8_OES

Accepted by the internalformat parameter of glCompressedTexImage2D.

int ETC_PKM_HEADER_SIZE

Size of a PKM file header, in bytes.

Public constructors

ETC1()

Public methods

static void decodeBlock(Buffer in, Buffer out)

Decode a block of pixels.

static void decodeImage(Buffer in, Buffer out, int width, int height, int pixelSize, int stride)

Decode an entire image.

static void encodeBlock(Buffer in, int validPixelMask, Buffer out)

Encode a block of pixels.

static void encodeImage(Buffer in, int width, int height, int pixelSize, int stride, Buffer out)

Encode an entire image.

static void formatHeader(Buffer header, int width, int height)

Format a PKM header

static int getEncodedDataSize(int width, int height)

Return the size of the encoded image data (does not include size of PKM header).

static int getHeight(Buffer header)

Read the image height from a PKM header

static int getWidth(Buffer header)

Read the image width from a PKM header

static boolean isValid(Buffer header)

Check if a PKM header is correctly formatted.

Inherited methods

Constants

DECODED_BLOCK_SIZE

Added in API level 8 
public static final int DECODED_BLOCK_SIZE

Size in bytes of a decoded block.

Constant Value: 48 (0x00000030)

ENCODED_BLOCK_SIZE

Added in API level 8 
public static final int ENCODED_BLOCK_SIZE

Size in bytes of an encoded block.

Constant Value: 8 (0x00000008)

ETC1_RGB8_OES

Added in API level 8 
public static final int ETC1_RGB8_OES

Accepted by the internalformat parameter of glCompressedTexImage2D.

Constant Value: 36196 (0x00008d64)

ETC_PKM_HEADER_SIZE

Added in API level 8 
public static final int ETC_PKM_HEADER_SIZE

Size of a PKM file header, in bytes.

Constant Value: 16 (0x00000010)

Public constructors

ETC1

public ETC1 ()

Public methods

decodeBlock

Added in API level 8 
public static void decodeBlock (Buffer in, 
                Buffer out)

Decode a block of pixels.

Parameters
in Buffer: a native order direct buffer of size ENCODED_BLOCK_SIZE that contains the ETC1 compressed version of the data.
out Buffer: a 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).

decodeImage

Added in API level 8 
public static void decodeImage (Buffer in, 
                Buffer out, 
                int width, 
                int height, 
                int pixelSize, 
                int stride)

Decode an entire image.

Parameters
in Buffer: native order direct buffer of the encoded data.
out Buffer: native 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.
width int

height int

pixelSize int: must be 2 or 3. 2 is an GL_UNSIGNED_SHORT_5_6_5 image, 3 is a GL_BYTE RGB image.
stride int

encodeBlock

Added in API level 8 
public static void encodeBlock (Buffer in, 
                int validPixelMask, 
                Buffer out)

Encode a block of pixels.

Parameters
in Buffer: a 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).
validPixelMask int: is 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.
out Buffer: a native order direct buffer of size ENCODED_BLOCK_SIZE that receives the ETC1 compressed version of the data.

encodeImage

Added in API level 8 
public static void encodeImage (Buffer in, 
                int width, 
                int height, 
                int pixelSize, 
                int stride, 
                Buffer out)

Encode an entire image.

Parameters
in Buffer: a native order direct buffer of the image data. Formatted such that pixel (x,y) is at pIn + pixelSize * x + stride * y;
width int

height int

pixelSize int: must be 2 or 3. 2 is an GL_UNSIGNED_SHORT_5_6_5 image, 3 is a GL_BYTE RGB image.
stride int

out Buffer: a native order direct buffer of the encoded data. Must be large enough to store entire encoded image.

formatHeader

Added in API level 8 
public static void formatHeader (Buffer header, 
                int width, 
                int height)

Format a PKM header

Parameters
header Buffer: native order direct buffer of the header.
width int: the width of the image in pixels.
height int: the height of the image in pixels.

getEncodedDataSize

Added in API level 8 
public static int getEncodedDataSize (int width, 
                int height)

Return the size of the encoded image data (does not include size of PKM header).

Parameters
width int

height int

Returns
int

getHeight

Added in API level 8 
public static int getHeight (Buffer header)

Read the image height from a PKM header

Parameters
header Buffer: native order direct buffer of the header.
Returns
int

getWidth

Added in API level 8 
public static int getWidth (Buffer header)

Read the image width from a PKM header

Parameters
header Buffer: native order direct buffer of the header.
Returns
int

isValid

Added in API level 8 
public static boolean isValid (Buffer header)

Check if a PKM header is correctly formatted.

Parameters
header Buffer: native order direct buffer of the header.
Returns
boolean