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1.0
28
Introduced
Gecko 1.8
Inherits from:
nsIAsyncInputStream
Last changed in Gecko 1.9 (Firefox 3)Method overview
void addImageFrame( [array, size_is(length), const] in PRUint8 data, in unsigned long length, in PRUint32 width, in PRUint32 height, in PRUint32 stride, in PRUint32 frameFormat, in AString frameOptions); |
void encodeClipboardImage(in nsIClipboardImage aClipboardImage, out nsIFile aImageFile); Obsolete since Gecko 1.9 |
void endImageEncode(); |
void initFromData([array, size_is(length), const] in PRUint8 data, in unsigned long length, in PRUint32 width, in PRUint32 height, in PRUint32 stride, in PRUint32 inputFormat, in AString outputOptions); |
void startImageEncode(in PRUint32 width, in PRUint32 height, in PRUint32 inputFormat, in AString outputOptions); |
Constants
Possible values for input format (note that not all image formats support saving alpha channels):
| Constant | Value | Description |
INPUT_FORMAT_RGB | 0 | Input is RGB each pixel is represented by three bytes: R, G, and B (in that order, regardless of host endianness) |
INPUT_FORMAT_RGBA | 1 | Input is RGB each pixel is represented by four bytes: R, G, and B (in that order, regardless of host endianness). POST-MULTIPLIED alpha us used (For example 50% transparent red is 0xff000080) |
INPUT_FORMAT_HOSTARGB | 2 | Input is host-endian ARGB: On big-endian machines each pixel is therefore ARGB, and for little-endian machiens (Intel) each pixel is BGRA (This is used by canvas to match it's internal representation) PRE-MULTIPLIED alpha is used (That is, 50% transparent red is 0x80800000, not 0x80ff0000) |
Possible values for outputOptions. Multiple values are semicolon-separated.
PNG:
----
transparency=[yes|no|none] -- default: "yes"
Overrides default from input format. "no" and "none" are equivalent.
APNG:
-----
The following options can be used with startImageEncode():
transparency=[yes|no|none] -- default: "yes"
Overrides default from input format. "no" and "none" are equivalent.
skipfirstframe=[yes|no] -- default: "no"
Controls display of the first frame in animations. PNG-only clients always display the first frame (and only that frame).
frames=# -- default: "1"
Total number of frames in the image. The first frame, even if skipped, is always included in the count.
plays=# -- default: "0"
Number of times to play the animation sequence. "0" will repeat forever.
The following options can be used for each frame, with addImageFrame():
transparency=[yes|no|none] -- default: "yes"
Overrides default from input format. "no" and "none" are equivalent.
delay=# -- default: "500"
Number of milliseconds to display the frame, before moving to the next frame.
dispose=[none|background|previous] -- default: "none"
What to do with the image's canvas before rendering the next frame. See APNG spec.
blend=[source|over] -- default: "source"
How to render the new frame on the canvas. See APNG spec.
xoffset=# -- default: "0"
yoffset=# -- default: "0"
Where to draw the frame, relative to the canvas.
JPEG:
-----
quality=# -- default: "92"
Quality of compression, 0-100 (worst-best).
Quality >= 90 prevents down-sampling of the color channels.
Methods
Requires Gecko 1.9 (Firefox 3)
addImageFrame()
void addImageFrame( [array, size_is(length), const] in PRUint8 data, in unsigned long length, in PRUint32 width, in PRUint32 height, in PRUint32 stride, in PRUint32 frameFormat, in AString frameOptions );
Parameters
data- List of bytes in the format specified by
inputFormat. length- Missing Description
width- Width in pixels.
height- Height in pixels.
stride- The number of bytes per row in the image. Normally (width*3) or (width*4), depending on your input format, but some data uses padding at the end of each row, which would be extra.
frameFormat- Missing Description
frameOptions- Missing Description
Obsolete since Gecko 1.9 (Firefox 3)
encodeClipboardImage()
void encodeClipboardImage( in nsIClipboardImage aClipboardImage, out nsIFile aImageFile );
Parameters
aClipboardImage- Missing Description
aImageFile- Missing Description
Requires Gecko 1.9 (Firefox 3)
endImageEncode()
void endImageEncode();
Parameters
None.
Requires Gecko 1.9 (Firefox 3)
initFromData()
void initFromData( [array, size_is(length), const] in PRUint8 data, in unsigned long length, in PRUint32 width, in PRUint32 height, in PRUint32 stride, in PRUint32 inputFormat, in AString outputOptions );
Parameters
data- List of bytes in the format specified by
inputFormat. length- Missing Description
width- Width in pixels.
height- Height in pixels.
stride- The number of bytes per row in the image. Normally (width*3) or (width*4), depending on your input format, but some data uses padding at the end of each row, which would be extra.
inputFormat- One of INPUT_FORMAT_* constants specifying the format of data.
outputOptions- Semicolon-delimited list of name=value pairs that can give options to the output encoder. Options are encoder-specific. Just give an empty string for default behavior.
Requires Gecko 1.9 (Firefox 3)
startImageEncode()
void startImageEncode( in PRUint32 width, in PRUint32 height, in PRUint32 inputFormat, in AString outputOptions );
Parameters
width- Width in pixels.
height- Height in pixels.
inputFormat- One of INPUT_FORMAT_* constants specifying the format of data.
outputOptions- Semicolon-delimited list of name=value pairs that can give options to the output encoder. Options are encoder-specific. Just give an empty string for default behavior.
Remarks
For encoding images which may contain multiple frames, the 1-shot initFromData() interface is too simplistic. The alternative is to use startImageEncode(), call addImageFrame() one or more times, and then finish initialization with endImageEncode().