зеркало из https://github.com/mozilla/gecko-dev.git
Bug 1141979 - part2 - implement ChannelPixelLayout; r=jrmuizel, r=smaug
MozReview-Commit-ID: DNUwRoxPwgE --HG-- extra : transplant_source : J%A5%3C%C9%FA%BB%A4r%9A%3Dg%84%19n%B3%90e%AE%E5%07
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Kaku Kuo
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ec2d98e4c3
Коммит
e5ade18f88
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@ -267,3 +267,144 @@ enum ChannelPixelLayoutDataType {
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"float64"
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};
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/*
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* Two concepts, ImagePixelLayout and ChannelPixelLayout, together generalize
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* the variety of pixel layouts among image formats.
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*
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* The ChannelPixelLayout represents the pixel layout of a single channel in a
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* certain image format and the ImagePixelLayout is just the collection of
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* ChannelPixelLayouts. So, the ChannelPixelLayout is defined as a dictionary
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* type with properties to describe the layout and the ImagePixelLayout is just
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* an alias name to a sequence of ChannelPixelLayout objects.
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*
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* Since an image format is composed of at least one channel, an
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* ImagePixelLayout object contains at least one ChannelPixelLayout object.
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*
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* Although an image or a video frame is a two-dimensional structure, its data
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* is usually stored in a one-dimensional array in the row-major way and the
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* ChannelPixelLayout objects use the following properties to describe the
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* layout of pixel values in the buffer.
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*
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* 1) offset:
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* denotes the beginning position of the channel's data relative to the
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* beginning position of the one-dimensional array.
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* 2) width & height:
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* denote the width and height of the channel respectively. Each channel in
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* an image format may have different height and width.
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* 3) data type:
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* denotes the format used to store one single pixel value.
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* 4) stride:
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* the number of bytes between the beginning two consecutive rows in memory.
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* (The total bytes of each row plus the padding bytes of each raw.)
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* 5) skip value:
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* the value is zero for the planar pixel layout, and a positive integer for
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* the interleaving pixel layout. (Describes how many bytes there are between
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* two adjacent pixel values in this channel.)
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*/
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/*
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* Example1: RGBA image, width = 620, height = 480, stride = 2560
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*
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* chanel_r: offset = 0, width = 620, height = 480, data type = uint8, stride = 2560, skip = 3
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* chanel_g: offset = 1, width = 620, height = 480, data type = uint8, stride = 2560, skip = 3
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* chanel_b: offset = 2, width = 620, height = 480, data type = uint8, stride = 2560, skip = 3
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* chanel_a: offset = 3, width = 620, height = 480, data type = uint8, stride = 2560, skip = 3
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*
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* <---------------------------- stride ---------------------------->
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* <---------------------- width x 4 ---------------------->
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* [index] 01234 8 12 16 20 24 28 2479 2559
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* |||||---|---|---|---|---|---|----------------------------|-------|
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* [data] RGBARGBARGBARGBARGBAR___R___R... A%%%%%%%%
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* [data] RGBARGBARGBARGBARGBAR___R___R... A%%%%%%%%
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* [data] RGBARGBARGBARGBARGBAR___R___R... A%%%%%%%%
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* ^^^
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* r-skip
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*/
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/*
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* Example2: YUV420P image, width = 620, height = 480, stride = 640
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*
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* chanel_y: offset = 0, width = 620, height = 480, stride = 640, skip = 0
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* chanel_u: offset = 307200, width = 310, height = 240, data type = uint8, stride = 320, skip = 0
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* chanel_v: offset = 384000, width = 310, height = 240, data type = uint8, stride = 320, skip = 0
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*
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* <--------------------------- y-stride --------------------------->
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* <----------------------- y-width ----------------------->
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* [index] 012345 619 639
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* ||||||--------------------------------------------------|--------|
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* [data] YYYYYYYYYYYYYYYYYYYYYYYYYYYYY... Y%%%%%%%%%
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* [data] YYYYYYYYYYYYYYYYYYYYYYYYYYYYY... Y%%%%%%%%%
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* [data] YYYYYYYYYYYYYYYYYYYYYYYYYYYYY... Y%%%%%%%%%
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* [data] ......
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* <-------- u-stride ---------->
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* <----- u-width ----->
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* [index] 307200 307509 307519
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* |-------------------|--------|
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* [data] UUUUUUUUUU... U%%%%%%%%%
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* [data] UUUUUUUUUU... U%%%%%%%%%
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* [data] UUUUUUUUUU... U%%%%%%%%%
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* [data] ......
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* <-------- v-stride ---------->
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* <- --- v-width ----->
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* [index] 384000 384309 384319
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* |-------------------|--------|
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* [data] VVVVVVVVVV... V%%%%%%%%%
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* [data] VVVVVVVVVV... V%%%%%%%%%
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* [data] VVVVVVVVVV... V%%%%%%%%%
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* [data] ......
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*/
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/*
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* Example3: YUV420SP_NV12 image, width = 620, height = 480, stride = 640
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*
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* chanel_y: offset = 0, width = 620, height = 480, stride = 640, skip = 0
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* chanel_u: offset = 307200, width = 310, height = 240, data type = uint8, stride = 640, skip = 1
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* chanel_v: offset = 307201, width = 310, height = 240, data type = uint8, stride = 640, skip = 1
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*
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* <--------------------------- y-stride -------------------------->
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* <----------------------- y-width ---------------------->
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* [index] 012345 619 639
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* ||||||-------------------------------------------------|--------|
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* [data] YYYYYYYYYYYYYYYYYYYYYYYYYYYYY... Y%%%%%%%%%
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* [data] YYYYYYYYYYYYYYYYYYYYYYYYYYYYY... Y%%%%%%%%%
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* [data] YYYYYYYYYYYYYYYYYYYYYYYYYYYYY... Y%%%%%%%%%
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* [data] ......
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* <--------------------- u-stride / v-stride -------------------->
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* <------------------ u-width + v-width ----------------->
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* [index] 307200(u-offset) 307819 307839
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* |------------------------------------------------------|-------|
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* [index] |307201(v-offset) |307820 |
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* ||-----------------------------------------------------||------|
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* [data] UVUVUVUVUVUVUVUVUVUVUVUVUVUVUV... UV%%%%%%%
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* [data] UVUVUVUVUVUVUVUVUVUVUVUVUVUVUV... UV%%%%%%%
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* [data] UVUVUVUVUVUVUVUVUVUVUVUVUVUVUV... UV%%%%%%%
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* ^ ^
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* u-skip v-skip
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*/
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/*
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* Example4: DEPTH image, width = 640, height = 480, stride = 1280
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*
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* chanel_d: offset = 0, width = 640, height = 480, data type = uint16, stride = 1280, skip = 0
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*
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* note: each DEPTH value uses two bytes
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*
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* <----------------------- d-stride ---------------------->
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* <----------------------- d-width ----------------------->
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* [index] 02468 1278
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* |||||---------------------------------------------------|
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* [data] DDDDDDDDDDDDDDDDDDDDDDDDDDDDD... D
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* [data] DDDDDDDDDDDDDDDDDDDDDDDDDDDDD... D
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* [data] DDDDDDDDDDDDDDDDDDDDDDDDDDDDD... D
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* [data] ......
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*/
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dictionary ChannelPixelLayout {
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required unsigned long offset;
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required unsigned long width;
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required unsigned long height;
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required ChannelPixelLayoutDataType dataType;
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required unsigned long stride;
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required unsigned long skip;
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};
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