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cleanup WebPPicture struct and API

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* add a real proper pointer for holding memory chunk pointer
  (instead of using y and argb fields)
* polish the doc with details
* add a WebPPictureView() that extract a view from a picture
  without any copy (kind of a fast-crop).
* properly snap the top-left corner for Crop/View. Previously,
  the luma position was not snapped, and was off compared to the chroma.

Change-Id: I8a3620c7f5fc6f7d1f8dd89d9da167c91e237439
This commit is contained in:
Pascal Massimino
2012-06-21 00:30:43 -07:00
parent 9144a18643
commit 31b68fe639
3 changed files with 145 additions and 39 deletions
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64
src/webp/encode.h
View File

@ -95,8 +95,8 @@ WEBP_EXTERN(int) WebPConfigInitInternal(
WebPConfig* const, WebPPreset, float, int);
// Should always be called, to initialize a fresh WebPConfig structure before
// modification. Returns 0 in case of version mismatch. WebPConfigInit() must
// have succeeded before using the 'config' object.
// modification. Returns false in case of version mismatch. WebPConfigInit()
// must have succeeded before using the 'config' object.
static WEBP_INLINE int WebPConfigInit(WebPConfig* const config) {
return WebPConfigInitInternal(config, WEBP_PRESET_DEFAULT, 75.f,
WEBP_ENCODER_ABI_VERSION);
@ -105,14 +105,15 @@ static WEBP_INLINE int WebPConfigInit(WebPConfig* const config) {
// This function will initialize the configuration according to a predefined
// set of parameters (referred to by 'preset') and a given quality factor.
// This function can be called as a replacement to WebPConfigInit(). Will
// return 0 in case of error.
// return false in case of error.
static WEBP_INLINE int WebPConfigPreset(WebPConfig* const config,
WebPPreset preset, float quality) {
return WebPConfigInitInternal(config, preset, quality,
WEBP_ENCODER_ABI_VERSION);
}
// Returns 1 if all parameters are in valid range and the configuration is OK.
// Returns true if 'config' is non-NULL and all configuration parameters are
// within their valid ranges.
WEBP_EXTERN(int) WebPValidateConfig(const WebPConfig* const config);
//------------------------------------------------------------------------------
@ -140,7 +141,7 @@ typedef struct {
// used during callbacks (like progress-report e.g.).
} WebPAuxStats;
// Signature for output function. Should return 1 if writing was successful.
// Signature for output function. Should return true if writing was successful.
// data/data_size is the segment of data to write, and 'picture' is for
// reference (and so one can make use of picture->custom_ptr).
typedef int (*WebPWriterFunction)(const uint8_t* data, size_t data_size,
@ -162,8 +163,9 @@ WEBP_EXTERN(void) WebPMemoryWriterInit(WebPMemoryWriter* const writer);
WEBP_EXTERN(int) WebPMemoryWrite(const uint8_t* data, size_t data_size,
const WebPPicture* const picture);
// Progress hook, called from time to time to report progress. It can return 0
// to request an abort of the encoding process, or 1 otherwise if all is OK.
// Progress hook, called from time to time to report progress. It can return
// false to request an abort of the encoding process, or true otherwise if
// everything is OK.
typedef int (*WebPProgressHook)(int percent, const WebPPicture* const picture);
typedef enum {
@ -237,13 +239,17 @@ struct WebPPicture {
int use_argb_input; // Flag for encoder to use argb pixels as input.
uint32_t* argb; // Pointer to argb (32 bit) plane.
int argb_stride; // This is stride in pixels units, not bytes.
// private fields:
void* memory_; // row chunk of memory for yuva planes
void* memory_argb_; // and for argb too.
};
// Internal, version-checked, entry point
WEBP_EXTERN(int) WebPPictureInitInternal(WebPPicture* const, int);
// Should always be called, to initialize the structure. Returns 0 in case of
// version mismatch. WebPPictureInit() must have succeeded before using the
// Should always be called, to initialize the structure. Returns false in case
// of version mismatch. WebPPictureInit() must have succeeded before using the
// 'picture' object.
static WEBP_INLINE int WebPPictureInit(WebPPicture* const picture) {
return WebPPictureInitInternal(picture, WEBP_ENCODER_ABI_VERSION);
@ -255,21 +261,23 @@ static WEBP_INLINE int WebPPictureInit(WebPPicture* const picture) {
// Convenience allocation / deallocation based on picture->width/height:
// Allocate y/u/v buffers as per colorspace/width/height specification.
// Note! This function will free the previous buffer if needed.
// Returns 0 in case of memory error.
// Returns false in case of memory error.
WEBP_EXTERN(int) WebPPictureAlloc(WebPPicture* const picture);
// Release memory allocated by WebPPictureAlloc() or WebPPictureImport*()
// Note that this function does _not_ free the memory pointed to by 'picture'.
// Release the memory allocated by WebPPictureAlloc() or WebPPictureImport*().
// Note that this function does _not_ free the memory used by the 'picture'
// object itself.
WEBP_EXTERN(void) WebPPictureFree(WebPPicture* const picture);
// Copy the pixels of *src into *dst, using WebPPictureAlloc.
// Returns 0 in case of memory allocation error.
// Copy the pixels of *src into *dst, using WebPPictureAlloc. Upon return,
// *dst will fully own the copied pixels (this is not a view).
// Returns false in case of memory allocation error.
WEBP_EXTERN(int) WebPPictureCopy(const WebPPicture* const src,
WebPPicture* const dst);
// Compute PSNR or SSIM distortion between two pictures.
// Result is in dB, stores in result[] in the Y/U/V/Alpha/All order.
// Returns 0 in case of error (pic1 and pic2 don't have same dimension, ...)
// Returns false in case of error (pic1 and pic2 don't have same dimension, ...)
// Warning: this function is rather CPU-intensive.
WEBP_EXTERN(int) WebPPictureDistortion(
const WebPPicture* const pic1, const WebPPicture* const pic2,
@ -277,11 +285,33 @@ WEBP_EXTERN(int) WebPPictureDistortion(
float result[5]);
// self-crops a picture to the rectangle defined by top/left/width/height.
// Returns 0 in case of memory allocation error, or if the rectangle is
// Returns false in case of memory allocation error, or if the rectangle is
// outside of the source picture.
// The rectangle for the view is defined by the top-left corner pixel
// coordinates (left, top) as well as its width and height. This rectangle
// must be fully be comprised inside the 'src' source picture. If the source
// picture uses the YUV420 colorspace, the top and left coordinates will be
// snapped to even values.
WEBP_EXTERN(int) WebPPictureCrop(WebPPicture* const picture,
int left, int top, int width, int height);
// Extracts a view from 'src' picture into 'dst'. The rectangle for the view
// is defined by the top-left corner pixel coordinates (left, top) as well
// as its width and height. This rectangle must be fully be comprised inside
// the 'src' source picture. If the source picture uses the YUV420 colorspace,
// the top and left coordinates will be snapped to even values.
// Picture 'src' must out-live 'dst' picture. Self-extraction of view is allowed
// ('src' equal to 'dst') as a mean of fast-cropping (but note that doing so,
// the original dimension will be lost).
// Returns false in case of memory allocation error or invalid parameters.
WEBP_EXTERN(int) WebPPictureView(const WebPPicture* const src,
int left, int top, int width, int height,
WebPPicture* const dst);
// Returns true if the 'picture' is actually a view and therefore does
// not own the memory for pixels.
WEBP_EXTERN(int) WebPPictureIsView(const WebPPicture* const picture);
// Rescale a picture to new dimension width x height.
// Now gamma correction is applied.
// Returns false in case of error (invalid parameter or insufficient memory).
@ -291,7 +321,7 @@ WEBP_EXTERN(int) WebPPictureRescale(WebPPicture* const pic,
// Colorspace conversion function to import RGB samples.
// Previous buffer will be free'd, if any.
// *rgb buffer should have a size of at least height * rgb_stride.
// Returns 0 in case of memory error.
// Returns false in case of memory error.
WEBP_EXTERN(int) WebPPictureImportRGB(
WebPPicture* const picture, const uint8_t* const rgb, int rgb_stride);
// Same, but for RGBA buffer.