研究了下，发现emWin的JPEG解码是用libjpeg

eric2013 · 发表于 2015-4-4 14:14:08

找了一下uCGUI3.98的源码，看了一下JPEG相关的文件，的确使用的是libjpeg，而PNG的解码用的libpng。
===============================================================
uCGUI3.98里面的JPEG部分：

JPEG.zip (383 KB, 下载次数: 104)

eric2013 · 发表于 2015-4-4 14:18:16

UCGUI和libjpeg的接口文件：

/*
*********************************************************************************************************
* uC/GUI
* Universal graphic software for embedded applications
*
* (c) Copyright 2002, Micrium Inc., Weston, FL
* (c) Copyright 2002, SEGGER Microcontroller Systeme GmbH
*
* 礐/GUI is protected by international copyright laws. Knowledge of the
* source code may not be used to write a similar product. This file may
* only be used in accordance with a license and should not be redistributed
* in any way. We appreciate your understanding and fairness.
*
----------------------------------------------------------------------
File : GUI_JPEG.c
Purpose : Implementation of GUI_JPEG... functions
---------------------------END-OF-HEADER------------------------------
*/
#include <stdlib.h>
#include "GUI_Private.h"
#include "jpeglib.h"
#include "jerror.h"
#include "jmemsys.h"
/*********************************************************************
*
* Local defines & data types
*
**********************************************************************
*/
#define INPUT_BUF_SIZE 4096 /* choose an efficiently fread'able size */
/* Expanded data source object for stdio input */
typedef struct {
struct jpeg_source_mgr pub; /* public fields */
const U8* pFileData;
I32 FileSize;
I32 Off;
boolean start_of_file; /* have we gotten any data yet? */
} SOURCE_MANAGER;
static const U8 _abEnd[2] = {
0xFF, JPEG_EOI
};
/*********************************************************************
*
* Static code
*
**********************************************************************
*/
/*
* Initialize source --- called by jpeg_read_header
* before any data is actually read.
*/
static void _InitSource (j_decompress_ptr cinfo) {
SOURCE_MANAGER* pSrc = (SOURCE_MANAGER*) cinfo->src;
/* We reset the empty-input-file flag for each image,
* but we don't clear the input buffer.
* This is correct behavior for reading a series of images from one source.
*/
pSrc->start_of_file = TRUE;
}
/*
* Fill the input buffer --- called whenever buffer is emptied.
*
* In typical applications, this should read fresh data into the buffer
* (ignoring the current state of next_input_byte & bytes_in_buffer),
* reset the pointer & count to the start of the buffer, and return TRUE
* indicating that the buffer has been reloaded. It is not necessary to
* fill the buffer entirely, only to obtain at least one more byte.
*
* There is no such thing as an EOF return. If the end of the file has been
* reached, the routine has a choice of ERREXIT() or inserting fake data into
* the buffer. In most cases, generating a warning message and inserting a
* fake EOI marker is the best course of action --- this will allow the
* decompressor to output however much of the image is there. However,
* the resulting error message is misleading if the real problem is an empty
* input file, so we handle that case specially.
*
* In applications that need to be able to suspend compression due to input
* not being available yet, a FALSE return indicates that no more data can be
* obtained right now, but more may be forthcoming later. In this situation,
* the decompressor will return to its caller (with an indication of the
* number of scanlines it has read, if any). The application should resume
* decompression after it has loaded more data into the input buffer. Note
* that there are substantial restrictions on the use of suspension --- see
* the documentation.
*
* When suspending, the decompressor will back up to a convenient restart point
* (typically the start of the current MCU). next_input_byte & bytes_in_buffer
* indicate where the restart point will be if the current call returns FALSE.
* Data beyond this point must be rescanned after resumption, so move it to
* the front of the buffer rather than discarding it.
*/
static boolean _FillInputBuffer(j_decompress_ptr cinfo) {
SOURCE_MANAGER* pSrc = (SOURCE_MANAGER*) cinfo->src;
size_t nbytes;
int RemBytes = pSrc->FileSize - pSrc->Off;
if (RemBytes > 0) {
nbytes = (RemBytes > INPUT_BUF_SIZE) ? INPUT_BUF_SIZE : RemBytes;
pSrc->pub.next_input_byte = pSrc->pFileData + pSrc->Off;
pSrc->Off += nbytes;
} else {
if (pSrc->start_of_file) /* Treat empty input file as fatal error */
ERREXIT(cinfo, JERR_INPUT_EMPTY);
WARNMS(cinfo, JWRN_JPEG_EOF);
/* Insert a fake EOI marker */
nbytes = 2;
pSrc->pub.next_input_byte = _abEnd;
}
pSrc->pub.bytes_in_buffer = nbytes;
pSrc->start_of_file = FALSE;
return TRUE;
}
/*
* Skip data --- used to skip over a potentially large amount of
* uninteresting data (such as an APPn marker).
*
* Writers of suspendable-input applications must note that skip_input_data
* is not granted the right to give a suspension return. If the skip extends
* beyond the data currently in the buffer, the buffer can be marked empty so
* that the next read will cause a fill_input_buffer call that can suspend.
* Arranging for additional bytes to be discarded before reloading the input
* buffer is the application writer's problem.
*/
static void _SkipInputData (j_decompress_ptr cinfo, long num_bytes) {
SOURCE_MANAGER* pSrc = (SOURCE_MANAGER*) cinfo->src;
/* Just a dumb implementation for now. Could use fseek() except
* it doesn't work on pipes. Not clear that being smart is worth
* any trouble anyway --- large skips are infrequent.
*/
if (num_bytes > 0) {
while (num_bytes > (long) pSrc->pub.bytes_in_buffer) {
num_bytes -= (long) pSrc->pub.bytes_in_buffer;
(void) _FillInputBuffer(cinfo);
/* note we assume that fill_input_buffer will never return FALSE,
* so suspension need not be handled.
*/
}
pSrc->pub.next_input_byte += (size_t) num_bytes;
pSrc->pub.bytes_in_buffer -= (size_t) num_bytes;
}
}
/*
* An additional method that can be provided by data source modules is the
* resync_to_restart method for error recovery in the presence of RST markers.
* For the moment, this source module just uses the default resync method
* provided by the JPEG library. That method assumes that no backtracking
* is possible.
*/
/*
* Terminate source --- called by jpeg_finish_decompress
* after all data has been read. Often a no-op.
*
* NB: *not* called by jpeg_abort or jpeg_destroy; surrounding
* application must deal with any cleanup that should happen even
* for error exit.
*/
static void _TermSource(j_decompress_ptr cinfo) {
/* no work necessary here */
GUI_USE_PARA(cinfo);
}
static void _InitSrc(j_decompress_ptr cinfo, const U8* pFileData, I32 FileSize) {
SOURCE_MANAGER* pSrc;
/* The source object and input buffer are made permanent so that a series
* of JPEG images can be read from the same file by calling jpeg_stdio_src
* only before the first one. (If we discarded the buffer at the end of
* one image, we'd likely lose the start of the next one.)
* This makes it unsafe to use this manager and a different source
* manager serially with the same JPEG object. Caveat programmer.
*/
if (cinfo->src == NULL) { /* first time for this JPEG object? */
cinfo->src = (jpeg_source_mgr *) (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT, sizeof(SOURCE_MANAGER));
}
pSrc = (SOURCE_MANAGER*) cinfo->src;
pSrc->pub.init_source = _InitSource;
pSrc->pub.fill_input_buffer = _FillInputBuffer;
pSrc->pub.skip_input_data = _SkipInputData;
pSrc->pub.resync_to_restart = jpeg_resync_to_restart; /* use default method */
pSrc->pub.term_source = _TermSource;
pSrc->pub.bytes_in_buffer = 0; /* forces fill_input_buffer on first read */
pSrc->pub.next_input_byte = NULL; /* until buffer loaded */
/*
* Init private part of Source manager
*/
pSrc->FileSize = FileSize;
pSrc->pFileData = pFileData;
pSrc->Off = 0;
}
/*********************************************************************
*
* Memory allocation
*
**********************************************************************
*/
int AllocCnt; /* for debugging only */
int TotalSize;
/*
* Memory allocation and freeing are controlled by the regular library
* routines malloc() and free().
*/
GLOBAL(void *) jpeg_get_small (j_common_ptr cinfo, size_t sizeofobject) {
GUI_USE_PARA(cinfo);
AllocCnt++;
TotalSize += sizeofobject;
return (void *) malloc(sizeofobject);
}
GLOBAL(void) jpeg_free_small (j_common_ptr cinfo, void * object, size_t sizeofobject) {
GUI_USE_PARA(cinfo);
GUI_USE_PARA(sizeofobject);
if (--AllocCnt) {
TotalSize = 0;
}
free(object);
}
/*
* This routine computes the total memory space available for allocation.
* Here we always say, "we got all you want bud!"
*/
GLOBAL(long) jpeg_mem_available (j_common_ptr cinfo, long min_bytes_needed, long max_bytes_needed, long already_allocated) {
GUI_USE_PARA(cinfo);
GUI_USE_PARA(min_bytes_needed);
GUI_USE_PARA(already_allocated);
return max_bytes_needed;
}
/*
* These routines take care of any system-dependent initialization and
* cleanup required. Here, there isn't any.
* just set max_memory_to_use to 0
*/
GLOBAL(long) jpeg_mem_init (j_common_ptr cinfo) {
GUI_USE_PARA(cinfo);
return 0;
}
GLOBAL(void) jpeg_mem_term (j_common_ptr cinfo) {
GUI_USE_PARA(cinfo);
}
/*********************************************************************
*
* _Init
*/
static void _Init(struct jpeg_error_mgr* pjerr, struct jpeg_decompress_struct *pcinfo, const void * pFileData, int DataSize) {
/* 1. Allocate and initialize a JPEG decompression object. */
pcinfo->err = jpeg_std_error(pjerr);
jpeg_create_decompress(pcinfo);
/* 2. Init the source manager so the library can retrieve data via methods */
_InitSrc(pcinfo, (const U8*)pFileData, DataSize);
/* 3. Call jpeg_read_header() to obtain image info. */
jpeg_read_header(pcinfo, TRUE);
}
/*********************************************************************
*
* _WritePixelsRGB
*/
static void _WritePixelsRGB(const U8*p, int x0, int y0, int xSize) {
U8 r,g,b;
while (xSize) {
r = *p++;
g = *p++;
b = *p++;
LCD_SetColor(r | (g << 8) | (U32)((U32)b << 16));
LCD_DrawPixel(x0++, y0);
xSize--;
}
}
/*********************************************************************
*
* _WritePixelsGray
*/
static void _WritePixelsGray(const U8*p, int x0, int y0, int xSize) {
U8 u;
while (xSize) {
u = *p++;
LCD_SetColor(u * (U32)0x10101);
LCD_DrawPixel(x0++, y0);
xSize--;
}
}
/*********************************************************************
*
* Public code
*
**********************************************************************
*/
/*********************************************************************
*
* GUI_JPEG_GetInfo
*/
int GUI_JPEG_GetInfo(const void * pFileData, int DataSize, GUI_JPEG_INFO* pInfo) {
struct jpeg_decompress_struct cinfo;
struct jpeg_error_mgr jerr;
_Init(&jerr, &cinfo, pFileData, DataSize);
/*
* Release the JPEG decompression object.
*/
jpeg_destroy_decompress(&cinfo);
if (pInfo) {
pInfo->XSize = cinfo.image_width;
pInfo->YSize = cinfo.image_height;
}
return 0;
}
/*********************************************************************
*
* GUI_JPEG_Draw
*/
int GUI_JPEG_Draw(const void * pFileData, int DataSize, int x0, int y0) {
#if (GUI_WINSUPPORT)
GUI_RECT r;
#endif
int Ret = 0;
GUI_HMEM hBuffer = 0;
struct jpeg_decompress_struct cinfo;
struct jpeg_error_mgr jerr;
GUI_LOCK();
_Init(&jerr, &cinfo, pFileData, DataSize);
#if (GUI_WINSUPPORT)
WM_ADDORG(x0,y0);
r.x1 = (r.x0 = x0) + cinfo.image_width - 1;
r.y1 = (r.y0 = y0) + cinfo.image_height - 1;
WM_ITERATE_START(&r) {
#endif
if (hBuffer) {
_Init(&jerr, &cinfo, pFileData, DataSize);
}
/* 4. Set up parameters for decompression (optional ...) */
/* 5. jpeg_start_decompress(...); Should normally return quickly */
jpeg_start_decompress(&cinfo);
/* 6. while (scan lines remain to be read) */
/* jpeg_read_scanlines(...); */
if (!hBuffer) {
hBuffer = GUI_ALLOC_AllocNoInit(cinfo.image_width * 3);
}
while (cinfo.output_scanline < cinfo.output_height) {
U8* p;
p = (U8*)GUI_ALLOC_h2p(hBuffer);
jpeg_read_scanlines(&cinfo, &p, 1);
if (cinfo.jpeg_color_space == JCS_GRAYSCALE) {
_WritePixelsGray(p, x0, y0 + cinfo.output_scanline, cinfo.image_width);
} else {
_WritePixelsRGB(p, x0, y0 + cinfo.output_scanline, cinfo.image_width);
}
}
/* 7. jpeg_finish_decompress(...); */
/* Complete the decompression cycle. This causes working memory associated */
/* with the JPEG object to be released. */
jpeg_finish_decompress(&cinfo);
/* 8. Release the JPEG decompression object. */
jpeg_destroy_decompress(&cinfo);
#if (GUI_WINSUPPORT)
} WM_ITERATE_END();
#endif
GUI_ALLOC_Free(hBuffer);
GUI_UNLOCK();
return Ret;
}
/*************************** End of file ****************************/

复制代码

qiousanxi · 发表于 2018-1-21 10:18:13

硬汉问下怎么覆盖 emwin的GUI_JPEG_Draw，我新建一个会报错. Symbol GUI_JPEG_Draw multiply defined (by gui_jpeg.o and gui_jpeg.o).

eric2013 · 发表于 2018-1-21 11:52:19

qiousanxi 发表于 2018-1-21 10:18
硬汉问下怎么覆盖 emwin的GUI_JPEG_Draw，我新建一个会报错. Symbol GUI_JPEG_Draw multiply defined ( ...

下载我们的这个V6综合Demo，里面有覆盖:
http://www.armbbs.cn/forum.php?m ... &extra=page%3D1

qiousanxi · 发表于 2018-1-21 12:14:34

我看了，用的是外部的lib我想问问，怎么覆盖的emwin的函数

eric2013 · 发表于 2018-1-21 12:19:28

qiousanxi 发表于 2018-1-21 12:14
我看了，用的是外部的lib我想问问，怎么覆盖的emwin的函数

直接添加新文件就好了，注意你的程序里面不要调用GUI_JPEG_DrawEx之类的其它函数，别的没有要注意的了。

qiousanxi · 发表于 2018-1-21 12:24:07

就是，我模仿你创建了个函数GUI_JPEG_Draw一直报错

qiousanxi · 发表于 2018-1-21 12:25:38

哦哦，如果需要用，也要去重新实现其他的jpeg函数对吗？

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[LibJPEG] 研究了下，发现emWin的JPEG解码是用libjpeg