笔记
1.基本概念
在链接阶段，编译器会将不同文件、库中的函数、全局变量进行链接（建立联系）。
2.字体库的使用
libfont
— font.h 字体库头文件
— libfont.a 字体静态库（2选1即可）
— libfont.so 字体动态库
使用静态库：
直接使用了库的源码函数，最终程序体积较大，运行时不需要依赖。
使用动态库：
只使用了库的链接，最终程序体积较小，运行时需要库依赖。
使用步骤：
1.将库的整个文件夹整体放入工程中。
2.将头文件加入到工程头文件中 head.h，按照头文件提示直接使用即可。
3.编译工程：
动态库：
arm-linux-gcc *.c -o demo -Wall -I./libfont -L./libfont -lfont
静态库：
arm-linux-gcc *.c -o demo -Wall -I./libfont -L./libfont –lfont -static
4.传输到开发板中运行
动态库：
第一次运行前，需将库文件本身传输到开发板的库目录/lib
静态库：
直接运行即可
备注：
1.如运行动态库的程序出现下列问题：
原因：没有将动态库放入开发板库目录/lib中。
解决方法：将库文件放入/lib中
2.如果出现中文显示乱码：
原因：因为没有使用GB2312编码（不可使用UTF-8编码） 解决方法：
需要将使用了显示函数的文件修改为GB2312编码。
（但是每次打开都是乱码，可按如下步骤让VSCode自动识别编码：
代码
项目1：proj1_显示中英文_字库使用
font.h
#ifndef __FONT__ #define __FONT__ int Init_Font(void); //显示字体库前先调用本函数进行初始化 void UnInit_Font(void); //程序退出前，调用本函数 int Clean_Area(int X, //x坐标起始点 int Y, //y坐标起始点 int width, //绘制的宽度 int height,//绘制的高度 unsigned long color); //往屏幕指定区域填充颜色 int Display_characterX(unsigned int x, //x坐标起始点 unsigned int y, //y坐标起始点 char *string, //GB2312 中文字符串 unsigned int color , //字体颜色值 int size); //字体放大倍数 1~8 #endif
head.h
#ifndef __HEAD_H #define __HEAD_H // 头文件 #include <stdio.h> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <unistd.h> #include <sys/mman.h> #include <linux/input.h> // 输入子系统头文件 #include "font.h" //字体库 // 打开LCD设备并初始化显存 extern int open_lcd(void); // 关闭LCD设备 extern void close_lcd(void); // 显示色块 extern void show_color(int x_start, int y_start, int w, int h, int color); // 打开触摸屏文件 extern int open_ts(void); // 关闭触摸屏 extern void close_ts(void); // 获取当前点击坐标 extern void get_xy(int *x, int *y); #endif
lcd.c
#include "head.h" static int *FB; // 显存首地址（内部链接类型） static int lcd_fd; // LCD文件描述符 // 打开LCD设备并初始化显存 int open_lcd(void) { // 1. 打开冰箱门 ——》打开屏幕设备文件 lcd_fd = open("/dev/fb0", O_RDWR); if(lcd_fd == -1) { perror("open lcd failed"); return -1; } // 显存映射(int *类型表示操作对象是像素点) FB = mmap( NULL, // 填NULL表示显存地址由系统自动分配 800*480*4, // 整块屏幕的显存大小 PROT_READ|PROT_WRITE, // 显存保护权限：可读可写 MAP_SHARED, // 多进程共享设置 lcd_fd, // LCD文件描述符 0); // 0表示不偏移 if(FB == MAP_FAILED) { perror("mmap failed"); return -2; } return 0; } // 关闭LCD设备 void close_lcd(void) { close(lcd_fd); } // 显示色块 void show_color(int x_start, int y_start, int w, int h, int color) { int x, y; for(y=y_start; y<y_start+h; y++) for(x=x_start; x<x_start+w; x++) *(FB+x+800*y) = color; }
main.c
#include "head.h" int main() { open_lcd(); // 打开并初始化LCD open_ts(); // 打开触摸屏 Init_Font(); // 初始化字体库 // 全屏刷白 show_color(0, 0, 800, 480, 0xFFFFFF); // 显示一段中英文 Display_characterX(100, 200, "GZ2203大家好!~", 0xFF0000, 2); UnInit_Font(); // 关闭字体库 close_ts(); // 关闭触摸屏 close_lcd(); // 关闭LCD return 0; }
ts.c
#include "head.h" static int ts_fd; // 触摸屏文件描述符全局变量 // 打开触摸屏文件 int open_ts(void) { ts_fd = open("/dev/input/event0", O_RDONLY); if(ts_fd == -1) { perror("open ts failed"); return -1; } return 0; } // 关闭触摸屏 void close_ts(void) { close(ts_fd); } // 获取当前点击坐标 void get_xy(int *x, int *y) { int x_ready=0, y_ready=0; struct input_event ts_buf; while(1) { read(ts_fd, &ts_buf, sizeof(ts_buf)); // printf("type:0x%x code:0x%x value:%d\n", ts_buf.type, ts_buf.code, ts_buf.value); // if(ts_buf.type==0x3 && ts_buf.code==0x0) if(ts_buf.type==EV_ABS && ts_buf.code==ABS_X) { *x = ts_buf.value; x_ready = 1; y_ready = 0; // 确保x坐标获取在前 } else if(ts_buf.type==EV_ABS && ts_buf.code==ABS_Y) { *y = ts_buf.value; y_ready = 1; } if(x_ready==1 && y_ready==1) break; } }
项目2：proj2_自行制作LCD-TS库
lcd.h
#ifndef _LCD_H #define _LCD_H // 头文件 #include <stdio.h> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <unistd.h> #include <sys/mman.h> // 打开LCD设备并初始化显存 extern int open_lcd(void); // 关闭LCD设备 extern void close_lcd(void); // 显示色块 extern void show_color(int x_start, int y_start, int w, int h, int color); #endif
ts.h
#ifndef _TS_H #define _TS_H // 头文件 #include <stdio.h> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <unistd.h> #include <linux/input.h> // 输入子系统头文件 // 打开触摸屏文件 extern int open_ts(void); // 关闭触摸屏 extern void close_ts(void); // 获取当前点击坐标 extern void get_xy(int *x, int *y); #endif
lcd.c
#include "lcd.h" static int *FB; // 显存首地址（内部链接类型） static int lcd_fd; // LCD文件描述符 // 打开LCD设备并初始化显存 int open_lcd(void) { // 1. 打开冰箱门 ——》打开屏幕设备文件 lcd_fd = open("/dev/fb0", O_RDWR); if(lcd_fd == -1) { perror("open lcd failed"); return -1; } // 显存映射(int *类型表示操作对象是像素点) FB = mmap( NULL, // 填NULL表示显存地址由系统自动分配 800*480*4, // 整块屏幕的显存大小 PROT_READ|PROT_WRITE, // 显存保护权限：可读可写 MAP_SHARED, // 多进程共享设置 lcd_fd, // LCD文件描述符 0); // 0表示不偏移 if(FB == MAP_FAILED) { perror("mmap failed"); return -2; } return 0; } // 关闭LCD设备 void close_lcd(void) { close(lcd_fd); } // 显示色块 void show_color(int x_start, int y_start, int w, int h, int color) { int x, y; for(y=y_start; y<y_start+h; y++) for(x=x_start; x<x_start+w; x++) *(FB+x+800*y) = color; }
ts.c
#include "ts.h" static int ts_fd; // 触摸屏文件描述符全局变量 // 打开触摸屏文件 int open_ts(void) { ts_fd = open("/dev/input/event0", O_RDONLY); if(ts_fd == -1) { perror("open ts failed"); return -1; } return 0; } // 关闭触摸屏 void close_ts(void) { close(ts_fd); } // 获取当前点击坐标 void get_xy(int *x, int *y) { int x_ready=0, y_ready=0; struct input_event ts_buf; while(1) { read(ts_fd, &ts_buf, sizeof(ts_buf)); // printf("type:0x%x code:0x%x value:%d\n", ts_buf.type, ts_buf.code, ts_buf.value); // if(ts_buf.type==0x3 && ts_buf.code==0x0) if(ts_buf.type==EV_ABS && ts_buf.code==ABS_X) { *x = ts_buf.value; x_ready = 1; y_ready = 0; // 确保x坐标获取在前 } else if(ts_buf.type==EV_ABS && ts_buf.code==ABS_Y) { *y = ts_buf.value; y_ready = 1; } if(x_ready==1 && y_ready==1) break; } }
head.h
#ifndef __HEAD_H #define __HEAD_H // 头文件 #include <stdio.h> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <unistd.h> #include <sys/mman.h> #include <linux/input.h> // 输入子系统头文件 #include "font.h" //字体库 #include "lcd.h" //LCD库 #include "ts.h" //TS库 #endif
main.c
#include "head.h" int main() { open_lcd(); // 打开并初始化LCD open_ts(); // 打开触摸屏 Init_Font(); // 初始化字体库 // 全屏刷白 show_color(0, 0, 800, 480, 0xFFFFFF); // 显示一段中英文 Display_characterX(100, 200, "GZ2203大家好!~", 0xFF0000, 2); UnInit_Font(); // 关闭字体库 close_ts(); // 关闭触摸屏 close_lcd(); // 关闭LCD return 0; }
项目3：proj3_jpeg图片显示
jconfig.h
/* jconfig.h. Generated from jconfig.cfg by configure. */ /* jconfig.cfg --- source file edited by configure script */ /* see jconfig.txt for explanations */ #define HAVE_PROTOTYPES 1 #define HAVE_UNSIGNED_CHAR 1 #define HAVE_UNSIGNED_SHORT 1 /* #undef void */ /* #undef const */ /* #undef CHAR_IS_UNSIGNED */ #define HAVE_STDDEF_H 1 #define HAVE_STDLIB_H 1 #define HAVE_LOCALE_H 1 /* #undef NEED_BSD_STRINGS */ /* #undef NEED_SYS_TYPES_H */ /* #undef NEED_FAR_POINTERS */ /* #undef NEED_SHORT_EXTERNAL_NAMES */ /* Define this if you get warnings about undefined structures. */ /* #undef INCOMPLETE_TYPES_BROKEN */ /* Define "boolean" as unsigned char, not int, on Windows systems. */ #ifdef _WIN32 #ifndef __RPCNDR_H__ /* don't conflict if rpcndr.h already read */ typedef unsigned char boolean; #endif #define HAVE_BOOLEAN /* prevent jmorecfg.h from redefining it */ #endif #ifdef JPEG_INTERNALS /* #undef RIGHT_SHIFT_IS_UNSIGNED */ #define INLINE __inline__ /* These are for configuring the JPEG memory manager. */ /* #undef DEFAULT_MAX_MEM */ /* #undef NO_MKTEMP */ #endif /* JPEG_INTERNALS */ #ifdef JPEG_CJPEG_DJPEG #define BMP_SUPPORTED /* BMP image file format */ #define GIF_SUPPORTED /* GIF image file format */ #define PPM_SUPPORTED /* PBMPLUS PPM/PGM image file format */ /* #undef RLE_SUPPORTED */ #define TARGA_SUPPORTED /* Targa image file format */ /* #undef TWO_FILE_COMMANDLINE */ /* #undef NEED_SIGNAL_CATCHER */ /* #undef DONT_USE_B_MODE */ /* Define this if you want percent-done progress reports from cjpeg/djpeg. */ /* #undef PROGRESS_REPORT */ #endif /* JPEG_CJPEG_DJPEG */
jerror.h
/* * jerror.h * * Copyright (C) 1994-1997, Thomas G. Lane. * Modified 1997-2009 by Guido Vollbeding. * This file is part of the Independent JPEG Group's software. * For conditions of distribution and use, see the accompanying README file. * * This file defines the error and message codes for the JPEG library. * Edit this file to add new codes, or to translate the message strings to * some other language. * A set of error-reporting macros are defined too. Some applications using * the JPEG library may wish to include this file to get the error codes * and/or the macros. */ /* * To define the enum list of message codes, include this file without * defining macro JMESSAGE. To create a message string table, include it * again with a suitable JMESSAGE definition (see jerror.c for an example). */ #ifndef JMESSAGE #ifndef JERROR_H /* First time through, define the enum list */ #define JMAKE_ENUM_LIST #else /* Repeated inclusions of this file are no-ops unless JMESSAGE is defined */ #define JMESSAGE(code,string) #endif /* JERROR_H */ #endif /* JMESSAGE */ #ifdef JMAKE_ENUM_LIST typedef enum { #define JMESSAGE(code,string) code , #endif /* JMAKE_ENUM_LIST */ JMESSAGE(JMSG_NOMESSAGE, "Bogus message code %d") /* Must be first entry! */ /* For maintenance convenience, list is alphabetical by message code name */ JMESSAGE(JERR_BAD_ALIGN_TYPE, "ALIGN_TYPE is wrong, please fix") JMESSAGE(JERR_BAD_ALLOC_CHUNK, "MAX_ALLOC_CHUNK is wrong, please fix") JMESSAGE(JERR_BAD_BUFFER_MODE, "Bogus buffer control mode") JMESSAGE(JERR_BAD_COMPONENT_ID, "Invalid component ID %d in SOS") JMESSAGE(JERR_BAD_CROP_SPEC, "Invalid crop request") JMESSAGE(JERR_BAD_DCT_COEF, "DCT coefficient out of range") JMESSAGE(JERR_BAD_DCTSIZE, "DCT scaled block size %dx%d not supported") JMESSAGE(JERR_BAD_DROP_SAMPLING, "Component index %d: mismatching sampling ratio %d:%d, %d:%d, %c") JMESSAGE(JERR_BAD_HUFF_TABLE, "Bogus Huffman table definition") JMESSAGE(JERR_BAD_IN_COLORSPACE, "Bogus input colorspace") JMESSAGE(JERR_BAD_J_COLORSPACE, "Bogus JPEG colorspace") JMESSAGE(JERR_BAD_LENGTH, "Bogus marker length") JMESSAGE(JERR_BAD_LIB_VERSION, "Wrong JPEG library version: library is %d, caller expects %d") JMESSAGE(JERR_BAD_MCU_SIZE, "Sampling factors too large for interleaved scan") JMESSAGE(JERR_BAD_POOL_ID, "Invalid memory pool code %d") JMESSAGE(JERR_BAD_PRECISION, "Unsupported JPEG data precision %d") JMESSAGE(JERR_BAD_PROGRESSION, "Invalid progressive parameters Ss=%d Se=%d Ah=%d Al=%d") JMESSAGE(JERR_BAD_PROG_SCRIPT, "Invalid progressive parameters at scan script entry %d") JMESSAGE(JERR_BAD_SAMPLING, "Bogus sampling factors") JMESSAGE(JERR_BAD_SCAN_SCRIPT, "Invalid scan script at entry %d") JMESSAGE(JERR_BAD_STATE, "Improper call to JPEG library in state %d") JMESSAGE(JERR_BAD_STRUCT_SIZE, "JPEG parameter struct mismatch: library thinks size is %u, caller expects %u") JMESSAGE(JERR_BAD_VIRTUAL_ACCESS, "Bogus virtual array access") JMESSAGE(JERR_BUFFER_SIZE, "Buffer passed to JPEG library is too small") JMESSAGE(JERR_CANT_SUSPEND, "Suspension not allowed here") JMESSAGE(JERR_CCIR601_NOTIMPL, "CCIR601 sampling not implemented yet") JMESSAGE(JERR_COMPONENT_COUNT, "Too many color components: %d, max %d") JMESSAGE(JERR_CONVERSION_NOTIMPL, "Unsupported color conversion request") JMESSAGE(JERR_DAC_INDEX, "Bogus DAC index %d") JMESSAGE(JERR_DAC_VALUE, "Bogus DAC value 0x%x") JMESSAGE(JERR_DHT_INDEX, "Bogus DHT index %d") JMESSAGE(JERR_DQT_INDEX, "Bogus DQT index %d") JMESSAGE(JERR_EMPTY_IMAGE, "Empty JPEG image (DNL not supported)") JMESSAGE(JERR_EMS_READ, "Read from EMS failed") JMESSAGE(JERR_EMS_WRITE, "Write to EMS failed") JMESSAGE(JERR_EOI_EXPECTED, "Didn't expect more than one scan") JMESSAGE(JERR_FILE_READ, "Input file read error") JMESSAGE(JERR_FILE_WRITE, "Output file write error --- out of disk space?") JMESSAGE(JERR_FRACT_SAMPLE_NOTIMPL, "Fractional sampling not implemented yet") JMESSAGE(JERR_HUFF_CLEN_OVERFLOW, "Huffman code size table overflow") JMESSAGE(JERR_HUFF_MISSING_CODE, "Missing Huffman code table entry") JMESSAGE(JERR_IMAGE_TOO_BIG, "Maximum supported image dimension is %u pixels") JMESSAGE(JERR_INPUT_EMPTY, "Empty input file") JMESSAGE(JERR_INPUT_EOF, "Premature end of input file") JMESSAGE(JERR_MISMATCHED_QUANT_TABLE, "Cannot transcode due to multiple use of quantization table %d") JMESSAGE(JERR_MISSING_DATA, "Scan script does not transmit all data") JMESSAGE(JERR_MODE_CHANGE, "Invalid color quantization mode change") JMESSAGE(JERR_NOTIMPL, "Not implemented yet") JMESSAGE(JERR_NOT_COMPILED, "Requested feature was omitted at compile time") JMESSAGE(JERR_NO_ARITH_TABLE, "Arithmetic table 0x%02x was not defined") JMESSAGE(JERR_NO_BACKING_STORE, "Backing store not supported") JMESSAGE(JERR_NO_HUFF_TABLE, "Huffman table 0x%02x was not defined") JMESSAGE(JERR_NO_IMAGE, "JPEG datastream contains no image") JMESSAGE(JERR_NO_QUANT_TABLE, "Quantization table 0x%02x was not defined") JMESSAGE(JERR_NO_SOI, "Not a JPEG file: starts with 0x%02x 0x%02x") JMESSAGE(JERR_OUT_OF_MEMORY, "Insufficient memory (case %d)") JMESSAGE(JERR_QUANT_COMPONENTS, "Cannot quantize more than %d color components") JMESSAGE(JERR_QUANT_FEW_COLORS, "Cannot quantize to fewer than %d colors") JMESSAGE(JERR_QUANT_MANY_COLORS, "Cannot quantize to more than %d colors") JMESSAGE(JERR_SOF_DUPLICATE, "Invalid JPEG file structure: two SOF markers") JMESSAGE(JERR_SOF_NO_SOS, "Invalid JPEG file structure: missing SOS marker") JMESSAGE(JERR_SOF_UNSUPPORTED, "Unsupported JPEG process: SOF type 0x%02x") JMESSAGE(JERR_SOI_DUPLICATE, "Invalid JPEG file structure: two SOI markers") JMESSAGE(JERR_SOS_NO_SOF, "Invalid JPEG file structure: SOS before SOF") JMESSAGE(JERR_TFILE_CREATE, "Failed to create temporary file %s") JMESSAGE(JERR_TFILE_READ, "Read failed on temporary file") JMESSAGE(JERR_TFILE_SEEK, "Seek failed on temporary file") JMESSAGE(JERR_TFILE_WRITE, "Write failed on temporary file --- out of disk space?") JMESSAGE(JERR_TOO_LITTLE_DATA, "Application transferred too few scanlines") JMESSAGE(JERR_UNKNOWN_MARKER, "Unsupported marker type 0x%02x") JMESSAGE(JERR_VIRTUAL_BUG, "Virtual array controller messed up") JMESSAGE(JERR_WIDTH_OVERFLOW, "Image too wide for this implementation") JMESSAGE(JERR_XMS_READ, "Read from XMS failed") JMESSAGE(JERR_XMS_WRITE, "Write to XMS failed") JMESSAGE(JMSG_COPYRIGHT, JCOPYRIGHT) JMESSAGE(JMSG_VERSION, JVERSION) JMESSAGE(JTRC_16BIT_TABLES, "Caution: quantization tables are too coarse for baseline JPEG") JMESSAGE(JTRC_ADOBE, "Adobe APP14 marker: version %d, flags 0x%04x 0x%04x, transform %d") JMESSAGE(JTRC_APP0, "Unknown APP0 marker (not JFIF), length %u") JMESSAGE(JTRC_APP14, "Unknown APP14 marker (not Adobe), length %u") JMESSAGE(JTRC_DAC, "Define Arithmetic Table 0x%02x: 0x%02x") JMESSAGE(JTRC_DHT, "Define Huffman Table 0x%02x") JMESSAGE(JTRC_DQT, "Define Quantization Table %d precision %d") JMESSAGE(JTRC_DRI, "Define Restart Interval %u") JMESSAGE(JTRC_EMS_CLOSE, "Freed EMS handle %u") JMESSAGE(JTRC_EMS_OPEN, "Obtained EMS handle %u") JMESSAGE(JTRC_EOI, "End Of Image") JMESSAGE(JTRC_HUFFBITS, " %3d %3d %3d %3d %3d %3d %3d %3d") JMESSAGE(JTRC_JFIF, "JFIF APP0 marker: version %d.%02d, density %dx%d %d") JMESSAGE(JTRC_JFIF_BADTHUMBNAILSIZE, "Warning: thumbnail image size does not match data length %u") JMESSAGE(JTRC_JFIF_EXTENSION, "JFIF extension marker: type 0x%02x, length %u") JMESSAGE(JTRC_JFIF_THUMBNAIL, " with %d x %d thumbnail image") JMESSAGE(JTRC_MISC_MARKER, "Miscellaneous marker 0x%02x, length %u") JMESSAGE(JTRC_PARMLESS_MARKER, "Unexpected marker 0x%02x") JMESSAGE(JTRC_QUANTVALS, " %4u %4u %4u %4u %4u %4u %4u %4u") JMESSAGE(JTRC_QUANT_3_NCOLORS, "Quantizing to %d = %d*%d*%d colors") JMESSAGE(JTRC_QUANT_NCOLORS, "Quantizing to %d colors") JMESSAGE(JTRC_QUANT_SELECTED, "Selected %d colors for quantization") JMESSAGE(JTRC_RECOVERY_ACTION, "At marker 0x%02x, recovery action %d") JMESSAGE(JTRC_RST, "RST%d") JMESSAGE(JTRC_SMOOTH_NOTIMPL, "Smoothing not supported with nonstandard sampling ratios") JMESSAGE(JTRC_SOF, "Start Of Frame 0x%02x: width=%u, height=%u, components=%d") JMESSAGE(JTRC_SOF_COMPONENT, " Component %d: %dhx%dv q=%d") JMESSAGE(JTRC_SOI, "Start of Image") JMESSAGE(JTRC_SOS, "Start Of Scan: %d components") JMESSAGE(JTRC_SOS_COMPONENT, " Component %d: dc=%d ac=%d") JMESSAGE(JTRC_SOS_PARAMS, " Ss=%d, Se=%d, Ah=%d, Al=%d") JMESSAGE(JTRC_TFILE_CLOSE, "Closed temporary file %s") JMESSAGE(JTRC_TFILE_OPEN, "Opened temporary file %s") JMESSAGE(JTRC_THUMB_JPEG, "JFIF extension marker: JPEG-compressed thumbnail image, length %u") JMESSAGE(JTRC_THUMB_PALETTE, "JFIF extension marker: palette thumbnail image, length %u") JMESSAGE(JTRC_THUMB_RGB, "JFIF extension marker: RGB thumbnail image, length %u") JMESSAGE(JTRC_UNKNOWN_IDS, "Unrecognized component IDs %d %d %d, assuming YCbCr") JMESSAGE(JTRC_XMS_CLOSE, "Freed XMS handle %u") JMESSAGE(JTRC_XMS_OPEN, "Obtained XMS handle %u") JMESSAGE(JWRN_ADOBE_XFORM, "Unknown Adobe color transform code %d") JMESSAGE(JWRN_ARITH_BAD_CODE, "Corrupt JPEG data: bad arithmetic code") JMESSAGE(JWRN_BOGUS_PROGRESSION, "Inconsistent progression sequence for component %d coefficient %d") JMESSAGE(JWRN_EXTRANEOUS_DATA, "Corrupt JPEG data: %u extraneous bytes before marker 0x%02x") JMESSAGE(JWRN_HIT_MARKER, "Corrupt JPEG data: premature end of data segment") JMESSAGE(JWRN_HUFF_BAD_CODE, "Corrupt JPEG data: bad Huffman code") JMESSAGE(JWRN_JFIF_MAJOR, "Warning: unknown JFIF revision number %d.%02d") JMESSAGE(JWRN_JPEG_EOF, "Premature end of JPEG file") JMESSAGE(JWRN_MUST_RESYNC, "Corrupt JPEG data: found marker 0x%02x instead of RST%d") JMESSAGE(JWRN_NOT_SEQUENTIAL, "Invalid SOS parameters for sequential JPEG") JMESSAGE(JWRN_TOO_MUCH_DATA, "Application transferred too many scanlines") #ifdef JMAKE_ENUM_LIST JMSG_LASTMSGCODE } J_MESSAGE_CODE; #undef JMAKE_ENUM_LIST #endif /* JMAKE_ENUM_LIST */ /* Zap JMESSAGE macro so that future re-inclusions do nothing by default */ #undef JMESSAGE #ifndef JERROR_H #define JERROR_H /* Macros to simplify using the error and trace message stuff */ /* The first parameter is either type of cinfo pointer */ /* Fatal errors (print message and exit) */ #define ERREXIT(cinfo,code) \ ((cinfo)->err->msg_code = (code), \ (*(cinfo)->err->error_exit) ((j_common_ptr) (cinfo))) #define ERREXIT1(cinfo,code,p1) \ ((cinfo)->err->msg_code = (code), \ (cinfo)->err->msg_parm.i[0] = (p1), \ (*(cinfo)->err->error_exit) ((j_common_ptr) (cinfo))) #define ERREXIT2(cinfo,code,p1,p2) \ ((cinfo)->err->msg_code = (code), \ (cinfo)->err->msg_parm.i[0] = (p1), \ (cinfo)->err->msg_parm.i[1] = (p2), \ (*(cinfo)->err->error_exit) ((j_common_ptr) (cinfo))) #define ERREXIT3(cinfo,code,p1,p2,p3) \ ((cinfo)->err->msg_code = (code), \ (cinfo)->err->msg_parm.i[0] = (p1), \ (cinfo)->err->msg_parm.i[1] = (p2), \ (cinfo)->err->msg_parm.i[2] = (p3), \ (*(cinfo)->err->error_exit) ((j_common_ptr) (cinfo))) #define ERREXIT4(cinfo,code,p1,p2,p3,p4) \ ((cinfo)->err->msg_code = (code), \ (cinfo)->err->msg_parm.i[0] = (p1), \ (cinfo)->err->msg_parm.i[1] = (p2), \ (cinfo)->err->msg_parm.i[2] = (p3), \ (cinfo)->err->msg_parm.i[3] = (p4), \ (*(cinfo)->err->error_exit) ((j_common_ptr) (cinfo))) #define ERREXIT6(cinfo,code,p1,p2,p3,p4,p5,p6) \ ((cinfo)->err->msg_code = (code), \ (cinfo)->err->msg_parm.i[0] = (p1), \ (cinfo)->err->msg_parm.i[1] = (p2), \ (cinfo)->err->msg_parm.i[2] = (p3), \ (cinfo)->err->msg_parm.i[3] = (p4), \ (cinfo)->err->msg_parm.i[4] = (p5), \ (cinfo)->err->msg_parm.i[5] = (p6), \ (*(cinfo)->err->error_exit) ((j_common_ptr) (cinfo))) #define ERREXITS(cinfo,code,str) \ ((cinfo)->err->msg_code = (code), \ strncpy((cinfo)->err->msg_parm.s, (str), JMSG_STR_PARM_MAX), \ (*(cinfo)->err->error_exit) ((j_common_ptr) (cinfo))) #define MAKESTMT(stuff) do { stuff } while (0) /* Nonfatal errors (we can keep going, but the data is probably corrupt) */ #define WARNMS(cinfo,code) \ ((cinfo)->err->msg_code = (code), \ (*(cinfo)->err->emit_message) ((j_common_ptr) (cinfo), -1)) #define WARNMS1(cinfo,code,p1) \ ((cinfo)->err->msg_code = (code), \ (cinfo)->err->msg_parm.i[0] = (p1), \ (*(cinfo)->err->emit_message) ((j_common_ptr) (cinfo), -1)) #define WARNMS2(cinfo,code,p1,p2) \ ((cinfo)->err->msg_code = (code), \ (cinfo)->err->msg_parm.i[0] = (p1), \ (cinfo)->err->msg_parm.i[1] = (p2), \ (*(cinfo)->err->emit_message) ((j_common_ptr) (cinfo), -1)) /* Informational/debugging messages */ #define TRACEMS(cinfo,lvl,code) \ ((cinfo)->err->msg_code = (code), \ (*(cinfo)->err->emit_message) ((j_common_ptr) (cinfo), (lvl))) #define TRACEMS1(cinfo,lvl,code,p1) \ ((cinfo)->err->msg_code = (code), \ (cinfo)->err->msg_parm.i[0] = (p1), \ (*(cinfo)->err->emit_message) ((j_common_ptr) (cinfo), (lvl))) #define TRACEMS2(cinfo,lvl,code,p1,p2) \ ((cinfo)->err->msg_code = (code), \ (cinfo)->err->msg_parm.i[0] = (p1), \ (cinfo)->err->msg_parm.i[1] = (p2), \ (*(cinfo)->err->emit_message) ((j_common_ptr) (cinfo), (lvl))) #define TRACEMS3(cinfo,lvl,code,p1,p2,p3) \ MAKESTMT(int * _mp = (cinfo)->err->msg_parm.i; \ _mp[0] = (p1); _mp[1] = (p2); _mp[2] = (p3); \ (cinfo)->err->msg_code = (code); \ (*(cinfo)->err->emit_message) ((j_common_ptr) (cinfo), (lvl)); ) #define TRACEMS4(cinfo,lvl,code,p1,p2,p3,p4) \ MAKESTMT(int * _mp = (cinfo)->err->msg_parm.i; \ _mp[0] = (p1); _mp[1] = (p2); _mp[2] = (p3); _mp[3] = (p4); \ (cinfo)->err->msg_code = (code); \ (*(cinfo)->err->emit_message) ((j_common_ptr) (cinfo), (lvl)); ) #define TRACEMS5(cinfo,lvl,code,p1,p2,p3,p4,p5) \ MAKESTMT(int * _mp = (cinfo)->err->msg_parm.i; \ _mp[0] = (p1); _mp[1] = (p2); _mp[2] = (p3); _mp[3] = (p4); \ _mp[4] = (p5); \ (cinfo)->err->msg_code = (code); \ (*(cinfo)->err->emit_message) ((j_common_ptr) (cinfo), (lvl)); ) #define TRACEMS8(cinfo,lvl,code,p1,p2,p3,p4,p5,p6,p7,p8) \ MAKESTMT(int * _mp = (cinfo)->err->msg_parm.i; \ _mp[0] = (p1); _mp[1] = (p2); _mp[2] = (p3); _mp[3] = (p4); \ _mp[4] = (p5); _mp[5] = (p6); _mp[6] = (p7); _mp[7] = (p8); \ (cinfo)->err->msg_code = (code); \ (*(cinfo)->err->emit_message) ((j_common_ptr) (cinfo), (lvl)); ) #define TRACEMSS(cinfo,lvl,code,str) \ ((cinfo)->err->msg_code = (code), \ strncpy((cinfo)->err->msg_parm.s, (str), JMSG_STR_PARM_MAX), \ (*(cinfo)->err->emit_message) ((j_common_ptr) (cinfo), (lvl))) #endif /* JERROR_H */
jmorecfg.h
/* * jmorecfg.h * * Copyright (C) 1991-1997, Thomas G. Lane. * Modified 1997-2009 by Guido Vollbeding. * This file is part of the Independent JPEG Group's software. * For conditions of distribution and use, see the accompanying README file. * * This file contains additional configuration options that customize the * JPEG software for special applications or support machine-dependent * optimizations. Most users will not need to touch this file. */ /* * Define BITS_IN_JSAMPLE as either * 8 for 8-bit sample values (the usual setting) * 12 for 12-bit sample values * Only 8 and 12 are legal data precisions for lossy JPEG according to the * JPEG standard, and the IJG code does not support anything else! * We do not support run-time selection of data precision, sorry. */ #define BITS_IN_JSAMPLE 8 /* use 8 or 12 */ /* * Maximum number of components (color channels) allowed in JPEG image. * To meet the letter of the JPEG spec, set this to 255. However, darn * few applications need more than 4 channels (maybe 5 for CMYK + alpha * mask). We recommend 10 as a reasonable compromise; use 4 if you are * really short on memory. (Each allowed component costs a hundred or so * bytes of storage, whether actually used in an image or not.) */ #define MAX_COMPONENTS 10 /* maximum number of image components */ /* * Basic data types. * You may need to change these if you have a machine with unusual data * type sizes; for example, "char" not 8 bits, "short" not 16 bits, * or "long" not 32 bits. We don't care whether "int" is 16 or 32 bits, * but it had better be at least 16. */ /* Representation of a single sample (pixel element value). * We frequently allocate large arrays of these, so it's important to keep * them small. But if you have memory to burn and access to char or short * arrays is very slow on your hardware, you might want to change these. */ #if BITS_IN_JSAMPLE == 8 /* JSAMPLE should be the smallest type that will hold the values 0..255. * You can use a signed char by having GETJSAMPLE mask it with 0xFF. */ #ifdef HAVE_UNSIGNED_CHAR typedef unsigned char JSAMPLE; #define GETJSAMPLE(value) ((int) (value)) #else /* not HAVE_UNSIGNED_CHAR */ typedef char JSAMPLE; #ifdef CHAR_IS_UNSIGNED #define GETJSAMPLE(value) ((int) (value)) #else #define GETJSAMPLE(value) ((int) (value) & 0xFF) #endif /* CHAR_IS_UNSIGNED */ #endif /* HAVE_UNSIGNED_CHAR */ #define MAXJSAMPLE 255 #define CENTERJSAMPLE 128 #endif /* BITS_IN_JSAMPLE == 8 */ #if BITS_IN_JSAMPLE == 12 /* JSAMPLE should be the smallest type that will hold the values 0..4095. * On nearly all machines "short" will do nicely. */ typedef short JSAMPLE; #define GETJSAMPLE(value) ((int) (value)) #define MAXJSAMPLE 4095 #define CENTERJSAMPLE 2048 #endif /* BITS_IN_JSAMPLE == 12 */ /* Representation of a DCT frequency coefficient. * This should be a signed value of at least 16 bits; "short" is usually OK. * Again, we allocate large arrays of these, but you can change to int * if you have memory to burn and "short" is really slow. */ typedef short JCOEF; /* Compressed datastreams are represented as arrays of JOCTET. * These must be EXACTLY 8 bits wide, at least once they are written to * external storage. Note that when using the stdio data source/destination * managers, this is also the data type passed to fread/fwrite. */ #ifdef HAVE_UNSIGNED_CHAR typedef unsigned char JOCTET; #define GETJOCTET(value) (value) #else /* not HAVE_UNSIGNED_CHAR */ typedef char JOCTET; #ifdef CHAR_IS_UNSIGNED #define GETJOCTET(value) (value) #else #define GETJOCTET(value) ((value) & 0xFF) #endif /* CHAR_IS_UNSIGNED */ #endif /* HAVE_UNSIGNED_CHAR */ /* These typedefs are used for various table entries and so forth. * They must be at least as wide as specified; but making them too big * won't cost a huge amount of memory, so we don't provide special * extraction code like we did for JSAMPLE. (In other words, these * typedefs live at a different point on the speed/space tradeoff curve.) */ /* UINT8 must hold at least the values 0..255. */ #ifdef HAVE_UNSIGNED_CHAR typedef unsigned char UINT8; #else /* not HAVE_UNSIGNED_CHAR */ #ifdef CHAR_IS_UNSIGNED typedef char UINT8; #else /* not CHAR_IS_UNSIGNED */ typedef short UINT8; #endif /* CHAR_IS_UNSIGNED */ #endif /* HAVE_UNSIGNED_CHAR */ /* UINT16 must hold at least the values 0..65535. */ #ifdef HAVE_UNSIGNED_SHORT typedef unsigned short UINT16; #else /* not HAVE_UNSIGNED_SHORT */ typedef unsigned int UINT16; #endif /* HAVE_UNSIGNED_SHORT */ /* INT16 must hold at least the values -32768..32767. */ #ifndef XMD_H /* X11/xmd.h correctly defines INT16 */ typedef short INT16; #endif /* INT32 must hold at least signed 32-bit values. */ #ifndef XMD_H /* X11/xmd.h correctly defines INT32 */ #ifndef _BASETSD_H_ /* Microsoft defines it in basetsd.h */ #ifndef _BASETSD_H /* MinGW is slightly different */ #ifndef QGLOBAL_H /* Qt defines it in qglobal.h */ typedef long INT32; #endif #endif #endif #endif /* Datatype used for image dimensions. The JPEG standard only supports * images up to 64K*64K due to 16-bit fields in SOF markers. Therefore * "unsigned int" is sufficient on all machines. However, if you need to * handle larger images and you don't mind deviating from the spec, you * can change this datatype. */ typedef unsigned int JDIMENSION; #define JPEG_MAX_DIMENSION 65500L /* a tad under 64K to prevent overflows */ /* These macros are used in all function definitions and extern declarations. * You could modify them if you need to change function linkage conventions; * in particular, you'll need to do that to make the library a Windows DLL. * Another application is to make all functions global for use with debuggers * or code profilers that require it. */ /* a function called through method pointers: */ #define METHODDEF(type) static type /* a function used only in its module: */ #define LOCAL(type) static type /* a function referenced thru EXTERNs: */ #define GLOBAL(type) type /* a reference to a GLOBAL function: */ #define EXTERN(type) extern type /* This macro is used to declare a "method", that is, a function pointer. * We want to supply prototype parameters if the compiler can cope. * Note that the arglist parameter must be parenthesized! * Again, you can customize this if you need special linkage keywords. */ #ifdef HAVE_PROTOTYPES #define JMETHOD(type,methodname,arglist) type (*methodname) arglist #else #define JMETHOD(type,methodname,arglist) type (*methodname) () #endif /* Here is the pseudo-keyword for declaring pointers that must be "far" * on 80x86 machines. Most of the specialized coding for 80x86 is handled * by just saying "FAR *" where such a pointer is needed. In a few places * explicit coding is needed; see uses of the NEED_FAR_POINTERS symbol. */ #ifndef FAR #ifdef NEED_FAR_POINTERS #define FAR far #else #define FAR #endif #endif /* * On a few systems, type boolean and/or its values FALSE, TRUE may appear * in standard header files. Or you may have conflicts with application- * specific header files that you want to include together with these files. * Defining HAVE_BOOLEAN before including jpeglib.h should make it work. */ #ifndef HAVE_BOOLEAN typedef int boolean; #endif #ifndef FALSE /* in case these macros already exist */ #define FALSE 0 /* values of boolean */ #endif #ifndef TRUE #define TRUE 1 #endif /* * The remaining options affect code selection within the JPEG library, * but they don't need to be visible to most applications using the library. * To minimize application namespace pollution, the symbols won't be * defined unless JPEG_INTERNALS or JPEG_INTERNAL_OPTIONS has been defined. */ #ifdef JPEG_INTERNALS #define JPEG_INTERNAL_OPTIONS #endif #ifdef JPEG_INTERNAL_OPTIONS /* * These defines indicate whether to include various optional functions. * Undefining some of these symbols will produce a smaller but less capable * library. Note that you can leave certain source files out of the * compilation/linking process if you've #undef'd the corresponding symbols. * (You may HAVE to do that if your compiler doesn't like null source files.) */ /* Capability options common to encoder and decoder: */ #define DCT_ISLOW_SUPPORTED /* slow but accurate integer algorithm */ #define DCT_IFAST_SUPPORTED /* faster, less accurate integer method */ #define DCT_FLOAT_SUPPORTED /* floating-point: accurate, fast on fast HW */ /* Encoder capability options: */ #define C_ARITH_CODING_SUPPORTED /* Arithmetic coding back end? */ #define C_MULTISCAN_FILES_SUPPORTED /* Multiple-scan JPEG files? */ #define C_PROGRESSIVE_SUPPORTED /* Progressive JPEG? (Requires MULTISCAN)*/ #define DCT_SCALING_SUPPORTED /* Input rescaling via DCT? (Requires DCT_ISLOW)*/ #define ENTROPY_OPT_SUPPORTED /* Optimization of entropy coding parms? */ /* Note: if you selected 12-bit data precision, it is dangerous to turn off * ENTROPY_OPT_SUPPORTED. The standard Huffman tables are only good for 8-bit * precision, so jchuff.c normally uses entropy optimization to compute * usable tables for higher precision. If you don't want to do optimization, * you'll have to supply different default Huffman tables. * The exact same statements apply for progressive JPEG: the default tables * don't work for progressive mode. (This may get fixed, however.) */ #define INPUT_SMOOTHING_SUPPORTED /* Input image smoothing option? */ /* Decoder capability options: */ #define D_ARITH_CODING_SUPPORTED /* Arithmetic coding back end? */ #define D_MULTISCAN_FILES_SUPPORTED /* Multiple-scan JPEG files? */ #define D_PROGRESSIVE_SUPPORTED /* Progressive JPEG? (Requires MULTISCAN)*/ #define IDCT_SCALING_SUPPORTED /* Output rescaling via IDCT? */ #define SAVE_MARKERS_SUPPORTED /* jpeg_save_markers() needed? */ #define BLOCK_SMOOTHING_SUPPORTED /* Block smoothing? (Progressive only) */ #undef UPSAMPLE_SCALING_SUPPORTED /* Output rescaling at upsample stage? */ #define UPSAMPLE_MERGING_SUPPORTED /* Fast path for sloppy upsampling? */ #define QUANT_1PASS_SUPPORTED /* 1-pass color quantization? */ #define QUANT_2PASS_SUPPORTED /* 2-pass color quantization? */ /* more capability options later, no doubt */ /* * Ordering of RGB data in scanlines passed to or from the application. * If your application wants to deal with data in the order B,G,R, just * change these macros. You can also deal with formats such as R,G,B,X * (one extra byte per pixel) by changing RGB_PIXELSIZE. Note that changing * the offsets will also change the order in which colormap data is organized. * RESTRICTIONS: * 1. The sample applications cjpeg,djpeg do NOT support modified RGB formats. * 2. These macros only affect RGB<=>YCbCr color conversion, so they are not * useful if you are using JPEG color spaces other than YCbCr or grayscale. * 3. The color quantizer modules will not behave desirably if RGB_PIXELSIZE * is not 3 (they don't understand about dummy color components!). So you * can't use color quantization if you change that value. */ #define RGB_RED 0 /* Offset of Red in an RGB scanline element */ #define RGB_GREEN 1 /* Offset of Green */ #define RGB_BLUE 2 /* Offset of Blue */ #define RGB_PIXELSIZE 3 /* JSAMPLEs per RGB scanline element */ /* Definitions for speed-related optimizations. */ /* If your compiler supports inline functions, define INLINE * as the inline keyword; otherwise define it as empty. */ #ifndef INLINE #ifdef __GNUC__ /* for instance, GNU C knows about inline */ #define INLINE __inline__ #endif #ifndef INLINE #define INLINE /* default is to define it as empty */ #endif #endif /* On some machines (notably 68000 series) "int" is 32 bits, but multiplying * two 16-bit shorts is faster than multiplying two ints. Define MULTIPLIER * as short on such a machine. MULTIPLIER must be at least 16 bits wide. */ #ifndef MULTIPLIER #define MULTIPLIER int /* type for fastest integer multiply */ #endif /* FAST_FLOAT should be either float or double, whichever is done faster * by your compiler. (Note that this type is only used in the floating point * DCT routines, so it only matters if you've defined DCT_FLOAT_SUPPORTED.) * Typically, float is faster in ANSI C compilers, while double is faster in * pre-ANSI compilers (because they insist on converting to double anyway). * The code below therefore chooses float if we have ANSI-style prototypes. */ #ifndef FAST_FLOAT #ifdef HAVE_PROTOTYPES #define FAST_FLOAT float #else #define FAST_FLOAT double #endif #endif #endif /* JPEG_INTERNAL_OPTIONS */
jpeg.c
#include <stdio.h> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <unistd.h> #include <sys/types.h> #include <dirent.h> #include <string.h> #include <sys/ioctl.h> #include <linux/videodev2.h> #include <stdlib.h> #include "jpeglib.h" #include <setjmp.h> #include <stdbool.h> #include <sys/mman.h> struct { void *start; size_t length; } *buffers; struct my_error_mgr { struct jpeg_error_mgr pub; /* "public" fields */ jmp_buf setjmp_buffer; /* for return to caller */ }; typedef struct my_error_mgr * my_error_ptr; METHODDEF(void) my_error_exit (j_common_ptr cinfo) { /* cinfo->err really points to a my_error_mgr struct, so coerce pointer */ my_error_ptr myerr = (my_error_ptr) cinfo->err; /* Always display the message. */ /* We could postpone this until after returning, if we chose. */ (*cinfo->err->output_message) (cinfo); /* Return control to the setjmp point */ longjmp(myerr->setjmp_buffer, 1); } //显示一张jpeg的图片 int show_jpg(char *filename,int X,int Y) { int fd; unsigned long *fb_mem; /* This struct contains the JPEG decompression parameters and pointers to * working space (which is allocated as needed by the JPEG library). */ struct jpeg_decompress_struct cinfo; /* We use our private extension JPEG error handler. * Note that this struct must live as long as the main JPEG parameter * struct, to avoid dangling-pointer problems. */ struct my_error_mgr jerr; /* More stuff */ FILE * infile; /* source file */ JSAMPARRAY buffer; /* Output row buffer */ int row_stride; /* physical row width in output buffer */ /* In this example we want to open the input file before doing anything else, * so that the setjmp() error recovery below can assume the file is open. * VERY IMPORTANT: use "b" option to fopen() if you are on a machine that * requires it in order to read binary files. */ if ((infile = fopen(filename, "rb")) == NULL) { fprintf(stderr, "can't open %s\n", filename); return 0; } fd = open("/dev/fb0",O_RDWR); if(fd == -1) { perror("open lcd"); return -1; } //显存映射 fb_mem = (unsigned long *)mmap(NULL, //映射到的地址 ，填NULL，由系统分配 800*480*4, //映射内存大小 PROT_READ |PROT_WRITE, //保护操作 MAP_SHARED, //共享操作 MAP_SHARED 或者 MAP_PRIVATE fd, //设备文件ID 0 //内存偏移地址 默认从0开始 ); if(fb_mem == MAP_FAILED) { perror("mmap"); return -1; } /* Step 1: allocate and initialize JPEG decompression object */ /* We set up the normal JPEG error routines, then override error_exit. */ cinfo.err = jpeg_std_error(&jerr.pub); jerr.pub.error_exit = my_error_exit; /* Establish the setjmp return context for my_error_exit to use. */ if (setjmp(jerr.setjmp_buffer)) { /* If we get here, the JPEG code has signaled an error. * We need to clean up the JPEG object, close the input file, and return. */ jpeg_destroy_decompress(&cinfo); fclose(infile); return 0; } /* Now we can initialize the JPEG decompression object. */ jpeg_create_decompress(&cinfo); /* Step 2: specify data source (eg, a file) */ jpeg_stdio_src(&cinfo, infile); /* Step 3: read file parameters with jpeg_read_header() */ (void) jpeg_read_header(&cinfo, TRUE); /* We can ignore the return value from jpeg_read_header since * (a) suspension is not possible with the stdio data source, and * (b) we passed TRUE to reject a tables-only JPEG file as an error. * See libjpeg.txt for more info. */ /* Step 4: set parameters for decompression */ /* In this example, we don't need to change any of the defaults set by * jpeg_read_header(), so we do nothing here. */ /* Step 5: Start decompressor */ (void) jpeg_start_decompress(&cinfo); /* We can ignore the return value since suspension is not possible * with the stdio data source. */ /* We may need to do some setup of our own at this point before reading * the data. After jpeg_start_decompress() we have the correct scaled * output image dimensions available, as well as the output colormap * if we asked for color quantization. * In this example, we need to make an output work buffer of the right size. */ /* JSAMPLEs per row in output buffer */ // no zoom function // printf("%d * %d , %d \n", cinfo.output_width,cinfo.output_height , cinfo.output_components); // cinfo 是像素点的信息 if(cinfo.output_width > 800) cinfo.output_width = 800; if(cinfo.output_height > 480) cinfo.output_height = 480; row_stride = cinfo.output_width * cinfo.output_components; /* Make a one-row-high sample array that will go away when done with image */ buffer = (*cinfo.mem->alloc_sarray) ((j_common_ptr) &cinfo, JPOOL_IMAGE, row_stride, 1); /* Step 6: while (scan lines remain to be read) */ /* jpeg_read_scanlines(...); */ /* Here we use the library's state variable cinfo.output_scanline as the * loop counter, so that we don't have to keep track ourselves. */ while (cinfo.output_scanline < cinfo.output_height) { /* jpeg_read_scanlines expects an array of pointers to scanlines. * Here the array is only one element long, but you could ask for * more than one scanline at a time if that's more convenient. */ int i =0,x=0; (void) jpeg_read_scanlines(&cinfo, buffer, 1); /* Assume put_scanline_someplace wants a pointer and sample count. */ // put_scanline_someplace(buffer[0], row_stride); // move pix to fb_mem JPG for(x=X;x<X+cinfo.output_width;x++) { fb_mem[ (cinfo.output_scanline-1+Y)*800+x] = (buffer[0][i] << 16 |buffer[0][i+1] << 8|buffer[0][i+2]); // 每个像素点的RGB i+=3; } } /* Step 7: Finish decompression */ (void) jpeg_finish_decompress(&cinfo); /* We can ignore the return value since suspension is not possible * with the stdio data source. */ /* Step 8: Release JPEG decompression object */ /* This is an important step since it will release a good deal of memory. */ jpeg_destroy_decompress(&cinfo); /* After finish_decompress, we can close the input file. * Here we postpone it until after no more JPEG errors are possible, * so as to simplify the setjmp error logic above. (Actually, I don't * think that jpeg_destroy can do an error exit, but why assume anything...) */ fclose(infile); /* At this point you may want to check to see whether any corrupt-data * warnings occurred (test whether jerr.pub.num_warnings is nonzero). */ munmap(fb_mem, //映射后的地址，mmap的返回值 800*480*4 //映射的大小 ); close(fd); return 0; } //显示一张jpeg的图片到显存 int show_jpg_fbmem(char *filename,int X,int Y,int *fb_mem)// mmap { /* This struct contains the JPEG decompression parameters and pointers to * working space (which is allocated as needed by the JPEG library). */ struct jpeg_decompress_struct cinfo; /* We use our private extension JPEG error handler. * Note that this struct must live as long as the main JPEG parameter * struct, to avoid dangling-pointer problems. */ struct my_error_mgr jerr; /* More stuff */ FILE * infile; /* source file */ JSAMPARRAY buffer; /* Output row buffer */ int row_stride; /* physical row width in output buffer */ /* In this example we want to open the input file before doing anything else, * so that the setjmp() error recovery below can assume the file is open. * VERY IMPORTANT: use "b" option to fopen() if you are on a machine that * requires it in order to read binary files. */ if ((infile = fopen(filename, "rb")) == NULL) { fprintf(stderr, "can't open %s\n", filename); return 0; } /* Step 1: allocate and initialize JPEG decompression object */ /* We set up the normal JPEG error routines, then override error_exit. */ cinfo.err = jpeg_std_error(&jerr.pub); jerr.pub.error_exit = my_error_exit; /* Establish the setjmp return context for my_error_exit to use. */ if (setjmp(jerr.setjmp_buffer)) { /* If we get here, the JPEG code has signaled an error. * We need to clean up the JPEG object, close the input file, and return. */ jpeg_destroy_decompress(&cinfo); fclose(infile); return 0; } /* Now we can initialize the JPEG decompression object. */ jpeg_create_decompress(&cinfo); /* Step 2: specify data source (eg, a file) */ jpeg_stdio_src(&cinfo, infile); /* Step 3: read file parameters with jpeg_read_header() */ (void) jpeg_read_header(&cinfo, TRUE); /* We can ignore the return value from jpeg_read_header since * (a) suspension is not possible with the stdio data source, and * (b) we passed TRUE to reject a tables-only JPEG file as an error. * See libjpeg.txt for more info. */ /* Step 4: set parameters for decompression */ /* In this example, we don't need to change any of the defaults set by * jpeg_read_header(), so we do nothing here. */ /* Step 5: Start decompressor */ (void) jpeg_start_decompress(&cinfo); /* We can ignore the return value since suspension is not possible * with the stdio data source. */ /* We may need to do some setup of our own at this point before reading * the data. After jpeg_start_decompress() we have the correct scaled * output image dimensions available, as well as the output colormap * if we asked for color quantization. * In this example, we need to make an output work buffer of the right size. */ /* JSAMPLEs per row in output buffer */ // no zoom function // printf("%d * %d , %d \n", cinfo.output_width,cinfo.output_height , cinfo.output_components); // cinfo 是像素点的信息 if(cinfo.output_width > 800) cinfo.output_width = 800; if(cinfo.output_height > 480) cinfo.output_height = 480; row_stride = cinfo.output_width * cinfo.output_components; /* Make a one-row-high sample array that will go away when done with image */ buffer = (*cinfo.mem->alloc_sarray) ((j_common_ptr) &cinfo, JPOOL_IMAGE, row_stride, 1); /* Step 6: while (scan lines remain to be read) */ /* jpeg_read_scanlines(...); */ /* Here we use the library's state variable cinfo.output_scanline as the * loop counter, so that we don't have to keep track ourselves. */ while (cinfo.output_scanline < cinfo.output_height) { /* jpeg_read_scanlines expects an array of pointers to scanlines. * Here the array is only one element long, but you could ask for * more than one scanline at a time if that's more convenient. */ int i =0,x=0; (void) jpeg_read_scanlines(&cinfo, buffer, 1); /* Assume put_scanline_someplace wants a pointer and sample count. */ // put_scanline_someplace(buffer[0], row_stride); // move pix to fb_mem JPG for(x=X;x<X+cinfo.output_width;x++) { fb_mem[ (cinfo.output_scanline-1+Y)*800+x] = (buffer[0][i] << 16 |buffer[0][i+1] << 8|buffer[0][i+2]); // 每个像素点的RGB i+=3; } } /* Step 7: Finish decompression */ (void) jpeg_finish_decompress(&cinfo); /* We can ignore the return value since suspension is not possible * with the stdio data source. */ /* Step 8: Release JPEG decompression object */ /* This is an important step since it will release a good deal of memory. */ jpeg_destroy_decompress(&cinfo); /* After finish_decompress, we can close the input file. * Here we postpone it until after no more JPEG errors are possible, * so as to simplify the setjmp error logic above. (Actually, I don't * think that jpeg_destroy can do an error exit, but why assume anything...) */ fclose(infile); /* At this point you may want to check to see whether any corrupt-data * warnings occurred (test whether jerr.pub.num_warnings is nonzero). */ return 0; } int show_jpegdata_fbmem(unsigned char * jpegdata, int size,int X,int Y, unsigned long *fb_mem) { // 声明解压缩结构体，以及错误管理结构体 struct jpeg_decompress_struct cinfo; struct jpeg_error_mgr jerr; // 使用缺省的出错处理来初始化解压缩结构体 cinfo.err = jpeg_std_error(&jerr); jpeg_create_decompress(&cinfo); // 配置该cinfo，使其从jpg_buffer中读取jpg_size个字节 // 这些数据必须是完整的JPEG数据 jpeg_mem_src(&cinfo, jpegdata, size); // 读取JPEG文件的头 jpeg_read_header(&cinfo, true); // 开始解压jpeg数据 jpeg_start_decompress(&cinfo); JSAMPARRAY buffer; //存放输出数据的缓冲区 int row_stride; //控制图像大小 if(cinfo.output_width > 800) cinfo.output_width = 800; if(cinfo.output_height > 480) cinfo.output_height = 480; row_stride = cinfo.output_width * cinfo.output_components; buffer = (*cinfo.mem->alloc_sarray) ((j_common_ptr) &cinfo, JPOOL_IMAGE, row_stride, 1); while (cinfo.output_scanline < cinfo.output_height) { /* cinfo.output_scanline为扫描线，一条扫描线为一行。即最高不能超出480行（及高度） */ int i =0,x=0; (void) jpeg_read_scanlines(&cinfo, buffer, 1); /* 通过扫描行的方式，得到一行的数据，并利用下列for循环将一行的数据显示*/ for(x=X;x<X+cinfo.output_width;x++) { // 将buffer中的24bit的图像数据写入32bit的fb_mem fb_mem[ (cinfo.output_scanline-1+Y)*800+x] = (buffer[0][i] << 16 |buffer[0][i+1] << 8|buffer[0][i+2]); // 每个像素点的RGB i+=3; } } // 释放相关结构体和内存，解压后的图片信息被保留在fb_mem，直接映射到了LCD jpeg_finish_decompress(&cinfo); jpeg_destroy_decompress(&cinfo); return 0; }
