Android keyevent抓图，使用jpeg565对数据压缩
「 前端时间为了做一个测试工具,做了一个快捷抓图功能 」
2013-03-07
实现功能
使用poll池方法监测event3，event5和对从FB_DEVICE获得的图像数据进行jpeg压缩，压缩图像由之前的2700k缩小为89k，压缩比显而易见（30倍）。
效果图
抓图实现
从FB_DEVICE "/dev/graphics/fb0"获得图像的原始数据，色彩数据分为头和rgba数据，在函数jpgscreencapture里case 16：中我对原始数据进行了处理，将rgba8888的数据转换为rgb565的数据，最后用generateJPEG对数据进行jpeg compress，具体的可以见capturejpg.c代码
* 这里要注意的一点是在读取fbvar.xres值必须为2^5=16的倍数，不够的要补足，也就是如下代码：
if((fb_var.xres&0x1F)==0)
fb->w = fb_var.xres;
else
fb->w =((fb_var.xres>>5)+1)<<5;
这样可以避免在抓图时出现像素移位，该问题在fb0的图像像素宽不是16的倍数时出现。
capture_jpg.c
/*=============================================================================
# FileName: capture_jpg.c
# Desc: capture jgp screenshoot
# Author: Lee Meng
# Email: leaveboy@gmail.com
# HomePage: http://leaveboy.is-programmer.com/
# Version: 0.0.1
# LastChange: 2013-01-15 09:33:23
# History:
=============================================================================*/
#include <string.h>
#include <stdlib.h>
#include <math.h>
#include <stdio.h>
#include <unistd.h>
#include <stdio.h>
#include <fcntl.h>
#include <linux/fb.h>
#include <sys/mman.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
typedef uint8_t BYTE;
#define true 1
#define false 0
#include <jpeglib.h>
#define FB_DEVICE "/dev/graphics/fb0"
static int g_fd;
typedef struct
{
int w; /* width */
int h; /* high */
int bpp; /* bits per pixel */
unsigned char *fbmem;
}screen;
static int init_fb(screen *fb)
{
if ((g_fd = open(FB_DEVICE, O_RDWR)) < 0)
{
fprintf(stderr, "Open %s failed:%s\n", FB_DEVICE, strerror(errno));
return -1;
}
struct fb_var_screeninfo fb_var;
struct fb_fix_screeninfo fb_fix;
if (ioctl(g_fd, FBIOGET_VSCREENINFO, &fb_var) < 0)
{
fprintf(stderr, "fb ioctl failed:%s\n", strerror(errno));
return -1;
}
/*
if (ioctl(g_fd, FBIOGET_FSCREENINFO, &fb_fix) < 0)
{
fprintf(stderr, "fb ioctl failed:%s\n", strerror(errno));
return -1;
}
*/
//fb->w = fb_var.xres;
if((fb_var.xres&0x1F)==0)
fb->w = fb_var.xres;
else
fb->w =((fb_var.xres>>5)+1)<<5;
fb->h = fb_var.yres;
fb->bpp = fb_var.bits_per_pixel;
// printf("capture_log %d, %d, %d, %d\n", fb_var.xres_virtual, fb_var.yres_virtual, fb_var.xoffset, fb_var.yoffset);
// printf("capture_log %d\n", fb_fix.line_length);
#if 1
printf("width:%d\thigh:%d\tbpp:%d\n",fb->w, fb->h, fb->bpp);
#endif
fb->fbmem = mmap(0, fb->w * fb->h * fb->bpp /8,PROT_READ | PROT_WRITE, MAP_SHARED, g_fd, 0);
if (fb->fbmem == MAP_FAILED)
{
fprintf(stderr, "fb mmap failed:%s\n", strerror(errno));
return -1;
}
close(g_fd);
return 0;
}
int term_fb(screen *fb)
{
munmap(fb->fbmem, fb->w * fb->h * fb->bpp / 8);
return 0;
}
static int generateJPEG(BYTE* data,int w, int h, const char* outfilename)
{
int nComponent = 3;
struct jpeg_compress_struct jcs;
struct jpeg_error_mgr jem;
jcs.err = jpeg_std_error(&jem);
jpeg_create_compress(&jcs);
FILE* f=fopen(outfilename,"wb");
if (f==NULL)
{
free(data);
return 0;
}
jpeg_stdio_dest(&jcs, f);
jcs.image_width = w;
jcs.image_height = h;
jcs.input_components = nComponent;
if (nComponent==1)
jcs.in_color_space = JCS_GRAYSCALE;
else
jcs.in_color_space = JCS_RGB;
jpeg_set_defaults(&jcs);
jpeg_set_quality (&jcs, 80, true);
jpeg_start_compress(&jcs, TRUE);
JSAMPROW row_pointer[1];
int row_stride;
row_stride = jcs.image_width*nComponent;
while (jcs.next_scanline < jcs.image_height) {
row_pointer[0] = & data[jcs.next_scanline*row_stride];
jpeg_write_scanlines(&jcs, row_pointer, 1);
}
jpeg_finish_compress(&jcs);
jpeg_destroy_compress(&jcs);
fclose(f);
return 1;
}
//int main(void)
extern int jpg_screen_capture(char * file_name)
{
int i = 0, j = 0;
int w = 0, h = 0;
int ret = 0;
unsigned char *p;
screen fb_screen;
init_fb(&fb_screen);
w = fb_screen.w;
h = fb_screen.h;
p = (unsigned char *)malloc(w * h * 3);
printf("0x%x %x %x %x\n", *fb_screen.fbmem, *(fb_screen.fbmem + 1), \
*(fb_screen.fbmem + 2), *(fb_screen.fbmem + 3));
short *cursor = (short*)fb_screen.fbmem;
switch(fb_screen.bpp)
{
case 32:
for(i = 0; i < h; i++)
{
for(j = 0; j < w; j++)
{
*(p + (i * w + j) * 3 + 0) = *(fb_screen.fbmem + (i * w + j) * 4 + 0);
*(p + (i * w + j) * 3 + 1) = *(fb_screen.fbmem + (i * w + j) * 4 + 1);
*(p + (i * w + j) * 3 + 2) = *(fb_screen.fbmem + (i * w + j) * 4 + 2);
}
}
break;
case 16:
while(i<w*h)
{
short pixel = *cursor;
int r = (pixel & 0xF800) << 8;
int g = (pixel & 0x7E0) << 5;
int b = (pixel & 0x1F) << 3;
int color = 0xFF000000 | r | g | b;
*(p + 3 * i + 0) = (unsigned char)(color>>16 &0xFF);
*(p + 3 * i + 1) = (unsigned char)(color>>8 &0xFF);
*(p + 3 * i + 2) = (unsigned char)(color>>0 &0xFF);
i++;
cursor++;
}
break;
default:
printf("not support bpp %d\n",fb_screen.bpp);
return -1;
break;
}
// ret = generateJPEG(p, fb_screen.w, fb_screen.h, "/data/test/test.jpg");
ret = generateJPEG(p, fb_screen.w, fb_screen.h, file_name);
term_fb(&fb_screen);
free(p);
return ret;
}
监听keyevent事件
这里为了避免单按键对使用造成影响，需同时监听两个keyevent 分别为event3 和 event5，对这两个事件的监听采用了无阻塞方式，在poll池中对两个event进行检测，通过event.code 和 event.value 区别按键（那个按键）动作（按下/松开）,最后通过fork_sound()
/*=============================================================================
# FileName: getevent.c
# Desc: get events of powerkey and volume +
# Author: Lee Meng
# Email: leaveboy@gmail.com
# HomePage: http://leaveboy.is-programmer.com/
# Version: 0.0.1
# LastChange: 2013-01-15 09:32:53
# History:
=============================================================================*/
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <time.h>
#include <errno.h>
#include <sys/poll.h>
#include <linux/input.h>
#define TIME_DELAY 6000
#define IN_FILES 2
#define SAVE_PATH "/data/logs"
#define SOUND_PATH "system/media/audio/alarms/Alarm_Buzzer.ogg"
struct timeval tv,tv_event3={0L, 0L},tv_event5={0L, 0L};
static unsigned char event3_down = 0x00;//
static unsigned char event5_down = 0x00;
struct input_event event;
static void fork_sound(void)
{
pid_t pid = fork();
if (pid == 0) {
execl("/system/bin/stagefright", "stagefright", "-o", "-a", SOUND_PATH, NULL);
/*execl("/system/bin/busybox", "busybox", "tar", "cvf", "/mnt/sdcard/logs.tar",SAVE_PATH, NULL);*/
//execl("/system/bin/busybox", "busybox", "bzip", "-9", "/mnt/sdcard/logs.tar",NULL);
}
}
/*int main(void) {*/
extern int event_capture_jpg(void) {
int pollres;
struct pollfd fds[2];
struct tm *p;
time_t now;
char capture_name[128];
int i, real_read;
printf("sizeof(struct input_event) = %d\n", sizeof(struct input_event));
fds[0].fd = open("/dev/input/event3", O_RDONLY|O_NONBLOCK);//volume button
fds[1].fd = open("/dev/input/event5", O_RDONLY|O_NONBLOCK);//power button
for (i = 0; i<IN_FILES; i++){
if ( fds[i].fd < 0 ) return -1;
fds[i].events = POLLIN;
}
while(1){
pollres = poll(fds,IN_FILES,TIME_DELAY);
for (i = 0; i< IN_FILES; i++){
if (fds[i].revents){
real_read = read(fds[i].fd, &event, sizeof(event));
if(real_read < (int)sizeof(event)) {
fprintf(stderr, "could not get event\n");
break;
}
time(&now);
p = localtime(&now);
sprintf(capture_name,"%s/%d-%d-%d_%d-%d-%d.jpg",
SAVE_PATH,
1900+p->tm_year, 1+p->tm_mon, p->tm_mday,
p->tm_hour, p->tm_min, p->tm_sec);
printf("%d %u %u %u\n", i, event.type, event.code, event.value);
if (i == 0x01 && event.type == 0x01 && event.code == 0x6B && event.value == 0x00)
event5_down = 0x00;
if (i == 0x00 && event.type == 0x01 && event.code == 0x73 && event.value == 0x00)
event3_down = 0x00;
if (i == 0x01 && event.type == 0x01 && event.code == 0x6B && event.value == 0x01)
{
event5_down = 0x01;
if(event3_down&event5_down)
{
jpg_screen_capture(capture_name);
fork_sound();
printf("Lee Meng capture jpg:%s\n",capture_name);
}
}
if (i == 0x00 && event.type == 0x01 && event.code == 0x73 && event.value == 0x01)
{
event3_down = 0x01;
if(event3_down&event5_down)
{
printf("Lee Meng capture jpg:%s\n",capture_name);
jpg_screen_capture(capture_name);
fork_sound();
}
}
}
}
//no sleep
}
for(i=0;i<2;i++){
if(fds[i].fd > 0){
close(fds[i].fd);
fds[i].fd = -1;
}
}
return 0;
}
main函数及Android.mk
main.c
#include <stdio.h>
int main(void)
{
while(1)
event_capture_jpg();
}
Android.mk
LOCAL_PATH := $(my-dir)
commonSources :=
commonIncludes := $(TARGET_OUT_HEADERS)/common/inc
commonSharedLibraries := liboncrpc
commonSharedLibraries += libnv
commonSharedLibraries += libcutils libxml2 libicuuc
commonSharedLibraries += libutils
commonSharedLibraries += libjpeg libc
include $(CLEAR_VARS)
LOCAL_MODULE := qlogd
LOCAL_CFLAGS := $(commonCflags)
LOCAL_C_INCLUDES := $(call include-path-for, system-core)/cutils
LOCAL_C_INCLUDES += $(commonIncludes)
LOCAL_C_INCLUDES += $(LOCAL_PATH)
LOCAL_C_INCLUDES += external/jpeg
LOCAL_SRC_FILES := main.c getevent.c capture_jpg.c
LOCAL_MODULE_TAGS := optional eng
LOCAL_SHARED_LIBRARIES += $(commonSharedLibraries)
LOCAL_MODULE_PATH := $(TARGET_OUT_OPTIONAL_EXECUTABLES)
include $(BUILD_EXECUTABLE)
这四个文件放到Android工程下面vendor/qlogd目录下，mmm编译之后就可以在/system/xbin/找到qlogd，将qlogd push到手机上相应的目录/system/xbin/，添加可以执行权限
chmod 777 qlogd
然后运行
/system/xbin/qlogd&
按下power键和音量-键,就可以听到Bi Bi Bi的提示音了。