android 使用jpeg库截屏

jtest.c

#include <string.h>  
#include <stdlib.h>
//#include <jni.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 x;
	int y;
}point;

typedef struct
{
	int w;    /* width */
	int h;    /* high */
	int bpp;  /* bits per pixel */
	unsigned char *fbmem;
}screen;

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_fix.line_length / 4;
	fb->h = fb_var.yres;
	fb->bpp = fb_var.bits_per_pixel;
	printf("--->^_^ %d, %d, %d, %d\n", fb_var.xres_virtual, fb_var.yres_virtual, fb_var.xoffset, fb_var.yoffset);
	printf("--->^_^ %d\n", fb_fix.line_length);
#if 1
	printf("width:%d\thign:%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;
}


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, 60, 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;  
}  


BYTE*  generateRGB24Data()  
{  
	struct {  
		BYTE r;  
		BYTE g;  
		BYTE b;  
	} pRGB[100][199];

	memset( pRGB, 0, sizeof(pRGB) ); 

	int i=0, j=0;  
	for(  i=50;i<70;i++ ){  
		for( j=70;j<140;j++ ){  
			pRGB[i][j].b = 0xff;  
		}  
	}  

	for(  i=0;i<10;i++ ){  
		for( j=0;j<199;j++ ){  
			pRGB[i][j].r = 0xff;  
		}  
	}  

	BYTE* ret = (BYTE*)malloc(sizeof(BYTE)*100*199*3);  
	memcpy(ret, (BYTE*)pRGB, sizeof(pRGB));  
	return ret;  
}  

int main(void)
{  
	int i, j;
	unsigned char *p;
	int w, h;

	//BYTE* data = generateRGB24Data();  
	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));
	for(i = 0; i < h; i++){
		for(j = 0; j < w; j++){
			*(p + (i * w + j) * 3) = *(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);
		}
	}

	generateJPEG(p, fb_screen.w, fb_screen.h, "/sdcard/test.jpg");  

	term_fb(&fb_screen);	
	free(p);
	//free(data);  
	return 0;
}

Android.mk

LOCAL_PATH:= $(call my-dir)
include $(CLEAR_VARS)

LOCAL_SRC_FILES:= jtest.c

LOCAL_MODULE:= jtest

#LOCAL_FORCE_STATIC_EXECUTABLE := true

#LOCAL_STATIC_LIBRARIES := libc 
LOCAL_SHARED_LIBRARIES:= libjpeg libc
LOCAL_C_INCLUDES := $(LOCAL_PATH)

LOCAL_MODULE_PATH := $(TARGET_OUT_OPTIONAL_EXECUTABLES)
LOCAL_MODULE_TAGS := debug

include $(BUILD_EXECUTABLE)

运行后在/sdcard/目录下，生产test.jpg