android后台获取当前屏幕截图（screencap.cpp修改）
本文基于android6.0。首先找到screencap在Android源码中的位置，若不清楚，可以通过在android目录下通过命令find . -namescreencap.cpp。本文直接给出路径/android/frameworks/base/cmds/screencap/screencap.cpp。入口函数为main，只要编译就可以直接使用。如果需要将数据传出来，需要利用socket，后面会更新，将当前屏幕信息实时传输到web端显示。（data->data(), data->size()是需求的数据和大小）。
screencap.cpp源码如下：
/*
* Copyright (C) 2010 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
// TODO: Fix Skia.
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-parameter"
#include
#include
#pragma GCC diagnostic pop
using namespace android;
static uint32_t DEFAULT_DISPLAY_ID = ISurfaceComposer::eDisplayIdMain;//eDisplayIdMain = 0
static void usage(const char* pname)
{
fprintf(stderr,
"usage: %s [-hp] [-d display-id] [FILENAME]\n"
" -h: this message\n"
" -p: save the file as a png.\n"
" -d: specify the display id to capture, default %d.\n"
"If FILENAME ends with .png it will be saved as a png.\n"
"If FILENAME is not given, the results will be printed to stdout.\n",
pname, DEFAULT_DISPLAY_ID
);
}
static SkColorType flinger2skia(PixelFormat f)
{
switch (f) {
case PIXEL_FORMAT_RGB_565:
return kRGB_565_SkColorType;
default:
return kN32_SkColorType;
}
}
static status_t vinfoToPixelFormat(const fb_var_screeninfo& vinfo,
uint32_t* bytespp, uint32_t* f)
{
switch (vinfo.bits_per_pixel) {
case 16:
*f = PIXEL_FORMAT_RGB_565;
*bytespp = 2;
break;
case 24:
*f = PIXEL_FORMAT_RGB_888;
*bytespp = 3;
break;
case 32:
// TODO: do better decoding of vinfo here
*f = PIXEL_FORMAT_RGBX_8888;
*bytespp = 4;
break;
default:
return BAD_VALUE;
}
return NO_ERROR;
}
static status_t notifyMediaScanner(const char* fileName) {
String8 cmd("am broadcast -a android.intent.action.MEDIA_SCANNER_SCAN_FILE -d file://");
String8 fileUrl("\"");
fileUrl.append(fileName);
fileUrl.append("\"");
cmd.append(fileName);
cmd.append(" > /dev/null");
int result = system(cmd.string());
if (result < 0) {
fprintf(stderr, "Unable to broadcast intent for media scanner.\n");
return UNKNOWN_ERROR;
}
return NO_ERROR;
}
int main(int argc, char** argv)
{
//while(1){
//创建ProcessState 当前进程属性,启动进程的线程池
ProcessState::self()->startThreadPool();
const char* pname = argv[0];
bool png = false;
int32_t displayId = DEFAULT_DISPLAY_ID;//DEFAULT_DISPLAY_ID = eDisplayIdMain = 0,
int c;
while ((c = getopt(argc, argv, "phd:")) != -1) {
switch (c) {
case 'p':
png = true;
break;
case 'd':
displayId = atoi(optarg);
break;
case '?':
case 'h':
usage(pname);
return 1;
}
}
argc -= optind;//optind = 1
argv += optind;
struct timeval tv; //超时时间设置
while(1){
gettimeofday(&tv,NULL);
ALOGE("tv.tv_sec = %ld ,tv.tv_usec = %ld\n", tv.tv_sec, tv.tv_usec);
int fd = -1;
const char* fn = NULL;
if (argc == 0) {
fd = dup(STDOUT_FILENO);//STDOUT_FILENO=1
} else if (argc == 1) {
fn = argv[0];
fd = open(fn, O_WRONLY | O_CREAT | O_TRUNC, 0664);
if (fd == -1) {
fprintf(stderr, "Error opening file: %s (%s)\n", fn, strerror(errno));
return 1;
}
const int len = strlen(fn);
if (len >= 4 && 0 == strcmp(fn+len-4, ".png")) {
png = true;
}
}
if (fd == -1) {
usage(pname);
return 1;
}
//------------------------------------------------------------------------------------
void const* mapbase = MAP_FAILED;
ssize_t mapsize = -1;
void const* base = NULL;
uint32_t w, s, h, f;
size_t size = 0;
// Maps orientations from DisplayInfo to ISurfaceComposer
static const uint32_t ORIENTATION_MAP[] = {
ISurfaceComposer::eRotateNone, // 0 == DISPLAY_ORIENTATION_0
ISurfaceComposer::eRotate270, // 1 == DISPLAY_ORIENTATION_90
ISurfaceComposer::eRotate180, // 2 == DISPLAY_ORIENTATION_180
ISurfaceComposer::eRotate90, // 3 == DISPLAY_ORIENTATION_270
};
//------------------------------------------------------------------------------------
ScreenshotClient screenshot;
sp display = SurfaceComposerClient::getBuiltInDisplay(displayId);
if (display == NULL) {
fprintf(stderr, "Unable to get handle for display %d\n", displayId);
return 1;
}
Vector configs;
SurfaceComposerClient::getDisplayConfigs(display, &configs);
int activeConfig = SurfaceComposerClient::getActiveConfig(display);
if (static_cast(activeConfig) >= configs.size()) {
fprintf(stderr, "Active config %d not inside configs (size %zu)\n",
activeConfig, configs.size());
return 1;
}
uint8_t displayOrientation = configs[activeConfig].orientation;
uint32_t captureOrientation = ORIENTATION_MAP[displayOrientation];
status_t result = screenshot.update(display, Rect(), 0, 0, 0, -1U,
false, captureOrientation);
if (result == NO_ERROR) {
base = screenshot.getPixels();
w = screenshot.getWidth();
h = screenshot.getHeight();
s = screenshot.getStride();
f = screenshot.getFormat();
size = screenshot.getSize();
} else {
const char* fbpath = "/dev/graphics/fb0";
int fb = open(fbpath, O_RDONLY);
if (fb >= 0) {
struct fb_var_screeninfo vinfo;
if (ioctl(fb, FBIOGET_VSCREENINFO, &vinfo) == 0) {
uint32_t bytespp;
if (vinfoToPixelFormat(vinfo, &bytespp, &f) == NO_ERROR) {
size_t offset = (vinfo.xoffset + vinfo.yoffset*vinfo.xres) * bytespp;
w = vinfo.xres;
h = vinfo.yres;
s = vinfo.xres;
size = w*h*bytespp;
mapsize = offset + size;
mapbase = mmap(0, mapsize, PROT_READ, MAP_PRIVATE, fb, 0);
if (mapbase != MAP_FAILED) {
base = (void const *)((char const *)mapbase + offset);
}
}
}
close(fb);
}
}
if (base != NULL) {
if (png) {
const SkImageInfo info = SkImageInfo::Make(w, h, flinger2skia(f), kPremul_SkAlphaType);
SkAutoTUnref data(SkImageEncoder::EncodeData(info, base, s*bytesPerPixel(f),
SkImageEncoder::kJPEG_Type, SkImageEncoder::kDefaultQuality));
if (data.get()) {
FILE *fp;
if((fp=fopen("/data/audioBuffer.txt","a+"))==NULL) {
ALOGE("00000000000000000\n");
}
else {
fwrite(data->data(),data->size(),1, fp);
ALOGE("data->size() = %zu\n",data->size());
}
fclose(fp);
write(fd, data->data(), data->size()); //data->data(), data->size()可以将数据传出去实时录制当前屏幕
}
if (fn != NULL) {
notifyMediaScanner(fn);
}
} else {
write(fd, &w, 4);
write(fd, &h, 4);
write(fd, &f, 4);
size_t Bpp = bytesPerPixel(f);
for (size_t y=0 ; y
修改后进行编译：
source build/envsetup.sh
lunch 6
make -j8
运行模拟器：emulator -sdcard /home/bruceking90/Documents/workplace/sdcard.img &
之后进行截屏：adb shell screencap -p | sed 's/\r$//' > screen.png
此命令可以直接将png存放在android即当前目录下。
或者adb shell screencap -p /sdcard/screen.png
sdcard创建可以参考：http://blog.csdn.net/ctrl_qun/article/details/52524993
点对点socket传输数据参考：http://blog.csdn.net/ctrl_qun/article/details/52454151
多个客户端socket传输数据参考：http://blog.csdn.net/ctrl_qun/article/details/52524086