android后台获取当前屏幕截图（screencap.cpp修改）
16lz
2021-12-04
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 popusing namespace android;static uint32_t DEFAULT_DISPLAY_ID = ISurfaceComposer::eDisplayIdMain;//eDisplayIdMain = 0static 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
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