android后台截屏实现(2) |
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首先找到screencap类在Android源码中的位置，/442/frameworks/base/cmds/screencap/screencap.cpp 源码如下： 1 /* 2 * Copyright (C) 2010 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #include 18 #include 19 #include 20 #include 21 22 #include 23 #include 24 #include 25 26 #include 27 28 #include 29 #include 30 31 #include 32 33 #include 34 #include 35 #include 36 #include 37 38 using namespace android; 39 40 static uint32_t DEFAULT_DISPLAY_ID = ISurfaceComposer::eDisplayIdMain; 41 42 static void usage(const char* pname) 43 { 44 fprintf(stderr, 45 "usage: %s [-hp] [-d display-id] [FILENAME]\n" 46 " -h: this message\n" 47 " -p: save the file as a png.\n" 48 " -d: specify the display id to capture, default %d.\n" 49 "If FILENAME ends with .png it will be saved as a png.\n" 50 "If FILENAME is not given, the results will be printed to stdout.\n", 51 pname, DEFAULT_DISPLAY_ID 52 ); 53 } 54 55 static SkBitmap::Config flinger2skia(PixelFormat f) 56 { 57 switch (f) { 58 case PIXEL_FORMAT_RGB_565: 59 return SkBitmap::kRGB_565_Config; 60 default: 61 return SkBitmap::kARGB_8888_Config; 62 } 63 } 64 65 static status_t vinfoToPixelFormat(const fb_var_screeninfo& vinfo, 66 uint32_t* bytespp, uint32_t* f) 67 { 68 69 switch (vinfo.bits_per_pixel) { 70 case 16: 71 *f = PIXEL_FORMAT_RGB_565; 72 *bytespp = 2; 73 break; 74 case 24: 75 *f = PIXEL_FORMAT_RGB_888; 76 *bytespp = 3; 77 break; 78 case 32: 79 // TODO: do better decoding of vinfo here 80 *f = PIXEL_FORMAT_RGBX_8888; 81 *bytespp = 4; 82 break; 83 default: 84 return BAD_VALUE; 85 } 86 return NO_ERROR; 87 } 88 89 int main(int argc, char** argv) 90 { 91 ProcessState::self()->startThreadPool(); 92 93 const char* pname = argv[0]; 94 bool png = false; 95 int32_t displayId = DEFAULT_DISPLAY_ID; 96 int c; 97 while ((c = getopt(argc, argv, "phd:")) != -1) { 98 switch (c) { 99 case 'p': 100 png = true; 101 break; 102 case 'd': 103 displayId = atoi(optarg); 104 break; 105 case '?': 106 case 'h': 107 usage(pname); 108 return 1; 109 } 110 } 111 argc -= optind; 112 argv += optind; 113 114 int fd = -1; 115 if (argc == 0) { 116 fd = dup(STDOUT_FILENO); 117 } else if (argc == 1) { 118 const char* fn = argv[0]; 119 fd = open(fn, O_WRONLY | O_CREAT | O_TRUNC, 0664); 120 if (fd == -1) { 121 fprintf(stderr, "Error opening file: %s (%s)\n", fn, strerror(errno)); 122 return 1; 123 } 124 const int len = strlen(fn); 125 if (len >= 4 && 0 == strcmp(fn+len-4, ".png")) { 126 png = true; 127 } 128 } 129 130 if (fd == -1) { 131 usage(pname); 132 return 1; 133 } 134 135 void const* mapbase = MAP_FAILED; 136 ssize_t mapsize = -1; 137 138 void const* base = 0; 139 uint32_t w, s, h, f; 140 size_t size = 0; 141 142 ScreenshotClient screenshot; 143 sp display = SurfaceComposerClient::getBuiltInDisplay(displayId); 144 if (display != NULL && screenshot.update(display) == NO_ERROR) { 145 base = screenshot.getPixels(); 146 w = screenshot.getWidth(); 147 h = screenshot.getHeight(); 148 s = screenshot.getStride(); 149 f = screenshot.getFormat(); 150 size = screenshot.getSize(); 151 } else { 152 const char* fbpath = "/dev/graphics/fb0"; 153 int fb = open(fbpath, O_RDONLY); 154 if (fb >= 0) { 155 struct fb_var_screeninfo vinfo; 156 if (ioctl(fb, FBIOGET_VSCREENINFO, &vinfo) == 0) { 157 uint32_t bytespp; 158 if (vinfoToPixelFormat(vinfo, &bytespp, &f) == NO_ERROR) { 159 size_t offset = (vinfo.xoffset + vinfo.yoffset*vinfo.xres) * bytespp; 160 w = vinfo.xres; 161 h = vinfo.yres; 162 s = vinfo.xres; 163 size = w*h*bytespp; 164 mapsize = offset + size; 165 mapbase = mmap(0, mapsize, PROT_READ, MAP_PRIVATE, fb, 0); 166 if (mapbase != MAP_FAILED) { 167 base = (void const *)((char const *)mapbase + offset); 168 } 169 } 170 } 171 close(fb); 172 } 173 } 174 175 if (base) { 176 if (png) { 177 SkBitmap b; 178 b.setConfig(flinger2skia(f), w, h, s*bytesPerPixel(f)); 179 b.setPixels((void*)base); 180 SkDynamicMemoryWStream stream; 181 SkImageEncoder::EncodeStream(&stream, b, 182 SkImageEncoder::kPNG_Type, SkImageEncoder::kDefaultQuality); 183 SkData* streamData = stream.copyToData(); 184 write(fd, streamData->data(), streamData->size()); 185 streamData->unref(); 186 } else { 187 write(fd, &w, 4); 188 write(fd, &h, 4); 189 write(fd, &f, 4); 190 size_t Bpp = bytesPerPixel(f); 191 for (size_t y=0 ; ystartThreadPool(); 81 82 int32_t displayId = DEFAULT_DISPLAY_ID; 83 84 const char* fn = env->GetStringUTFChars(jpath,NULL); 85 LOGI("=====jpath:%s \n", fn); 86 87 if (fn == NULL) { 88 LOGE("=====path = %s \n =====err: %s \n",fn, strerror(errno)); 89 return 1; 90 } 91 int fd = -1; 92 fd = open(fn, O_WRONLY | O_CREAT | O_TRUNC, 0664); 93 LOGI("=====after open ,fd:%d \n",fd); 94 if (fd == -1) { 95 LOGE("=====err: %s \n", strerror(errno)); 96 return 2; 97 } 98 99 void const* mapbase = MAP_FAILED; 100 ssize_t mapsize = -1; 101 102 void const* base = 0; 103 uint32_t w, s, h, f; 104 size_t size = 0; 105 106 ScreenshotClient screenshot; 107 sp < IBinder > display = SurfaceComposerClient::getBuiltInDisplay(displayId); 108 if (display != NULL && screenshot.update(display) == NO_ERROR) { 109 base = screenshot.getPixels(); 110 w = screenshot.getWidth(); 111 h = screenshot.getHeight(); 112 s = screenshot.getStride(); 113 f = screenshot.getFormat(); 114 size = screenshot.getSize(); 115 } else { 116 const char* fbpath = "/dev/graphics/fb0"; 117 int fb = open(fbpath, O_RDONLY); 118 LOGI("=====read framebuffer, fb:%d \n", fb); 119 if (fb >= 0) { 120 struct fb_var_screeninfo vinfo; 121 if (ioctl(fb, FBIOGET_VSCREENINFO, &vinfo) == 0) { 122 uint32_t bytespp; 123 if (vinfoToPixelFormat(vinfo, &bytespp, &f) == NO_ERROR) { 124 size_t offset = (vinfo.xoffset + vinfo.yoffset * vinfo.xres) 125 * bytespp; 126 w = vinfo.xres; 127 h = vinfo.yres; 128 s = vinfo.xres; 129 size = w * h * bytespp; 130 mapsize = offset + size; 131 mapbase = mmap(0, mapsize, PROT_READ, MAP_PRIVATE, fb, 0); 132 if (mapbase != MAP_FAILED) { 133 base = (void const *) ((char const *) mapbase + offset); 134 } 135 } 136 } 137 close(fb); 138 }else{ 139 LOGE("=====fb = %d , err: %s \n",fb, strerror(errno)); 140 return 3; 141 } 142 } 143 144 if (base) { 145 SkBitmap b; 146 b.setConfig(flinger2skia(f), w, h, s * bytesPerPixel(f)); 147 b.setPixels((void*) base); 148 SkDynamicMemoryWStream stream; 149 SkImageEncoder::EncodeStream(&stream, b, SkImageEncoder::kPNG_Type, 150 SkImageEncoder::kDefaultQuality); 151 SkData* streamData = stream.copyToData(); 152 write(fd, streamData->data(), streamData->size()); 153 streamData->unref(); 154 } 155 close (fd); 156 if (mapbase != MAP_FAILED) { 157 munmap((void *) mapbase, mapsize); 158 } 159 return 0; 160 } 161 162 163 static JNINativeMethod methods[] = { 164 {"currentscreen","(Ljava/lang/String;)I",(void*)ScreenCap_currentscreen}, 165 }; 166 167 static int registerNativeMethods(JNIEnv* env,const char* classname,JNINativeMethod* gMethods,int numMethods ){ 168 jclass clazz; 169 clazz = env->FindClass(classname); 170 if(clazz == NULL){ 171 return JNI_FALSE; 172 } 173 if(env->RegisterNatives(clazz,gMethods,numMethods) GetEnv(&uenv.venv, JNI_VERSION_1_6) != JNI_OK) { 206 return result; 207 } 208 env = uenv.env; 209 210 if (registerNatives(env) != JNI_TRUE) { 211 return result; 212 } 213 214 result = JNI_VERSION_1_6; 215 216 return result; 217 }
修改后的代码入口是ScreenCap_currentscreen，该方法接收一个地址，将当前屏幕截取到该地址下。代码中加入了日志，可以打印native层的错误信息。
此处需采用动态方式注册本地方法，静态方式好像会有问题。
参考链接： Android: How to Capture Screen in Gingerbread(2.3中实现截屏) Android: How to Capture Screen in Gingerbread(2.3中实现截屏)(续) Android系统截屏的实现（附代码）
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