android截屏代码：C++实现

示例代码在: 

frameworks\base\services\surfaceflinger\tests\screencap\screencap.cpp 

/* 
* 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 <utils/Log.h> 
#include <binder/IPCThreadState.h> 
#include <binder/ProcessState.h> 
#include <binder/IServiceManager.h> 
#include <binder/IMemory.h> 
#include <surfaceflinger/ISurfaceComposer.h> 
#include <SkImageEncoder.h> 
#include <SkBitmap.h> 
using namespace android; 
int main(int argc, char** argv) 
{ 
if (argc != 2) { 
printf("usage: %s path\n", argv[0]); 
exit(0); 
} 
const String16 name("SurfaceFlinger"); 
sp<ISurfaceComposer> composer; 
getService(name, &composer); 
getService(name, &composer); 
sp<IMemoryHeap> heap; 
uint32_t w, h; 
PixelFormat f; 
status_t err = composer->captureScreen(0, &heap, &w, &h, &f, 0, 0); 
if (err != NO_ERROR) { 
fprintf(stderr, "screen capture failed: %s\n", strerror(-err)); 
exit(0); 
} 
printf("screen capture success: w=%u, h=%u, pixels=%p\n", 
w, h, heap->getBase()); 
printf("saving file as PNG in %s ...\n", argv[1]); 
SkBitmap b; 
b.setConfig(SkBitmap::kARGB_8888_Config, w, h); 
b.setPixels(heap->getBase()); 
SkImageEncoder::EncodeFile(argv[1], b, 
SkImageEncoder::kPNG_Type, SkImageEncoder::kDefaultQuality); 
return 0; 
} 

编译后生成/system/bin/test-screencap 
测试时终端输入test-screencap /mnt/sdcard/scapxx.png 
可以看到SD卡生成截屏文件scapxx.png，默认大小为屏幕分辨率 
如果想把这个功能写到自己的应用里 
写个JNI，参考上面代码即可，但记得权限声明 
<span style="font-size:24px;"><uses-permission android:name="android.permission.READ_FRAME_BUFFER" 
/></span> 
当然最好是系统级实现，响应某个组合键来截屏，像Android4.0