Android: (2.3中实现截屏How to Capture Screen in Gingerbread)

http://blog.csdn.net/zmyde2010/article/details/6925498#reply

示例代码在:

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

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/*

* 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);

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

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<span style="font-size:24px;"><uses-permission android:name="android.permission.READ_FRAME_BUFFER" /></span>

贴出JNI代码，或资源下载地址:http://download.csdn.net/detail/zmyde2010/3835127

jni/com_android_ScreenCap_ScreenCapNative.cpp

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/*

* 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.

*/

#define LOG_TAG "ScreenCapNative-JNI"

//#define LOG_NDEBUG 0

#include "JNIHelp.h"

#include "jni.h"

#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>

namespace android {

static void android_ScreenCap_ScreenCapNative_nativeCaptureScreen(JNIEnv* env,

jobject obj, jstring file)

{

const char *file_path = env->GetStringUTFChars(file, NULL);

const String16 name("SurfaceFlinger");

sp<ISurfaceComposer> 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) {

LOGE("screen capture failed: %s\n", strerror(-err));

exit(0);

}

LOGD("screen capture success: w=%u, h=%u, pixels=%p\n",

w, h, heap->getBase());

LOGD("saving file as PNG in %s ...\n", file_path);

SkBitmap b;

b.setConfig(SkBitmap::kARGB_8888_Config, w, h);

b.setPixels(heap->getBase());

SkImageEncoder::EncodeFile(file_path, b,

SkImageEncoder::kPNG_Type, SkImageEncoder::kDefaultQuality);

}

static JNINativeMethod gScreenCapNativeMethods[] = {

/* name, signature, funcPtr */

{ "nativeCaptureScreen", "(Ljava/lang/String;)V",

(void*) android_ScreenCap_ScreenCapNative_nativeCaptureScreen },

};

int register_android_ScreenCap_ScreenCapNative(JNIEnv* env) {

int res = jniRegisterNativeMethods(env, "com/android/ScreenCap/ScreenCapNative",

gScreenCapNativeMethods, NELEM(gScreenCapNativeMethods));

LOG_FATAL_IF(res < 0, "Unable to register native methods.");

return 0;

}

extern "C" jint JNI_OnLoad(JavaVM* vm, void* reserved)

{

JNIEnv* env = NULL;

jint result = -1;

if (vm->GetEnv((void**) &env, JNI_VERSION_1_4) != JNI_OK) {

LOGE("GetEnv failed!");

return result;

}

LOG_ASSERT(env, "Could not retrieve the env!");

register_android_ScreenCap_ScreenCapNative(env);

return JNI_VERSION_1_4;

}

} /* namespace android */

jni/Android.mk

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LOCAL_PATH:= $(call my-dir)

include $(CLEAR_VARS)

LOCAL_SRC_FILES := com_android_ScreenCap_ScreenCapNative.cpp

LOCAL_C_INCLUDES += \

$(JNI_H_INCLUDE)

LOCAL_SHARED_LIBRARIES := \

libnativehelper \

libcutils \

libutils \

libbinder \

libskia \

libui \

libsurfaceflinger_client

LOCAL_C_INCLUDES += \

external/skia/include/core \

external/skia/include/effects \

external/skia/include/images \

external/skia/src/ports \

external/skia/include/utils

LOCAL_MODULE:= libscreencapjni

LOCAL_MODULE_TAGS := optional

LOCAL_PRELINK_MODULE := false

include $(BUILD_SHARED_LIBRARY)

看到有人问Java怎么调用JNI，贴出例子:

src/com/android/ScreenCap/ScreenCapNative.java

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/* zmyde2010@csdn */

package com.android.ScreenCap;

import java.io.File;

import android.os.Environment;

public class ScreenCapNative {

static {

System.loadLibrary("screencapjni");

};

private native static void nativeCaptureScreen(String file);

public static String startCaptureScreen() {

String file_name = getUniqueFileName();

if (file_name != null) {

nativeCaptureScreen(file_name);

}

return file_name;

}

private static String getUniqueFileName() {

File file = null;

if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {

file = createUniqueFile(Environment.getExternalStorageDirectory(),

"ScreenCap.PNG");

} else if (Environment.getInternalStorageState().equals(Environment.MEDIA_MOUNTED)) {

file = createUniqueFile(Environment.getInternalStorageDirectory(),

"ScreenCap.PNG");

}

return (file != null) ? file.getAbsolutePath() : null;

}

private static File createUniqueFile(File directory, String filename) {

File file = new File(directory, filename);

if (!file.exists()) {

return file;

}

// Get the extension of the file, if any.

int index = filename.lastIndexOf('.');

String format;

if (index != -1) {

String name = filename.substring(0, index);

String extension = filename.substring(index);

format = name + "-%d" + extension;

}

else {

format = filename + "-%d.PNG";

}

for (int i = 2; i < Integer.MAX_VALUE; i++) {

file = new File(directory, String.format(format, i));

if (!file.exists()) {

return file;

}

}

return null;

}

}

可以在你的Acitvity或Service里面调用 ScreenCapNative.startCaptureScreen();来截屏

4.0源码已经公布了，大家不要花时间研究2.3的截屏了

当然最好是系统级实现，响应某个组合键来截屏，像Android4.0

发两张截图:







我上传了全部源码，包括编译后的APK,so，稍后请到我的资源里面下载:

http://download.csdn.net/detail/zmyde2010/3911916

例子中截屏作为一个开机启动的后台service，在需要截屏的任何地方(系统servic或其他APK)，发送

Intent "com.android.CAPTURE_SCREEN" 即可

我的测试版本是2.3.4，其它不保证能用