android平台下基于ANativeWindow实现渲染bitmap图像

OpenGL ES 3.0学习实践

android平台下OpenGL ES 3.0从零开始
android平台下OpenGL ES 3.0绘制纯色背景
android平台下OpenGL ES 3.0绘制圆点、直线和三角形
android平台下OpenGL ES 3.0绘制彩色三角形
android平台下OpenGL ES 3.0从矩形中看矩阵和正交投影
android平台下OpenGL ES 3.0着色语言基础知识(上)
android平台下OpenGL ES 3.0着色语言基础知识(下)
android平台下OpenGL ES 3.0实例详解顶点属性、顶点数组
android平台下OpenGL ES 3.0实例详解顶点缓冲区对象(VBO)和顶点数组对象(VAO)
android平台下OpenGL ES 3.0绘制立方体的几种方式
android平台下OpenGL ES 3.0实现2D纹理贴图显示bitmap
android平台下OpenGL ES 3.0基于GLSurfaceView对相机Camera预览实时处理
android平台下OpenGL ES 3.0基于TextureView对相机Camera预览实时处理
android平台下基于ANativeWindow实现渲染bitmap图像

概述

原生Window API支持我们在ndk下开发原生的绘制功能，后续的一些视频渲染，包括相机采集预览等都可以通过这些API来实现，笔者今天通过几个简单的API来实践一下native层的绘制功能

配置环境

笔者Android Studio配置的是android-ndk-r16b版本，操作系统是ubuntu 16.05

绘制背景色

还是从最简单的入手，开始尝试绘制背景颜色，我们此次使用的方案是SurfaceView+ANativeWindow的方式，基于之前的项目工程

先定义Java层的本地方法：

/*** @anchor: andy* @date: 2018-11-13* @description:*/
public class NativeWindowSample {static {System.loadLibrary("native-window");}/*** 绘制指定颜色背景** @param surface* @param color*/public native void drawColor(Object surface, int color);/*** 绘制指定颜色背景** @param surface* @param bitmap*/public native void drawBitmap(Object surface, Object bitmap);}

配置CMakeLists.txt文件内容如下：


cmake_minimum_required(VERSION 3.4.1)##官方标准配置
set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall")
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -fno-rtti -fno-exceptions -Wall")add_library(native-windowSHAREDsrc/main/cpp/native_window.cpp)target_link_libraries(native-window${OPENGL_LIB}androidjnigraphicslog)

build.gradle中的配置，这里不赘述，比较简单

在我们的子工程目录src/main/cpp下新建我们的native_window.cpp和native_window.h文件：

来看看native_window.cpp中drawColor的实现：

void drawColor(JNIEnv *env, jobject obj, jobject surface, jint colorARGB) {//分离ARGBint alpha = (colorARGB >> 24) & 0xFF;int red = (colorARGB >> 16) & 0xFF;int green = (colorARGB >> 8) & 0xFF;int blue = colorARGB & 0xFF;int colorABGR = (alpha << 24) | (blue << 16) | (green << 8) | red;//获取目标surfaceANativeWindow *window = ANativeWindow_fromSurface(env, surface);if (NULL == window) {ThrowException(env, "java/lang/RuntimeException", "unable to get native window");return;}//默认的是RGB_565int32_t result = ANativeWindow_setBuffersGeometry(window, 640, 640, WINDOW_FORMAT_RGBA_8888);if (result < 0) {ThrowException(env, "java/lang/RuntimeException", "unable to set buffers geometry");//释放窗口ANativeWindow_release(window);window = NULL;return;}ANativeWindow_acquire(window);ANativeWindow_Buffer buffer;if (ANativeWindow_lock(window, &buffer, NULL) < 0) {ThrowException(env, "java/lang/RuntimeException", "unable to lock native window");//释放窗口ANativeWindow_release(window);window = NULL;return;}uint32_t *line = (uint32_t *) buffer.bits;for (int y = 0; y < buffer.height; y++) {for (int x = 0; x < buffer.width; x++) {line[x] = colorABGR;}line = line + buffer.stride;}if (ANativeWindow_unlockAndPost(window) < 0) {ThrowException(env, "java/lang/RuntimeException","unable to unlock and post to native window");}//释放窗口ANativeWindow_release(window);
}

这里要注意的就是，我们从Java层传入的是32位的ARGB的颜色，直接写入我们的windowBuffer，颜色显示可能不正确，需要按照ANativeWindow_Buffer指定的颜色顺序作一次转换

绘制一个灰色背景：

mNativeWindowSample.drawColor(mSurfaceView.getHolder().getSurface(), Color.GRAY);

绘制bitmap

直接绘制bitmap也比较简单，但是我们需要通过AndroidBitmap_lockPixels方法获取bitmap对应的本地的数据的指针，通过这个指针来读取对应的像素数据，注释也比较清楚

void drawBitmap(JNIEnv *env, jobject obj, jobject surface, jobject bitmap) {//获取bitmap的信息,比如宽和高AndroidBitmapInfo info;if (AndroidBitmap_getInfo(env, bitmap, &info) < 0) {ThrowException(env, "java/lang/RuntimeException", "unable to get bitmap info");return;}char *data = NULL;//获取bitmap对应的native指针if (AndroidBitmap_lockPixels(env, bitmap, (void **) &data) < 0) {ThrowException(env, "java/lang/RuntimeException", "unable to lock pixels");return;}if (AndroidBitmap_unlockPixels(env, bitmap) < 0) {ThrowException(env, "java/lang/RuntimeException", "unable to unlock pixels");return;}//获取目标surfaceANativeWindow *window = ANativeWindow_fromSurface(env, surface);if (NULL == window) {ThrowException(env, "java/lang/RuntimeException", "unable to get native window");return;}//这里设置为RGBA的方式,总共是4字节32位int32_t result = ANativeWindow_setBuffersGeometry(window, info.width, info.height,WINDOW_FORMAT_RGBA_8888);if (result < 0) {ThrowException(env, "java/lang/RuntimeException", "unable to set buffers geometry");//释放窗口ANativeWindow_release(window);window = NULL;return;}ANativeWindow_acquire(window);ANativeWindow_Buffer buffer;//锁定窗口的绘图表面if (ANativeWindow_lock(window, &buffer, NULL) < 0) {ThrowException(env, "java/lang/RuntimeException", "unable to lock native window");//释放窗口ANativeWindow_release(window);window = NULL;return;}//转换为像素点来处理int32_t *bitmapPixes = (int32_t *) data;uint32_t *line = (uint32_t *) buffer.bits;for (int y = 0; y < buffer.height; y++) {for (int x = 0; x < buffer.width; x++) {line[x] = bitmapPixes[buffer.height * y + x];}line = line + buffer.stride;}//解锁窗口的绘图表面if (ANativeWindow_unlockAndPost(window) < 0) {ThrowException(env, "java/lang/RuntimeException","unable to unlock and post to native window");}//释放ANativeWindow_release(window);
}

绘制一个bitmap对象

BitmapFactory.Options options = new BitmapFactory.Options();
options.inScaled = false;
Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.main, options);
mNativeWindowSample.drawBitmap(mSurfaceView.getHolder().getSurface(), bitmap);

项目地址：
https://github.com/byhook/opengles4android