/**
 * Creates new <code>GraphicBuffer</code> instance. This method will return null
 * if the buffer cannot be created.
 *
 * @param width The width in pixels of the buffer
 * @param height The height in pixels of the buffer
 * @param format The format of each pixel as specified in {@link PixelFormat}
 * @param usage Hint indicating how the buffer will be used
 *
 * @return A <code>GraphicBuffer</code> instance or null
 */
public static GraphicBuffer create(int width, int height, int format, int usage) {
    long nativeObject = nCreateGraphicBuffer(width, height, format, usage);
    if (nativeObject != 0) {
        return new GraphicBuffer(width, height, format, usage, nativeObject);
    }
    return null;
}

静态方法 create() 中先调用 nCreateGraphicBuffer() 方法创建 GraphicBuffer native，然后创建一个 GraphicBuffer 对象返回。

static jlong android_graphics_GraphicBuffer_create(JNIEnv* env, jobject clazz,
        jint width, jint height, jint format, jint usage) {
    sp<GraphicBuffer> buffer = new GraphicBuffer(
            uint32_t(width), uint32_t(height), PixelFormat(format), uint32_t(usage),
            std::string("android_graphics_GraphicBuffer_create pid [") +
                    std::to_string(getpid()) +"]");

    status_t error = buffer->initCheck();
    if (error < 0) {
        ALOGW_IF(kDebugGraphicBuffer, "createGraphicBuffer() failed in GraphicBuffer.create()");
        return NULL;
    }

    GraphicBufferWrapper* wrapper = new GraphicBufferWrapper(buffer);
    return reinterpret_cast<jlong>(wrapper);
}

nCreateGraphicBuffer() 方法绑定的是 android_graphics_GraphicBuffer_create() 函数，它调用 GraphicBuffer 构造函数创建一个 native 对象。如果创建成功，用 GraphicBufferWrapper 包装之后返回地址。

GraphicBuffer 构造函数中会调用 GraphicBuffer::initWithSize()。