undocumented native window format in NDK

You can find only 3 formats in android/native_window.h.

enum {
    WINDOW_FORMAT_RGBA_8888          = 1,
    WINDOW_FORMAT_RGBX_8888          = 2,
    WINDOW_FORMAT_RGB_565            = 4,
};

But actually, it has others.
When you set up the attributes like this

const EGLint attribs[] = {
    EGL_SURFACE_TYPE, EGL_PBUFFER_BIT,
    EGL_BLUE_SIZE, 8,
    EGL_GREEN_SIZE, 8,
    EGL_RED_SIZE, 8,
    EGL_ALPHA_SIZE, 8,
    EGL_DEPTH_SIZE, 16,
//      EGL_BIND_TO_TEXTURE_RGB, EGL_TRUE,
//      EGL_BIND_TO_TEXTURE_RGBA, EGL_TRUE,
    EGL_NONE
};

you may get format 5 by eglChooseConfig.
Galaxy S I-9000 is the case.