how to force landscape mode with NDK using pure c++ codes

Issue

generally,it works ok. but if i lock the screen,and wait APP_CMD_LOST_FOCUS occur,and then i unlock the srceen. it change to portrait! but i find the egl buff is still landscape setting, and all coordinate bigger.

my AndroidManifest.xml setting:

<activity android:name="android.app.NativeActivity"
        android:theme="@android:style/Theme.NoTitleBar.Fullscreen"
        android:configChanges="orientation|keyboardHidden"
        android:screenOrientation="landscape"
        android:clearTaskOnLaunch="true">
    <meta-data android:name="android.app.lib_name"
            android:value="sunred" />

    <intent-filter>
          <action android:name="android.intent.action.MAIN" />
        <category android:name="android.intent.category.LAUNCHER" />
    </intent-filter>

</activity>

my egl init c++ code

int engine_init_display(OSCONTEXTENGINE* pEngine, const DISPLAY_CONFIG* pConfig)
{
    // initialize OpenGL ES and EGL
    /*
     * Here specify the attributes of the desired configuration.
     * Below, we select an EGLConfig with at least 8 bits per color
     * component compatible with on-screen windows
     */
    const EGLint attribs[] =
    { EGL_SURFACE_TYPE, EGL_WINDOW_BIT, EGL_RENDERABLE_TYPE, EGL_OPENGL_ES2_BIT,
            EGL_BLUE_SIZE, 8, EGL_GREEN_SIZE, 8, EGL_RED_SIZE, 8,
            EGL_DEPTH_SIZE, 8, EGL_NONE };
    EGLint w, h, dummy, format;
    EGLint numConfigs;
    EGLConfig config;
    EGLSurface surface;
    EGLContext context;

    EGLDisplay display = eglGetDisplay(EGL_DEFAULT_DISPLAY);

    eglInitialize(display, 0, 0);

    //eglBindAPI(EGL_OPENGL_ES_API);
    /* Here, the application chooses the configuration it desires. In this
     * sample, we have a very simplified selection process, where we pick
     * the first EGLConfig that matches our criteria */
    EGLBoolean bres = eglChooseConfig(display, attribs, &config, 1,
            &numConfigs);

    if (!bres)
    {
        __android_log_print(LOGINFO_ERROR, "engine_init_display",
                "numConfigs = %d", numConfigs);
    }

    /* EGL_NATIVE_VISUAL_ID is an attribute of the EGLConfig that is
     * guaranteed to be accepted by ANativeWindow_setBuffersGeometry().
     * As soon as we picked a EGLConfig, we can safely reconfigure the
     * ANativeWindow buffers to match, using EGL_NATIVE_VISUAL_ID. */
    eglGetConfigAttrib(display, config, EGL_NATIVE_VISUAL_ID, &format);

    ANativeWindow_setBuffersGeometry(pEngine->m_app->window, 0, 0, format);

    surface = eglCreateWindowSurface(display, config, pEngine->m_app->window,
            NULL);
    const EGLint ai32ContextAttribs[] =
    { EGL_CONTEXT_CLIENT_VERSION, 2, EGL_NONE };

    context = eglCreateContext(display, config, NULL,
            ai32ContextAttribs);

    if (eglMakeCurrent(display, surface, surface, context) == EGL_FALSE)
    {
        LOGW("Unable to eglMakeCurrent");
        return P_ERR;
    }

    eglQuerySurface(display, surface, EGL_WIDTH, &w);
    eglQuerySurface(display, surface, EGL_HEIGHT, &h);

    pEngine->m_EglDisplay = display;
    pEngine->m_EglContext = context;
    pEngine->m_EglSurface = surface;
    pEngine->m_iWidth = w;
    pEngine->m_iHeight = h;

    return 0;
}

when the APP_CMD_INIT_WINDOW occurs,i call engine_init_display.

has any method to force set it into landscape mode using c++?

the render frame:

works ok:

pEngine->m_iWidth = 960;
pEngine->m_iHeight = 540;

lock screeen -> APP_CMD_LOST_FOCUS -> unlock screen

pEngine->m_iWidth = 540;
pEngine->m_iHeight = 960;

windows change to portrait! but egl buff is still landscape setting, and all coordinate bigger.

Solution

When you get APP_CMD_CONFIG_CHANGED, try doing another init:

    case APP_CMD_CONFIG_CHANGED:
        if (engine->app->window != NULL && ((engine->width != ANativeWindow_getWidth(app->window)) || (engine->height != ANativeWindow_getHeight(app->window)))) {
            engine_handle_cmd(app, APP_CMD_TERM_WINDOW);
            engine_handle_cmd(app, APP_CMD_INIT_WINDOW);
        }
        break;

(Variable names, etc from the NativeActivity sample code.) You'll end up going through init multiple times on wake; if this is a problem, you can also do lazy init and just invalidate the configuration in both APP_CMD_CONFIG_CHANGED and APP_CMD_INIT_WINDOW.

This is from live code; in our testing, it works about 99% of the time in 2.3 and later (untested earlier), but a very small amount of the time starting the program from the lock screen and then unlocking causes a race condition where the CONFIG_CHANGED isn't called and we wake up stuck in landscape. For our game, this is not a user code path (launching from lock screen), so I haven't investigated further.

Answered By - addaon