Android OpenGL的显示尺寸不正确

Question

I am using the DisplayMetrics to get the display dimensions of the Android phone as follow:

DisplayMetrics dm = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(dm);
int width = dm.widthPixels;
int height = dm.heightPixels;

Results give me height=854, width=480 .

When I want the viewport to cover the whole screen as below, the viewport does not cover the complete display.

GLES20.glViewport(0,0,480,854);

Any explanations?

Answer 1

It is probably a better idea to get screen width and height from onSurfaceChanged since it takes orientation under account (and is called when it changes). What does it mean does not cover the whole display? If it is the status bar and navigation bar that "take" screen space then you can hide them.

    View decorView = getWindow().getDecorView();
    int uiOptions = View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY |
                    View.SYSTEM_UI_FLAG_HIDE_NAVIGATION |
                    View.SYSTEM_UI_FLAG_FULLSCREEN;
    decorView.setSystemUiVisibility(uiOptions);

Answer 2

It looks like the quad does not cover the whole screen. OpenGL screen coordinates range from -1 to 1 on both axis. Make sure the quad has a width and height of 2 if your not using a projection matrix. If you are using a projection matrix adjust the projection matrix parameters to project the quad on the entire screen or scale the quad to fit the the screen with current projection matrix.