From QB64 Wiki
The _FULLSCREEN function returns the present full screen mode setting of the screen window.
Syntax:: full% = _FULLSCREEN
- Function Returns:
- 0 = _OFF (any positive non-0 value means fullscreen is on)
- 1 = _STRETCH
- 2 = _SQUAREPIXELS
It cannot be assumed that calling _FULLSCREEN will succeed. It cannot be assumed that the type of full screen will match the requested one. Always check the _FULLSCREEN function return in your programs!
Warning: Despite your software, the user's hardware, drivers and monitor may not function in some modes. Thus, it is highly recommended that you manually confirm with the user whether the switch to full screen was successful. This can be done "quietly" in some cases by getting the user to click on a button on screen with their mouse or press an unusual key. If the user does not respond after about 8 seconds, switch them back to windowed mode.
Example: Shows how fonts and the _FULLSCREEN mode can resize a program window.
CLS fontpath$ = ENVIRON$("SYSTEMROOT") + "\fonts\lucon.ttf" 'Find Windows Folder Path. f& = _FONT: defaultf& = f& DO INPUT "1) DEFAULT 2) SIZE WINDOW 3) FULL SCREEN 4) FULL STRETCHED Q) QUIT: ", winmode$ IF UCASE$(winmode$) = "Q" THEN EXIT DO style$ = "MONOSPACE" SELECT CASE winmode$ CASE "1" full = _FULLSCREEN 'get current full screen mode IF full <> 0 THEN _FULLSCREEN _OFF GOSUB ChangeFont CASE "2" DO PRINT INPUT "Enter a FONT SIZE 5 to 25: ", fontsize% LOOP UNTIL fontsize% > 4 AND fontsize% < 26 DO PRINT INPUT "Enter (0) for REGULAR or (1) for ITALIC FONT: ", italic% LOOP UNTIL italic% = 0 or italic% = 1 DO PRINT INPUT "Enter (0) for REGULAR or (1) for BOLD FONT: ", bold% LOOP UNTIL italic% = 0 or italic% = 1 IF italic% = 1 THEN style$ = style$ + ", ITALIC" IF bold% = 1 THEN style$ = style$ + ", BOLD" full = _FULLSCREEN 'get current full screen mode IF full <> 0 THEN _FULLSCREEN _OFF GOSUB ChangeFont CASE "3" GOSUB ChangeFont _FULLSCREEN _SQUAREPIXELS GOSUB CheckFull CASE "4" GOSUB ChangeFont _FULLSCREEN _STRETCH GOSUB CheckFull END SELECT PRINT: PRINT "_FullScreen mode ="; _FULLSCREEN PRINT LOOP GOSUB ChangeFont END CheckFull: '<<<<<<<<<<<<<< turn off full screen if function returns 0! full = _FULLSCREEN 'get current full screen mode IF full = 0 THEN _FULLSCREEN _OFF: SOUND 100, .75 RETURN ChangeFont: IF winmode$ <> "2" THEN _FONT 16 'select inbuilt 8x16 default font currentf& = _FONT ELSE currentf& = _LOADFONT(fontpath$, fontsize%, style$) _FONT currentf& END IF IF currentf& <> f& AND f& <> defaultf& THEN _FREEFONT f& f& = currentf& RETURN
Explanation: The _FULLSCREEN function can avoid screen display and monitor problems when used to monitor the success of the full screen operation! If a full screen mode is NOT achieved (the function will return 0), turn it OFF!