SCREENRES

• Source: https://www.freebasic.net/wiki/wikka.php?wakka=KeyPgScreenres
• Last revised: 2024-04-06

---

SCREENRES — Initialize a graphics mode

Syntax

Statement form:

Screenres width, height [, [depth] [, [num_pages] [, [flags] [, refresh_rate] ] ] ]

Function form:

result = Screenres( width, height [, [depth] [, [num_pages] [, [flags] [, refresh_rate] ] ] ] )

Parameters

Parameter	Type	Description
width	Long	Horizontal resolution (display width in pixels)
height	Long	Vertical resolution (display height in pixels)
depth	Long	Color depth in bits-per-pixel. Default = 8. Valid values: 1, 2, 4, 8, 16, 32 (15 treated as 16; 24 treated as 32)
num_pages	Long	Number of video pages. Default = 1
flags	Long	Screen attribute flags. Default = 0
refresh_rate	Long	Refresh rate (fullscreen mode only). Default = 0

Return Value

• On success: returns 0
• On failure: returns a non-zero error code (a runtime error is also thrown)

Flags

Graphics mode flags

Flag	Description
GFX_NULL	Starts QB-on-GUI graphics mode: creates a graphics buffer but no window
GFX_OPENGL	Initializes OpenGL mode (only OpenGL commands may be used)
(none)	Enters QB-only graphics mode (default)

Window mode flags

Flag	Description
GFX_WINDOWED	Windowed mode (default)
GFX_FULLSCREEN	Fullscreen mode
GFX_NO_SWITCH	Disables Alt+Enter toggle between fullscreen/windowed
GFX_NO_FRAME	Creates a borderless window
GFX_SHAPED_WINDOW	Creates a shaped/transparent window (RGBA(255,0,255,0) = transparent)
GFX_ALWAYS_ON_TOP	Window is always on top of other windows

Option flags

Flag	Description
GFX_ALPHA_PRIMITIVES	Enables alpha channel support for all drawing primitives
GFX_HIGH_PRIORITY	Enables higher priority graphics processing
GFX_NO_X86_MMX	Disables MMX blitters (x86 platforms, since fbc 1.20.0)

OpenGL buffer flags (used only with GFX_OPENGL)

Flag	Description
GFX_STENCIL_BUFFER	Use a stencil buffer
GFX_ACCUMULATION_BUFFER	Use an accumulation buffer
GFX_MULTISAMPLE	Request full-scene antialiasing

Description

Screenres initializes a graphics mode. Three modes are supported:

1. QB-compatible graphics mode — windowed or fullscreen. Standard FreeBASIC graphics commands work as expected.
2. QB-on-GUI mode (GFX_NULL) — the user manages the window and refreshing manually. A graphics buffer is created but no window is shown.
3. OpenGL mode (GFX_OPENGL) — provides a portable way to initialize OpenGL. Only OpenGL commands should be used; FreeBASIC graphics primitives are not available.

The default font is 8×8 pixels. The Width function can be used to adjust the number of text rows and columns. Console commands such as Locate and Print work in graphics mode.

Example

' Set a 320x200 resolution with 8-bit color depth
ScreenRes 320, 200, 8

' Draw a colored diagonal pattern
For y As Long = 0 To 200 - 1
    For x As Long = 0 To 320 - 1
        PSet (x, y), (x + y) And 255
    Next x
Next y

' Display text in the upper-left corner
Print "Hello world!!"

' Wait for a key press
Sleep

Platform Differences

• Windowed mode and OpenGL flags are not supported under DOS.

See Also

• KeyPgScreengraphics — Screen (Graphics): QB-style graphics mode initialization
• KeyPgScreenlist — Screenlist: query available display modes
• KeyPgScreencontrol — Screencontrol: select driver, etc.
• KeyPgScreenptr — Screenptr: semi-low-level framebuffer access