SCREENCONTROL

Sets or gets internal graphics library settings

Syntax:
declare sub ScreenControl ( byval what as long, byref param1 as integer = 0, byref param2 as integer = 0, byref param3 as integer = 0, byref param4 as integer = 0 )
declare sub ScreenControl ( byval what as long, byref param as string = "" )

Usage:
ScreenControl( what [, [ param1 ][, [ param2 ][, [ param3 ][, [ param4 ]]]]] )
or,
ScreenControl( what [, param ] )

Parameters:
what
specifies the function to perform
param1
optional first integer parameter, contains value to be set on entry or value got on exit
param2
optional second integer parameter, contains value to be set on entry or value got on exit
param3
optional third integer parameter, contains value to be set on entry or value got on exit
param4
optional fourth integer parameter, contains value to be set on entry or value got on exit
param
optional string parameter, contains text to be set on entry or text got on exit

Description:
This function can be used to set or get internal GfxLib states. The what parameter specifies which operation to perform. On operations that set states, the param* parameters must contain the values to be set. On operations that get states, param* will hold the values returned by GfxLib when the function returns.
The meaning of the param* parameters depend on the what parameter, whose possible values are defined as constants in fbgfx.bi. In lang fb, they are set to be stored in the FB Namespace.
Below is a list of the supported what constants - and their values as defined at time of writing - along with the parameters associated with them.

Supported operations

Note:
(*) denotes operations that are allowed while a graphics mode has not yet been set via Screen (Graphics) or ScreenRes,
(**) denotes the operations that must be performed before the graphics mode is set via Screen (Graphics) or ScreenRes,
for all other operations, return values are zero (0) or the empty string ("") and the operation has no effect if a graphics mode is not available at call time.

Get operations

Examples:
'' include fbgfx.bi for some useful definitions
#include "fbgfx.bi"

'' use FB namespace for easy access to types/constants
Using FB

Dim e As EVENT
Dim As Integer x0, y0, x, y
Dim As Integer shakes = 0
Dim As Any Ptr img

ScreenRes 320, 200, 32
Print "Click to shake window"

'' find window coordinates
ScreenControl GET_WINDOW_POS, x0, y0

Do

    If (shakes > 0) Then
       
        '' do a shake of the window

        If (shakes > 1) Then

            '' move window to a random position near its original coordinates
            x = x0 + Int(32 * (Rnd() - 0.5))
            y = y0 + Int(32 * (Rnd() - 0.5))
            ScreenControl SET_WINDOW_POS, x, y

        Else

            '' move window back to its original coordinates
            ScreenControl SET_WINDOW_POS, x0, y0

        End If

        shakes -= 1

    End If

    If (ScreenEvent(@e)) Then
        Select Case e.Type
       
        '' user pressed the mouse button
        Case EVENT_MOUSE_BUTTON_PRESS

            If (shakes = 0) Then
                '' set to do 20 shakes
                shakes = 20

                '' find current window coordinates to shake around
                ScreenControl GET_WINDOW_POS, x0, y0
            End If

        '' user closed the window or pressed a key
        Case EVENT_WINDOW_CLOSE, EVENT_KEY_PRESS
            '' exit to end of program
            Exit Do

        End Select
    End If

    '' free up CPU for other programs
    Sleep 5

Loop


'' include fbgfx.bi for some useful definitions
#include "fbgfx.bi"

Dim As String driver

#ifdef __FB_WIN32__
'' set graphics driver to GDI (Win32 only), before calling ScreenRes
ScreenControl FB.SET_DRIVER_NAME, "GDI"
#endif

ScreenRes 640, 480

'' fetch graphics driver name and display it to user
ScreenControl FB.GET_DRIVER_NAME, driver
Print "Graphics driver name: " & driver

'' wait for a keypress before closing the window
Sleep


Dialect Differences:
Differences from QB:
See also:
Back to Screen Functions
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