Screen (Console)

Gets the character or color attribute at a given location

Syntax

Declare Function Screen ( ByVal row As Integer, ByVal column As Integer, ByVal colorflag As Integer = 0 ) As Integer

Usage

result = Screen( row, column [, colorflag ] )

Parameters

row

1-based offset from the top left corner of the console.

column

1-based offset from the top left corner of the console.

colorflag

If equal to 0, the ASCII code is returned, otherwise the color attribute is returned. If omitted, it defaults to 0.

Return Value

The ASCII or color attribute of the character.
At the moment (v0.18.5), if coordinates are out of screen, no error number is set and the value returned is not reliable.

Description

Screen returns the character or the color attribute found at a given position of a console output. It works in console mode and in graphics mode.

The format of the color attribute depends on the current color depth:

If the color type is a palette type with up to 4 bits per pixel (such as the Win32 console), then the color attribute is an 8-bit value, where the higher four bits hold the cell background color and the lower four bits hold the foreground (character) color.

If the color type is an 8-bit palette, then the color attribute is a 16-bit value, where the high byte holds the background color and the low byte holds the foreground color.

If the color type is full color, then the color attribute is a 32-bit integer, holding a single color value. If colorflag is equal to 1, then the foreground color is returned; if colorflag is equal to 2, then the background color is returned.

The color values for the standard 16 color palette are:

Value	Color	Value	Color
0	Black	8	Gray
1	Blue	9	Bright Blue
2	Green	10	Bright Green
3	Cyan	11	Bright Cyan
4	Red	12	Bright Red
5	Magenta	13	Pink
6	Brown	14	Yellow
7	White	15	Bright White

Example

Dim character_ascii_value As Integer Dim attribute As Integer Dim background As Integer Dim cell_color As Integer Dim row As Integer, col As Integer character_ascii_value = Screen( row, col ) attribute = Screen( row, col, 1 ) background = attribute Shr 4 cell_color = attribute And &hf

'' open a graphics screen with 4 bits per pixel '' (alternatively, omit this line to use the console) ScreenRes 320, 200, 4 '' print a character Color 7, 1 Print "A" Dim As UInteger char, col, fg, bg '' get the ASCII value of the character we've just printed char = Screen(1, 1, 0) ''get the color attributes col = Screen(1, 1, 1) fg = col And &HF bg = (col Shr 4) And &HF Print Using "ASCII value: ### (""!"")"; char; Chr(char) Print Using "Foreground color: ##"; fg Print Using "Background color: ##"; bg Sleep

'' open a graphics screen with 8 bits per pixel ScreenRes 320, 200, 8 '' print a character Color 30, 16 Print "Z" Dim As UInteger char, col, fg, bg '' get the ASCII value of the character we've just printed char = Screen(1, 1, 0) ''get the color attributes col = Screen(1, 1, 1) fg = col And &HFF bg = (col Shr 8) And &HFF Print Using "ASCII value: ### (""!"")"; char; Chr(char) Print Using "Foreground color: ###"; fg Print Using "Background color: ###"; bg Sleep

'' open a full-color graphics screen ScreenRes 320, 200, 32 '' print a character Color RGB(255, 255, 0), RGB(0, 0, 255) 'yellow on blue Print "M" Dim As Integer char, fg, bg '' get the ASCII value of the character we've just printed char = Screen(1, 1, 0) ''get the color attributes fg = Screen(1, 1, 1) bg = Screen(1, 1, 2) Print Using "ASCII value: ### (""!"")"; char; Chr(char) Print Using "Foreground color: &"; Hex(fg, 8) Print Using "Background color: &"; Hex(bg, 8) Sleep

Platform Differences

On the Linux version, the value returned can differ from the character shown on the console. For example, unprintable control codes - such as the LF character (10) that implicitly occurs after the end of Printed text - may be picked up instead of the untouched character in its place.

Differences from QB

In QB Screen triggered an error if the coordinates were out of screen.