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https://github.com/QB64-Phoenix-Edition/QB64pe.git
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6e01fc8dce
Added new _STRCMP and _STRICMP commands for quick string comparisons. Cleaned up QB64 to finish removing the QUI (quick user insert) code and folders. Altered UCASE and LCASE routines to be faster in some situations for us.
102 lines
4.3 KiB
Plaintext
102 lines
4.3 KiB
Plaintext
The '''SCREEN''' function returns the [[ASCII]] code of a text character or the color attribute at a set text location on the screen.
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{{PageSyntax}}
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:: codeorcolor% = '''SCREEN (''row%'', ''column%''''' [, colorflag%]''')'''
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{{Parameters}}
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* ''row'' and ''column'' are the [[INTEGER]] text coordinates of the [[SCREEN]] mode used.
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* Optional ''colorflag'' [[INTEGER]] value can be zero for [[ASCII]] code values or 1 for colors.
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''Usage:''
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* The ''code'' value returned is the [[ASCII]] code from 0 to 255. Returns 32([[SPACE$|space]]) when no character is found at a coordinate.
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* If the ''colorflag'' value is omitted or it is 0, the function returns the [[ASCII]] code of the text character at the position designated.
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* When the ''flag'' value is greater than 0, the function returns the foreground color attribute of the text character position.
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* '''QB64''' can return color values in screen modes other than [[SCREEN]] 0. Qbasic returned the wrong color values in graphic screen modes!
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''Example 1:'' Reading the [[ASCII]] code and color of a text character using the SCREEN function. Graphic screen colors were not reliable in Qbasic!
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{{CodeStart}} '' ''
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{{Cl|SCREEN (statement)|SCREEN}} 12
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row = 10: column = 10
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{{Cl|COLOR}} 9: {{Cl|LOCATE}} row, column: {{Cl|PRINT}} "Hello"
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code% = {{Cl|SCREEN (function)|SCREEN}}(row, column, 0) ' character code return parameter 0
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attrib% = {{Cl|SCREEN (function)|SCREEN}}(row, column, 1) ' character color return parameter 1
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{{Cl|COLOR}} 14: {{Cl|LOCATE}} 15, 10: {{Cl|PRINT}} "ASCII:"; code%, "COLOR:"; attrib%
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{{Cl|END}} '' ''
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{{CodeEnd}}
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{{OutputStart}}
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{{Text| Hello|blue}}
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{{Text| ASCII: 72 COLOR: 9|yellow}}
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{{OutputEnd}}
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:''Explanation:'' The SCREEN function returns the [[ASCII]] code for "H" and the color 9.
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''Example 2:'' SCREEN 0 will return the values for both foreground and background colors. The combined color attribute value is returned.
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{{CodeStart}} '' ''
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{{Cl|SCREEN}} 0
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row = 10: column = 10
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{{Cl|COLOR}} 9, 10: {{Cl|LOCATE}} row, column: {{Cl|PRINT}} "Hello" 'use the background color of bright green
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code% = {{Cl|SCREEN (function)|SCREEN}}(row, column, 0) ' character code return parameter 0
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attrib% = {{Cl|SCREEN (function)|SCREEN}}(row, column, 1) ' character color return parameter 1
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{{Cl|COLOR}} 14, 0: {{Cl|LOCATE}} 15, 10: {{Cl|PRINT}} "ASCII:"; code%, "{{Cl|COLOR}}:"; attrib%
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fg% = (attrib% {{Cl|AND (boolean)|AND}} {{Cl|&H}}F) 'get the lower nibble
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bg% = (attrib% {{Cl|AND (boolean)|AND}} {{Cl|&H}}F0) / 16 'get the upper nibble
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{{Cl|IF...THEN|IF}} bg% > 7 {{Cl|THEN}} 'MSB set in the bg% nibble indicates blinking fg%
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fg% = fg% + 16
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bg% = bg% - 8
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{{Cl|END IF}}
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{{Cl|LOCATE}} 20, 10:{{Cl|PRINT}} "FG:"; fg%, "BG:"; bg% '' ''
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{{CodeEnd}}{{small|Contributed by RhoSigma}}
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{{OutputStart}}
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{{Text| Hello|blue}}
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{{Text| ASCII: 72 COLOR: 41|yellow}}
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{{text| FG: 9 BG: 2|yellow}}
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{{OutputEnd}}
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:''Note:'' SCREEN 0 background colors are limited to colors 0 to 7 so [[COLOR]] 10 is converted to attribute 2 (8 less than the high intensity background color value of 10).
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''Example 3:'' Finding the current program path placed on the screen using [[FILES]] and the SCREEN function in SCREEN 0.
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{{CodeStart}} '' ''
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{{Cl|SCREEN}} 0, 0, 0, 0
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{{Cl|CLS}}
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{{Cl|PRINT}} "This is a directory test..."
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{{Cl|SCREEN}} 0, 0, 1, 0
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{{Cl|COLOR}} 0 'blank out the screen text
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{{Cl|FILES}} "qb64.exe" 'the current program's filename can also be used
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{{Cl|FOR...NEXT|FOR}} i = 1 {{Cl|TO}} 80
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a$ = a$ + {{Cl|CHR$}}({{Cl|SCREEN (function)|SCREEN}}(1, i)) 'scan the black text on the screen
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{{Cl|NEXT}}
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{{Cl|CLS}}
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{{Cl|COLOR}} 7
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a$ = {{Cl|RTRIM$}}(a$)
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{{Cl|SLEEP}}
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{{Cl|SCREEN (statement)|SCREEN}} 0, 0, 0, 0
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{{Cl|LOCATE}} 3, 1: {{Cl|PRINT}} "The current directory is: "; a$
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{{Cl|END}} '' ''
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{{CodeEnd}}
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{{small|Code by Pete from the N54 QB site}}
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:''Explanation:'' The SCREEN page one is used to hide the [[FILES]] display using COLOR 0. The [[SCREEN (function)|SCREEN]] function reads the top of the screen page text and creates the current path string. It is then printed on the visual page.
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''See also:''
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* [[PRINT]], [[SCREEN]]
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* [[COLOR]], [[CHR$]], [[POINT]]
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* [[CSRLIN]], [[POS]], [[ASCII]]
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* [[Screen Memory]]
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{{PageNavigation}} |