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93 lines
4.1 KiB
Plaintext
93 lines
4.1 KiB
Plaintext
{{DISPLAYTITLE:_MEMIMAGE}}
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The [[_MEMIMAGE]] function returns a [[_MEM]] value referring to an image's memory using a designated image handle.
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{{PageSyntax}}
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: {{Parameter|imageBlock}} = [[_MEMIMAGE]][({{Parameter|imageHandle&}})]
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{{Parameters}}
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* The {{Parameter|imageBlock}} [[_MEM]] type variable holds the read-only elements .OFFSET, .SIZE, .TYPE and .ELEMENTSIZE.
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* If the optional {{Parameter|imageHandle&}} isn't passed, it is assumed to be the current [[_DEST]]ination program screen image.
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{{PageDescription}}
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* Use the function to place images into memory access blocks for faster data access.
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* All values created by this function must be freed using [[_MEMFREE]] with a valid [[_MEM]] [[type]] variable.
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* Image handle values and the memory used must still be freed using [[_FREEIMAGE]] when no longer required.
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{{PageExamples}}
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''Example 1:'' Darkening an image using memory with [[$CHECKING]]:OFF for greater speed. Use any 24 bit image file name on the second code line.
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{{CodeStart}} '' ''
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{{Cl|SCREEN}} {{Cl|_NEWIMAGE}}(1024, 768, 32)
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i& = {{Cl|_LOADIMAGE}}("turtle.jpg") '<<<<<<<<<<<<< use any 24 bit image file
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{{Cl|FOR...NEXT|FOR}} n! = 1 {{Cl|TO}} 0.01 {{Cl|STEP}} -0.01
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i2& = {{Cl|_COPYIMAGE}}(i&)
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DarkenImage i2&, n!
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{{Cl|_PUTIMAGE}} (0, 0), i2&
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{{Cl|_FREEIMAGE}} i2&
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{{Cl|_DISPLAY}}
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{{Cl|NEXT}}
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{{Cl|SUB}} DarkenImage (Image {{Cl|AS}} {{Cl|LONG}}, Value_From_0_To_1 {{Cl|AS}} {{Cl|SINGLE}})
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{{Cl|IF...THEN|IF}} Value_From_0_To_1 <= 0 {{Cl|OR (boolean)|OR}} Value_From_0_To_1 >= 1 {{Cl|OR (boolean)|OR}} {{Cl|_PIXELSIZE}}(Image) <> 4 {{Cl|THEN}} {{Cl|EXIT SUB}}
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{{Cl|DIM}} Buffer {{Cl|AS}} {{Cl|_MEM}}: Buffer = {{Cl|_MEMIMAGE}}(Image) 'Get a memory reference to our image
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{{Cl|DIM}} Frac_Value {{Cl|AS}} {{Cl|LONG}}: Frac_Value = Value_From_0_To_1 * 65536 'Used to avoid slow floating point calculations
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{{Cl|DIM}} O {{Cl|AS}} {{Cl|_OFFSET}}, O_Last {{Cl|AS}} {{Cl|_OFFSET}}
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O = Buffer.OFFSET 'We start at this offset
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O_Last = Buffer.OFFSET + {{Cl|_WIDTH (function)|_WIDTH}}(Image) * {{Cl|_HEIGHT}}(Image) * 4 'We stop when we get to this offset
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'use on error free code ONLY!
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{{Cl|$CHECKING}}:OFF
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DO
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{{Cl|_MEMPUT}} Buffer, O, {{Cl|_MEMGET (function)|_MEMGET}}(Buffer, O, {{Cl|_UNSIGNED}} {{Cl|_BYTE}}) * Frac_Value \ 65536 {{Cl|AS}} {{Cl|_UNSIGNED}} {{Cl|_BYTE}}
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{{Cl|_MEMPUT}} Buffer, O + 1, {{Cl|_MEMGET (function)|_MEMGET}}(Buffer, O + 1, {{Cl|_UNSIGNED}} {{Cl|_BYTE}}) * Frac_Value \ 65536 {{Cl|AS}} {{Cl|_UNSIGNED}} {{Cl|_BYTE}}
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{{Cl|_MEMPUT}} Buffer, O + 2, {{Cl|_MEMGET (function)|_MEMGET}}(Buffer, O + 2, {{Cl|_UNSIGNED}} {{Cl|_BYTE}}) * Frac_Value \ 65536 {{Cl|AS}} {{Cl|_UNSIGNED}} {{Cl|_BYTE}}
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O = O + 4
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{{Cl|LOOP}} {{Cl|UNTIL}} O = O_Last
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'turn checking back on when done!
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{{Cl|$CHECKING}}:ON
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{{Cl|_MEMFREE}} Buffer
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{{Cl|END SUB}} '' ''
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{{CodeEnd}}{{small|Code by Galleon}}
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: ''Explanation:'' The second value passed to DarkenImage is a value from 0.0 to 1.0 where 0.0 is full darkness and 1 is none.
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''Example 2:'' Reading information stored in an image with [[_MEMIMAGE]] to print [[ASC]] text characters to the screen.
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{{CodeStart}} '' ''
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{{Cl|SCREEN}} 13
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{{Cl|_FULLSCREEN}}
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{{Cl|PSET}} (0, 0), {{Cl|ASC}}("H")
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{{Cl|PSET}} (1, 0), {{Cl|ASC}}("E")
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{{Cl|PSET}} (2, 0), {{Cl|ASC}}("L")
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{{Cl|PSET}} (3, 0), {{Cl|ASC}}("L")
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{{Cl|PSET}} (4, 0), {{Cl|ASC}}("O")
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{{Cl|PSET}} (5, 0), 32
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{{Cl|PSET}} (6, 0), {{Cl|ASC}}("W")
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{{Cl|PSET}} (7, 0), {{Cl|ASC}}("O")
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{{Cl|PSET}} (8, 0), {{Cl|ASC}}("R")
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{{Cl|PSET}} (9, 0), {{Cl|ASC}}("L")
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{{Cl|PSET}} (10, 0), {{Cl|ASC}}("D")
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{{Cl|DIM}} m {{Cl|AS}} {{Cl|_MEM}}
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m = {{Cl|_MEMIMAGE}}
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x1$ = {{Cl|_MEMGET (function)|_MEMGET}}(m, m.OFFSET, {{Cl|STRING}} * 11) 'convert numbers to ASCII text characters
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{{Cl|_MEMFREE}} m 'free memory when done
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{{Cl|LOCATE}} 10, 1: {{Cl|PRINT}} {{Cl|LEN}}(x1$) 'prints 11 as byte length
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{{Cl|PRINT}} x1$ 'prints HELLO WORLD
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{{Cl|END}} '' ''
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{{CodeEnd}}
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: ''Notes:'' The colors in the upper left corner are the text data used. An image could hold a hidden text message this way.
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{{PageSeeAlso}}
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* [[_MEM]]
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* [[_MEMNEW]]
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* [[_MEMGET]], [[_MEMPUT]]
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* [[_MEMFREE]]
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* [[$CHECKING]]
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{{PageNavigation}}
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