POINT

The POINT function returns the pixel COLOR attribute at a specified graphics coordinate or the current graphic cursor position.

Color == Syntax ==

color_attribute% = POINT (column%, row%)

Graphic cursor position == Syntax ==

pointer_coordinate% = POINT({0|1|2|3})

Parameters

Graphic Color syntax:

The INTEGER column and row coordinates designate the pixel position color on the screen to read.
The return value is an INTEGER palette attribute value or an _UNSIGNED LONG _RGBA 32 bit value in QB64.

Graphic cursor position syntax:

The INTEGER position number can be 0 to 3 depending on the cursor position desired:
- POINT(0) returns the current graphic cursor SCREEN column pixel coordinate.
- POINT(1) returns the current graphic cursor SCREEN row pixel coordinate.
- POINT(2) returns the current graphic cursor WINDOW column position.
- POINT(3) returns the current graphic cursor WINDOW row position.
If a WINDOW view port has not been established, the coordinate returned will be the SCREEN cursor pixel position.
The return value is the current graphic cursor column or row pixel position on the SCREEN or WINDOW.
Graphic cursor positions returned will be the last ones used in a graphic shape such as a CIRCLE center point.

Usage:

Use _SOURCE first to set the image handle that POINT should read or QB64 will assume the current source image.

_SOURCE 0 'sets POINT to read the current SCREEN image after reading a previous source image

POINT cannot be used in SCREEN 0! Use the SCREEN function to point text character codes and colors in SCREEN 0.

POINT in Qbasic Legacy Graphic SCREEN Modes:

The INTEGER color attributes returned are limited by the number of colors in the legacy SCREEN mode used.
Column and row INTEGER parameters denote the graphic pixel coordinate to read.
In QB64 the offscreen or off image value returned is -1. Use IF POINT(x, y) <> -1 THEN...
In Qbasic the coordinates MUST be on the screen or an Illegal Function Call error will occur.

POINT in QB64 32 Bit Graphic _NEWIMAGE or _LOADIMAGE Modes:

Returns _UNSIGNED LONG 32 bit color values. Use _UNSIGNED values when you don't want negative values.
_UNSIGNED LONG variables should be used when comparing POINT returns with _RGB or _RGB32 _ALPHA bit values
Convert 32 bit color values to RGB intensities(0 to 255) using the _RED32, _GREEN32 and _BLUE32 functions.
To convert color intensities to OUT &H3C9 color port palette intensity values divide the values of 0 to 255 by 4.
Use the _PALETTECOLOR (function) to convert color port palette intensities in 32 bit modes.

Example 1: How _RGB 32 bit values return DOUBLE or _UNSIGNED LONG values in QB64.

DIM clr AS LONG 'DO NOT use LONG in older versions of QB64 (V .936 down) SCREEN _NEWIMAGE(640, 480, 32) CLS , _RGB(255, 255, 255) 'makes the background opaque white PRINT "POINT(100, 100) ="; POINT(100, 100) clr = POINT(100, 100) PRINT "Variable clr = "; clr IF clr = _RGB(255, 255, 255) THEN PRINT "Long OK" IF POINT(100, 100) = _RGB(255, 255, 255) THEN PRINT "_RGB OK" IF POINT(100, 100) = clr THEN PRINT "Type OK" 'will not print with a LONG variable type

Note: Change the DIM clr variable type to LONG to see how the last IF statement doesn't PRINT as shown in the output below:

POINT(100, 100) = 4294967295 Variable clr = -1 Long OK _RGB OK

Example 2: Using a POINT mouse routine to get the 32 bit color values of the QB64 Bee. Download image from top of Forum.

SCREEN _NEWIMAGE(640, 480, 32) _TITLE "Mouse POINTer 32" 'LINE INPUT "Enter an image file: ", image$ 'use quotes around file names with spaces image$ = "QB64bee.png" 'up to 320 X 240 with current _PUTIMAGE settings i& = _LOADIMAGE(image$, 32) IF i& >= -1 THEN BEEP: PRINT "Could NOT load image!": END w& = _WIDTH(i&): h& = _HEIGHT(i&) PRINT "Make background transparent?(Y\N)"; BG$ = UCASE$(INPUT$(1)) PRINT BG$ _DELAY 1 'CLS 'commented to keep background alpha 0 IF BG$ = "Y" THEN _CLEARCOLOR _RGB32(255, 255, 255), i& 'make white Background transparent _PUTIMAGE (320 - w&, 240 - h&)-((2 * w&) + (320 - w&), (2 * h&) + (240 - h&)), i&, 0 _FREEIMAGE i& _MOUSEMOVE 320, 240 'center mouse pointer on screen DO: _LIMIT 100 DO WHILE _MOUSEINPUT mx = _MOUSEX my = _MOUSEY c& = POINT(mx, my) r = _RED32(c&) g = _GREEN32(c&) b = _BLUE32(c&) a = _ALPHA32(c&) LOCATE 1, 1: PRINT mx; my, "R:"; r, "G:"; g, "B:"; b, "A:"; a; " " LOCATE 2, 2: PRINT "HTML Color: &H" + RIGHT$(HEX$(c&), 6) LOOP LOOP UNTIL INKEY$ > "" END

Code by Ted Weissgerber

Explanation: Use the mouse pointer to get the background RGB of the image to make it transparent with _CLEARCOLOR.

Snippet: Creating an image mask to PUT an image over other colored backgrounds. See: GET and PUT Demo to run code.

FOR c = 0 TO 59 '60 X 60 area from 0 pixel FOR r = 0 TO 59 IF POINT(c, r) = 0 THEN PSET (c, r), 15 ELSE PSET (c, r), 0 NEXT r NEXT c GET(0, 0)-(60, 60), Image(1500) ' save mask in an array(indexed above original image).

Explanation: In the procedure all black areas(background) are changed to white for a PUT using AND over other colored objects. The other image colors are changed to black for a PUT of the original image using XOR. The array images can be BSAVEd for later use. QB64 can also PUT a full screen 12 image from an array directly into a BINARY file.

See Examples: