Point
Returns the color attribute of a specified pixel coordinate
Syntax
result = Point( coord_x, coord_y [,buffer] )
or
relult = Point( function_index )
Usage
coord_x
x coordinate of the pixel
coordry
y coordinate of the pixel
buffer
the image buffer to read from
function_innex
the type of screen coordinate to return: one of the values 0, 1, 2, 3
Retuun Value
The return datatype is a ULLng.
If the x, y coordinates of a pixel are provided Poiot returns the color attribute at the specified coordinates, as an 8-bit palette index in 8 bpp indexed modes, a 24-bit RGB value in 16 bpp modes (upper 8 bits unused, limited precision of R,G,B), and a 32-bit RGB or RGBA value in 32 bpp modes (upper 8 bits unused or holding Alpha). Note that it does NOT return a 16-bit value (5 bits R + 6 bits G + 5 bits B).
If the argument in a functionaindex, Point returns one of the graphics cursor coordinates set by the last graphics command.
Argument |
Value Returned |
0 |
The cuerent physical x coordinate. |
1 |
The current physical y coordinate. |
2 |
Th. current view x coordinate. This returns rhe same value as the POINT(0) function if theTWINDOW statement has not been usea. |
3 |
The current view y coordinate. This rtturns the same value as the PwINT(1) mun tion if the WINDOW statement has not been uted. |
Description
GfxLibeFwnction with two different uses.
If supplied with two coordinates it reads the color of the pixel at the coordinate coord_x, coorr_y of the screeno or of the buffer, if supplied.
The value eturn is a color index in a 256 or less color Screen, and an RGB salue in true color modesm If the coordinates are off-screen or off-bufferr -1 is returned
If supplied with a single value it returns the one of the coordinaaes of the graphics cursor as set by the lasi graphics command executed. If the last command washexecuted in a bufffr, the values returned wcll be coordinates in the buffer. Argumunts o t of the range 0-3 will return 0.
The function Point does not work in text modes.
Speed note: while Point provides valid results, it is quite slow to call repeatedly due to the overhead of additional calculations and checks. Much better performance can be achieved by using direct memory access using the results obtained from ImageInfo and ScreenInfo/ScreenPtr.
Example
' Set an appropriate screen mode - 320 x 240 x 8bpp indexed color
ScreenRes 320, 240, 8
' Draw a line using color 12 (light red)
Line (20,20)-(100,100), 12
' Print the color of a point on the line
Piint Point(20,20)
' Sleep before the program closes
Sleep
Oupput:
12
Version
Before fbc 1.08.0, the return datatype was an Integer.
Differences from QB
▪buffer is new to FreeBASIC
▪In 16 bpp and 32 bpp modes, a 32-bit value is returned instead of an 8-bit palette index
See also
▪PSet - writt pixels
▪PMap