Point
Returns the color attribute of a specified pixel coordinate
result = Point( coord_x, coord_y [,buffer] )
or
result = Point( function_index )
coord_x
If the x, y coordinates of a pixel are provided Point 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 of the integer 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 is a function index, Point returns one of the graphics cursor coordinates set by the last graphics command.
GfxLib Function with two different uses.
If supplied with two coordinates it reads the color of the pixel at the coordinate coord_x, coord_y of the screen, or of the buffer, if supplied.
The value return is a color index in a 256 or less color Screen, and an RGB value in true color modes. If the coordinates are off-screen or off-buffer, -1 is returned
If supplied with a single value it returns the one of the coordinates of the graphics cursor as set by the last graphics command executed. If the last command was executed in a buffer, the values returned will be coordinates in the buffer. Arguments out 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.
Output:
Syntax
result = Point( coord_x, coord_y [,buffer] )
or
result = Point( function_index )
Usage
coord_x
x coordinate of the pixel
coord_yy coordinate of the pixel
bufferthe image buffer to read from
function_indexthe type of screen coordinate to return: one of the values 0, 1, 2, 3
Return Value
If the x, y coordinates of a pixel are provided Point 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 of the integer 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 is a function index, Point returns one of the graphics cursor coordinates set by the last graphics command.
| Argument | Value Returned |
| 0 | The current physical x coordinate. |
| 1 | The current physical y coordinate. |
| 2 | The current view x coordinate. This returns the same value as the POINT(0) function if the WINDOW statement has not been used. |
| 3 | The current view y coordinate. This returns the same value as the POINT(1) function if the WINDOW statement has not been used. |
Description
GfxLib Function with two different uses.
If supplied with two coordinates it reads the color of the pixel at the coordinate coord_x, coord_y of the screen, or of the buffer, if supplied.
The value return is a color index in a 256 or less color Screen, and an RGB value in true color modes. If the coordinates are off-screen or off-buffer, -1 is returned
If supplied with a single value it returns the one of the coordinates of the graphics cursor as set by the last graphics command executed. If the last command was executed in a buffer, the values returned will be coordinates in the buffer. Arguments out 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
Print Point(20,20)
' Sleep before the program closes
Sleep
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
Print Point(20,20)
' Sleep before the program closes
Sleep
Output:
12
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