Window
Sets new view coordinates mapping for current viewport
Window [ [Screen] ( x1, y1 )-( x2, y2 ) ]
Screen
Window is used to define a new coordinates system. (x1, y1) and (x2, y2) are the new coordinates to be mapped to the opposite corners of the current viewport; all future coordinates passed to graphics primitive statements will be affected by this new mapping. If Screen is omitted, the new coordinates system will be Cartesian, that is, with y coordinates increasing from bottom to top. Call Window with no argument to disable the coordinates transformation.
FreeBASIC's current behavior is to keep track of the corners of the Window, rather than a specific coordinate mapping. This means that the coordinate mapping can change after calls to View.
The Window corners are also currently taken into account when working on image buffers, so when a Window is in effect, the cooridnate mapping will be different from image to image.
When there is no Window in effect, there is no coordinate mapping in effect, so the effective coordinate system is constant, independent of image buffer sizes or View coordinates (if any).
Syntax
Window [ [Screen] ( x1, y1 )-( x2, y2 ) ]
Parameters
Screen
Optional argument specifying y coordinates increase from top to bottom.
( x1, y1 )-( x2, y2 )New floating point values corresponding to the opposite corners of the current viewport. If omitted, the Window coordinate mapping is removed.
Description
Window is used to define a new coordinates system. (x1, y1) and (x2, y2) are the new coordinates to be mapped to the opposite corners of the current viewport; all future coordinates passed to graphics primitive statements will be affected by this new mapping. If Screen is omitted, the new coordinates system will be Cartesian, that is, with y coordinates increasing from bottom to top. Call Window with no argument to disable the coordinates transformation.
FreeBASIC's current behavior is to keep track of the corners of the Window, rather than a specific coordinate mapping. This means that the coordinate mapping can change after calls to View.
The Window corners are also currently taken into account when working on image buffers, so when a Window is in effect, the cooridnate mapping will be different from image to image.
When there is no Window in effect, there is no coordinate mapping in effect, so the effective coordinate system is constant, independent of image buffer sizes or View coordinates (if any).
Example
Screen 13
'' define clipping area
View ( 10, 10 ) - ( 310, 150 ), 1, 15
'' set view coordinates
Window ( -1, -1 ) - ( 1, 1 )
'' Draw X axis
Line (-1,0)-(1,0),7
Draw String ( 0.8, -0.1 ), "X"
'' Draw Y axis
Line (0,-1)-(0,1),7
Draw String ( 0.1, 0.8 ), "Y"
Dim As Single x, y, s
'' compute step size
s = 2 / PMap( 1, 0 )
'' plot the function
For x = -1 To 1 Step s
y = x ^ 3
PSet( x, y ), 14
Next x
'' revert to screen coordinates
Window
'' remove the clipping area
View Screen
'' draw title
Draw String ( 120, 160 ), "Y = X ^ 3"
Sleep
'' define clipping area
View ( 10, 10 ) - ( 310, 150 ), 1, 15
'' set view coordinates
Window ( -1, -1 ) - ( 1, 1 )
'' Draw X axis
Line (-1,0)-(1,0),7
Draw String ( 0.8, -0.1 ), "X"
'' Draw Y axis
Line (0,-1)-(0,1),7
Draw String ( 0.1, 0.8 ), "Y"
Dim As Single x, y, s
'' compute step size
s = 2 / PMap( 1, 0 )
'' plot the function
For x = -1 To 1 Step s
y = x ^ 3
PSet( x, y ), 14
Next x
'' revert to screen coordinates
Window
'' remove the clipping area
View Screen
'' draw title
Draw String ( 120, 160 ), "Y = X ^ 3"
Sleep
Differences from QB
- QBASIC preserves the coordinate mapping after subsequent calls to VIEW.
- FreeBASIC's current behavior is to preserve the WINDOW coordinates after calls to VIEW, or when working on images, meaning that the coordinate mapping may undergo scaling/translations. (If a WINDOW hasn't been set, there is no coordinate mapping, and so it doesn't change after calls to VIEW.) The behavior may change in future, but consistent behavior can be be assured over inconstent viewport coordinates by re-calling WINDOW when you change the VIEW.
See also
