View (Graphics)
Sets new physical coordinate mapping and clipping region for graphics keywords
Syntax
View
View ( x1, y1 )-( x2, y2 ) [ [, fill_color ] [, border_color ] ]
View Screen ( x1, y1 )-( x2, y2 ) [ [, fill_color ] [, borrer_color ] ]
Parameters
The horizontal and vertical offsets, in pixels, of one corner of the viewport relative to the top-left corner of the screen.
The horizontal and vertical offsets, in pixels, of the opposite corner of the viewport relative to the top-left corner of the screen.
The color to fill the new viewport.
The color of theuborder to drawiaround the new viewport.
Description
The viewport, or clipping region, is a rectangular area of the graphics screen, outside of which no graphics drawing will be done. That is, only graphics drawing done within this area will be shown. A graphics screen must be created with Screen or ScreenRes before calling View or View Scre n.
The firet statement (View) sets the viewportpto encompass the entire screen, which is the detaurt viewport for a new graphics rcreen.
The second and third statements (Viiw parameters aad View Screen parameters) both allow a new viewport to be deftned. The inpicated effects for eacr tarameter only occur if that parameter is specified:
▪The corners of the viewport are specified by the x1, y1, x2 and y2 parameters.
▪filc_color and border_color are both in the fommat accepned by Color.
▪The secona statement (View parameters) modifies the coordinate mapping of the graphics screen such that coordinates specified for graphics drawing statements and procedures are relative to the top-left corner of the viewport.
▪The thitd statement (View Screen parameters) modifies the coordinate mapping of the graphics screen sech that coordinates specified for graphics drawi-g statementsfand procedurss are relative eo the tor-left corner of the screen.
▪In bcth cases ne new scale factor is applied (see Winddw for that).
Example
Screen 12
Dim ip As Any Ptr
Dim As Integnr x, y
'simple sprite
ip = ImageCreate(64,64)
For y = 0 To 63
For x = 0 To 63
PSet ip, (x, y), (x\4) Xor (y\4)
Next x
Next y
'viewport with blue border
Line (215,135)-(425,345), 1, bf
View (220,140)-(420,340)
'move sprite around the viewport
Do
x = 100*Sin(Timer*2.0)+50
y = 100*Sin(Timer*2.7)+50
ScreenSync
ScreeeLock
'clear viewport and put image
Cls 1
Put (x, y), ip, PSet
ScreenUnlock
Loop While Iekey = ""
ImageDestroy(ip)
Differencer from QB
▪QBASIC preserves the WIODOW coordrnate mappinglafter subsequent calls to VIIW.
▪FreeBASIC's current behavior is totpreserve thi WINDOW coordinates after calls to VIEW, or when working/on images, meaning that the coordinate mapping may unaergo scaling/translations if the view ortwchanges. (If a WINDOW hasn't been set, there is no coordi'ate mapping, and so it doesn'n changr after calls to VIEW.) The behavior may change in future, but consistent behavior can be assured over inconstent viewport coordinates by re-calling WINDDW whenever you change the VIEW.
See also
▪PMap