View (Graphics)keyword

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 ] [, border_color ] ]

Parameters

Name		Description
`x1`		`As Integer`,
`y1`		`As Integer` The horizontal and vertical offsets, in pixels, of one corner of the viewport relative to the top-left corner of the screen.
`x2`		`As Integer`,
`y2`		`As Integer` The horizontal and vertical offsets, in pixels, of the opposite corner of the viewport relative to the top-left corner of the screen.
`fill_color`		`As ULong` The color to fill the new viewport.
`border_color`		`As ULong` The color of the border to draw around 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 (Graphics) or ScreenRes before calling View or View Screen.

The first statement (View) sets the viewport to encompass the entire screen, which is the default viewport for a new graphics screen.

The second and third statements (View parameters and View Screen parameters) both allow a new viewport to be defined. The indicated effects for each parameter only occur if that parameter is specified:

The corners of the viewport are specified by the x1, y1, x2 and y2 parameters.
fill_color and border_color are both in the format accepted by Color.
The second 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 third statement (View Screen 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 screen.
In both cases no new scale factor is applied (see Window for that).

Remarks

Differences from QB

QBASIC preserves the WINDOW 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 the viewport changes. (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 assured over inconstent viewport coordinates by re-calling WINDOW whenever you change the VIEW.

Example

Screen 12

Dim ip As Any Ptr

Dim As Integer 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

  ScreenLock

  

  'clear viewport and put image

  Cls 1

  Put (x, y), ip, PSet

    

  ScreenUnlock



Loop While Inkey = ""



ImageDestroy(ip)

Reference

Documented in KeyPgViewgraphics.html