qb64/internal/help/GET_(graphics_statement).txt

The {{KW|GET (graphics statement)|GET}} statement is used in graphics to store a box area image of the screen into an {{KW|INTEGER}} array.


{{PageSyntax}} 
::: '''GET''' [STEP] '''(''column1'', ''row1'')-'''[STEP]'''(''column2'', ''row2''),''' ''Array''([''index''])[, ''offscreen_color'']


''[[Parameters]]:'' 
* ''Column'' and ''row'' [[INTEGER]] coordinates for the box area must be on the screen except when using an ''offscreen color''.
* [[INTEGER]] Array sizes must be large enough (use width * height of the box area + 4) to hold the data or an error will occur!
* The [[arrays|array]] ''index'' offset is optional. If the offset is zero the brackets may be empty (Qbasic does not require the brackets).
* The ''off screen color'' pixels will be returned as the designated color when part of an image is off screen in QB64 only.


''Usage:''
* The [[STEP]] keyword can be used to for coordinates relative to the last graphic coordinates used.
* A graphic screen mode MUST be used! See the [[SCREEN]] statement for graphic screen dimensions.
* '''QB64''' GET statements can use coordinates off of the screen when an ''off screen color'' is designated. [[STEP]] can be used for relative coordinates.
* The GET box coordinates are set just like a {{KW|LINE}} box statement is placed. You can use a box to find the correct GET area.
* Once GET has placed the pixel image data in the array, PUT the image or BSAVE it to a file.
* Once the image is stored in an array {{KW|PUT (graphics statement)|PUT}} can be used to place the image on the screen.
* SCREEN 12 can only GET 1/3 of a full SCREEN 12 image (QB64 can save entire screen). Rows would increment 160 each GET. 
* A [[_SOURCE]] [[handle]] can be set to GET image areas other than the ones on the current screen. Use [[_DEST]] to [[PUT (graphics statement)|PUT]] images there.
* To GET more than one image to the same array, designate an offset index that is not being used and is large enough to hold the data.
* The [[INTEGER]] array size can be calculated as slightly larger than the box area width times the height. A closer estimate can be done by reading the array indices from [[UBOUND]] to [[LBOUND]] after a [[GET (graphics statement)|GET]] of a white box area. In QB64 a [[LONG]] array can be used for large or full screen images.
* RGB color settings can be embedded at the beginning of the array for transferring custom colors. ''Index'' the GET image data after the settings.
* In QB64 [[_PUTIMAGE]] is recommended over PUT as it can also do the [[GET (graphics statement)|GET]] directly from the image source without requiring an array.
* [[PUT]] and [[GET]] file statements can also write and read image array data using [[BINARY]] files instead of using [[BSAVE]] or [[BLOAD]].


''Example 1:'' How to use GET and PUT to move a sprite with the arrow keys.
{{CodeStart}} '' ''
 {{Cl|DEFINT}} A-Z
 {{Cl|DIM}} BG(300), Box(300), SC(127) ' BG holds background images. Box holds the Box image.
 {{Cl|SCREEN (statement)|SCREEN}} 13 ' graphic coordinate minimums are 0 to 319 column or 199 row maximums.
            ' set up screen background
  {{Cl|COLOR}} 4: {{Cl|LOCATE}} 10, 5: {{Cl|PRINT}} "Multikey Keyboard input routine"
  {{Cl|COLOR}} 10: {{Cl|LOCATE}} 12, 4: {{Cl|PRINT}} "Use the arrow keys to move the box."
  {{Cl|LOCATE}} 13, 4: {{Cl|PRINT}} "Note that you can press two or more"
  {{Cl|LOCATE}} 14, 4: {{Cl|PRINT}} "keys at once for diagonal movement!"
  {{Cl|COLOR}} 14: {{Cl|LOCATE}} 16, 4: {{Cl|PRINT}} " Also demonstrates how {{Cl|GET (graphics statement)|GET}} and PUT "
  {{Cl|LOCATE}} 17, 4: {{Cl|PRINT}} "are used to preserve the background."
  {{Cl|COLOR}} 11: {{Cl|LOCATE}} 20, 11: {{Cl|PRINT}} "Press [Esc] to quit"
  x = 150: y = 50: PX = x: PY = y ' actual box starting position

 {{Cl|GET (graphics statement)|GET}} (x, y)-(x + 15, y + 15), BG  ' {{Cl|GET (graphics statement)|GET}} original BG at start box position
 {{Cl|LINE}} (x, y)-(x + 15, y + 15), 9, BF ' the plain blue box to move
 {{Cl|GET (graphics statement)|GET}} (x, y)-(x + 15, y + 15), Box   ' {{Cl|GET (graphics statement)|GET}} to Box Array
 
 {{Cl|DO...LOOP|DO}}  'main loop
  t! = {{Cl|TIMER}} + .05
  {{Cl|DO...LOOP|DO}}         ' 1 Tick (1/18th second) keypress scancode read loop
    a$ = {{Cl|INKEY$}} ' So the keyboard buffer won't get full
    code% = {{Cl|INP}}({{Cl|&H}}60) ' Get keyboard scan code from port 96
    {{Cl|IF...THEN|IF}} code% < 128 {{Cl|THEN}} SC(code%) = 1 {{Cl|ELSE}} SC(code% - 128) = 0 'true/false values to array
  {{Cl|LOOP}} {{Cl|UNTIL}}  {{Cl|TIMER}} > t!' loop until one tick has passed

  PX = x: PY = y  ' previous coordinates
  {{Cl|IF...THEN|IF}} SC(75) = 1 {{Cl|THEN}} x = x - 5: {{Cl|IF...THEN|IF}} x < 0 {{Cl|THEN}} x = 0
  {{Cl|IF...THEN|IF}} SC(77) = 1 {{Cl|THEN}} x = x + 5: {{Cl|IF...THEN|IF}} x > 304 {{Cl|THEN}} x = 304
  {{Cl|IF...THEN|IF}} SC(72) = 1 {{Cl|THEN}} y = y - 5: {{Cl|IF...THEN|IF}} y < 0 {{Cl|THEN}} y = 0
  {{Cl|IF...THEN|IF}} SC(80) = 1 {{Cl|THEN}} y = y + 5: {{Cl|IF...THEN|IF}} y > 184 {{Cl|THEN}} y = 184
  {{Cl|IF...THEN|IF}} x <> PX {{Cl|OR (boolean)|OR}} y <> PY {{Cl|THEN}}             ' look for a changed coordinate value
    {{Cl|WAIT}} 936, 8: {{Cl|PUT (graphics statement)|PUT}}(PX, PY), BG, {{Cl|PSET}}  ' replace previous BG first
    {{Cl|GET (graphics statement)|GET}} (x, y)-(x + 15, y + 15), BG      ' {{Cl|GET (graphics statement)|GET}} BG at new position before box is set
    {{Cl|PUT (graphics statement)|PUT}}(x, y), Box, {{Cl|PSET}}                ' PUT box image at new position
  {{Cl|END IF}}
{{Cl|LOOP}} {{Cl|UNTIL}} SC(1) = 1 ' main loop until [Esc] key (scan code 1) is pressed '' ''
{{CodeEnd}}


''Example 2:'' How to GET graphics from an image other than the present screen using [[_SOURCE]] and [[_DEST]]ination.

{{CodeStart}} '' ''
{{Cl|DIM}} img(20 * 20 + 4) {{Cl|AS}} {{Cl|INTEGER}}  'create img% array to hold 20 by 20 image data 
a& = {{Cl|_NEWIMAGE}}(800, 600, 13)     'larger surface a& emulates screen 13 colors & resolution

{{Cl|SCREEN (statement)|SCREEN}} 13     'program screen 13

{{Cl|_DEST}} a&                         'set desination as the image page a&
{{Cl|CIRCLE}} (700, 300), 10, 10        'draw green circle on image page

{{Cl|_SOURCE}} a&                       'set source as image page a&
{{Cl|GET}} (690, 290)-(710, 310), img() 'GET a square screen area similar to a LINE Box.


{{Cl|_DEST}} 0                          'set destination as the program screen
{{Cl|PUT}} (100, 100), img()            'PUT the Top Left Corner of box area to pixel 100, 100
{{CodeEnd}}
: ''Notes:'' A [[_LOADIMAGE]] handle could also be used as a [[_SOURCE|source]] to GET a portion or all of an image file.


{{PageSeeAlso}}
* [[_PUTIMAGE]], [[_LOADIMAGE]]
* [[_MAPTRIANGLE]]
* [[PUT (graphics statement)|PUT]], [[STEP]] 
* [[BSAVE]], [[BLOAD]]
* [[Scancodes]], [[Creating Sprite Masks]] {{text|(for non-box shaped sprites)}}
* [[Bitmaps]], [[GET and PUT Demo]]


{{PageNavigation}}