GrabImage

GrabImage image,x,y,[frame]

Parameters:

image = variable of image handle
x = starting x location to grab
y = starting y location to grab
frame = optional frame to insert the grabbed image into

Description:

Quite possibly one of the most useful yet underdocumented, confusing commands in the Blitz Basic language is GrabImage.

This command allows you to grab a portion of the current drawing buffer (this could be an image too if you've set it as an ImageBuffer) and stick it into an image.

There are a million and one uses for this command, so I'll let you use your imagination. However, the command doesn't make much sense as it is documented, so let me clarify.

First, you must use CreateImage to create a new blank image in which to grab to. Whatever size you create the image, THAT is how much of the buffer will be grabbed from the x,y location you specify in GrabImage.

For example, you create a new image with a size of 50 pixels by 50 pixels. When you call GrabImage, you choose x=100, y=100. The area you will grab and put into your new image will be 100,100 to 150,150. If you attempt to GrabImage into an image variable that hasn't been created yet, you will get an error.

Note: You can REPLACE an existing image with a grabbed one.

See the example for a more practical look.

Example:

; GrabImage example

; Turn on graphics
Graphics 640,480,16

; We'll be drawing right to the front buffer
SetBuffer FrontBuffer()

; You must create an empty image to grab from first
gfxGrab=CreateImage(100,100)

; Draw random rectangles on the screen until the
; user presses ESC
While Not KeyHit(1)
; random color
Color Rnd(255),Rnd(255),Rnd(255)
; super random rectangles
Rect Rnd(640),Rnd(480),Rnd(100),Rnd(100),Rnd(1)
Delay 50
Wend

; Now, grab an image, starting at 100,100 and put it in gfxGrab
GrabImage gfxGrab,100,100

; Clear screen and show user the grabbed image
Cls
Text 0,0, "Here is your grabbed image! Press a mouse key ..."
DrawImage gfxgrab,50,50

; Wait for a mouse press
WaitMouse()

Comments

julianbury

(Posted 1+ years ago)

Thank you for that :-)
Gonna try it now

Ross C

(Posted 1+ years ago)

Isn't CopyRect a LOT faster?

Charrua

(Posted 1+ years ago)

I tested that last month and in my computer copyrect were 10 or more times faster than grabimage even with small rectangles. I wasn't shure if that was only for me or in general.

Ross C

(Posted 1+ years ago)

Seems to be the most redundant command in blitz :o)

mv333

(Posted 1+ years ago)

So, what's the difference between this and CopyRect?

Matty

(Posted 1+ years ago)

Copyrect let's you specify more information - you can transfer between any set of buffers, whlie grabimage simply grabs from the current drawing buffer and puts it into the image specified.

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