1. bitmap cropping (was: )
At 17:56 9/03/98 +1300, you wrote:
>How do I clip an image that has been loaded by read_bitmap()?
>I am trying to fit a large picture into a 533x370 area.
>I have the following section to clip the width that doesn't work.
>It does run all of the lines, and length(tmp_img) is 800
>
>if length(tmp_img) > 533 then
> tmp_img1=tmp_img[1..533]
> tmp_img=tmp_img1
>end if
> display_image({11,49},tmp_img1)
>
You're on the right track, however you're trying to access the
birmap as if it were one dimensional (as against two).
"tmp_img[1..533]" refers to the first 533 elements of the
sequence, which in this case is the first 533 horizontal lines.
You want the first 533 pixels on each of the first 370 lines.
try this:
function crop(sequence bitmap,sequence dim)
sequence temp
temp=repeat(repeat(0,dim[1]),dim[2])
if dim[1]>length(bitmap[1]) then dim[1]=length(bitmap[1]) end if
for x=1 to length(bitmap) do -- Number of horizontal lines
if x>dim[2] then exit end if
temp[x]=bitmap[x][1..dim[1]] -- first n pixels of line x
end for
return temp
end function
tmp_img1=crop(tmp_img,{533,370})
This function should return a bitmap of the specified size regardless of the
size of the bitmap passed to it. In the case of a smaller bitmap than the
requested size, a black border will be inserted.
The "If dim[1]>length(bitmap[1])" line is there in case a narrower bitmap
than the target width is passed. It lowers the target width 'dim[1]' to
the width of the bitmap ('length(bitmap[1])' being the length of the top line
of the bitmap) *after* generating the blank target sequence (temp=repeat...).
WARNING - Untested code - I just typed it into Eudora (should work though)
Hope this helps.
Graeme.
