how to create low resolution Jpeg file

[Ken Tjia]

The article below is from Alpha Help sample.
it is referring to reducing bitmap resolution (version 8?)

i am wandering if such function is now available to reduce a high resolution jpeg photo/picture file.

Appreciate your guidance,
thanks
Ken Tjia

Creating a Low Resolution Viewfile

When you create an image database, you may want to have a low resolution viewfile to represent a higher resolution image. Typically, the viewfile would be used when you want to quickly put an image on the screen, without moving megabytes of data.

The following script illustrates a technique for creating a low resolution viewfile on the fly. Presumably, you would save the viewfiles you create along side their higher resolution partners. This script was attached to the OnFetch() event of a form with an image control named bitmap1. and a text field named Fname.

dim imag as B

dim pth as C

dim fptr as P

pth = a5.get_path()+ chr(92)


Test whether we have a filename for the picture in the control Fname. If yes, then read the picture into a blob variable named imag. Next, load imag into a memory buffer named hres with UI_BITMAP_LOAD().

if (alltrim(Fname.text) <> "") then

imag = file.to_blob(Fname.text)

ui_bitmap_load("hres", imag)


Create a new memory buffer named lres with UI_BITMAP_CREATE(), then fill it with a stretched version of hres.

ui_bitmap_create("lres", 4, 3)

ui_bitmap_draw("lres", <<%code%

bitmap("hres", 0, 0, 4, 3, "stretch")

%code%)


Move the memory buffer named lres into the imag variable with UI_BITMAP_SAVE() and save it to disk with <FILE>.WRITEB() . Remove the lres and hres buffers from memory.

imag = ui_bitmap_save("lres")

fptr = file.create(pth + "lres.bmp", FILE_RW_EXCLUSIVE)

fptr.writeb(imag)

fptr.close()

ui_bitmap_drop("lres")

ui_bitmap_drop("hres")


Display the low resolution image on the form. If there was no high resolution image to display, display white.bmp.

bitmap1.bitmap.filename = pth + "lres.bmp"

bitmap1.Refresh()

else

bitmap1.bitmap.filename = pth + "white.bmp"

bitmap1.Refresh()

end if

[MikeC]

Re: how to create low resolution Jpeg file

Ken,
From the same help file but from the UI_Bitmap_Load() page http://support.alphasoftware.com/alp...MAP_LOAD().htm check out the example given...it shows you can also do the same with jpg -- convert to bitmap and then at the end convert the bitmap back to jpg. So first convert from jpg to bitmap--->use the example you have--->convert back to jpg.

One way at least---could be an easier one but did not look.

[Ken Tjia]

Re: how to create low resolution Jpeg file

Thank you Mike for the link, i will study it this morning.
i don't seems to be able to up load the alpha "help" file to my notebook. i version always refer to alpha version 8 hi

do you know any trick to get a copy of version 10's help file
i do alpha hen i fly and internet not always available.

[MikeC]

Re: how to create low resolution Jpeg file

Ken,
As far as I can determine there is NO v10 help file available offline. But for the most part, both v8 and v9's help file has everything but the new features and is available as a PDF download. http://www.alphasoftware.com/documentation/

So if you really need the What's new for v8, v9, and v10 for additional features that have not made it yet into the helps, I hope you have a REALLY good memory!!

Unless maybe someone has an easy way to scrape the info from the web into a text/pdf/chm file? :)