Convert .pkg folder to .pkg.tar.gz?

Question

I just build a package gmchess-0.20-1-i686.pkg.tar.gz from PKGBUILD,  I unpack the gmchess-0.20-1-i686.pkg.tar.gz and create a folder gmchess-0.20-1-i686.pkg, after changing some .png files in this folder, I compress the gmchess-0.20-1-i686.pkg folder back to gmchess-0.20-1-i686.pkg.tar.gz, however it can not be installed with command pacman -U, I try to search wiki, but get no clues, thanks for help.
$ sudo pacman -U gmchess-0.20-1-i686.pkg.tar.gz
Password:
loading package data...
error: missing package metadata in gmchess-0.20-1-i686.pkg.tar.gz
error: 'gmchess-0.20-1-i686.pkg.tar.gz': invalid or corrupted package

Answer 1

Xyne wrote:
Open up the PKGBUILD and replace the names of the old png files with the names of the new ones in the "source" array, e.g.:
source=(old_img_1.png old_img_2.png old_img_3.png)
source=(new_img_1.png new_img_2.png new_img_3.png)
Then run "makepkg -g" to generate the new md5sum array. Open the PKGBUILD again and replace the old md5sum array with the new one.
Thanks for your detailed reply, here is PKGBUILD, there is no source array about png, can I just put in the source array for new pngs?
=================================================================================================
# Contributor: yetist <[email protected]>
pkgname=gmchess
pkgver=0.20
pkgrel=1
pkgdesc="Chinese chess game"
arch=("i686" "x86_64")
url="http://code.google.com/p/gmchess/"
license=('GPL2')
depends=("gtkmm" "libglademm")
source=("http://gmchess.googlecode.com/files/$pkgname-$pkgver.tar.bz2")
md5sums=('14ac37609c2fd6f0611001ed4508d688')
build() {
        cd "$startdir/src/$pkgname-$pkgver"
    ./configure --prefix=/usr || return 1
        make || return 1
        make DESTDIR="$startdir/pkg" install || return 1