What is the best way to create drawables for different dpi

Question

Do you create the MDPI drawable first and just scale it accordinly to the .075/1.00/1.50/2 ratio by pixels in photoshop or do you recreate each individual drawable?

Answer 1

I suggest a little script write in powershell for Inkscape.

Example :

Put Inkscape in "c:\bin\inkscape" (dir without any space) and draw all your images in mdpi (1x) resolution.

in Inkscape object properties box (i.e id in xml), give an Id name for each object that you would to export in png.

Save your SVG to " C:\users\rone\Pictures\design-MyApps-forscript.svg"

Create a dir "d:\temp".

And put this script in "C:\app\scripts\"

---

Powershell script name is "inkscape_to_png.ps1" :

param (
    $inkscape_dir="C:\bin\Inkscape\",
    $inkscape_bin="inkscape.exe",
    $img_id="",
    $fichier_svg="C:\Users\rone\Pictures\design-MyMap-forscript.svg",
    $tmp_dir="d:\temp\"
)

$inkscape=$(Resolve-Path "$inkscape_dir\$inkscape_bin")


function getWidthHeight($img_id) {
    $size=@{}

    $old_pwd=$pwd.path

    cd $inkscape_dir

    write-host -foreground yellow "détermine la taille de $img_id"

    $size.width=invoke-command {./inkscape --file=$fichier_svg --query-id=$img_id --query-width 2>$null}
    $size.height=invoke-command {./inkscape --file=$fichier_svg --query-id=$img_id --query-height 2>$null}

    write-host -foreground yellow "width : $($size.width)"
    write-host -foreground yellow "height : $($size.height)"

    cd $old_pwd

    return $size
}

function convertTo($size, $format) {
    $rsize=@{}

    if ($format -eq "MDPI") {
        $rsize.width=[int]$size.width*1
        $rsize.height=[int]$size.height*1
    } elseif ($format -eq "LDPI") {
        $rsize.width=[int]$size.width*0.75
        $rsize.height=[int]$size.height*0.75
    } elseif ($format -eq "HDPI") {
        $rsize.width=[int]$size.width*1.5
        $rsize.height=[int]$size.height*1.5
    } elseif ($format -eq "XHDPI") {
        $rsize.width=[int]$size.width*2
        $rsize.height=[int]$size.height*2
    } elseif ($format -eq "XXHDPI") {
        $rsize.width=[int]$size.width*3
        $rsize.height=[int]$size.height*3   
    } elseif ($format -eq "XXXHDPI") {
        $rsize.width=[int]$size.width*4
        $rsize.height=[int]$size.height*4
    }

    write-host -foreground yellow "après conversion : $format"

    write-host -foreground yellow "width : $($rsize.width)"
    write-host -foreground yellow "height : $($rsize.height)"

    return $rsize
}

function inkscape_convert() {

    $mdpi_size=getWidthHeight $img_id

    write-host -foreground gray "----------------------------------------"
    "MDPI,LDPI,HDPI,XHDPI,XXHDPI,XXXHDPI" -split ","|% {


        $new_size=convertTo $mdpi_size $_
        if ($new_size.width -eq 0 -or $new_size.height -eq 0) {
            write-host -foreground red "erreur lors de la recherche de la taille de l'image"
            exit
        }
        $w=$new_size.width
        $h=$new_size.height
        $dir="$tmp_dir\drawable-$($_.toLower())"
        if (-not $(test-path $dir)) {
            write-host -foreground yellow "création du répertoire $dir"
            mkdir $dir
        }
        $new_file_name="$dir\$($img_id).png"
        $cmd="$inkscape -z -i $img_id -j -f $fichier_svg -w $w -h $h -e $new_file_name"
        write-host -foreground gray $cmd
        invoke-expression -command $cmd
        if ($? -eq $true) {
            write-host -foreground yellow "conversion OK"
        }

    }
    write-host -foreground gray "----------------------------------------"

}


inkscape_convert

---

now, call this script as this example :

@("btn_button_name_1","btn_button_name_3","btn_other", "btn_zoom", "btn_dezoom", "btn_center", "btn_wouwou", "im_abcdef", "ic_half", "ic_star", "ic_full") | % { C:\app\scripts\inkscape_to_png.ps1 -img $_ -f design-MyMap-forscript.svg }

And the script will create all your drawables in all resolutions (ldpi, mdpi, hdpi, xhdpi, xxhdpi, xxxhdpi) in d:\temp\drawable-xyz ...

So a confortable time saving.