Motivation

there are a number of free icon generating web sites available which begs the question whether a script like this provides any value… but leveraging a robust image manipulation utility like imageMagick to apply unique aesthetics makes a DIY approach like this more compelling… along those lines, in the current script, i’m applying:

• custom “centering” – for the splash images where the icon sits inside of a larger background, i’ve found positioning the icon 2/7ths of the way down from top to be the most pleasing
• outer glow
   

Result

!generate.cmd

@echo off

::keeps all variable definitions local to batch file so no need to cleanup after
setlocal

::*** make sure to start with 1024x1024 original ***
set inFile=!original.png
if not [%1] EQU [] set inFile=%1

rename "%inFile%" "%inFile%.save"
erase Default*.png Icon.ico Icon*.png Icon.ico Splash*.png Itunes*.png
rename "%inFile%.save" "%inFile%"

:: this was a handy page that did most BUT NOT ALL of what i saw in the "Resources" folder generated from the Xamarin project template...
:: http://icon.angrymarmot.org/index.html#c9a51e815eac3df5c54f

:: so i decided to have a crack at generating the remaining "Default" aka splash screen images since they represented an interesting challenge of:
:: 1) resizing onto a larger background
:: 2) applying "outer glow" to mitigate the blue-on-blue...
::    albeit, i could've chosen a more simpatico background color, but i favor sticking with defaults until something really kicks me in a different direction

::***install fantastically handy ImageMagick tool from => http://www.imagemagick.org/script/binary-releases.php
::main options docs: http://www.imagemagick.org/script/command-line-options.php#compose

::clarify options used:
::-channel portion yields more desireable hard edge on shadow, see: http://www.imagemagick.org/Usage/blur/#shadow_outline
::+swap is necessary because we need the input image to initially come first in order to render it's corresponding shadow but then we want the shadow behind... and the + sign is handy shortcut to swap the last 2 layers in pipeline w/o having to explicitly specify
::-gravity North centers horizontally and at top vertically and then the -extent sets the outer "canvas" size with the negative offset bringing the icon down from the top
::the double %% on -level is required to escape the normal processing of "%" as a batch variable

@echo on
goto pause

magick "%inFile%" -define icon:auto-resize="256,128,96,64,48,32,16" ( +clone -shadow 100x80-0-0 -channel A -level 0,50%% +channel ) +swap -background none -layers merge -gravity center "Icon.ico"

:Icons
call :IconSub 29 Icon-Small
call :IconSub 40 Icon-Small-40
call :IconSub 50 Icon-Small-50
call :IconSub 57 Icon
call :IconSub 58 Icon-Small@2x
call :IconSub 60 Icon-60 ::including this one only because it's referenced in LaunchScreen.storyboard, even though i'm not using LaunchScreen because i want the app to Splash with the big background style image
call :IconSub 72 Icon-72
call :IconSub 76 Icon-76
call :IconSub 80 Icon-Small-40@2x
call :IconSub 100 Icon-Small-50@2x
call :IconSub 114 Icon@2x
call :IconSub 120 Icon-60@2x
call :IconSub 144 Icon-72@2x
call :IconSub 152 Icon-76@2x
call :IconSub 512 iTunesArtwork
call :IconSub 1024 iTunesArtwork@2x

:Splashes
call :SplashSub 320 480 Default
call :SplashSub 640 960 Default@2x
call :SplashSub 640 1136 Default
call :SplashSub 768 1004 Default-Portrait
call :SplashSub 1536 2008 Default-Portrait@2x
call :SplashSub 1024 748 Default-Landscape
call :SplashSub 2048 1496 Default-Landscape

@echo off
echo  ____                                               _   _ 
echo / ___^|   _   _    ___    ___    ___   ___   ___    ^| ^| ^| ^|
echo \___ \  ^| ^| ^| ^|  / __^|  / __^|  / _ \ / __^| / __^|   ^| ^| ^| ^|
echo  ___) ^| ^| ^|_^| ^| ^| (__  ^| (__  ^|  __/ \__ \ \__ \   ^|_^| ^|_^|
echo ^|____/   \__,_^|  \___^|  \___^|  \___^| ^|___/ ^|___/   (_) (_)

@ping localhost -n 10 >nul:
exit

:IconSub
@echo off
:: %1 = desired size
:: %2 = file name
SETLOCAL
set /a shadowSize=%1*8/100
if %shadowSize% EQU 0 set shadowSize=1
magick "%inFile%" -resize %1 ( +clone -shadow 100x%shadowSize%-0-0 -channel A -level 0,50%% +channel ) +swap -background none -layers merge -gravity center -resize %1 %2.png
@echo on
@goto :EOF


:SplashSub
@echo off
:: %1 = width
:: %2 = height
:: %3 = file name
SETLOCAL
set smallestDimension=%2
if %1 LSS %2 set smallestDimension=%1
::the shadow creates a natural "padding" effect, so start out with icon same as smallest dimension
set /a iconSize=%smallestDimension%
set /a shadowSize=%smallestDimension%*8/100
::center the icon 1/3 of the whitespace available down from top
set /a verticalOffset=(%2-%iconSize%)*2/7

::default Xamarin project blue background #3498DB
:: handy script to generate following commands if you already have a folder with the desired resulting images:
:: >magick identify -format "magick \"\%inFile\%\" -resize %w %f\n" Icon*.png iTunes*.png
magick "%inFile%" -resize %iconSize% ( +clone -shadow 100x%shadowSize%-0-0 -channel A -level 0,50%% +channel ) +swap -background "#3498DB" -layers merge -resize %iconSize% -gravity North -extent %1x%2+0-%verticalOffset% %3.png

@echo on
@goto :EOF

Looks pretty cool =)