Breaking: #102020 - Removed legacy setting 'GFX/gdlib_png'

Description

GFX/gdlib_png is a setting that adjusted rendering of temporary images used by GDLib to be PNG files instead of GIF files.

PNG files offer many benefits over GIF files, one of them being faster processing times using Image/GraphicsMagick.

In line with this change, the property GraphicalFunctions::$gifExtension has been removed, as it mainly was used by this class and GifBuilder to determine if a temporary PNG or GIF image should be rendered.

GFX/processor_colorspace now defaults to an empty value and is migrated to one if you use the recommended colorspace for the given processor (sRGB for ImageMagick, RGB for GraphicsMagick). Image processing now will pick the recommended colorspace unless you configure it to be another one.

Additionally, all GIF assets that are now not shown anymore due to those changes have been removed as well:

• EXT:core/Resources/Public/Images/NotFound.gif
• EXT:install/Resources/Public/Images/TestReference/Gdlib-*.gif

Impact

Temporary layers/masks are now saved as PNG files instead of GIF files.

Affected installations

Every instance that already didn't set gdlib_png to true. Output differences may only occur on instances that use GIFBUILDER functionality (see Migration section for more information).

Migration

The configuration value has been removed without replacement. GFX/processor_colorspace is automatically migrated to the recommended value for setups using the default configuration.

GraphicalFunctions::$gifExtension has been removed without replacement. If this has been used to determine what type of file should be rendered using GraphicalFunctions::imageMagickConvert, please specify the filetype manually now.