Crop variants configuration per content element

It is possible to provide a configuration per content element. If you want a different cropping configuration for tt_content images, then you can add the following to your image field configuration of tt_content records:

'config' => [
    'overrideChildTca' => [
        'columns' => [
            'crop' => [
                'config' => [
                    'cropVariants' => [
                        'mobile' => [
                            'title' => 'LLL:EXT:ext_key/Resources/Private/Language/locallang.xlf:imageManipulation.mobile',
                            'cropArea' => [
                                'x' => 0.1,
                                'y' => 0.1,
                                'width' => 0.8,
                                'height' => 0.8,
                            ],
                        ],
                    ],
                ],
            ],
        ],
    ],
]

Please note, you need to specify the target column name as array key. Most of the time this will be crop as this is the default field name for image manipulation in sys_file_reference

It is also possible to set the cropping configuration only for a specific tt_content element type by using the columnsOverrides feature:

$GLOBALS['TCA']['tt_content']['types']['textmedia']['columnsOverrides']['assets']['config']['overrideChildTca']['columns']['crop']['config'] = [
    'cropVariants' => [
       'default' => [
           'disabled' => true,
       ],
       'mobile' => [
           'title' => 'LLL:EXT:ext_key/Resources/Private/Language/locallang.xlf:imageManipulation.mobile',
           'cropArea' => [
               'x' => 0.1,
               'y' => 0.1,
               'width' => 0.8,
               'height' => 0.8,
           ],
           'allowedAspectRatios' => [
               '4:3' => [
                   'title' => 'LLL:EXT:core/Resources/Private/Language/locallang_wizards.xlf:imwizard.ratio.4_3',
                   'value' => 4 / 3
               ],
               'NaN' => [
                   'title' => 'LLL:EXT:core/Resources/Private/Language/locallang_wizards.xlf:imwizard.ratio.free',
                   'value' => 0.0
               ],
           ],
       ],
    ],
];

Disable crop variants

Please note, as the array for overrideChildTca is merged with the child TCA, so are the crop variants that are defined in the child TCA (most likely sys_file_reference). Because you cannot remove crop variants easily, it is possible to disable them for certain field types by setting the array key for a crop variant disabled to the value true as you can see in the example above for the default variant.