The default image assigned to an image layer sets the dimension and aspect ratio for any other images that will occupy that layer.
Image Layer Properties
There are two properties of an image layer that determine the images that can populate that layer: the layer dimensions and the aspect ratio. These properties are set by the initial asset that is chosen to populate the image layer.
Layer Dimensions
The dimensions of the image layer set the minimum requirements for all other images that might populate that layer (images that come from content groups, the content database, or are uploaded by End Users). An image smaller in dimension than the image layer dimensions cannot be populated. The dimensions of the layer are measured in inches or millimeters in the drawer and are calculated against the dimensions of the image measured in pixels.
Aspect Ratio
The aspect ratio of the image layer sets the width to height relationship for all other images that might populate that layer (images that come from content groups, the content database, or are uploaded by End Users.)
"Position Lock" and "Can Crop" affect how image layers work with aspect ratio. For images that are not position locked, the selection of a new image with a different aspect ratio will place that image on the template with the same width dimension as the original and will adjust the height to fit the aspect ratio of the new image (the same way that placing the initial image keeps the width at 1" and changes the height to match the aspect ratio of the initial image). If "Can Crop" is turned on for this image layer, then the End User may crop the image to any aspect ratio they wish.
The aspect ratio is fixed for image layers that are position locked. When the layer is position locked, "Can Crop" determines whether or not images of a different aspect ratio from the original may be used for the layer.
- If "Can Crop" is turned on, the user may populate the layer with an image of any aspect ratio and the cropper is fixed at the aspect ratio of the original image.
- If "Can Crop" is turned off, then only an image that matches the original aspect ratio exactly may be chosen. Any other image will show an "Invalid Aspect Ratio" error and will not be selectable.
Setting the Image Layer Properties
A new text layer may be set to any width and height independently and irrespective of the text within the layer. However, an image layer works a little differently. The width and height of any image layer are set by the first asset chosen to populate that layer.
The default measurements for an image layer are 1" x 1" when the layer is newly created. However, as soon as an asset is chosen, the default width remains at 1" and the height changes to match the aspect ratio of the selected asset. At this point, the template composer can adjust the size of this image by either changing the width or height measurements in the image layer modal or by dragging on the corners or sides to adjust the asset.
When typing either width or height adjustments, the other dimension will adjust automatically to maintain the aspect ratio and dragging on the image to re-size also maintains the aspect ratio of the image - it will not stretch out of shape. The final width and height of this initial image become the default measurements for the image layer and determine the properties of any images that can be chosen for this layer.
Image Layer Dimensions vs Image Asset Dimensions
It is important to understand that the image layer dimensions are not the same as the image asset dimensions. The initial image asset is used to set the layer dimensions but these could be different from the native size of the default image. Once the image layer dimensions are set, the system will measure these dimensions against the dimensions of any replacement images to determine if they meet the minimum criteria to populate the layer. This can mean that the default image used to set the image layer could become un-selectable by End Users if this image was increased in size beyond its native size when it was used to set the layer.
As an example: An image that was natively 3" x 3" was placed on a template and enlarged to 4" x 4" by the template composer to set the image layer dimensions. This image is fine as long as it remains the default image. However, if it is also a selection available in the image drawer, it cannot be selected as a replacement image because it doesn't meet the minimum requirement of 4" x 4" set by the image layer.
Setting the Layer with FPO Images
Image layers always require an initial image to set the layer properties. Instead of using a "real" image, the template composer can set up an "FPO" image (For Placement Only). This might be a graphic that is transparent or has messaging for the End User to "Click This Layer to Select Image". The FPO image sets the layer properties of size and aspect ratio and the image selections come from other image content management strategies.