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Transform any selected layer using the powerful features of the Affine filter in Affinity Photo. Select a layer, any layer (it does not matter if the layer is locked or not which makes the tool slightly different from the standard manipulation of the layer).
Go to the filters menu of the application and then to the distort menu and then affine. The panel will be placed in the bottom right as usual and can be dragged to the middle of the application
You will now see rotate / scale x and scale y as well as offset x and y. The x and y are really horizontal and vertical, not sure why they didn't say that as x and y are more mathematical terms.
The rotation entry is odd as it offers no origin point for the rotation but you can use it to rotate the image the full 360 degrees, the transformation can then be applied by clicking apply.
You can scale the image horizontally using the x entry and set it between 10 and 1000 to create a squeezed or stretched transformation for the current selected layer. You can also drag across the 'scale x' text to interactively scale the image / layer horizontally. You can do the same with the scale y but in that case, the transformation is vertically. The result will depend on the extend mode at the bottom of the panel.
If you scale transform the image, you may not see the entire image if the scale is greater than 100% and in that case you may wish to reposition the image / layer using the offset fields. The offset x shifts the image by -100% through to 100%, no more. You can use it to re-position the image horizontally, the offset y can be used to shift it in the vertical.
The extend mode is also super useful and that is at the bottom (really should be at the top of the panel). ZERO is just a single image re-size and shift and rotate and it is useful as it means you can get a transparent background from your image. You can also do the same with image if you use the FULL option but in this case, you get the area displaced filled not with transparency but white pixels.
The extend mode also has the transformation REPEAT which doesn't really repeat the image but it does repeat the edges so if you have a white edge around your image, the white will be extended out to the edge of the document (though it does depend on the offset and scale settings). Personally, it looks the most ugly of effects but there must be some uses for it.
The extend mode also has a useful repeating transformation in WRAP and MIRROR. The wrap one create multiple copies of the image so you will only see this if you offset the image or if the scale is less than 100% or you rotate the image, if you have a scale of 400% then you won't see the WRAP. It does create a seam where the image hit the edge and repeat, though if the image is a seamless tile then it will not matter. The MIRROR is much nicer and flips and transforms the image layers so you have no edges or seams in your transformation.
You can also repeat the transformation over and over by going to the top of the menu for the filters and apply the repeat command at the top. You can also fade and blend the result with the original using the layer menu fade. You can create all kinds of amazing transformations with your images using the filter though much of the functionality and a lot more is available in the equations filter.