We’ll borrow a play from the SVG playbook for this post. We’ll use clip path to generate masks around an image to control what the user gets to see and what shapes the image takes without changing the image itself.
We’ll look at the process and then we’ll build an e-book with examples to test if this works with iBooks (and whatever other reader you want to test with) and how can we better leverage the feature in our reflowable projects.
CSS clip-path attribute is the star of the show either in CSS, via SVG or a mix of the two of them, it will clip the image and hide portions outside the clipping region (and therefore changing the image’s visible shape) without changing the image file.
Rather than figure out the coordinates for each point in the shape or polygon I’ll be working on I chose to use Clippy, a tool by Bennett Feely. It is certainly not the only one but it is certainly the easiest to use of those I’ve found. If you use Brackets you may want to look at the CSS Shapes Editor that’s available for the editor.
For this example I took a triangle and put it on its side, the same shape in the Demosthenes example but with a different image.
The code looks like this:
SVG Clip path
All is well and good for browsers that support the CSS clip-path property whether prefixed or not. But what happens to older browsers? Fortunately for us support for SVG is wider than the support for CSS clip path.
SO we take a two-pronged approach, we create an SVG clip path element and then we reference the SVG from our CSS.
This bit looks like this:
I’ve discussed CSS shapes in other blog posts so I won’t cover it again here. But it’s important to keep this in mind as it’ll be what will pull the components together below.
Putting it all together
We have all the components we need. It’s time to put them together. We use
shapte-outside to tel the CSS engine to put the content closer to masked shape of the image.
The final code looks like this:
Moving it to ePub and the result thereof
I had initially targeted iBooks but even within the iBooks platform, the results are inconsistent. I’m working on trying to figure out if it’s a code issue or if the different versions of iBooks really are that inconsistent with each other.
iBooks for Mac (1.1.1 (600) running on OS X 10.10.3) produces no visible result. The image is not displayed at all.
iBooks for iOS in an iPad Air 2 produces a distorted image and not the sharp triangle like the one provided for the open web.
I’m researching if this is an issue with the way I’m using clip-path, the limitations for using SVG clip path inside an XHTML document, or just that it’s not supported.
If you want to help me test the epub I created (with the cover and title for Peter Pan) is available here
Links and credits
Image used in this post courtesy of Craig Deakin used under a Creative Commons attribution license
image is available in codepen