An Android layout that properly scales its content in order to display physical objects such as credit cards, passports, etc.

Download Sample App APK

Ensure that you have JitPack repo added to your project build.gradle file:

allprojects {
	repositories {
		...
		maven { url 'https://jitpack.io' }
	}
}

Add the library to your app build.gradle file:

dependencies {
	implementation 'com.github.radiokot:physical-object-layout:1.0.1'
}

If you have ever tried to design and display a representation of physical world object, i.e. a credit card, in your Android app I’m pretty sure you have noticed, that the way it appears on the screen is… different 🤔

In Android we make fluid layouts. We specify sizes and margins in device-related units, set gravity for views and constraining them to each other to avoid overlaps. As a result, our layout looks good on different screens.

But when it comes to displaying a physical object, things get messy:

Unlike our regular layouts, physical objects are not fluid, they must be proportionally scaled instead. When you figure this out you also realize, that such scaling of a layout is not an ordinary thing to do in Android.

• You can’t use post-scaling because it looks blurry and requires drawing outside of the view frame
• You can’t just make this view a vector drawable because some of the elements have variable content
• Creating many-many dimens for every screen width is just crazy

All you need to do is:

1. Create your layout with all sizes and margins fixed and set in px. Without any tricky layouts, without dimens, literally a copy of what the designers sent to you
2. Put the view into the PhysicalObjectLayout
3. Enjoy your view properly scaled to fit the container width or height, just like if it was an image

PhysicalObjectLayout has a few attributes that controls scaling and appearance:

PhysicalObjectLayout allows you to specify custom scaling strategies in order to scale custom views.

You can implement your own ViewScalingStrategy and apply it programmatically using addScalingStrategies or addScalingStrategy methods.

Examples of custom scaling strategies can be found in the library itself: CardViewScalingStrategy, TextViewScalingStrategy

Copyright (c) 2020 Oleg Koretsky

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