How do I support variable screen ratios using AndEngine?

Question

When displaying a background, AndEngine produces black bars above the image on certain devices. How do I support variable screen ratios for different devices using AndEngine?

Answer 1

I believe what you're asking is how to get rid of letterboxing, like this:

By default, AndEngine assumes you want some fixed aspect ratio. It then uses letterboxing to handle devices with different display aspect ratios then what you're providing. The advantage is you have certainty about your layout.

There's more than one approach to get rid of them, but here's what I do. The following code takes a fixed height (in this case 320) and adjusts the width based on the aspect ratio of the device.

//Pick some value for your height.
float cameraHeight = 320;

//Get the display metrics object.
final DisplayMetrics displayMetrics = new DisplayMetrics();

//Populate it with data about your display.
this.getWindowManager().getDefaultDisplay().getMetrics(displayMetrics);

//Calculate the aspect ratio ofthe device.
float aspectRatio = (float) displayMetrics.widthPixels / (float) displayMetrics.heightPixels;

//Multiply the aspect ratio by the fixed height.
float cameraWidth = Math.round(aspectRatio * CAMERA_HEIGHT);

//Create the camera using those values.
this.mCamera = new Camera(0, 0, cameraWidth, cameraHeight);

Answer 2

I used CropResolutionPolicy, a new policy developed and later further extended by members of the AndEngine community. Crop policy is similar to Ratio that comes with the AndEngine, but instead of padding, it scales the scene while keeping aspect ratio to cover the whole screen and crops the overflow.

Crop policy is illustrated on the following image from this website that explains all the AndEngine resolution policies.

image used with permission of the author