TabletTransformer.java

/*
 * Copyright (c) 2014. Marshal Chen.
 */

package com.marshalchen.common.uimodule.viewpagertransforms;

import android.graphics.Camera;
import android.graphics.Matrix;
import android.view.View;

public class TabletTransformer extends ABaseTransformer {

	private static final Matrix OFFSET_MATRIX = new Matrix();
	private static final Camera OFFSET_CAMERA = new Camera();
	private static final float[] OFFSET_TEMP_FLOAT = new float[2];

	@Override
	protected void onTransform(View view, float position) {
		final float rotation = (position < 0 ? 30f : -30f) * Math.abs(position);

		view.setTranslationX(getOffsetXForRotation(rotation, view.getWidth(), view.getHeight()));
		view.setPivotX(view.getWidth() * 0.5f);
		view.setPivotY(0);
		view.setRotationY(rotation);
	}

	protected static final float getOffsetXForRotation(float degrees, int width, int height) {
		OFFSET_MATRIX.reset();
		OFFSET_CAMERA.save();
		OFFSET_CAMERA.rotateY(Math.abs(degrees));
		OFFSET_CAMERA.getMatrix(OFFSET_MATRIX);
		OFFSET_CAMERA.restore();

		OFFSET_MATRIX.preTranslate(-width * 0.5f, -height * 0.5f);
		OFFSET_MATRIX.postTranslate(width * 0.5f, height * 0.5f);
		OFFSET_TEMP_FLOAT[0] = width;
		OFFSET_TEMP_FLOAT[1] = height;
		OFFSET_MATRIX.mapPoints(OFFSET_TEMP_FLOAT);
		return (width - OFFSET_TEMP_FLOAT[0]) * (degrees > 0.0f ? 1.0f : -1.0f);
	}

}