package com.by_syk.lib.nanoiconpack.util; import android.support.annotation.IntDef; import android.support.v4.view.ViewPager; import android.view.View; import java.lang.annotation.Retention; import java.lang.annotation.RetentionPolicy; import java.util.Random; /** * Created by By_syk on 2016-11-04. */ public class SimplePageTransformer implements ViewPager.PageTransformer { private int animType = ANIM_ZOOM_OUT; public static final int ANIM_RANDOM = 0; public static final int ANIM_DEFAULT = 1; public static final int ANIM_ZOOM_OUT = 2; public static final int ANIM_DEPTH = 3; public static final int ANIM_FLIP = 4; @IntDef({ANIM_RANDOM, ANIM_DEFAULT, ANIM_ZOOM_OUT, ANIM_DEPTH, ANIM_FLIP}) @Retention(RetentionPolicy.SOURCE) public @interface AnimType {} public SimplePageTransformer() {} public SimplePageTransformer(int animType) { if (animType == ANIM_RANDOM) { int[] animTypes = {ANIM_DEFAULT, ANIM_ZOOM_OUT, ANIM_DEPTH}; this.animType = animTypes[(new Random()).nextInt(animTypes.length)]; } else { this.animType = animType; } } public void transformPage(View view, float position) { switch (animType) { case ANIM_ZOOM_OUT: transformPageZoomOut(view, position); break; case ANIM_DEPTH: transformPageDepth(view, position); break; case ANIM_FLIP: transformPageFlip(view, position); break; case ANIM_DEFAULT: // Do nothing } } private void transformPageZoomOut(View view, float position) { final float MIN_SCALE = 0.85f; final float MIN_ALPHA = 0.5f; int pageWidth = view.getWidth(); int pageHeight = view.getHeight(); if (position < -1) { // [-Infinity,-1) // This page is way off-screen to the left. view.setAlpha(0); } else if (position <= 1) { // [-1,1] // Modify the default slide transition to shrink the page as well float scaleFactor = Math.max(MIN_SCALE, 1 - Math.abs(position)); float verMargin = pageHeight * (1 - scaleFactor) / 2; float horzMargin = pageWidth * (1 - scaleFactor) / 2; if (position < 0) { view.setTranslationX(horzMargin - verMargin / 2); } else { view.setTranslationX(-horzMargin + verMargin / 2); } // Scale the page down (between MIN_SCALE and 1) view.setScaleX(scaleFactor); view.setScaleY(scaleFactor); // Fade the page relative to its size. view.setAlpha(MIN_ALPHA + (scaleFactor - MIN_SCALE) / (1 - MIN_SCALE) * (1 - MIN_ALPHA)); } else { // (1,+Infinity] // This page is way off-screen to the right. view.setAlpha(0); } } private void transformPageDepth(View view, float position) { final float MIN_SCALE = 0.75f; int pageWidth = view.getWidth(); if (position < -1) { // [-Infinity,-1) // This page is way off-screen to the left. view.setAlpha(0); } else if (position <= 0) { // [-1,0] // Use the default slide transition when moving to the left page view.setAlpha(1); view.setTranslationX(0); view.setScaleX(1); view.setScaleY(1); } else if (position <= 1) { // (0,1] // Fade the page out. view.setAlpha(1 - position); // Counteract the default slide transition view.setTranslationX(pageWidth * -position); // Scale the page down (between MIN_SCALE and 1) float scaleFactor = MIN_SCALE + (1 - MIN_SCALE) * (1 - Math.abs(position)); view.setScaleX(scaleFactor); view.setScaleY(scaleFactor); } else { // (1,+Infinity] // This page is way off-screen to the right. view.setAlpha(0); } } private void transformPageFlip(View view, float position) { float percentage = 1 - Math.abs(position); view.setCameraDistance(12000); setVisibility(view, position); setTranslation(view); setSize(view, position, percentage); setRotation(view, position, percentage); } private void setVisibility(View view, float position) { if (position < 0.5 && position > -0.5) { view.setVisibility(View.VISIBLE); } else { view.setVisibility(View.INVISIBLE); } } private void setTranslation(View view) { ViewPager viewPager = (ViewPager) view.getParent(); int scroll = viewPager.getScrollX() - view.getLeft(); view.setTranslationX(scroll); } private void setSize(View view, float position, float percentage) { if (percentage < 0.85f) { percentage = 0.85f; } view.setScaleX((position != 0 && position != 1) ? percentage : 1); view.setScaleY((position != 0 && position != 1) ? percentage : 1); } private void setRotation(View view, float position, float percentage) { if (position > 0) { view.setRotationY(-180 * (percentage + 1)); } else { view.setRotationY(180 * (percentage + 1)); } } }