Android support library View Pages: page switching and pre -loading strategies

Android support library View Pages: page switching and pre -loading strategies Overview: ViewPager in Android is a powerful UI component to implement the function of sliding interface switching.When using ViewPager for page switching, we often need to pay attention to the switching effect and pre -load strategy of the page.This article will discuss the use of page switching and pre -loading strategies in the Android support library, and provide some Java code examples. Page switching effect: ViewPager supports a variety of page switching effects, including the default left and right sliding switching, fading into fading.We can achieve customized page switching effects by setting the PageTransFormer of ViewPager. Example code: ViewPager viewPager = findViewById(R.id.viewPager); viewPager.setPageTransformer(true, new ZoomOutPageTransformer()); ... public class ZoomOutPageTransformer implements ViewPager.PageTransformer { private static final float MIN_SCALE = 0.85f; private static final float MIN_ALPHA = 0.5f; public void transformPage(View view, float position) { int pageWidth = view.getWidth(); int pageHeight = view.getHeight(); if (pose <-1) {// page has passed view.setAlpha(0); } else if (pose <= 1) {// slide page // scaling ratio float scaleFactor = Math.max(MIN_SCALE, 1 - Math.abs(position)); // X -axis zoom in the direction float scaleX = scaleFactor; // Y axis zoom in the direction float scaleY = scaleFactor; // Central point displacement float centerX = (pageWidth * (1 - scaleX)) / 2; float centerY = (pageHeight * (1 - scaleY)) / 2; // Set page transformation and transparency view.setScaleX(scaleX); view.setScaleY(scaleY); view.setTranslationX(centerX - (pageWidth * position)); view.setTranslationY(centerY); view.setAlpha(MIN_ALPHA + (scaleX - MIN_SCALE) / (1 - MIN_SCALE) * (1 - MIN_ALPHA)); } Else {// Page is coming soon view.setAlpha(0); } } } Pre -load strategy: ViewPager will pre -load the page on the left and right sides of the current page by default to quickly load the page content when the user is switched to the adjacent page.We can modify the number of pre -loaded pages by setting the setoffscreenPagelimit method. Example code: ViewPager viewPager = findViewById(R.id.viewPager); viewpager.setoffscreenPagelimit (2); // Pre -load two pages on the left and right sides By setting the appropriate page pre -load, we can balance the memory occupation and user experience when sliding the interface. Summarize: The ViewPager in the Android support library provides a powerful page switching function, and it can achieve cool page switching effects by setting PageTransformer.By setting the SetOffScreenPagelimit method, we can adjust the pre -loading strategy of the ViewPager page to optimize the memory occupation and user experience.By using these characteristics flexibly, we can provide users with a smooth and attractive interface switching experience. I hope this article will help you understand the page switching and pre -load strategy of ViewPager in the Android support library.If you have any questions or need further help, ask questions at any time.