替代setAlpha在API级别8 [英] Alternative to setAlpha in api level 8

问题描述

我工作的一个应用程序，它可以在升级Froyo 以及软糖运行。我有一个类扩展PageTransformer如下：

I am working on an app, which can run on Froyo as well as JellyBean. I have a class that extends PageTransformer as below:

import android.support.v4.view.ViewPager.PageTransformer;
import android.view.View;

public class ZoomOutPageTransformer implements PageTransformer {
    private static float MIN_SCALE = 0.85f;
    private static float MIN_ALPHA = 0.5f;

    public void transformPage(View view, float position) {
        int pageWidth = view.getWidth();
        int pageHeight = view.getHeight();

        if (position < -1) { 
            view.setAlpha(0);

        } else if (position <= 1) { 
            float scaleFactor = Math.max(MIN_SCALE, 1 - Math.abs(position));
            float vertMargin = pageHeight * (1 - scaleFactor) / 2;
            float horzMargin = pageWidth * (1 - scaleFactor) / 2;
            if (position < 0) {
                view.setTranslationX(horzMargin - vertMargin / 2);
            } else {
                view.setTranslationX(-horzMargin + vertMargin / 2);
            }


            view.setScaleX(scaleFactor);
            view.setScaleY(scaleFactor);


            view.setAlpha(MIN_ALPHA +
                    (scaleFactor - MIN_SCALE) /
                    (1 - MIN_SCALE) * (1 - MIN_ALPHA));

        } else { 
            view.setAlpha(0);
        }
    }
}

问题是，写在这个类中的方法是在加入 API级别11 和我的 API级别8最低SDK版本。以下是这些添加的API级11的方法：

The problem is, the methods written in this class were added in API level 11 and i have minimum sdk version of API level 8. The following are those methods that were added in API level 11:

1. setAlpha（）
2. setTranslationX（）
3. setScaleX（）
4. setScaleY（）

1. setAlpha()
2. setTranslationX()
3. setScaleX()
4. setScaleY()

有什么可以为这个问题的解决方案？

What can be the solution for this problem ?

推荐答案

最简单的解决方法是使用 NineOldAndroids 库，反向移植动画所有版本的Andr​​oid。该使用部分有你如何使用图书馆的例子。

The easiest solution is to use the NineOldAndroids library, which backports the animations to all versions of Android. The Usage section has examples of how you'd use the library.

这篇关于替代setAlpha在API级别8的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！