感谢@mttmllns!以前的答案。
由于前面的答案显示了用 C# 编写的示例,并且我很好奇,因此我将其移植到 java。完整的 GitHub 示例 https://github.com/rnrneverdies/ImageLoadingPattern
它概述了一个三步过程,其中结合使用不透明度、对比度/亮度和饱和度来帮助挽救我们较差的用户视力。
有关详细说明,请阅读本文 http://blog.neteril.org/blog/2014/11/23/android-material-image-loading/.
EDIT:
瞧,优秀的answer https://stackoverflow.com/a/27301389/2573335由@DavidCrawford 提供。
顺便说一句:我修复了链接的 GitHubProject 以支持 Lollipop 之前的设备。 (自 API 级别 11 起)
The Code
AlphaSatColorMatrixEvaluator.java
import android.animation.TypeEvaluator;
import android.graphics.ColorMatrix;
public class AlphaSatColorMatrixEvaluator implements TypeEvaluator {
private ColorMatrix colorMatrix;
float[] elements = new float[20];
public AlphaSatColorMatrixEvaluator() {
colorMatrix = new ColorMatrix ();
}
public ColorMatrix getColorMatrix() {
return colorMatrix;
}
@Override
public Object evaluate(float fraction, Object startValue, Object endValue) {
// There are 3 phases so we multiply fraction by that amount
float phase = fraction * 3;
// Compute the alpha change over period [0, 2]
float alpha = Math.min(phase, 2f) / 2f;
// elements [19] = (float)Math.round(alpha * 255);
elements [18] = alpha;
// We substract to make the picture look darker, it will automatically clamp
// This is spread over period [0, 2.5]
final int MaxBlacker = 100;
float blackening = (float)Math.round((1 - Math.min(phase, 2.5f) / 2.5f) * MaxBlacker);
elements [4] = elements [9] = elements [14] = -blackening;
// Finally we desaturate over [0, 3], taken from ColorMatrix.SetSaturation
float invSat = 1 - Math.max(0.2f, fraction);
float R = 0.213f * invSat;
float G = 0.715f * invSat;
float B = 0.072f * invSat;
elements[0] = R + fraction; elements[1] = G; elements[2] = B;
elements[5] = R; elements[6] = G + fraction; elements[7] = B;
elements[10] = R; elements[11] = G; elements[12] = B + fraction;
colorMatrix.set(elements);
return colorMatrix;
}
}
设置方法如下:
ImageView imageView = (ImageView)findViewById(R.id.imageView);
final BitmapDrawable drawable = (BitmapDrawable) getResources().getDrawable(R.drawable.image);
imageView.setImageDrawable(drawable);
AlphaSatColorMatrixEvaluator evaluator = new AlphaSatColorMatrixEvaluator ();
final ColorMatrixColorFilter filter = new ColorMatrixColorFilter(evaluator.getColorMatrix());
drawable.setColorFilter(filter);
ObjectAnimator animator = ObjectAnimator.ofObject(filter, "colorMatrix", evaluator, evaluator.getColorMatrix());
animator.addUpdateListener( new ValueAnimator.AnimatorUpdateListener() {
@Override
public void onAnimationUpdate(ValueAnimator animation) {
drawable.setColorFilter (filter);
}
});
animator.setDuration(1500);
animator.start();
这是结果: