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本篇内容主要讲解“Android怎么实现颜色渐变动画效果”,感兴趣的朋友不妨来看看。本文介绍的方法操作简单快捷,实用性强。下面就让小编来带大家学习“Android怎么实现颜色渐变动画效果”吧!
效果图:
TypeEvaluator是一个接口,在开发中可以自定义该接口实例,利用ValueAnimator的setEvaluator(TypeEvaluator)方法来控制动画的更新计算表达式。在日常开发中,不可能只是需要操纵单一数值的变化,如果需要同时操纵对象的多个属性,如定义动画的x,y移动的坐标等,那就需要对TypeEvaluator有所了解了。
ValueAnimator colorAnim = ObjectAnimator.ofInt(this, "backgroundColor", RED, BLUE); colorAnim.setDuration(4000); colorAnim.setEvaluator(new ArgbEvaluator()); colorAnim.setRepeatCount(ValueAnimator.INFINITE); colorAnim.setRepeatMode(ValueAnimator.REVERSE); colorAnim.start();
@Override public Object evaluate(float fraction, Object startValue, Object endValue) { int startInt = (Integer) startValue; float startA = ((startInt >> 24) & 0xff) / 255.0f; float startR = ((startInt >> 16) & 0xff) / 255.0f; float startG = ((startInt >> 8) & 0xff) / 255.0f; float startB = ( startInt & 0xff) / 255.0f; int endInt = (Integer) endValue; float endA = ((endInt >> 24) & 0xff) / 255.0f; float endR = ((endInt >> 16) & 0xff) / 255.0f; float endG = ((endInt >> 8) & 0xff) / 255.0f; float endB = ( endInt & 0xff) / 255.0f; // 将sRGB转化成线性 startR = (float) Math.pow(startR, 2.2); startG = (float) Math.pow(startG, 2.2); startB = (float) Math.pow(startB, 2.2); endR = (float) Math.pow(endR, 2.2); endG = (float) Math.pow(endG, 2.2); endB = (float) Math.pow(endB, 2.2); //在线性空间中计算插值的颜色 float a = startA + fraction * (endA - startA); float r = startR + fraction * (endR - startR); float g = startG + fraction * (endG - startG); float b = startB + fraction * (endB - startB); //转换回sRGB在[0..255]范围 a = a * 255.0f; r = (float) Math.pow(r, 1.0 / 2.2) * 255.0f; g = (float) Math.pow(g, 1.0 / 2.2) * 255.0f; b = (float) Math.pow(b, 1.0 / 2.2) * 255.0f; return Math.round(a) << 24 | Math.round(r) << 16 | Math.round(g) << 8 | Math.round(b); }
public class MyColorEvaluator implements TypeEvaluator
接下来换一种颜色的计算方式,在本人看相关api的过程中,发现Color中有colorToHSV和HSVToColor的方法,于是在网上找了一个HVS的计算方式。(以下代码来源于网络)。
@Override public Integer evaluate(float fraction, Integer startValue, Integer endValue) { Color.colorToHSV(startValue,startHsv); Color.colorToHSV(endValue,endHsv); int alpha = startValue >> 24 + (int) ((endValue >> 24 - startValue >> 24) * fraction); // 计算当前动画完成度(fraction)所对应的颜色值 if (endHsv[0] - startHsv[0] > 180) { endHsv[0] -= 360; } else if (endHsv[0] - startHsv[0] < -180) { endHsv[0] += 360; } outHsv[0] = startHsv[0] + (endHsv[0] - startHsv[0]) * fraction; if (outHsv[0] > 360) { outHsv[0] -= 360; } else if (outHsv[0] < 0) { outHsv[0] += 360; } outHsv[1]=startHsv[1]+(endHsv[1]-startHsv[1])*fraction; outHsv[2]=startHsv[2]+(endHsv[2]-startHsv[2])*fraction; return Color.HSVToColor(alpha,outHsv); }
ValueAnimator colorAnim = ObjectAnimator.ofInt(this, "backgroundColor", RED, BLUE); colorAnim.setDuration(4000); colorAnim.setEvaluator(new MyColorEvaluator()); colorAnim.setRepeatCount(ValueAnimator.INFINITE); colorAnim.setRepeatMode(ValueAnimator.REVERSE); colorAnim.start();
ColorGradient.java:
public class ColorGradient extends View { public ColorGradient(Context context) { super(context); } public ColorGradient(Context context, @Nullable AttributeSet attrs) { super(context, attrs); animation(); } public ColorGradient(Context context, @Nullable AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); } private void animation(){ ValueAnimator colorAnim = ObjectAnimator.ofInt(this, "backgroundColor", RED, BLUE); colorAnim.setDuration(4000); colorAnim.setEvaluator(new MyColorEvaluator()); colorAnim.setRepeatCount(ValueAnimator.INFINITE); colorAnim.setRepeatMode(ValueAnimator.REVERSE); colorAnim.start(); } }
MyColorEvaluator.java:
public class MyColorEvaluator implements TypeEvaluator<Integer> { float[] startHsv=new float[3]; float[] endHsv=new float[3]; float[] outHsv=new float[3]; @Override public Integer evaluate(float fraction, Integer startValue, Integer endValue) { Color.colorToHSV(startValue,startHsv); Color.colorToHSV(endValue,endHsv); int alpha = startValue >> 24 + (int) ((endValue >> 24 - startValue >> 24) * fraction); // 计算当前动画完成度(fraction)所对应的颜色值 if (endHsv[0] - startHsv[0] > 180) { endHsv[0] -= 360; } else if (endHsv[0] - startHsv[0] < -180) { endHsv[0] += 360; } outHsv[0] = startHsv[0] + (endHsv[0] - startHsv[0]) * fraction; if (outHsv[0] > 360) { outHsv[0] -= 360; } else if (outHsv[0] < 0) { outHsv[0] += 360; } outHsv[1]=startHsv[1]+(endHsv[1]-startHsv[1])*fraction; outHsv[2]=startHsv[2]+(endHsv[2]-startHsv[2])*fraction; return Color.HSVToColor(alpha,outHsv); } }
到此,相信大家对“Android怎么实现颜色渐变动画效果”有了更深的了解,不妨来实际操作一番吧!这里是亿速云网站,更多相关内容可以进入相关频道进行查询,关注我们,继续学习!
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