有没有办法将BackgroundColorSpan设置为SpannableString的动画?

时间:2019-06-15 22:42:51

标签: android android-animation android-transitions spannablestring

当我向此TextView中添加更多字母时,我的TextView中的字符串在运行时中每个(小标题)被分成三个字母的范围。我周期性地为这些三胞胎设置了四种不同的背景色:

void color(TextView textView) {
        String sequenceColored = textView.getText().toString();
        SpannableString ss = new SpannableString(sequenceColored);
        int iter = 0;
        if (textView.getId() == R.id.sequence) {
            for (int i = 0; i < sequenceColored.length(); i += 3, iter++) {
                if (iter == 0) {
                    ss.setSpan(new BackgroundColorSpan(Color.argb(123, 255, 136, 0)), i, i + 3, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
                } else if (iter == 1) {
                    ss.setSpan(new BackgroundColorSpan(Color.argb(123, 255, 187, 51)), i, i + 3, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
                } else if (iter == 2) {
                    ss.setSpan(new BackgroundColorSpan(Color.argb(123, 0, 153, 204)), i, i + 3, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
                } else if (iter == 3) {
                    ss.setSpan(new BackgroundColorSpan(Color.argb(123, 170, 102, 204)), i, i + 3, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
                    iter = -1;
                }
            }
        }
    }

因此,问题是:是否可以为这种背景颜色变化设置动画,使其在没有背景颜色的情况下缓慢而美观地显示?

SpannableString不是View,所以我传统上不能设置动画,对吧?


更新

我尝试通过在第一个内部if中执行以下代码来设置此动画:

ValueAnimator animation = ValueAnimator.ofInt(0, 123);

animation.start();
final int finalI = i;
animation.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
    @Override
    public void onAnimationUpdate(ValueAnimator animation) {
        ss.setSpan(new BackgroundColorSpan(Color.argb((int)animation.getAnimatedValue(), 255, 136, 0)), finalI, finalI + 3, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
    }
});

但是它根本没有将背景色设置为跨度。

1 个答案:

答案 0 :(得分:0)

最后,我做了@CommonsWare建议的内容。
首先,我创建了一个自定义MutableBackgroundColorSpan

public class MutableBackgroundColorSpan extends BackgroundColorSpan {

    private int mAlpha = 255;
    private int mBackgroundColor;

    public MutableBackgroundColorSpan(int alpha, int color) {
        super(color);
        mAlpha = alpha;
        mBackgroundColor = color;
    }

    public MutableBackgroundColorSpan(Parcel src) {
        super(src);
        mBackgroundColor = src.readInt();
        mAlpha = src.readInt();
    }

    public void writeToParcel(Parcel dest, int flags) {
        super.writeToParcel(dest, flags);
        dest.writeInt(mBackgroundColor);
        dest.writeFloat(mAlpha);
    }

    @Override
    public void updateDrawState(TextPaint ds) {
        ds.bgColor = getBackgroundColor();
    }

    /**
     * @param alpha from 0 to 255
     */
    public void setAlpha(int alpha) {
        mAlpha = alpha;
    }

    public void setBackgroundColor(int backgroundColor) {
        mBackgroundColor = backgroundColor;
    }

    public float getAlpha() {
        return mAlpha;
    }

    @Override
    public int getBackgroundColor() {
        return Color.argb(mAlpha, Color.red(mBackgroundColor), Color.green(mBackgroundColor), Color.blue(mBackgroundColor));
    }
}

然后,我初始化了一个自定义Property

private static final Property<MutableBackgroundColorSpan, Integer> MUTABLE_BACKGROUND_COLOR_SPAN_FC_PROPERTY =
            new Property<MutableBackgroundColorSpan, Integer>(Integer.class, "MUTABLE_BACKGROUND_COLOR_SPAN_FC_PROPERTY") {

                @Override
                public void set(MutableBackgroundColorSpan span, Integer value) {
                    span.setBackgroundColor(value);
                }

                @Override
                public Integer get(MutableBackgroundColorSpan span) {
                    return span.getBackgroundColor();
                }
            };

执行其功能的实际代码是:

MutableBackgroundColorSpan span = new MutableBackgroundColorSpan(123, Color.WHITE);
ss.setSpan(span,  i, i + 3, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
ObjectAnimator objectAnimator = ObjectAnimator.ofInt(span, MUTABLE_BACKGROUND_COLOR_SPAN_FC_PROPERTY, Color.WHITE, Color.rgb(r, g, b));
objectAnimator.setDuration(100);
objectAnimator.setEvaluator(new ArgbEvaluator());
objectAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
    @Override
    public void onAnimationUpdate(ValueAnimator animation) {
        //refresh
        textView.setText(ss);
    }
});
objectAnimator.start();