`setClearBackgroundColor(true)`, 在 `android 4.4.2` 上无效，背景仍是白色的 about aachartcore HOT 9 OPEN

public class AAChartModel {
    ...
    public Object backgroundColor; //图表背景色
    ...
    public AAChart backgroundColor(Object prop) {
        backgroundColor = prop;
        return this;
    }
    ...
}

    public void setIsClearBackgroundColor(Boolean isClearBackgroundColor) {
        this.isClearBackgroundColor = isClearBackgroundColor;
        if (this.isClearBackgroundColor) {
            this.setBackgroundColor(0);
            this.getBackground().setAlpha(0);
        } else {
            this.setBackgroundColor(1);
            this.getBackground().setAlpha(255);
        }
    }

 private void configureChartOptionsAndDrawChart(AAOptions chartOptions) {
        if (isClearBackgroundColor) {
            chartOptions.chart.backgroundColor("rgba(0,0,0,0)"); //这里就是为了避免开发者忘了设置 `<div>` 的透明度
        }

        Gson gson = new Gson();
        String aaOptionsJsonStr = gson.toJson(chartOptions);
        this.optionsJson = aaOptionsJsonStr;
        String javaScriptStr = "loadTheHighChartView('"
                + aaOptionsJsonStr + "','"
                + this.contentWidth + "','"
                + this.contentHeight + "')";
        this.safeEvaluateJavaScriptString(javaScriptStr);
    }

        if (isClearBackgroundColor) {
            chartOptions.chart.backgroundColor("rgba(0,0,0,0)"); //这里就是为了避免开发者忘了设置 `<div>` 的透明度
        }

aaChartView.setLayerType(View.LAYER_TYPE_SOFTWARE, null);