android-自定义视图中的渐变文本颜色

我有这个GradientTextView类,它扩展了AppCompatTextView

public class GradientTextView extends android.support.v7.widget.AppCompatTextView {

public GradientTextView(Context context) {
    super(context);
}

public GradientTextView(Context context,AttributeSet attrs) {
    super(context,attrs);
}

public GradientTextView(Context context,AttributeSet attrs,int defStyleAttr) {
    super(context,attrs,defStyleAttr);
}

@Override
protected void onLayout(boolean changed,int left,int top,int right,int bottom) {
    super.onLayout(changed,left,top,right,bottom);

    //Setting the gradient if layout is changed
    if (changed) {
        getPaint().setShader(new LinearGradient(0,getWidth(),getHeight(),ContextCompat.getColor(getContext(),R.color.colorStart),//Red Color
                ContextCompat.getColor(getContext(),R.color.colorEnd),// Blue Color
                Shader.TileMode.CLAMP));
    }
}

}

这是渐变textview的xml

<package.GradientTextView
        android:id="@+id/textLogin"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Login."
        android:textStyle="bold"
        android:padding="4dp"
        android:layout_marginStart="8dp"/>

现在我有一个带有红色和蓝色渐变的textview.
我想动态更改渐变颜色.

以编程方式更改颜色的最佳方法是什么？

在回答@Nicola gallazzi之后,我正在更新我的问题现在GradientTextView的新文件是

public class GradientTextView extends android.support.v7.widget.AppCompatTextView {


int colorStart = ContextCompat.getColor(getContext(),R.color.colorStart);
int colorEnd = ContextCompat.getColor(getContext(),R.color.colorEnd);

public GradientTextView(Context context) {
    super(context);
}

public GradientTextView(Context context,bottom);
    //Setting the gradient if layout is changed
    if (changed) {
        getPaint().setShader(new LinearGradient(0,colorStart,colorEnd,Shader.TileMode.CLAMP));
    }
}

public void setGradientColors(int colorStart,int colorEnd) {
    this.colorStart = colorStart;
    this.colorEnd = colorEnd;
    // this forces view redrawing
    invalidate();
}

}

但是这是一个新问题,就是我在@Nicola gallazzi这样的活动中使用它时显示错误.

码

        textView.setGradientColors(ContextCompat.getColor(this,R.color.ncolorEnd,R.color.ncolorStart));

错误

最佳答案

您应该将colorStart和colorEnd定义为GradientTextView类的实例变量.
然后,在类中定义一个公共方法,以编程方式设置colorStart和colorEnd：

public class GradientTextView extends android.support.v7.widget.AppCompatTextView {

    private int colorStart = ContextCompat.getColor(getContext(),R.color.colorPrimary);
    private int colorEnd = ContextCompat.getColor(getContext(),R.color.colorAccent);


    public GradientTextView(Context context) {
        super(context);
    }

    public GradientTextView(Context context,AttributeSet attrs) {
        super(context,attrs);
    }

    public GradientTextView(Context context,int defStyleAttr) {
        super(context,defStyleAttr);
    }

    @Override
    protected void onSizeChanged(int w,int h,int oldw,int oldh) {
        super.onSizeChanged(w,h,oldw,oldh);
    }

    @Override
    protected void onLayout(boolean changed,int bottom) {
        super.onLayout(changed,bottom);
        //Setting the gradient if layout is changed
        if (changed) {
            getPaint().setShader(new LinearGradient(0,Shader.TileMode.CLAMP));
        }
    }

    public void setGradientColors(int colorStart,int colorEnd) {
        this.colorStart = colorStart;
        this.colorEnd = colorEnd;
        // this forces view redrawing
        invalidate();
    }

}