自定义视图中的渐变文本颜色

Question

我有这个扩展 AppCompatTextView

的 GradientTextView class

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, 0, getWidth(), getHeight(),
                ContextCompat.getColor(getContext(), R.color.colorStart),//Red Color
                ContextCompat.getColor(getContext(), R.color.colorEnd),// Blue Color
                Shader.TileMode.CLAMP));
    }
}

}

这里是渐变textviewxml

<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文本视图。我想动态改变渐变颜色。

以编程方式更改颜色的最佳方法是什么？

@Nicola Gallazzi 回答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, 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, 0, getWidth(), getHeight(), colorStart, colorEnd,
                Shader.TileMode.CLAMP));
    }
}

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

}

但这是一个新问题，当我在 activity 中使用它时，@Nicola Gallazzi 显示错误。

代码

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

错误

Answer 1

您可以简单地从 java 代码创建渐变可绘制对象，如下所示 -

GradientDrawable drawable = new GradientDrawable();
drawable.setStroke(width, Color.RED);
drawable.setCornerRadius(8);
drawable.setColor(ContextCompat.getColor(context,R.color.colorRed));

并将可绘制对象设置为图像视图，如下所示

    imageView.setBackgroundDrawable(drawable);

Answer 2

您应该将 colorStart 和 colorEnd 定义为 GradientTextView class 的实例变量。然后，在 class 中定义一个 public 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, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, 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 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, 0, getWidth(), getHeight(), colorStart, colorEnd,
                    Shader.TileMode.CLAMP));
        }
    }

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

}

自定义视图中的渐变文本颜色

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