android - 试图画一个按钮 : how to set a stroke color and how to "align" a gradient to the bottom without knowing the height?

Question

我正在以编程方式创建一个按钮。它是圆形的，具有渐变背景，工作正常，看起来也不错，但我无法做我想做的两件事:

1. 设置具有给定颜色的 1 像素笔划。我尝试了 getPaint().setStroke()，但不知道如何设置描边颜色。我应该怎么做？
2. 将渐变与按钮的底部对齐，无论它的高度是多少。这可能吗？

作为引用，这是我正在使用的代码:

Button btn = new Button(context);
btn.setPadding(7, 3, 7, 5);
btn.setTextColor(text_color);

// Create a gradient for the button. Height is hardcoded to 30 (I don't know the height beforehand). 
// I wish I could set the gradient aligned to the bottom of the button.
final Shader shader = new LinearGradient(0, 0, 0, 30,
    new int[] { color_1, color_2 },
    null, Shader.TileMode.MIRROR);

float[] roundedCorner = new float[] { 5, 5, 5, 5, 5, 5, 5, 5 }
ShapeDrawable normal = new ShapeDrawable(new RoundRectShape(roundedCorner, null, null));
normal.getPaint().setShader(shader);
normal.setPadding(7, 3, 7, 5);

// Create a state list (I suppressed settings for pressed).
StateListDrawable state_list = new StateListDrawable();
state_list.addState(new int[] { }, normal);

btn.setBackgroundDrawable(state_list);

Answer 1

关于您的第一个问题，我也曾为此苦恼过，看起来 Drawables 本身(我使用的是 ShapeDrawable)或 Paint 类中没有任何合适的方法。但是，我能够扩展 ShapeDrawable 并覆盖 draw 方法，如下所示，以提供相同的结果:

public class CustomBorderDrawable extends ShapeDrawable {
    private Paint fillpaint, strokepaint;
    private static final int WIDTH = 3; 

    public CustomBorderDrawable(Shape s) {
        super(s);
        fillpaint = this.getPaint();
        strokepaint = new Paint(fillpaint);
        strokepaint.setStyle(Paint.Style.STROKE);
        strokepaint.setStrokeWidth(WIDTH);
        strokepaint.setARGB(255, 0, 0, 0);
    }

    @Override
    protected void onDraw(Shape shape, Canvas canvas, Paint fillpaint) {
        shape.draw(canvas, fillpaint);
        shape.draw(canvas, strokepaint);
    }

    public void setFillColour(int c){
        fillpaint.setColor(c);
    }
}