如何在一个可绘制的程序中添加一个笔画？

Question

我有这样的代码。

我的可画线包裹着另一个可画线（圆形）。

我如何以编程方式为内部的可绘制对象添加笔触？

public final class HighlightCircleDrawable extends Drawable implements Drawable.Callback {

  private final Drawable toHighlight;
  private final Paint paint = new Paint();

//...

  public HighlightCircleDrawable(Drawable toHighlight) {
    this.toHighlight = toHighlight;
    toHighlight.setCallback(this);
    paint.setStyle(Paint.Style.FILL);
    paint.setColor(Color.GRAY);
  }

  @Override
  public void draw(Canvas canvas) {
    canvas.drawOval(pulseBounds, paint);
    toHighlight.draw(canvas);
  }

Answer 1

首先，你需要做背景，你应该使用整个画布来做。从填充画布开始，然后应用你的填充，但关键是对背景Paint使用较小的bounds，使borderPaint包围高光Paint。

final Paint borderPaint = new Paint();
borderPaint.setStyle(Paint.Style.FILL);
borderPaint.setColor(borderColor);
borderPaint.setAntiAlias(true);
borderPaint.setDither(true);

...

canvas.drawOval(rect, borderPaint);
canvas.drawOval(pulseBounds, paint);