使用带有旋转的android中的画布创建一个包含4个段的圆圈

Question

我需要创建一个带有四种随机颜色的分段圆，如下所示：

http://vectips.com/wp-content/uploads/2015/04/39.png。 “一个圆圈中的4个部分”

我在引用有关使用canvas.drawArc（）的android文档时做了以下代码，但是根据我的预期，它只能显示一个段。

           Bitmap bitMap = Bitmap.createBitmap(100, 100, Bitmap.Config.ARGB_8888);

    bitMap = bitMap.copy(bitMap.getConfig(), true);
    // Construct a canvas with the specified bitmap to draw into
    Canvas canvas = new Canvas(bitMap);
    // Create a new paint with default settings.
    Paint paint = new Paint();
    // smooths out the edges of what is being drawn
    paint.setAntiAlias(true);
    // set color
    paint.setColor(Color.BLUE);

    paint.setStrokeWidth(4.5f);


    RectF oval = new RectF(200F, 200F, 450F, 450F);

    paint.setStyle(Paint.Style.FILL);
    canvas.drawArc(oval, 0F, 90F, true, paint);
    paint.setColor(Color.GREEN);
    canvas.drawArc(oval, 90F, 90F, true, paint);
    paint.setColor(Color.RED);

    canvas.drawArc(oval, 180F, 90F, true, paint);
    paint.setColor(Color.BLACK);

    canvas.drawArc(oval, 270F, 90F, true, paint);

    imageView.setImageBitmap(bitMap);

Answer 1

你的弧角是错误的。请参阅drawArc Canvas reference，角度参数如下：

• startAngle - 弧开始的起始角度（以度为单位）
• sweepAngle - 顺时针测量的扫描角度（以度为单位）

你的最后一个弧覆盖了之前的所有弧线。你应该做类似的事情（下面的Kotlin代码）：

private val oval = RectF(200F, 200F, 450F, 450F)

private val paint = Paint()

override fun onDraw(canvas: Canvas) {
  paint.style = Paint.Style.FILL

  paint.color = Color.BLACK
  canvas.drawArc(oval, 0F, 90F, true, paint)
  paint.color = Color.BLUE
  canvas.drawArc(oval, 90F, 90F, true, paint)
  paint.color = Color.RED
  canvas.drawArc(oval, 180F, 90F, true, paint)
  paint.color = Color.GREEN
  canvas.drawArc(oval, 270F, 90F, true, paint)
}

将绘制类似于：

Java版本：

  private RectF oval = new RectF(0F,0F,100F,100F);

  private Paint paint = new Paint();

  @Override
  protected void onDraw(Canvas canvas) {
    paint.setStyle(Paint.Style.FILL);

    paint.setColor(Color.BLACK);
    canvas.drawArc(oval, 0F, 90F, true, paint);
    paint.setColor(Color.BLUE);
    canvas.drawArc(oval, 90F, 1800F, true, paint)
    paint.setColor(Color.RED);
    canvas.drawArc(oval, 0F, 190F, true, paint)
    paint.setColor(Color.GREEN);
    canvas.drawArc(oval, 270F, 360F, true, paint)
  }