如何在Android的MapView上绘制带有边框的文本？

Question

我正在尝试在Android的MapView上绘制一些文本。文字的绘制效果很好，但是很难阅读，因为它是白色的，没有黑色边框（就像其余的文字自然出现在MapView上以表示城市，州和国家一样）。我似乎无法弄清楚如何用黑色边框绘制文本。有人知道该怎么做吗？

这是我现在正在使用的那种代码（这只是示例代码，可以在我的一个叠加层中找到：]

@Override
public void draw(Canvas canvas, MapView mapView, boolean shadow) {
    Paint textPaint = new Paint();
    textPaint.setARGB(255, 255, 255, 255);
    textPaint.setTextAlign(Paint.Align.CENTER);
    textPaint.setTextSize(16);
    textPaint.setTypeface(Typeface.DEFAULT_BOLD);

    canvas.drawText("Some Text", 100, 100, textPaint);

    super.draw(canvas, mapView, shadow);
}

Answer 1

@Override
public void draw(Canvas canvas, MapView mapView, boolean shadow) {
    Paint strokePaint = new Paint();
    strokePaint.setARGB(255, 0, 0, 0);
    strokePaint.setTextAlign(Paint.Align.CENTER);
    strokePaint.setTextSize(16);
    strokePaint.setTypeface(Typeface.DEFAULT_BOLD);
    strokePaint.setStyle(Paint.Style.STROKE);
    strokePaint.setStrokeWidth(2);

    Paint textPaint = new Paint();
    textPaint.setARGB(255, 255, 255, 255);
    textPaint.setTextAlign(Paint.Align.CENTER);
    textPaint.setTextSize(16);
    textPaint.setTypeface(Typeface.DEFAULT_BOLD);

    canvas.drawText("Some Text", 100, 100, strokePaint);
    canvas.drawText("Some Text", 100, 100, textPaint);

    super.draw(canvas, mapView, shadow);
}

这将在文本的外部绘制2个像素的边框，然后在文本的顶部绘制文本，给您轮廓的错觉。

此外，可能值得在构造函数中设置Paints，然后仅重用它们。

Answer 2

canvas.drawText("Some Text", 100, 100, strokePaint);
canvas.drawText("Some Text", 100, 100, textPaint);

尝试与Path一起使用：

Path path = new Path();
String text = "Some Text";
textPaint.getTextPath(text, 0, text.length(), 0, 100, path);
canvas.drawPath(path, strokePaint);
canvas.drawPath(path, textPaint);

看起来更好吗？

Answer 3

textPaint.setShadowLayer(3, 0, 0, Color.BLACK);

阴影有助于使文本突出显示，但不如黑色边框好。我仍然很好奇如何解决原始问题。

Answer 4

canvas.drawText("Some Text", 99, 99, borderPaint);
canvas.drawText("Some Text", 99, 101, borderPaint);
canvas.drawText("Some Text", 101, 99, borderPaint);
canvas.drawText("Some Text", 101, 101, borderPaint);

canvas.drawText("Some Text", 100, 100, textPaint);