Question

我在下面提供了以下代码。

public class CompassActivity extends Activity {  

  public class OuterCircle extends View {
    Paint paint = new Paint();
    Path path = new Path();
    private static final String s = "Hello world example";

    public OuterCircle(Context context) {
      super(context);
      init();
    }

    private void init() {
      paint.setColor(Color.WHITE);
      paint.setStyle(Style.STROKE);
      paint.setStrokeWidth(2);
      paint.setAntiAlias(true);
    }

    private void drawDegreesOnCircle(Canvas c) {
      path.addCircle(getWidth()/2, getHeight()/2, 180, Direction.CW);
      c.drawTextOnPath(s, path, 0, 10, paint);
    }

    public void onDraw(Canvas c) {      
      int cx = getWidth()/2;
      int cy = getHeight()/2;
      c.drawCircle(cx, cy, 170, paint);      
      drawDegreesOnCircle(c);
    } 
  }
}

圆圈已成功绘制。但是，不显示指定的字符串。代码中没有错误或警告。我在代码中遗漏了什么吗？我试图在圆圈周围显示字符串。我被困在这里。：d

Answer 1

我通过添加

解决了上述问题

setLayerType(View.LAYER_TYPE_SOFTWARE, null)

需要使用上述方法和

Canvas.drawTextOnPath(String text, Path path, float hOffset, float vOffset, Paint paint)

适用于Android API等级11或更高版本。现在，该字符串在圆圈周围成功显示。这是正确的代码。

public class CompassActivity extends Activity {  

  public class OuterCircle extends View {
    Paint paint = new Paint();
    Path path = new Path();
    private static final String s = "Hello world example";

    public OuterCircle(Context context) {
      super(context);
      init();
    }

    private void init() {
      paint.setColor(Color.WHITE);
      paint.setStyle(Style.STROKE);
      paint.setStrokeWidth(2);
      paint.setAntiAlias(true);
    }

    private void drawDegreesOnCircle(Canvas c) {
      path.addCircle(getWidth()/2, getHeight()/2, 180, Direction.CW);
      c.drawTextOnPath(s, path, 0, 10, paint);
      setLayerType(View.LAYER_TYPE_SOFTWARE, null); // Required for API level 11 or higher.
    }

    public void onDraw(Canvas c) {      
      int cx = getWidth()/2;
      int cy = getHeight()/2;
      c.drawCircle(cx, cy, 170, paint);      
      drawDegreesOnCircle(c);
    } 
  }
}

Answer 2

您错过了对drawPath()

的来电

private void drawDegreesOnCircle(Canvas c) {
  path.addCircle(getWidth()/2, getHeight()/2, 180, Direction.CW);
  c.drawPath(path, paint);
  c.drawTextOnPath(s, path, 0, 10, paint);
}

Answer 3

一个非常简单的例子，只是为了在显示屏的中心以一个角度获取文字。

public class DrawSomeText extends View {
  Paint mPaint;
  public DrawSomeText(Context context) {
    super(context);
    mPaint = new Paint();
    mPaint.setColor(Color.BLACK);
  }

  @Override
  public void onDraw(Canvas canvas) {
    Path path = new Path();
    path.moveTo(getWidth()/2, getHeight()/2);
    path.lineTo(getWidth(), getHeight());
    path.close();

    canvas.drawPath(path, mPaint);

    canvas.drawTextOnPath("Hello World", path, 0, 0, mPaint);
  }
}

Android drawTextOnPath（）不显示输出

3 个答案: