android实现文字水印效果 支持多行水印

package cn.fulushan.watermark.view;import android.content.Context;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.ColorFilter;import android.graphics.Paint;import android.graphics.PixelFormat;import android.graphics.drawable.Drawable;import android.support.annotation.IntRange;import android.support.annotation.NonNull;import android.support.annotation.Nullable;import java.util.List;/** * Created by fulushan on 18/4/5. */public class WaterMarkBg extends Drawable {  private Paint paint = new Paint();  private List<String> labels;  private Context context;  private int degress;//角度  private int fontSize;//字体大小 单位sp  /**   * 初始化构造   * @param context 上下文   * @param labels 水印文字列表 多行显示支持   * @param degress 水印角度   * @param fontSize 水印文字大小   */  public WaterMarkBg(Context context,List<String> labels, int degress,int fontSize) {    this.labels = labels;    this.context = context;    this.degress = degress;    this.fontSize = fontSize;  }  @Override  public void draw(@NonNull Canvas canvas) {    int width = getBounds().right;    int height = getBounds().bottom;    canvas.drawColor(Color.parseColor("#40F3F5F9"));    paint.setColor(Color.parseColor("#50AEAEAE"));    paint.setAntiAlias(true);    paint.setTextSize(sp2px(context,fontSize));    canvas.save();    canvas.rotate(degress);    float textWidth = paint.measureText(labels.get(0));    int index = 0;    for (int positionY = height / 10; positionY <= height; positionY += height / 10+80) {      float fromX = -width + (index++ % 2) * textWidth;      for (float positionX = fromX; positionX < width; positionX += textWidth * 2) {        int spacing = 0;//间距        for(String label:labels){          canvas.drawText(label, positionX, positionY+spacing, paint);          spacing = spacing+50;        }      }    }    canvas.restore();  }  @Override  public void setAlpha(@IntRange(from = 0, to = 255) int alpha) {  }  @Override  public void setColorFilter(@Nullable ColorFilter colorFilter) {  }  @Override  public int getOpacity() {    return PixelFormat.UNKNOWN;  }  public static int sp2px(Context context, float spValue) {    final float fontScale = context.getResources().getDisplayMetrics().scaledDensity;    return (int) (spValue * fontScale + 0.5f);  }}

public class MainActivity extends AppCompatActivity {  private TextView bg_tv;  @Override  protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);    bg_tv = findViewById(R.id.bg_tv);    SimpleDateFormat createTimeSdf1 = new SimpleDateFormat("yyyy-MM-dd");    List<String> labels = new ArrayList<>();    labels.add("用户名：张三");    labels.add("日期："+ createTimeSdf1.format(new Date()));    labels.add("不可扩散");    bg_tv.setBackgroundDrawable(new WaterMarkBg(MainActivity.this,labels,-30,13));  }}