一、需求分析
（1）水印文字旋转
（2）水印效果处于内容布局之下
（3）水印文字的具体位置
（4）水印文字的特殊效果,例如图中的空心字体效果
二、功能实现
- 自定义view(大家瞬间就能想到Canvas工具),直接上代码
package com.newbjgoodwill.mobilecwr.view;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.support.annotation.Nullable;
import android.util.AttributeSet;
import android.view.View;
/**
* Created by zhangjianmin on 2017/7/4.
*/
public class WaterView extends View {
private String water_name;//需要回传的值
public WaterView(Context context, String user_name) {
super(context);
this.water_name = user_name;
}
public WaterView(Context context, @Nullable AttributeSet attrs) {
super(context, attrs);
}
public WaterView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
setMeasuredDimension(widthMeasureSpec, heightMeasureSpec);
}
public WaterView(Context context, @Nullable AttributeSet attrs, int defStyleAttr, int defStyleRes) {
super(context, attrs, defStyleAttr, defStyleRes);
}
@Override
protected void onDraw(Canvas canvas) {
canvas.save();
Paint paint = new Paint();
paint.setColor(Color.argb(191, 200, 215, 200));
//设置字体大小
paint.setTextSize(46);
//让画出的图形是空心的
paint.setStyle(Paint.Style.STROKE);
//设置画出的线的 粗细程度
paint.setStrokeWidth(1);
// 以文字中心轴旋转
canvas.rotate(-20, this.getWidth() / 2f, this.getHeight() / 2f);
// 按照指定点的坐标绘制文本(在这里画了四个);water_name 不能为空
canvas.drawText(water_name + "", this.getWidth() / 4f, this.getHeight() / 2f, paint);
canvas.drawText(water_name + "", this.getWidth() / 1.5f, this.getHeight() / 2f, paint);
canvas.drawText(water_name + "", this.getWidth() / 1.5f, this.getHeight() / 4f, paint);
canvas.drawText(water_name + "", this.getWidth() / 4f, this.getHeight() / 4f, paint);
super.onDraw(canvas);
canvas.restore();
}
public void setWater_name(String water_name) {
this.water_name = water_name;
}
}
- 添加水印到当前布局
如何将水印布局添加到内容布局之下，我们可以利用DecoerView来实现。在onCreate中设置了根布局后，会生成DecoerView，那么我们可以通过addView的方式，将水印布局添加，通过第二个参数来控制布局层次即可
package com.newbjgoodwill.mobilecwr;
import android.app.Activity;
import android.os.Bundle;
import android.view.ViewGroup;
import watermark.WaterView;
public class MainActivity extends Activity {
private WaterView view;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
@Override
protected void onStart() {
addWaterMarkView();
super.onStart();
}
private void addWaterMarkView() {
view=new WaterView(this,"水印");
getRootView().addView(view,-1);
}
private ViewGroup getRootView() {
ViewGroup rootView = (ViewGroup)findViewById(android.R.id.content);
return rootView;
}
}
好了，水印效果实现就是这么简单,效果图如下:
20170705162251110.jpg
