Android 自定义VIew实现设置防截屏、添加水印

一、自定义VIew，添加VIew的带文字斜体的背景：MarkBgView

package com.zdmtech.backgroundtextdemo;

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 androidx.annotation.IntRange;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;

import java.util.List;

public class MarkBgView 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

    public MarkBgView(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;

        // 画布背景色
        canvas.drawColor(Color.parseColor("#40F3F5F9"));
        // 水印文字的颜色
        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);
    }

}

二、Activity

1.activity代码：MarkViewActivity

package com.zdmtech.backgroundtextdemo;

import android.os.Bundle;
import android.view.WindowManager;
import android.widget.RelativeLayout;

import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;

import java.util.ArrayList;
import java.util.List;

/**
 * 设置防截屏、添加水印
 * */

public class MarkViewActivity extends AppCompatActivity {

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //设置防截屏
        getWindow().addFlags(WindowManager.LayoutParams.FLAG_SECURE);
        setContentView(R.layout.activity_main);
        initView();
    }

    public void initView() {
        RelativeLayout reView = findViewById(R.id.reView);
        // 添加水印
        List<String> labels = new ArrayList<>();
        labels.add("你");
        labels.add("我");
        labels.add("他");

        reView.setBackground(new MarkBgView(MarkViewActivity.this, labels, -30, 14));

    }
}

2.布局xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/reView"
    android:orientation="vertical">

    <TextView
        android:id="@+id/tcContent"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:text="防截屏" />

</RelativeLayout>

设置防截屏、添加水印