Android给图片加文字和图片水印实例代码

我们在做项目的时候有时候需要给图片添加水印，水寒今天就遇到了这样的问题，所以搞了一个工具类，贴出来大家直接调用就行。

/**
 * 图片工具类
 * @author 水寒
 *
 */
public class imageutil {

  /**
   * 设置水印图片在左上角
   * @param context
   * @param src
   * @param watermark
   * @param paddingleft
   * @param paddingtop
   * @return
   */
  public static bitmap createwatermasklefttop(
      context context, bitmap src, bitmap watermark,
      int paddingleft, int paddingtop) {
    return createwatermaskbitmap(src, watermark, 
        dp2px(context, paddingleft), dp2px(context, paddingtop));
  }

  private static bitmap createwatermaskbitmap(bitmap src, bitmap watermark,
      int paddingleft, int paddingtop) {
    if (src == null) {
      return null;
    }
    int width = src.getwidth();
    int height = src.getheight();
    //创建一个bitmap
    bitmap newb = bitmap.createbitmap(width, height, config.argb_8888);// 创建一个新的和src长度宽度一样的位图
    //将该图片作为画布
    canvas canvas = new canvas(newb);
    //在画布 0，0坐标上开始绘制原始图片
    canvas.drawbitmap(src, 0, 0, null);
    //在画布上绘制水印图片
    canvas.drawbitmap(watermark, paddingleft, paddingtop, null);
    // 保存
    canvas.save(canvas.all_save_flag);
    // 存储
    canvas.restore();
    return newb;
  }

  /**
   * 设置水印图片在右下角
   * @param context
   * @param src
   * @param watermark
   * @param paddingright
   * @param paddingbottom
   * @return
   */
  public static bitmap createwatermaskrightbottom(
      context context, bitmap src, bitmap watermark,
      int paddingright, int paddingbottom) {
    return createwatermaskbitmap(src, watermark, 
        src.getwidth() - watermark.getwidth() - dp2px(context, paddingright), 
        src.getheight() - watermark.getheight() - dp2px(context, paddingbottom));
  }

  /**
   * 设置水印图片到右上角
   * @param context
   * @param src
   * @param watermark
   * @param paddingright
   * @param paddingtop
   * @return
   */
  public static bitmap createwatermaskrighttop(
      context context, bitmap src, bitmap watermark,
      int paddingright, int paddingtop) {
    return createwatermaskbitmap( src, watermark, 
        src.getwidth() - watermark.getwidth() - dp2px(context, paddingright), 
        dp2px(context, paddingtop));
  }

  /**
   * 设置水印图片到左下角
   * @param context
   * @param src
   * @param watermark
   * @param paddingleft
   * @param paddingbottom
   * @return
   */
  public static bitmap createwatermaskleftbottom(
      context context, bitmap src, bitmap watermark,
      int paddingleft, int paddingbottom) {
    return createwatermaskbitmap(src, watermark, dp2px(context, paddingleft), 
        src.getheight() - watermark.getheight() - dp2px(context, paddingbottom));
  }

  /**
   * 设置水印图片到中间
   * @param context
   * @param src
   * @param watermark
   * @return
   */
  public static bitmap createwatermaskcenter(bitmap src, bitmap watermark) {
    return createwatermaskbitmap(src, watermark, 
        (src.getwidth() - watermark.getwidth()) / 2,
        (src.getheight() - watermark.getheight()) / 2);
  }

  /**
   * 给图片添加文字到左上角
   * @param context
   * @param bitmap
   * @param text
   * @return
   */
  public static bitmap drawtexttolefttop(context context, bitmap bitmap, string text,
      int size, int color, int paddingleft, int paddingtop) {
    paint paint = new paint(paint.anti_alias_flag);
    paint.setcolor(color);
    paint.settextsize(dp2px(context, size));
    rect bounds = new rect();
    paint.gettextbounds(text, 0, text.length(), bounds);
    return drawtexttobitmap(context, bitmap, text, paint, bounds, 
        dp2px(context, paddingleft), 
        dp2px(context, paddingtop) + bounds.height());
  }

  /**
   * 绘制文字到右下角
   * @param context
   * @param bitmap
   * @param text
   * @param size
   * @param color
   * @param paddingleft
   * @param paddingtop
   * @return
   */
  public static bitmap drawtexttorightbottom(context context, bitmap bitmap, string text,
      int size, int color, int paddingright, int paddingbottom) {
    paint paint = new paint(paint.anti_alias_flag);
    paint.setcolor(color);
    paint.settextsize(dp2px(context, size));
    rect bounds = new rect();
    paint.gettextbounds(text, 0, text.length(), bounds);
    return drawtexttobitmap(context, bitmap, text, paint, bounds, 
        bitmap.getwidth() - bounds.width() - dp2px(context, paddingright), 
        bitmap.getheight() - dp2px(context, paddingbottom));
  }

  /**
   * 绘制文字到右上方
   * @param context
   * @param bitmap
   * @param text
   * @param size
   * @param color
   * @param paddingright
   * @param paddingtop
   * @return
   */
  public static bitmap drawtexttorighttop(context context, bitmap bitmap, string text,
      int size, int color, int paddingright, int paddingtop) {
    paint paint = new paint(paint.anti_alias_flag);
    paint.setcolor(color);
    paint.settextsize(dp2px(context, size));
    rect bounds = new rect();
    paint.gettextbounds(text, 0, text.length(), bounds);
    return drawtexttobitmap(context, bitmap, text, paint, bounds, 
        bitmap.getwidth() - bounds.width() - dp2px(context, paddingright), 
        dp2px(context, paddingtop) + bounds.height());
  }

  /**
   * 绘制文字到左下方
   * @param context
   * @param bitmap
   * @param text
   * @param size
   * @param color
   * @param paddingleft
   * @param paddingbottom
   * @return
   */
  public static bitmap drawtexttoleftbottom(context context, bitmap bitmap, string text,
      int size, int color, int paddingleft, int paddingbottom) {
    paint paint = new paint(paint.anti_alias_flag);
    paint.setcolor(color);
    paint.settextsize(dp2px(context, size));
    rect bounds = new rect();
    paint.gettextbounds(text, 0, text.length(), bounds);
    return drawtexttobitmap(context, bitmap, text, paint, bounds, 
        dp2px(context, paddingleft), 
        bitmap.getheight() - dp2px(context, paddingbottom));
  }

  /**
   * 绘制文字到中间
   * @param context
   * @param bitmap
   * @param text
   * @param size
   * @param color
   * @return
   */
  public static bitmap drawtexttocenter(context context, bitmap bitmap, string text,
      int size, int color) {
    paint paint = new paint(paint.anti_alias_flag);
    paint.setcolor(color);
    paint.settextsize(dp2px(context, size));
    rect bounds = new rect();
    paint.gettextbounds(text, 0, text.length(), bounds);
    return drawtexttobitmap(context, bitmap, text, paint, bounds, 
        (bitmap.getwidth() - bounds.width()) / 2, 
        (bitmap.getheight() + bounds.height()) / 2);
  }

  //图片上绘制文字
  private static bitmap drawtexttobitmap(context context, bitmap bitmap, string text,
      paint paint, rect bounds, int paddingleft, int paddingtop) {
    android.graphics.bitmap.config bitmapconfig = bitmap.getconfig();

    paint.setdither(true); // 获取跟清晰的图像采样
    paint.setfilterbitmap(true);// 过滤一些
    if (bitmapconfig == null) {
      bitmapconfig = android.graphics.bitmap.config.argb_8888;
    }
    bitmap = bitmap.copy(bitmapconfig, true);
    canvas canvas = new canvas(bitmap);

    canvas.drawtext(text, paddingleft, paddingtop, paint);
    return bitmap;
  }

  /**
   * 缩放图片
   * @param src
   * @param w
   * @param h
   * @return
   */
  public static bitmap scalewithwh(bitmap src, double w, double h) {
    if (w == 0 || h == 0 || src == null) {
      return src;
    } else {
      // 记录src的宽高
      int width = src.getwidth();
      int height = src.getheight();
      // 创建一个matrix容器
      matrix matrix = new matrix();
      // 计算缩放比例
      float scalewidth = (float) (w / width);
      float scaleheight = (float) (h / height);
      // 开始缩放
      matrix.postscale(scalewidth, scaleheight);
      // 创建缩放后的图片
      return bitmap.createbitmap(src, 0, 0, width, height, matrix, true);
    }
  }

  /**
   * dip转pix
   * @param context
   * @param dp
   * @return
   */
  public static int dp2px(context context, float dp) { 
    final float scale = context.getresources().getdisplaymetrics().density; 
    return (int) (dp * scale + 0.5f); 
  } 
}

使用方法如下：

添加一个布局，上面是原始图片，下面是添加水印后的图片

<linearlayout xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:tools="http://schemas.android.com/tools"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:orientation="vertical">

  <textview
    android:id="@+id/sour_pic_title"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="原图" />

  <imageview 
    android:id="@+id/sour_pic"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:scaletype="centerinside"/>

  <textview
    android:id="@+id/watermark_pic_title"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="水印" />

  <imageview 
    android:id="@+id/wartermark_pic"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:scaletype="centerinside"/>

</linearlayout>

在activity中获取到imageview对象，并且获取bitmap对象，对bitmap进行canva绘图，添加水印：

/**
 * 图片工具类
 * @author 水寒
 *
 */
public class mainactivity extends activity {

  private imageview msourimage;
  private imageview mwartermarkimage;

  @override
  protected void oncreate(bundle savedinstancestate) {
    super.oncreate(savedinstancestate);
    setcontentview(r.layout.activity_main);

    initview();
  }

  private void initview(){
    msourimage = (imageview) findviewbyid(r.id.sour_pic);
    mwartermarkimage = (imageview) findviewbyid(r.id.wartermark_pic);
    bitmap sourbitmap = bitmapfactory.decoderesource(getresources(), r.drawable.sour_pic);
    msourimage.setimagebitmap(sourbitmap);

    bitmap waterbitmap = bitmapfactory.decoderesource(getresources(), r.drawable.weixin);

    bitmap watermarkbitmap = imageutil.createwatermaskcenter(sourbitmap, waterbitmap);
    watermarkbitmap = imageutil.createwatermaskleftbottom(this, watermarkbitmap, waterbitmap, 0, 0);
    watermarkbitmap = imageutil.createwatermaskrightbottom(this, watermarkbitmap, waterbitmap, 0, 0);
    watermarkbitmap = imageutil.createwatermasklefttop(this, watermarkbitmap, waterbitmap, 0, 0);
    watermarkbitmap = imageutil.createwatermaskrighttop(this, watermarkbitmap, waterbitmap, 0, 0);

    bitmap textbitmap = imageutil.drawtexttolefttop(this, watermarkbitmap, "左上角", 16, color.red, 0, 0);
    textbitmap = imageutil.drawtexttorightbottom(this, textbitmap, "右下角", 16, color.red, 0, 0);
    textbitmap = imageutil.drawtexttorighttop(this, textbitmap, "右上角", 16, color.red, 0, 0);
    textbitmap = imageutil.drawtexttoleftbottom(this, textbitmap, "左下角", 16, color.red, 0, 0);
    textbitmap = imageutil.drawtexttocenter(this, textbitmap, "中间", 16, color.red);

    mwartermarkimage.setimagebitmap(textbitmap);
  }
}

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。