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我们。