Android开发常用的工具类：ImageUtils添加文字或图片水印

ImageUtils
设置水印图片在左上角
调用createWaterMaskLeftTop(Context context, Bitmap src, Bitmap watermark,int paddingLeft, int paddingTop)
设置水印图片到右上角
调用createWaterMaskRightTop( Context context, Bitmap src, Bitmap watermark,int paddingRight, int paddingTop)
设置水印图片到中间
调用createWaterMaskCenter(Bitmap src, Bitmap watermark)
设置水印图片到左下角
调用createWaterMaskLeftBottom( Context context, Bitmap src, Bitmap watermark,int paddingLeft, int paddingBottom)
设置水印图片在右下角
调用reateWaterMaskLeftTop(Context context, Bitmap src, Bitmap watermark,int paddingLeft, int paddingTop)

给图片添加文字到左上角
调用drawTextToLeftTop(Context context, Bitmap bitmap, String text,int size, int color, int paddingLeft, int paddingTop)
给图片添加文字到右上角
调用drawTextToRightTop(Context context, Bitmap bitmap, String text, int size, int color, int paddingRight, int paddingTop)
给图片添加文字到中间
调用reateWaterMaskLeftTop(Context context, Bitmap src, Bitmap watermark,int paddingLeft, int paddingTop)
给图片添加文字到左下角
调用drawTextToLeftBottom(Context context, Bitmap bitmap, String text, int size, int color, int paddingLeft, int paddingBottom)
给图片添加文字到右下角
调用drawTextToRightBottom(Context context, Bitmap bitmap, String text, int size, int color, int paddingRight, int paddingBottom)

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Rect;

/**
 * Created by cs_android on 2018/1/12.
 * 添加文字或水印
 */

public class ImageUtils {


    /**
     * 设置水印图片在左上角
     */
    public static Bitmap createWaterMaskLeftTop(Context context, Bitmap src, Bitmap watermark,
                                                int paddingLeft, int paddingTop) {
        return createWaterMaskBitmap(src, watermark, dp_to_px(context, paddingLeft),
                dp_to_px(context, paddingTop));
    }
    /**
     * 设置水印图片到右上角
     *
     */
    public static Bitmap createWaterMaskRightTop(
            Context context, Bitmap src, Bitmap watermark,
            int paddingRight, int paddingTop) {
        return createWaterMaskBitmap(src, watermark,
                src.getWidth() - watermark.getWidth() - dp_to_px(context, paddingRight),
                dp_to_px(context, paddingTop));
    }
    /**
     * 设置水印图片到中间
     */
    public static Bitmap createWaterMaskCenter(Bitmap src, Bitmap watermark) {
        return createWaterMaskBitmap(src, watermark,
                (src.getWidth() - watermark.getWidth()) / 2,
                (src.getHeight() - watermark.getHeight()) / 2);
    }
    /**
     * 设置水印图片到左下角
     */
    public static Bitmap createWaterMaskLeftBottom(
            Context context, Bitmap src, Bitmap watermark,
            int paddingLeft, int paddingBottom) {
        return createWaterMaskBitmap(src, watermark, dp_to_px(context, paddingLeft),
                src.getHeight() - watermark.getHeight() - dp_to_px(context, paddingBottom));
    }

    /**
     * 设置水印图片在右下角
    */
    public static Bitmap createWaterMaskRightBottom(
            Context context, Bitmap src, Bitmap watermark,
            int paddingRight, int paddingBottom) {
        return createWaterMaskBitmap(src, watermark,
                src.getWidth() - watermark.getWidth() - dp_to_px(context, paddingRight),
                src.getHeight() - watermark.getHeight() - dp_to_px(context, paddingBottom));
    }

    /**
     * 添加图片水印
     * @param bitmap
     * @param watermark
     * @param paddingLeft
     * @param paddingTop
     * @return
     */
    private static Bitmap createWaterMaskBitmap(Bitmap bitmap, Bitmap watermark, int paddingLeft, int paddingTop) {
        if (bitmap == null) {
            return null;
        }
        int width = bitmap.getWidth();
        int height = bitmap.getHeight();
        //创建一个bitmap
        Bitmap newb = Bitmap.createBitmap(width, height, Bitmap.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(bitmap, 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;
    }

    /**
     * 给图片添加文字到左上角
     */
    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(dp_to_px(context, size));
        Rect bounds = new Rect();
        paint.getTextBounds(text, 0, text.length(), bounds);
        return drawTextToBitmap(context, bitmap, text, paint, bounds,
                dp_to_px(context, paddingLeft),
                dp_to_px(context, paddingTop) + bounds.height());
    }
    /**
     *  给图片添加文字到右上角
     */
    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(dp_to_px(context, size));
        Rect bounds = new Rect();
        paint.getTextBounds(text, 0, text.length(), bounds);
        return drawTextToBitmap(context, bitmap, text, paint, bounds,
                bitmap.getWidth() - bounds.width() - dp_to_px(context, paddingRight),
                dp_to_px(context, paddingTop) + bounds.height());
    }
    /**
     *  给图片添加文字到中间
     */
    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(dp_to_px(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);
    }
    /**
     *  给图片添加文字到左下角
     */
    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(dp_to_px(context, size));
        Rect bounds = new Rect();
        paint.getTextBounds(text, 0, text.length(), bounds);
        return drawTextToBitmap(context, bitmap, text, paint, bounds,
                dp_to_px(context, paddingLeft),
                bitmap.getHeight() - dp_to_px(context, paddingBottom));
    }

    /**
     *  给图片添加文字到右下角
     */
    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(dp_to_px(context, size));
        Rect bounds = new Rect();
        paint.getTextBounds(text, 0, text.length(), bounds);
        return drawTextToBitmap(context, bitmap, text, paint, bounds,
                bitmap.getWidth() - bounds.width() - dp_to_px(context, paddingRight),
                bitmap.getHeight() - dp_to_px(context, paddingBottom));
    }


    /**
     *
     * @param context
     * @param bitmap
     * @param text
     * @param paint
     * @param bounds
     * @param paddingLeft
     * @param paddingTop
     * @return
     */
    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;
    }


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