Android开发自定义水印图片

上一篇的自定义View中的测量绘制 http://blog.csdn.net/jinjin10086/article/details/54947301

在此基础上，本次在此基础上继续进行学习。

本次的目标是在上一篇的基础上给普通的图片加上水印，实际的应用如csdn上传图片、微信公众号上传图片，都会自动给图片加上水印，当然本次只是给加上水印，可设置水印的颜色，内容，规格大小（small为14号字体，normal为16号字体，big为18号字体）等。

实现的效果如下：

接下来解析具体得实现过程：

1）和上次的一样，继承自View重写其构造方法，如下：

 public DemoImageView01(Context context) {
        this(context,null);
    }

    public DemoImageView01(Context context, AttributeSet attrs) {
        this(context, attrs,0);
    }

    public DemoImageView01(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    
    }

2）自定义属性如下：

    1，属性的自定义内容：

2，取到相关的属性如下（对于图片资源进行直接解析）：

    TypedArray array = context.getTheme().obtainStyledAttributes(attrs, R.styleable.DemoImageView01,defStyleAttr,0);
        for (int i = 0; i < array.getIndexCount(); i++) {
            int attr = array.getIndex(i);
            switch (attr){
                case R.styleable.DemoImageView01_image:
                    Log.d("test","image-->" + array.getResourceId(attr,0));
                    mImageSrc = BitmapFactory.decodeResource(getResources(),array.getResourceId(attr,0));
                    break;
                case R.styleable.DemoImageView01_watermark:
                    mWatermark = array.getString(attr);
                    break;
                case R.styleable.DemoImageView01_watermarkcolor:
                    mWatermarkColor = array.getColor(attr, Color.BLUE);
                    break;
                case R.styleable.DemoImageView01_watermarksize:
                    int style = array.getInt(attr,0);
                    switch (style){
                        case 0:
                            mWatermarkSize = (int)TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP, 14, getResources().getDisplayMetrics());
                            break;
                        case 1:
                            mWatermarkSize = (int)TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP, 16, getResources().getDisplayMetrics());
                            break;
                        case 2:
                            mWatermarkSize = (int)TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP, 18, getResources().getDisplayMetrics());
                            break;
                        default:
                            break;
                    }
                    break;
                default:
                    break;
            }
        }

3）初始化画笔及绘制范围如下：

 mPaint = new Paint();
        mBound = new Rect();
        mWaterMarkBound = new Rect();
        mPaint.setTextSize(mWatermarkSize);
        mPaint.getTextBounds(mWatermark, 0, mWatermark.length(), mWaterMarkBound);

4）测量，重写方法onMeasure如下：

  @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        int widthMode = MeasureSpec.getMode(widthMeasureSpec);
        int widthSize = MeasureSpec.getSize(widthMeasureSpec);
        int heightMode = MeasureSpec.getMode(heightMeasureSpec);
        int heightSize = MeasureSpec.getSize(heightMeasureSpec);
        if (widthMode == MeasureSpec.EXACTLY){
            mWidth = widthSize;
        }else {
            //图片的宽度  （注：水印覆盖在图片上，不占宽度）
            int desire = getPaddingLeft() + getPaddingRight() + mImageSrc.getWidth();
            mWidth = Math.min(desire,widthSize);
        }
        if (heightMode == MeasureSpec.EXACTLY){
            mHeight  = heightSize;
        }else {
            ///图片的宽度  （注：水印覆盖在图片上，不占高度）
            int desire = getPaddingTop() + getPaddingBottom() + mImageSrc.getHeight();
            mHeight = Math.min(desire,heightSize);
        }
        Log.d("test","mWidth" + mWidth);
        Log.d("test","mHeight" + mHeight);
        setMeasuredDimension(mWidth,mHeight);
    }

5）绘制，重写onDraw方法如下：

 @Override
    protected void onDraw(Canvas canvas) {

        /*
        整体绘制区域的规定
         */
        mBound.left = getPaddingLeft();
        mBound.right = mWidth - getPaddingRight();
        mBound.top = getPaddingTop();
        mBound.bottom = mHeight - getPaddingBottom();

        mPaint.setStyle(Paint.Style.FILL);
        mPaint.setColor(Color.YELLOW);
        //绘制图片
        canvas.drawBitmap(mImageSrc,null,mBound,mPaint);

        mPaint.setTextSize(mWatermarkSize);
        mPaint.getTextBounds(mWatermark,0,mWatermark.length(),mWaterMarkBound);
        mPaint.setColor(mWatermarkColor);
        /*
            如果水印的宽度 大于整体区域的宽度
         */
        if (mWaterMarkBound.width() > mWidth){
            TextPaint paint = new TextPaint(mPaint);
            String mWaterMarkNow = TextUtils.ellipsize(mWatermark,paint,(float) (mWidth - getPaddingLeft() - getPaddingRight()), TextUtils.TruncateAt.END).toString();
            canvas.drawText(mWaterMarkNow,getPaddingLeft(), mHeight - getPaddingBottom() - mWaterMarkBound.height(), mPaint);
        }else {
            canvas.drawText(mWatermark, mWidth - mWaterMarkBound.width() - getPaddingRight() , mHeight - getPaddingBottom() - mWaterMarkBound.height(), mPaint);
        }

    }

6）自定义控件的使用如下：

到此，即可实现上述的显示效果。

源码下载：

MyDemo