Android：实现IM多人员组合的群组头像

说明：

此头像类似微信群组头像，整个头像由组内前N位人员的头像组合而成，可用网络或本地图片进行组合，最终显示为一个头像整体，看效果图：

一、自定义整体头像的ViewGroup，计算并保存宽高(重写onMeasure)：

@Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        mWidth = getWidth(widthMeasureSpec);
        mHeight = getHeight(heightMeasureSpec);
        setMeasuredDimension(mWidth, mHeight);
    }

    private int getWidth(int measureSpec) {
        int width = MIN_WIDTH_AND_HEIGHT;
        int specMode = MeasureSpec.getMode(measureSpec);
        int specSize = MeasureSpec.getSize(measureSpec);
        if (specMode == MeasureSpec.EXACTLY) {
            width = specSize;
        } else if (specMode == MeasureSpec.AT_MOST) {
            width = Math.min(MIN_WIDTH_AND_HEIGHT, specSize);
        }
        return width;
    }

    private int getHeight(int measureSpec) {
        int height = MIN_WIDTH_AND_HEIGHT;
        int specMode = MeasureSpec.getMode(measureSpec);
        int specSize = MeasureSpec.getSize(measureSpec);
        if (specMode == MeasureSpec.EXACTLY) {
            height = specSize;
        } else if (specMode == MeasureSpec.AT_MOST) {
            height = Math.min(MIN_WIDTH_AND_HEIGHT, specSize);
        }
        return height;
    }

二、布局子头像的View(重写onLayout，对每个子头像进行布局)：

@Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        layoutChild();
    }

    private void layoutChild() {
        if (mImgUrls == null || mImgUrls.isEmpty()) {
            return;
        }
        for (int i = 0; i < mImgSize; i++) {
            ImageView itemV = (ImageView) getChildAt(i);
            int left = 0, top = 0, right = 0, bottom = 0;
            /*
            对每个item的View计算left、top、right、bottom四个值
             */
            ...
            itemV.layout(left, top, right, bottom);  //真正布局子头像位置
            showImage(itemV, mImgUrls.get(i));  //加载并显示子头像图片
        }
    }

三、加载并显示各子头像(使用Glide加载并显示每个子头像)

private void showImage(Context context, ImageView iv, String url) {
        if (TextUtils.isEmpty(url)) {
            Bitmap bmp = BitmapFactory.decodeResource(context.getResources(), R.mipmap.user_default_icon);
            iv.setImageBitmap(bmp);
            return;
        }
        Glide.with(context).load(url)
                .diskCacheStrategy(DiskCacheStrategy.ALL)
                .dontAnimate()
                .placeholder(R.mipmap.user_default_icon)
                .error(R.mipmap.user_default_icon)
                .into(iv);
    }

到此多图片组合头像已经完成，不过想要圈形的还需要进行以下步奏

四、裁剪整个群头像为圆形(重写dispatchDraw)：

@Override
    protected void dispatchDraw(Canvas canvas) {
        Path path = new Path();
        path.addCircle(mWidth / 2, mHeight / 2, mWidth / 2, Path.Direction.CW);
        canvas.clipPath(path);
        canvas.drawColor(Color.TRANSPARENT);
        super.dispatchDraw(canvas);
        drawGroupView(canvas);
    }

    /**
     * 绘制各头像间隔线
     * @param canvas
     */
    private void drawGroupView(Canvas canvas) {
        /*
        计算各条线的x和y坐标值
         */
        float[] point1 = new float[2], point2 = new float[2];
        ...
        drawLine(canvas, point1, point2);
    }

    /**
     * 绘制直线
     */
    private void drawLine(Canvas canvas, float[] point1, float[] point2) {
        mPaint.reset();
        mPaint.setAntiAlias(true);
        mPaint.setStrokeWidth(mInterval);
        mPaint.setColor(Color.WHITE);
        mPaint.setStyle(Paint.Style.STROKE);
        canvas.drawLine(point1[0], point1[1], point2[0], point2[1], mPaint);
    }

五、暴露公共方法供外部调用：

/**
     * 设置图片url集合
     *
     * @param imgs 图片url集合
     */
    public void setImages(List<String> imgs) {
        if (imgs == null || imgs.isEmpty()) {
            return;
        }
        if (imgs.size() > MAX_SIZE) {
            imgs = imgs.subList(0, MAX_SIZE);
        }
        removeAllViews();
        mImgUrls = imgs;
        mImgSize = imgs.size();
        for (int i = 0; i < mImgSize; i++) {
            View v = getItemView(i);
            if (v == null) {
                return;
            }
            addView(v, generateDefaultLayoutParams());
        }
        requestLayout();
    }

    /**
     * 设置单个图片url
     *
     * @param img 图片url
     */
    public void setImageUrl(String img) {
        ArrayList imgUrls = new ArrayList<>();
        imgUrls.add(img);
        setImages(imgUrls);
    }

    /**
     * 生成一个头像布局
     */
    private ImageView getItemView(int position) {
        ...
    }

六、使用：

1.写一个布局文件放自定义群组头像控件：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:layout_width="match_parent"
              android:layout_height="match_parent"
              android:background="#f2f2f2"
              android:orientation="vertical">

    <com.yyh.im.ui.widget.HeadView
        android:id="@+id/cv_head"
        android:layout_width="150dp"
        android:layout_height="150dp"/>

</LinearLayout>

2.代码中群组头像控件显示图片：

@BindView(R2.id.cv_head)
    public HeadView mHeadCv;

    private String[] IMG_URL_LIST = {
            "https://ss3.bdstatic.com/70cFv8Sh_Q1YnxGkpoWK1HF6hhy/it/u=416954025,2289731303&fm=27&gp=0.jpg",
            "https://ss1.bdstatic.com/70cFuXSh_Q1YnxGkpoWK1HF6hhy/it/u=704997830,3098922597&fm=27&gp=0.jpg",
            "https://ss1.bdstatic.com/70cFvXSh_Q1YnxGkpoWK1HF6hhy/it/u=1375449509,557259337&fm=27&gp=0.jpg",
            "https://ss2.bdstatic.com/70cFvnSh_Q1YnxGkpoWK1HF6hhy/it/u=2825392570,1862752263&fm=27&gp=0.jpg",
            "https://ss1.bdstatic.com/70cFvXSh_Q1YnxGkpoWK1HF6hhy/it/u=3252489351,440833245&fm=27&gp=0.jpg",
            "https://ss0.bdstatic.com/70cFuHSh_Q1YnxGkpoWK1HF6hhy/it/u=3586311245,3082636880&fm=27&gp=0.jpg"
    };

    private void showImage(){
        ArrayList<String> list = new ArrayList<>();
        for (int i = 0; i < 6; i++) {
            list.add(IMG_URL_LIST[i]);
        }
        mHeadCv.setImageUrls(list);
    }