Android 在图片的指定位置添加标记

  这些天，项目里加了一个功能效果，场景是： 假如有一个家居图片，图片里，有各样的家居用品： 桌子，毛巾，花瓶等等，需要在指定的商品处添加标记，方便用户直接看到商品，点击该标记，可以进入到商品详情页 。实现的效果图如下：

  要实现如上效果，有两个思路。

  思路1，通过addView，在容器（如FrameLayout）的特定位置，添加标记组件，同事在将ImageView页添加进容器中，保证容器的大小和ImageView的大小相同，这样可以确认标记点的位置不会出现错差。 

  思路2，通过绘制Bitmap，将背景图片和标记点绘制成同一张图片。

  比较两种方法，思路2有些不太妥的地方，1是不好实现标记图标的点击事件；2是不太容易扩展，比如标记点不仅仅是一个图片，而是一个弹框组件，有图有文。 所以，考虑再三后，决定选择第一种实现方式。

1. 自定义布局，包含放置标记图标的容器及显示底部图片的ImageView。

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <ImageView
        android:id="@+id/imgBg"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:adjustViewBounds="true"
        android:maxHeight="1000dp"
        android:scaleType="centerCrop" />

    <FrameLayout
        android:id="@+id/layouPoints"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="center" />

</FrameLayout>

2. 自定义组件，便于添加标记图标、加载背景图

import android.content.Context;
import android.graphics.drawable.AnimationDrawable;
import android.util.AttributeSet;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.FrameLayout;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.Toast;

import com.bumptech.glide.Glide;
import com.lnyp.imgdots.R;
import com.lnyp.imgdots.bean.PointSimple;

import java.util.ArrayList;

public class ImageLayout extends FrameLayout implements View.OnClickListener {

    ArrayList<PointSimple> points;

    FrameLayout layouPoints;

    ImageView imgBg;

    Context mContext;

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

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

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

        initView(context, attrs);
    }


    private void initView(Context context, AttributeSet attrs) {

        mContext = context;

        View imgPointLayout = inflate(context, R.layout.layout_imgview_point, this);

        imgBg = (ImageView) imgPointLayout.findViewById(R.id.imgBg);
        layouPoints = (FrameLayout) imgPointLayout.findViewById(R.id.layouPoints);
    }

    public void setImgBg(int width, int height, String imgUrl) {

        ViewGroup.LayoutParams lp = imgBg.getLayoutParams();
        lp.width = width;
        lp.height = height;

        imgBg.setLayoutParams(lp);

        ViewGroup.LayoutParams lp1 = layouPoints.getLayoutParams();
        lp1.width = width;
        lp1.height = height;

        layouPoints.setLayoutParams(lp1);

        Glide.with(mContext).load(imgUrl).asBitmap().into(imgBg);

        addPoints(width, height);

    }

    public void setPoints(ArrayList<PointSimple> points) {

        this.points = points;
    }

    private void addPoints(int width, int height) {

        layouPoints.removeAllViews();

        for (int i = 0; i < points.size(); i++) {

            double width_scale = points.get(i).width_scale;
            double height_scale = points.get(i).height_scale;


            LinearLayout view = (LinearLayout) LayoutInflater.from(mContext).inflate(R.layout.layout_img_point, this, false);
            ImageView imageView = (ImageView) view.findViewById(R.id.imgPoint);
            imageView.setTag(i);

            AnimationDrawable animationDrawable = (AnimationDrawable) imageView.getDrawable();
            animationDrawable.start();

            LayoutParams layoutParams = (LayoutParams) view.getLayoutParams();

            layoutParams.leftMargin = (int) (width * width_scale);
            layoutParams.topMargin = (int) (height * height_scale);

            imageView.setOnClickListener(this);

            layouPoints.addView(view, layoutParams);
        }
    }


    @Override
    public void onClick(View view) {
        int pos = (int) view.getTag();
        Toast.makeText(getContext(), "pos : " + pos, Toast.LENGTH_SHORT).show();
    }
}

  来看看ImageLayout源码，里面有两个重要的方法：

·public void setImgBg(int width, int height, String imgUrl) 该方法主要根据图片的大小，设置标记图容器的大小，然后加载背景图。

·private void addPoints(int width, int height)  该方法主要向记图容器中添加标记图。

3.PointSimple.java

public class PointSimple {

    // 标记点相对于横向的宽度的比例
    public double width_scale;
    // 标记点相对于横向的高度的比例
    public double height_scale;

}

4. 添加背景图和标记图

 4.1 首先，准备一些测试数据

 private void initData() {

        imgSimples = new ArrayList<>();

        ImgSimple imgSimple1 = new ImgSimple();
        imgSimple1.url = "http://o79w6dswy.bkt.clouddn.com/img5.png";
        imgSimple1.scale = 1.6f;

        ArrayList<PointSimple> pointSimples = new ArrayList<>();
        PointSimple pointSimple1 = new PointSimple();
        pointSimple1.width_scale = 0.36f;
        pointSimple1.height_scale = 0.75f;

        PointSimple pointSimple2 = new PointSimple();
        pointSimple2.width_scale = 0.64f;
        pointSimple2.height_scale = 0.5f;


        PointSimple pointSimple3 = new PointSimple();
        pointSimple3.width_scale = 0.276f;
        pointSimple3.height_scale = 0.764f;

        PointSimple pointSimple4 = new PointSimple();
        pointSimple4.width_scale = 0.638f;
        pointSimple4.height_scale = 0.74f;

        PointSimple pointSimple5 = new PointSimple();
        pointSimple5.width_scale = 0.796f;
        pointSimple5.height_scale = 0.526f;

        PointSimple pointSimple6 = new PointSimple();
        pointSimple6.width_scale = 0.486f;
        pointSimple6.height_scale = 0.364f;

        pointSimples.add(pointSimple1);
        pointSimples.add(pointSimple2);
        pointSimples.add(pointSimple3);
        pointSimples.add(pointSimple4);
        pointSimples.add(pointSimple5);
        pointSimples.add(pointSimple6);

        imgSimple1.pointSimples = pointSimples;


        ImgSimple imgSimple2 = new ImgSimple();
        imgSimple2.url = "http://o79w6dswy.bkt.clouddn.com/img3.png";
        imgSimple2.scale = 1.6f;

        ArrayList<PointSimple> pointSimples2 = new ArrayList<>();
        PointSimple pointSimple7 = new PointSimple();
        pointSimple7.width_scale = 0.36f;
        pointSimple7.height_scale = 0.75f;

        PointSimple pointSimple8 = new PointSimple();
        pointSimple8.width_scale = 0.64f;
        pointSimple8.height_scale = 0.5f;


        PointSimple pointSimple9 = new PointSimple();
        pointSimple9.width_scale = 0.276f;
        pointSimple9.height_scale = 0.764f;


        pointSimples2.add(pointSimple7);
        pointSimples2.add(pointSimple8);
        pointSimples2.add(pointSimple9);

        imgSimple2.pointSimples = pointSimples2;


        ImgSimple imgSimple3 = new ImgSimple();
        imgSimple3.url = "http://o79w6dswy.bkt.clouddn.com/421428.jpg";
        imgSimple3.scale = 0.75f;

        ArrayList<PointSimple> pointSimples3 = new ArrayList<>();
        PointSimple pointSimple11 = new PointSimple();
        pointSimple11.width_scale = 0.1f;
        pointSimple11.height_scale = 0.3f;

        PointSimple pointSimple12 = new PointSimple();
        pointSimple12.width_scale = 0.3f;
        pointSimple12.height_scale = 0.5f;


        PointSimple pointSimple13 = new PointSimple();
        pointSimple13.width_scale = 0.5f;
        pointSimple13.height_scale = 0.8f;


        pointSimples3.add(pointSimple11);
        pointSimples3.add(pointSimple12);
        pointSimples3.add(pointSimple13);

        imgSimple3.pointSimples = pointSimples3;

        imgSimples.add(imgSimple1);
        imgSimples.add(imgSimple2);
        imgSimples.add(imgSimple3);
    }

 4.2 加载图片和添加标记物，因为要做可以滑动展示的效果，所以在ViewPager的PagerAdapter中进行功能添加。

import android.app.Activity;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.util.DisplayMetrics;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.LinearLayout;

import com.lnyp.imgdots.R;
import com.lnyp.imgdots.bean.ImgSimple;
import com.lnyp.imgdots.bean.PointSimple;
import com.lnyp.imgdots.view.ImageLayout;

import java.util.ArrayList;
import java.util.List;

public class ImgBrowsePagerAdapter extends PagerAdapter {

    List<ImgSimple> imgSimples;

    List<View> views;

    Activity mContext;

    private int width;

    public ImgBrowsePagerAdapter(Activity context, List<ImgSimple> imgSimples) {

        this.mContext = context;
        this.imgSimples = imgSimples;

        this.views = new ArrayList<>();

        DisplayMetrics dm = new DisplayMetrics();
        context.getWindowManager().getDefaultDisplay().getMetrics(dm);

        width = dm.widthPixels;
    }

    @Override
    public int getCount() { // 获得size
        return imgSimples.size();
    }

    @Override
    public boolean isViewFromObject(View arg0, Object arg1) {
        return arg0 == arg1;
    }

    @Override
    public void destroyItem(ViewGroup container, int position, Object object) {

        ((ViewPager) container).removeView((View) object);
    }

    @Override
    public Object instantiateItem(ViewGroup container, int position) {

        LinearLayout view = (LinearLayout) LayoutInflater.from(mContext).inflate(R.layout.layout_img_browse, null);
        ImageLayout layoutContent = (ImageLayout) view.findViewById(R.id.layoutContent);

        try {

            String imgUrl = imgSimples.get(position).url;
            float scale = imgSimples.get(position).scale;
            ArrayList<PointSimple> pointSimples = imgSimples.get(position).pointSimples;

            layoutContent.setPoints(pointSimples);

            int height = (int) (width * scale);

            layoutContent.setImgBg(width, height, imgUrl);
        } catch (Exception e) {
            e.printStackTrace();
        }

        ((ViewPager) container).addView(view);

        return view;
    }
}

  4.3 适配器的布局文件layout_img_browse.xml，其中包含了上方自定义的组件ImageLayout

<?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:gravity="center"
    android:orientation="vertical">

    <com.lnyp.imgdots.view.ImageLayout
        android:id="@+id/layoutContent"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true" />

</LinearLayout>

  此处，稍微讲下ImgBrowsePagerAdapter的instantiateItem(ViewGroup container, int position)方法，在该方法中，我们根据屏幕的宽度，对图片进行等比缩放，计算出了缩放后图片的大小（height和width）， 该height和width也就是我们将要添加标记物所在的容器的大小。

  通过加载了布局文件，获取ImageLayout对象； 然后，有了这个对象，及计算出的height和width，我们就可以动态的添加背景图及标记物的位置。

  因为图片是经过等比缩放的，而标记物的位置是相对于图片的，所以在相同大小的容器添加标记物，它的位置不会出现偏差。

  通过以上几步，便可以实现前面动态图中的功能效果了。

  如有疑问或建议，欢迎进QQ群讨论：487786925（ Android研发村 ）

 

项目github地址：https://github.com/zuiwuyuan/ImgDots