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;
}
4.1 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>
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
