BGABannerAdapter 自适应屏幕宽度且保持原图片尺寸 优化方法

<pre>

package com.yourname.pro;

import android.content.Context;
import android.graphics.Point;
import android.view.ViewGroup;
import android.view.WindowManager;
import android.widget.ImageView;

import com.bumptech.glide.Glide;
import com.yourname.pro.R;

import cn.bingoogolapple.bgabanner.BGABanner;

public class BGABannerAdapter implements BGABanner.Adapter<ImageView, String> {

private Context context;
//设置图片宽高比
float scale = (float) 750 / (float) 320;
int screenWidth;

public BGABannerAdapter(Context context) {
    this.context = context;
    this.screenWidth = getScreenWidth();
}

private int getScreenWidth(){

    //获取屏幕的宽度
    WindowManager wm = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);

    Point size = new Point();
    wm.getDefaultDisplay().getSize(size);
    screenWidth = size.x;

    System.out.println("screenWidth:" + screenWidth);

    return screenWidth;
}



@Override
public void fillBannerItem(final BGABanner banner, final ImageView itemView, String model, int position) {


    System.out.println("fillBannerItem() running");

    //计算BGABanner的应有高度
    int viewHeight = Math.round(screenWidth / scale);

    //设置BGABanner的宽高属性
    ViewGroup.LayoutParams banner_params = banner.getLayoutParams();

    banner_params.width = screenWidth;
    banner_params.height = viewHeight;

    banner.setLayoutParams(banner_params);

    //此处使用的是glide的override函数直接设置图片尺寸
    Glide.with(context)
            .load(model)
            .placeholder(R.mipmap.banner_holder)
            .override(banner_params.width,banner_params.height)
            .into(itemView);
}

}

</pre>

优化为只获取一次屏幕宽度，避免fillBannerItem()函数里面多次调用。