頭像預覽幫助類，使用方法 new AvatarScanHelper(context, url).show();

import android.app.Dialog;
import android.content.Context;
import android.graphics.Rect;
import android.net.Uri;
import android.util.DisplayMetrics;
import android.view.View;
import android.view.ViewGroup;

import com.facebook.drawee.view.SimpleDraweeView;
import
 
 com.sunland.app.R;

/**
 * 頭像預覽幫助類，使用方法 new AvatarScanHelper(context, url).show();
 * 作者： FebMaple on 10/10/2016.
 * 郵箱： [email protected]
 * 版權： FebMaple
 * ====================================================
 */

public class AvatarScanHelper extends Dialog {
    private String avatarUrl;
    private
 
 Context mContext;
    private SimpleDraweeView mSimpleDraweeView;


    public AvatarScanHelper(Context context, String avatarUrl) {
        // 設定自定義樣式
        super(context, R.style.CustomDialog_fill);
        this.mContext = context;
        this.avatarUrl = avatarUrl;
        initImageView(avatarUrl);
    }


    //直接使用imageview展示頭像圖片
 

    private void initImageView(String avatarUrl) {
    //重點在於用setContentView()載入自定義佈局
        setContentView(R.layout.dialog_avatar_scan);
        mSimpleDraweeView = (SimpleDraweeView) findViewById(R.id.simple_image);
//fresco載入圖片       mSimpleDraweeView.setImageURI(Uri.parse(avatarUrl));
//點選取消對話方塊
mSimpleDraweeView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                dismiss();
            }
        });
       //todo:長按圖片儲存圖片到相簿
        setParams();
    }

    //設定對話方塊的寬高適應全屏
    private void setParams() {
        ViewGroup.LayoutParams lay = this.getWindow().getAttributes();
        DisplayMetrics dm = new DisplayMetrics();
        this.getWindow().getWindowManager().getDefaultDisplay().getMetrics(dm);
        Rect rect = new Rect();
        View view = getWindow().getDecorView();
        view.getWindowVisibleDisplayFrame(rect);
        lay.height = dm.heightPixels - rect.top;
        lay.width = dm.widthPixels;

    }
}

自定義的dialog佈局：只有一個imageview用來展示圖片

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:fresco="http://schemas.android.com/apk/res-auto"//名稱空間記得寫
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <com.facebook.drawee.view.SimpleDraweeView
        android:id="@+id/simple_image"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_gravity="center_vertical"
        fresco:actualImageScaleType="fitCenter"//圖片顯示方式必須寫，不寫不顯示圖片
        fresco:failureImage="@drawable/button_avatar_default"
        fresco:failureImageScaleType="fitCenter" />
</LinearLayout>

配置dialog的style

<style name="CustomDialog_fill" parent="@android:style/Theme.Dialog">
        <item name="android:windowFrame">@null</item>
        <item name="android:windowIsFloating">true</item>
        <item name="android:windowIsTranslucent">true</item>
        <item name="android:windowNoTitle">true</item>
        <item name="android:backgroundDimEnabled">false</item>
        <item name="android:windowBackground">@color/black</item>
    </style>