2022-09-16 Android app 让图片在ScrollView里面等比例完整显示不变形，继承ImageView ，对ImageView 进行修改。

一、我这里有三张图片，分辨率分别是214x800、1040x375、1635x747

二、用原生的 ImageView 布局

1、布局文件

<?xml version="1.0" encoding="utf-8"?>
 
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="fill_parent">
 
    <ScrollView
        android:id="@+id/id_scrollView"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:scrollbars="vertical">
 
        <LinearLayout
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:orientation="vertical">
 
            <ImageView
                android:id="@+id/img"
                android:layout_width="fill_parent"
                android:layout_height="fill_parent"
                android:background="@drawable/one" />
 
            <ImageView
                android:id="@+id/img_two"
                android:layout_width="fill_parent"
                android:layout_height="fill_parent"
                android:background="@drawable/two" />
            <ImageView
                android:id="@+id/img_three"
                android:layout_width="fill_parent"
                android:layout_height="fill_parent"
                android:background="@drawable/three" />
        </LinearLayout>
 
    </ScrollView>
 
</RelativeLayout>

2、在1080x1920分辨率的手机上运行的效果图，会变形。

三、用继承 ImageView，对ImageView进行改造。

1、布局文件

<?xml version="1.0" encoding="utf-8"?>
 
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="fill_parent">
 
    <ScrollView
        android:id="@+id/id_scrollView"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:scrollbars="vertical">
 
        <LinearLayout
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:orientation="vertical">
 
            <com.example.animation.Image.FitImageView
                android:id="@+id/img"
                android:layout_width="fill_parent"
                android:layout_height="fill_parent"
                android:background="@drawable/one" />
 
            <com.example.animation.Image.FitImageView
                android:id="@+id/img_two"
                android:layout_width="fill_parent"
                android:layout_height="fill_parent"
                android:background="@drawable/two" />
            <com.example.animation.Image.FitImageView
                android:id="@+id/img_three"
                android:layout_width="fill_parent"
                android:layout_height="fill_parent"
                android:background="@drawable/three" />
        </LinearLayout>
 
    </ScrollView>
 
</RelativeLayout>

1、app\src\main\java\com\example\animation\Image\FitImageView.java继承ImageView类

package com.example.animation.Image;
 
import android.annotation.SuppressLint;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;
import android.view.WindowManager;
import android.widget.ImageView;
 
import com.example.animation.R;
 
 
@SuppressLint("AppCompatCustomView")
public class FitImageView extends ImageView {
    private final String TAG="FitImageView";
 
    private int screenWidth;
    private int screenHeight;
    private int displayWidth  = 0;
    private int displayHeight = 0;
    private int backgroundId;
 
    public FitImageView(Context context) {
        this(context, null);
        Log.d(TAG, "FitImageView (Context context)");
    }
 
    public FitImageView(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
        Log.d(TAG, "FitImageView(Context context, AttributeSet attrs)");
    }
 
    public FitImageView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        int textId = attrs.getAttributeResourceValue(null, "ShowText", 0);
        Log.d(TAG, "FitImageView textId "+ textId);
        backgroundId = attrs.getAttributeResourceValue("http://schemas.android.com/apk/res/android","background",0);
        Log.d(TAG, "FitImageView backgroundId "+ backgroundId );
        init();
    }
 
    public int getDisplayWidth(Context context) {
        DisplayMetrics dm = new DisplayMetrics();
        WindowManager wm = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
        wm.getDefaultDisplay().getMetrics(dm);
        return dm.widthPixels;
    }
 
    public int getDisplayHeight(Context context) {
 
        DisplayMetrics dm = new DisplayMetrics();
        WindowManager wm = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
        wm.getDefaultDisplay().getMetrics(dm);
        return  dm.heightPixels;
    }
    private void init() {
        Log.d(TAG, "init");
        screenWidth  = getDisplayWidth(getContext());
        screenHeight = getDisplayHeight(getContext());
 
        Log.d(TAG, "R.drawable.one id " + R.drawable.one);
        BitmapFactory.Options  options= new  BitmapFactory.Options();
        BitmapFactory.decodeResource(getResources(), backgroundId,options);
        Log.d(TAG, "options.outWidth&options.outHeight:" + options.outWidth + " "+options.outHeight );
 
       // Bitmap bitmap= BitmapFactory.decodeResource(getResources(), backgroundId);
       /// setImageBitmap(bitmap);
        //setImageResource(backgroundId);
        //setBackgroundResource(backgroundId);
        //setSize(bitmap.getWidth(),bitmap.getHeight());
        setSize(options.outWidth,options.outHeight);
    }
 
    public void setSize(int bitmapWidth, int bitmapHeight) {
 
        //计算出按比例拉伸后的宽度和高度
        //判断如果以图片高度拉伸到屏幕的高度,按照相应的拉伸比是否能够拉伸超过屏幕宽度或者等于屏幕宽度,否则以另一边为基准
        /*
        displayWidth = screenHeight * bitmapWidth / bitmapHeight;
        displayHeight = screenWidth * bitmapHeight / bitmapWidth;
 
        if(displayWidth>=screenWidth){
            displayHeight=screenHeight;
        }else{
            displayWidth=screenWidth;
        }
        */
        displayWidth = screenWidth;
        displayHeight = screenWidth * bitmapHeight / bitmapWidth;
        //TODO 拉伸后截取中间的部分
        /*
        ViewGroup.MarginLayoutParams lp = (ViewGroup.MarginLayoutParams) getLayoutParams();
        lp.leftMargin = (screenWidth - displayWidth) / 2;
        lp.topMargin = ((screenHeight - displayHeight) / 2);
        setLayoutParams(lp);
       */
        Log.d(TAG, "bitmapWidth:" + bitmapWidth);
        Log.d(TAG, "bitmapHeight:" + bitmapHeight);
        Log.d(TAG, "screenWitdth:" + screenWidth);
        Log.d(TAG, "screenHeight:" + screenHeight);
        Log.d(TAG, "fit width:" + displayWidth);
        Log.d(TAG, "fit height:" + displayHeight);
    }
 
    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        Log.d(TAG, "onMeasure "+displayWidth+" "+displayHeight);
        if(displayWidth !=0  && displayHeight !=0)
            setMeasuredDimension(displayWidth,displayHeight);
        else
            ;//setMeasuredDimension(displayWidth,displayHeight);
    }
}

3、在1080x1920分辨率的手机上运行的效果图，如下图，不会变形。

 4、看运行log，会打印分辨率等相关信息。 

四、代码主要参考文章

(646条消息) Android 图像的拉伸适配解决_rong_wz的博客-CSDN博客_android 图像拉伸

 五、其他的参考文章

写自定义view该有的的流程和思路 - 知乎 (zhihu.com)

【技巧】获取android xml文件中控件的属性的值 - cirno_9 - 博客园 (cnblogs.com)

Android 获取屏幕宽度和高度的几种方法 - 简书 (jianshu.com)

android 自定义控件中获取属性的三种方式(转) - 走看看 (zoukankan.com)