通过按钮缩放图片

小咪咪 2024-03-30 10:52 73阅读 0赞

运行效果：

![6a93d1dae6ab4ff5a3243b9dc4540970.gif][]

要用到的知识点：

imageWidth = ivBear.getLayoutParams().width;  
imageHeight = ivBear.getLayoutParams().height;

通过图像视图对象的getLayoutParams()方法得到布局参数对象，然后再利用布局参数对象提供的width与height属性即可获得图像的尺寸。

ivBear.setLayoutParams(new LinearLayout.LayoutParams(newWidth, newHeight));

图像视图对象的`setLayoutParams()`方法来设置设置图像尺寸须要传入一个布局参数对象，而该布局参数对象初始化时传入新的图像尺寸

#### 创建安卓应用【ZoomImageByButton】 ####

![7131ab3e8bb14575a23cbe457a4df243.png][]

#### 将三张图片拷贝到drawable目录 ####

![a226828ad307466587152573ad0f6e03.png][]

#### 打开主布局资源文件activity\_main.[xml][]输入内容 ####

![c7ae2b3f75ad4fe4952999dee64cbea8.png][]

具体代码：

<?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@drawable/background"
        android:padding="10dp"
        android:orientation="vertical"
        tools:context=".MainActivity">
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:gravity="center">
            <Button
                android:id="@+id/btn_shrink_image"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginRight="10dp"
                android:onClick="doShinkImage"
                android:text="@string/shrink_imge"/>
            <Button
                android:id="@+id/btn_enlarge_image"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginRight="10dp"
                android:onClick="doEnlargeImage"
                android:text="@string/enlarge_image"/>
            <ImageButton
                android:id="@+id/btu_enlarge_image"
                android:layout_width="40dp"
                android:layout_height="40dp"
                android:background="@drawable/img1"
                android:onClick="doExit"/>
    
    
        </LinearLayout>
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:gravity="center">
            <ImageView
                android:id="@+id/iv_mickey"
                android:layout_width="200dp"
                android:layout_height="300dp"
                android:background="@drawable/mickey"/>
    
        </LinearLayout>
    
    
    </LinearLayout>

#### 打开字符串资源文件strings.xml ####

![995fb12f797b408caa26dbb710711839.png][]

具体代码：

<resources>
        <string name="app_name">通过按钮缩放图片</string>
        <string name="enlarge_image">放大图片</string>
        <string name="shrink_imge">缩小图片</string>
    </resources>

#### 打开主界面类MainActivity ####

![b7e1c78ee4e2402aabc85f913cbadbed.png][]

![6cf1db5831c9466a8cca57957d4e17ca.png][]

具体代码：

package net.zyt.zoom_image;
    
    import androidx.appcompat.app.AppCompatActivity;
    
    import android.os.Bundle;
    import android.view.View;
    import android.widget.ImageView;
    import android.widget.LinearLayout;
    import android.widget.Toast;
    
    public class MainActivity extends AppCompatActivity {
        private ImageView ivMickey;
        private double imageWidth;
        private double imageHeight;
        private double screenWidth;
        private double screenHeight;
        private double scale = 0.95;
    
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            //利用布局资源文件设置用户界面
            setContentView(R.layout.activity_main);
            //通过资源标识符获取控件实例
            ivMickey=findViewById(R.id.iv_mickey);
            //获得屏幕尺寸
            screenHeight=getWindowManager().getDefaultDisplay().getHeight();
            screenWidth=getWindowManager().getDefaultDisplay().getWidth();
            //获取图像尺寸
            imageWidth=ivMickey.getLayoutParams().width;
            imageHeight=ivMickey.getLayoutParams().height;
    
        }
        public void doShinkImage(View view){
            //按比例缩小图片尺寸
            int newWidth=(int)(imageWidth*scale);
            int newHeight=(int)(imageHeight*scale);
            //按新的尺寸设置图像（不能缩小为零，否则不能再放大）
            if(newWidth>50){
                ivMickey.setLayoutParams(new LinearLayout.LayoutParams(newWidth,newHeight));
                imageWidth=ivMickey.getLayoutParams().width;
                imageHeight=ivMickey.getLayoutParams().height;
    
            }else {
                Toast.makeText(this,"温馨提示：图片不能再缩小",Toast.LENGTH_SHORT).show();
            }
        }
        public void doEnlargeImage(View view){
            //按比例放大图片尺寸
            int newWidth=(int)(imageWidth/scale);
            int newHeight=(int)(imageHeight/scale);
            //按新的尺寸设置图像（不能在放大，否则出界了）
            if(newWidth<screenWidth){
                ivMickey.setLayoutParams(new LinearLayout.LayoutParams(newWidth,newHeight));
                imageWidth=ivMickey.getLayoutParams().width;
                imageHeight=ivMickey.getLayoutParams().height;
    
            }else {
                Toast.makeText(this,"温馨提示：图片不能再放大",Toast.LENGTH_SHORT).show();
            }
        }
        public void  doExit(View view){
            finish();
    
        }
    }

[6a93d1dae6ab4ff5a3243b9dc4540970.gif]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/30/6a77b4ea235b496d9f7978cc27c7cc57.gif
[7131ab3e8bb14575a23cbe457a4df243.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/30/9f6bb25ff6324d95aa66501d8d2edffb.png
[a226828ad307466587152573ad0f6e03.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/30/22d17f2bfa9446c3b8c51834a3069405.png
[xml]: https://so.csdn.net/so/search?q=xml&spm=1001.2101.3001.7020
[c7ae2b3f75ad4fe4952999dee64cbea8.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/30/73a003534c644b14b1174e8b429a8bba.png
[995fb12f797b408caa26dbb710711839.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/30/8f248264d20d483c902a5426d5b0ea2e.png
[b7e1c78ee4e2402aabc85f913cbadbed.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/30/84e7fec04be041a785363e0f3fade44b.png
[6cf1db5831c9466a8cca57957d4e17ca.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/30/f708f5d49cfd45d1a4a3215ab7761a26.png