ImageView中的一些用法

来源：互联网发布：如何测试网络丢包编辑：程序博客网时间：2024/06/06 04:23

这个demo实现了点击按钮改变图片的透明度，对图片的局部放大。有一点bitmap位图的内容有些不太明白。后期会专门研究这个类。

MainActivity.java

package lzl.edu.com.imageviewtest;import android.app.Activity;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.graphics.drawable.BitmapDrawable;import android.os.Bundle;import android.util.Log;import android.view.MotionEvent;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.ImageView;public class FirstActivity extends Activity implements OnClickListener{    Button increase,reduce,next;    ImageView image1,image2;    private int alpha=255;    int images[] = {R.mipmap.my_hotel_a,R.mipmap.my_hotel_b,R.mipmap.my_hotel_c,            R.mipmap.my_hotel_d,R.mipmap.my_hotel_e};    int currentImage = 0;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        init();    }    void init(){        increase = (Button)findViewById(R.id.increase);        reduce = (Button)findViewById(R.id.reduce);        next = (Button)findViewById(R.id.next);        image1 = (ImageView)findViewById(R.id.image1);        image2 = (ImageView)findViewById(R.id.image2);        increase.setOnClickListener(this);        reduce.setOnClickListener(this);        next.setOnClickListener(this);        image1.setOnTouchListener(new touchImages());    }    @Override    public void onClick(View v) {        if(v.getId() == R.id.increase){            alpha +=5;            Log.i("增加",""+alpha);        }        if(v.getId() == R.id.reduce){            alpha -= 5;            Log.i("减少",""+alpha);        }        if(v.getId()==R.id.next){            nextImageSource();        }        if(alpha >255){            alpha = 255;        }        if(alpha <0){            alpha = 0;        }        //改变图片的透明度        image2.setAlpha(alpha);    }    //查看下一张图片    public void nextImageSource(){        if(currentImage >= images.length){            currentImage = -1;        }        BitmapDrawable bitmapDrawable = (BitmapDrawable)image1.getDrawable();                //如果图片还未回收，先强制回收该图片        if(!bitmapDrawable.getBitmap().isRecycled()){            bitmapDrawable.getBitmap().recycle();        }        //改变ImageView显示的图片        image1.setImageBitmap(BitmapFactory.decodeResource(getResources(),images[currentImage]));        currentImage++;    }    //接触到图片的位置，在下方放大    class touchImages implements View.OnTouchListener{        @Override        public boolean onTouch(View v, MotionEvent event) {            Log.i("viewid----",""+v.getId());            BitmapDrawable bitmapDrawable = (BitmapDrawable)image1.getDrawable();            //获取第一个图片显示框中的位图            Bitmap bitmap = bitmapDrawable.getBitmap();            //bitmap图片实际大小与一个ImageView的缩放比例            double scale = bitmap.getWidth() / 320.0;            //获取需要显示的图片的开始点            int x = (int)(event.getX()*scale);            int y = (int)(event.getY()*scale);            if(x + 120 >=bitmap.getWidth()){                x = bitmap.getWidth() -120;            }            if(y + 120 >=bitmap.getHeight()){                y = bitmap.getHeight() -120;            }            image2.setImageBitmap(Bitmap.createBitmap(bitmap,x,y,120,120));            image2.setAlpha(alpha);            return false;        }    }}

activity_main.xml

<RelativeLayout 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:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity"    >    <LinearLayout        android:orientation="vertical"        android:layout_width="wrap_content"        android:layout_height="wrap_content">    <LinearLayout        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:orientation="horizontal">        <Button            android:id="@+id/increase"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:layout_marginRight="20dp"            android:text="增加"/>        <Button            android:id="@+id/reduce"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="减少"/>        <Button            android:id="@+id/next"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="下一张"/>    </LinearLayout>    <LinearLayout        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:orientation="vertical">    <ImageView        android:id="@+id/image1"        android:layout_width="150dp"        android:layout_height="150dp"        android:src="@mipmap/my_hotel"        android:scaleType="fitCenter"        />        <ImageView        android:id="@+id/image2"        android:layout_width="300dp"        android:layout_height="300dp"            android:src="@mipmap/my_hotel"        android:contentDescription="124" />    </LinearLayout>    </LinearLayout>    </RelativeLayout>

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