刚开始安卓，记录一个刚做的图片缩放程序

刚开始做安卓，写了一个简陋的图片缩放程序。费了一点时间，看来还是有必要记录下来。

布局代码：

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="fill_parent"    android:layout_height="fill_parent"    android:layout_gravity="clip_vertical" >    <LinearLayout        android:layout_width="fill_parent"        android:layout_height="fill_parent"        android:gravity="bottom|center_horizontal"        android:orientation="horizontal" >        <Button            android:id="@+id/bsx"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="缩小" />        <Button            android:id="@+id/bfd"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="放大" />    </LinearLayout>    <LinearLayout        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:orientation="vertical" >        <ImageView            android:id="@+id/img"            android:layout_width="wrap_content"            android:layout_height="wrap_content" >        </ImageView>    </LinearLayout></FrameLayout>

java代码：

package com.example.myscalepic;import android.os.Bundle;import android.app.Activity;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.graphics.Matrix;import android.util.DisplayMetrics;import android.util.Log;import android.view.Menu;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.ImageView;import android.widget.Toast;public class MainActivity extends Activity implements OnClickListener {    ImageView imgView;    Bitmap bmp;    int screenWidth; //屏幕宽度    int screenHeight;//屏幕高度    float scaleWidth = 1f; //缩放倍率    float scaleHeight = 1f;
    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        bmp = BitmapFactory.decodeResource(getResources(), R.drawable.feng);        DisplayMetrics dm = new DisplayMetrics();        getWindowManager().getDefaultDisplay().getMetrics(dm);        screenWidth = dm.widthPixels;        screenHeight = dm.heightPixels - 80;        imgView = (ImageView) this.findViewById(R.id.img);        Button b1 = (Button) this.findViewById(R.id.bsx);        Button b2 = (Button) this.findViewById(R.id.bfd);        //设置图片        imgView.setImageBitmap(bmp);        b1.setOnClickListener(this);        b2.setOnClickListener(this);    }
    @Override    public boolean onCreateOptionsMenu(Menu menu) {        // Inflate the menu; this adds items to the action bar if it is present.        getMenuInflater().inflate(R.menu.activity_main, menu);        return true;    }    @Override    public void onClick(View v) {        if (v.getId() == R.id.bfd) {//点击放大按钮            scaleWidth *= 1.2;            scaleHeight *= 1.2;        } else { //点击缩小按钮            scaleWidth *= 0.8;            scaleHeight *= 0.8;        }        //设置新的图片        imgView.setImageBitmap(scaleToFit());    }    /**     * 缩放函数     * @return     */    private Bitmap scaleToFit() {        int width = bmp.getWidth();        int height = bmp.getHeight();        Matrix ma = new Matrix();        ma.postScale(scaleWidth, scaleHeight);        Bitmap tewmpmap;        if (width * scaleWidth > screenWidth|| height * scaleHeight > screenHeight) {            scaleWidth=1f;            scaleHeight=1f;            return bmp;        } else {            //得到图片缩放后的副本            tewmpmap = Bitmap.createBitmap(bmp, 0, 0, width, height, ma, true);            return tewmpmap;        }    }}

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