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;

        }

    }

}