android点击实现图片放大缩小

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mainactivity类

Java代码

package com.example.androidsvg;
import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
public class MainActivityextends Activity {
private static final double ZOOM_IN_SCALE = 1.25;//放大系数
private static final double ZOOM_OUT_SCALE = 0.8;//缩小系数
@SuppressWarnings("null")
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(new Zoom(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;
}
}

package com.example.androidsvg; import android.app.Activity; import android.os.Bundle; import android.view.Menu; public class MainActivity extends Activity  { private static final double ZOOM_IN_SCALE = 1.25;//放大系数  private static final double ZOOM_OUT_SCALE = 0.8;//缩小系数 @SuppressWarnings("null") @Override protected void onCreate(Bundle savedInstanceState) {   super.onCreate(savedInstanceState);   setContentView(new Zoom(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; } }

Zoom类

Java代码

package com.example.androidsvg;
import android.view.View;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.drawable.Drawable;
import android.view.KeyEvent;
public class Zoom extends View {
private Drawable image;
private int zoomControler=20;
public Zoom(Context context){
super(context);
image=context.getResources().getDrawable(R.drawable.icon);
setFocusable(true);
}
@Override
protected void onDraw(Canvas canvas) {
// TODO Auto-generated method stub
super.onDraw(canvas);
//控制图像的宽度和高度
image.setBounds((getWidth()/2)-zoomControler, (getHeight()/2)-zoomControler, (getWidth()/2)+zoomControler, (getHeight()/2)+zoomControler);
image.draw(canvas);
}
@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if(keyCode==KeyEvent.KEYCODE_DPAD_UP)//放大
zoomControler+=10;
if(keyCode==KeyEvent.KEYCODE_DPAD_DOWN) //缩小
zoomControler-=10;
if(zoomControler<10)
zoomControler=10;
invalidate();
return true;
}
}