android点击实现图片放大缩小

mainactivity类

Java代码







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;
}

}

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;
}
}