玩转Android---UI篇 ZoomControls放大缩小图片

ZoomControls控件是一个可以缩放但控件，效果如下图

以下是它但一些主要但方法

hasFocus ()：判断焦点

hide ()：隐藏

onTouchEvent (MotionEvent event)：现这个方法来处理触摸屏移动事件

setIsZoomInEnabled (boolean isEnabled)：是否允许放大

setIsZoomOutEnabled (boolean isEnabled)：是否允许缩小

setOnZoomInClickListener (View.OnClickListener listener)：注册放大监听器

setOnZoomOutClickListener (View.OnClickListener listener)：注册缩小监听器

setZoomSpeed (long speed)：设置缩放速度

show ()：显示

这里面，如果将setIsZoomInEnabled()方法设置为false，那么这个放大的按钮就变成了灰色，不能用了，其实这个控件就是两个按钮而已，只是有外观，没有功能，如果你要放大图片或者缩小图片，还是要在监听事件中实现

开始看代码

main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:id="@+id/layout1"
    >
<ImageView
	android:id="@+id/imgview"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:src="@drawable/yuanyuan"
    />
    
<ZoomControls
	android:id="@+id/zoomcontrol"
	android:layout_gravity="bottom"
	android:layout_width="wrap_content"
	android:layout_height="wrap_content" 
/>
</LinearLayout>

package com.loulijun.zoomcontroltest;

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Matrix;
import android.os.Bundle;
import android.util.DisplayMetrics;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.ZoomControls;

public class ZoomExampleActivity extends Activity {
	private LinearLayout layout1;
	private ZoomControls zoom;
	private ImageView img;
	private int id=0;
	private int displayWidth;
	private int displayHeight;
	private float scaleWidth = 1;
	private float scaleHeight = 1;
	private Bitmap bmp;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        layout1 = (LinearLayout)findViewById(R.id.layout1);
        //取得屏幕分辨率大小
        DisplayMetrics dm = new DisplayMetrics();
        getWindowManager().getDefaultDisplay().getMetrics(dm);
        displayWidth = dm.widthPixels;
        //屏幕高度减去zoomControls的高度
        displayHeight = dm.heightPixels;
        bmp = BitmapFactory.decodeResource(getResources(), R.drawable.yuanyuan);
        img = (ImageView)findViewById(R.id.imgview);
        //zoom.hide();隐藏zoomControls
        //zoom.show();显示zoomCOntrols
        
        zoom = (ZoomControls)findViewById(R.id.zoomcontrol);
        img = (ImageView)findViewById(R.id.imgview);
        zoom.setIsZoomInEnabled(true);
        zoom.setIsZoomOutEnabled(true);
        //图片放大
        zoom.setOnZoomInClickListener(new OnClickListener()
        {
        	public void onClick(View v)
        	{
        		int bmpWidth = bmp.getWidth();
				int bmpHeight = bmp.getHeight();
				//设置图片放大但比例
				double scale = 1.25;
				//计算这次要放大的比例
				scaleWidth = (float)(scaleWidth*scale);
				scaleHeight = (float)(scaleHeight*scale);
				//产生新的大小但Bitmap对象
				Matrix matrix = new Matrix();
				matrix.postScale(scaleWidth, scaleHeight);
				Bitmap resizeBmp = 
                Bitmap.createBitmap(bmp,0,0,bmpWidth,bmpHeight,matrix,true);
				img.setImageBitmap(resizeBmp);

        	}
        });
        //图片减小
        zoom.setOnZoomOutClickListener(new OnClickListener()
        {

			public void onClick(View v) {
				int bmpWidth = bmp.getWidth();
				int bmpHeight = bmp.getHeight();
				//设置图片放大但比例
				double scale = 0.8;
				//计算这次要放大的比例
				scaleWidth = (float)(scaleWidth*scale);
				scaleHeight = (float)(scaleHeight*scale);
				//产生新的大小但Bitmap对象
				Matrix matrix = new Matrix();
				matrix.postScale(scaleWidth, scaleHeight);
				Bitmap resizeBmp = 
                        Bitmap.createBitmap(bmp,0,0,bmpWidth,bmpHeight,matrix,true);
				img.setImageBitmap(resizeBmp);
			}
        	
        });
    }
}