【转】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>

 

ZoomExampleActivity.java

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);
            }

        });
    }
}

 效果如下：