android ImagView缩放方法之一(Bitmap)

packagecom.myandroid.test;
importandroid.app.Activity;
importandroid.graphics.Bitmap;
importandroid.graphics.BitmapFactory;
importandroid.graphics.Matrix;
importandroid.os.Bundle;
importandroid.view.View;
importandroid.view.View.OnClickListener;
importandroid.widget.Button;
importandroid.widget.ImageView;
importandroid.widget.RelativeLayout;
publicclassAlterImageSizeextendsActivity{
privateImageViewimageView;
privateButtonbt_bigger;
privateButtonbt_smaller;
privateRelativeLayoutlayout;//容器
privateBitmapbmp;//bitmap图片对象
privateintprimaryWidth;//原图片宽
privateintprimaryHeight;//原图片高
privatedoublescaleWidth,scaleHeight;//高宽比例
/**Calledwhentheactivityisfirstcreated.*/
@Override
publicvoidonCreate(BundlesavedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
//初始化
getWidget();
}
/**
*获取控件对象并初始化
*/
privatevoidgetWidget(){
imageView=(ImageView)findViewById(R.id.imageView);
layout=(RelativeLayout)findViewById(R.id.relativeLayout);
bt_bigger=(Button)findViewById(R.id.bt_bigger);
bt_smaller=(Button)findViewById(R.id.bt_smaller);
//创建BitMap对象，用于显示图片
bmp=BitmapFactory.decodeResource(this.getResources(),R.drawable.butterfly);
//原始大小
primaryWidth=bmp.getWidth();
primaryHeight=bmp.getHeight();
//初始比例为1
scaleWidth=scaleHeight=1;
imageView.setImageBitmap(bmp);
bt_bigger.setOnClickListener(newOnClickListener(){
@Override
publicvoidonClick(Viewv){
//TODOAuto-generatedmethodstub
scale(1.25,1.25);
}
});
bt_smaller.setOnClickListener(newOnClickListener(){
@Override
publicvoidonClick(Viewv){
//TODOAuto-generatedmethodstub
scale(0.8,0.8);
}
});
}
/**
*缩放
*/
privatevoidscale(doublescale_width,doublescale_height){
//这种方法，有点不好是：如果图片大小超出屏幕会报错。
if((scale_width>1&&scaleWidth*primaryWidth>=getWindowManager().getDefaultDisplay().getWidth())
||(scale_width>1&&scale_height*primaryHeight>=getWindowManager().getDefaultDisplay().getHeight())){
bt_bigger.setEnabled(false);
}else{
bt_bigger.setEnabled(true);
}
scaleWidth=scaleWidth*scale_width;//缩放到原来的*倍
scaleHeight=scaleHeight*scale_height;
Matrixmatrix=newMatrix();//矩阵，用于图片比例缩放
matrix.postScale((float)scaleWidth,(float)scaleHeight);//设置高宽比例（三维矩阵）
//缩放后的BitMap
BitmapnewBmp=Bitmap.createBitmap(bmp,0,0,primaryWidth,primaryHeight,matrix,true);
//重新设置BitMap
imageView.setImageBitmap(newBmp);
}
}

xml:

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:id="@+id/relativeLayout"    android:layout_width="fill_parent"    android:layout_height="fill_parent"    android:gravity="center_horizontal" >    <ScrollView        android:id="@+id/scroll"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_centerInParent="true"        android:layout_gravity="center" >        <HorizontalScrollView            android:id="@+id/hs"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:layout_gravity="center_horizontal" >            <ImageView                android:id="@+id/imageView"                android:layout_width="fill_parent"                android:layout_height="wrap_content"                android:gravity="center" />        </HorizontalScrollView>    </ScrollView>    <LinearLayout        android:id="@+id/linearLayout"        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:layout_alignParentBottom="true"        android:layout_alignParentLeft="true"        android:gravity="center" >        <Button            android:id="@+id/bt_smaller"            android:layout_width="100px"            android:layout_height="50px"            android:text="缩小" >        </Button>        <Button            android:id="@+id/bt_bigger"            android:layout_width="100px"            android:layout_height="50px"            android:text="放大" >        </Button>    </LinearLayout></RelativeLayout>

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