Android开发--Matrix（二）--实现图片的旋转

      Matrix功能很是强大，利用这个类提供的一系列方法，我们可以实现图片的旋转。

      下面以一个例子说明实现方法。

首先，我们看下实现的截图：

下面给出具体的实现代码：

1.xml布局文件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:background="@drawable/white"
  android:orientation="vertical"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  >
  <TextView
    android:id="@+id/myTextView1"
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:textColor="#ff0000"
    android:text="@string/app_name"/>
  <LinearLayout
    android:orientation="horizontal"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
  >
    <Button
      android:id="@+id/myButton1"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:text="@string/str_button1" />
    <ImageView
      android:id="@+id/myImageView1" 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:layout_gravity="center" />
    <Button
      android:id="@+id/myButton2"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:text="@string/str_button2" />
  </LinearLayout>
</LinearLayout>

public class EX04_24 extends Activity
{
  private Button mButton1;
  private Button mButton2; 
  private TextView mTextView1; 
  private ImageView mImageView1; 
  private int ScaleTimes; private int ScaleAngle; 
  /** Called when the activity is first created. */ 
  @Override
  public void onCreate(Bundle savedInstanceState) 
  { 
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    
    mButton1 =(Button) findViewById(R.id.myButton1);
    mButton2 =(Button) findViewById(R.id.myButton2); 
    mTextView1 = (TextView) findViewById(R.id.myTextView1); 
    mImageView1 = (ImageView) findViewById(R.id.myImageView1); 
   
    //定义旋转的角度和图像转变的比例（大小）
    ScaleTimes = 1; 
    ScaleAngle = 1; 
    
    final Bitmap mySourceBmp = 
      BitmapFactory.decodeResource(getResources(), R.drawable.hippo); 
    
    final int widthOrig = mySourceBmp.getWidth(); 
    final int heightOrig = mySourceBmp.getHeight(); 
    
    /* 程序刚执行，加载默认的Drawable */ 
    mImageView1.setImageBitmap(mySourceBmp); 
   
    /* 向左选转按钮 */
    mButton1.setOnClickListener(new Button.OnClickListener()
    {
      
       @Override
       public void onClick(View v) 
      { 
     // TODO Auto-generated method stub 
     ScaleAngle--; 
     if(ScaleAngle<-5) 
     {
       ScaleAngle = -5; 
       } 
     
     /* ScaleTimes=1，维持1:1的宽高比例*/ 
     int newWidth = widthOrig * ScaleTimes;
     int newHeight = heightOrig * ScaleTimes; 
     
     float scaleWidth = ((float) newWidth) / widthOrig;
     float scaleHeight = ((float) newHeight) / heightOrig; 
     
     Matrix matrix = new Matrix(); 
     /* 使用Matrix.postScale设定维度 */
     matrix.postScale(scaleWidth, scaleHeight);
     /* 使用Matrix.postRotate方法旋转Bitmap*/
     //matrix.postRotate(5*ScaleAngle); 
     matrix.setRotate(5*ScaleAngle); 
     /* 建立新的Bitmap对象 */
     Bitmap resizedBitmap = 
       Bitmap.createBitmap(mySourceBmp, 0, 0, widthOrig, heightOrig, matrix, true);
     /**/ 
     BitmapDrawable myNewBitmapDrawable = 
       new BitmapDrawable(resizedBitmap); 
     mImageView1.setImageDrawable(myNewBitmapDrawable); 
     mTextView1.setText(Integer.toString(5*ScaleAngle));
     }
       });
    /* 向右选转按钮 */
    mButton2.setOnClickListener(new Button.OnClickListener() 
    { 
      @Override
      public void onClick(View v) 
      { 
        // TODO Auto-generated method stub 
        ScaleAngle++; 
        if(ScaleAngle>5) 
        { 
          ScaleAngle = 5; 
          } 
        /* ScaleTimes=1，维持1:1的宽高比例*/ 
        int newWidth = widthOrig * ScaleTimes; 
        int newHeight = heightOrig * ScaleTimes; 
        /* 计算旋转的Matrix比例 */ 
        float scaleWidth = ((float) newWidth) / widthOrig; 
        float scaleHeight = ((float) newHeight) / heightOrig; 
        Matrix matrix = new Matrix();
        /* 使用Matrix.postScale设定维度 */
        matrix.postScale(scaleWidth, scaleHeight); 
        /* 使用Matrix.postRotate方法旋转Bitmap*/
        //matrix.postRotate(5*ScaleAngle);
        matrix.setRotate(5*ScaleAngle);
        /* 建立新的Bitmap对象 */ 
        Bitmap resizedBitmap = 
          Bitmap.createBitmap(mySourceBmp, 0, 0, widthOrig, heightOrig, matrix, true);
        /**/ BitmapDrawable myNewBitmapDrawable = 
          new BitmapDrawable(resizedBitmap); 
        mImageView1.setImageDrawable(myNewBitmapDrawable); 
        mTextView1.setText(Integer.toString(5*ScaleAngle)); 
        } 
      }); 
    } 
  }