android.graphics.Camera实现图像的旋转、缩放

     <p>android.graphics.Camera可以对图像执行一些比较复杂的操作，诸如旋转与绽放，与Matrix可实现图像的倾斜。</p>    <p>个人总结Camera与Matrix的一些区别如下：</p>    <ol>     <li>Camera的rotate()相关方法是指定某一维度上旋转指定的角度。</li>     <li>Matrix的rotate()相关方法实现的效果是顺时针旋转指定的角度；与Camera指定Z轴旋转效果相同，但方向相反。</li>     <li>Camera的translate()方法根据某一维度上视点的位移实现图像的缩放，与Matrix的scale()相关方法作用效果相似，只是Matrix的scale()相关方法是直接指定缩放比例。</li>     <li>Camera不支持倾斜操作，Matrix可以直接实现倾斜操作。</li>    </ol>    <p>本文为练习Camera的使用。实现效果图如下：</p>    <p><a href="https://simg.open-open.com/show/584a8cf5d0d30fbe91b8a20d35b77ef4.gif" target="_blank"><img style="cursor:pointer;" alt="android.graphics.Camera实现图像的旋转、缩放" src="https://simg.open-open.com/show/584a8cf5d0d30fbe91b8a20d35b77ef4.gif" width="328" height="487" /></a></p>    <p>Camera的处理结果只是生成一个Matrix，该Matrix用于Bitmap或Canvas绘制Bitmap时才能产生旋转或缩放的效果。</p>    <p>代码如下：</p>    <pre class="brush:java; toolbar: true; auto-links: false;">package lab.sodino.camera;   import android.app.Activity; import android.graphics.Bitmap; import android.graphics.Camera; import android.graphics.Matrix; import android.graphics.drawable.BitmapDrawable; import android.os.Bundle; import android.util.Log; import android.widget.ImageView; import android.widget.SeekBar; import android.widget.SeekBar.OnSeekBarChangeListener; import android.widget.TextView;   /**  * Camera与Matrix的比较：<br/>  * Camera的rotate()相关方法是指定某一维度上旋转指定的角度。<br/>  * Matrix的rotate()相关方法实现的效果是顺时针旋转指定的角度；与Camera指定Z轴旋转效果相同，但方向相反。<br/>  *   * Camera的translate()方法根据某一维度上视点的位移实现图像的缩放，与Matrix的scale()相关方法作用效果相似，  * 只是Matrix的scale()相关方法是直接指定缩放比例。<br/>  *   * Camera不支持倾斜操作，Matrix可以直接实现倾斜操作。<br/>  *   * <a href="http://my.oschina.net/arthor" class="referer" target="_blank">@author</a> Sodino E-mail:sodinoopen@hotmail.com  * @version Time：2011-9-26 下午04:17:49  */ public class ActCamera extends Activity implements OnSeekBarChangeListener {     private Camera camera;     // views     private SeekBar seekbarXRotate;     private SeekBar seekbarYRotate;     private SeekBar seekbarZRotate;     private TextView txtXRotate;     private TextView txtYRotate;     private TextView txtZRotate;     private SeekBar seekbarXSkew;     private SeekBar seekbarYSkew;     private SeekBar seekbarZTranslate;     private TextView txtXTranslate;     private TextView txtYTranslate;     private TextView txtZTranslate;     private ImageView imgResult;     // integer params     private int rotateX, rotateY, rotateZ;     private float skewX, skewY;     private int translateZ;       /** Called when the activity is first created. */     @Override     public void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.main);         // camera         camera = new Camera();         // initViews         // rotate         seekbarXRotate = (SeekBar) findViewById(R.id.seekbarXRotate);         seekbarXRotate.setOnSeekBarChangeListener(this);         seekbarYRotate = (SeekBar) findViewById(R.id.seekbarYRotate);         seekbarYRotate.setOnSeekBarChangeListener(this);         seekbarZRotate = (SeekBar) findViewById(R.id.seekbarZRotate);         seekbarZRotate.setOnSeekBarChangeListener(this);         txtXRotate = (TextView) findViewById(R.id.txtXRotate);         txtYRotate = (TextView) findViewById(R.id.txtYRotate);         txtZRotate = (TextView) findViewById(R.id.txtZRotate);         // translate         seekbarXSkew = (SeekBar) findViewById(R.id.seekbarXSkew);         seekbarXSkew.setOnSeekBarChangeListener(this);         seekbarYSkew = (SeekBar) findViewById(R.id.seekbarYSkew);         seekbarYSkew.setOnSeekBarChangeListener(this);         seekbarZTranslate = (SeekBar) findViewById(R.id.seekbarZTranslate);         seekbarZTranslate.setOnSeekBarChangeListener(this);         txtXTranslate = (TextView) findViewById(R.id.txtXSkew);         txtYTranslate = (TextView) findViewById(R.id.txtYSkew);         txtZTranslate = (TextView) findViewById(R.id.txtZTranslate);         imgResult = (ImageView) findViewById(R.id.imgResult);         // refresh         refreshImage();     }       private void refreshImage() {         // 获取待处理的图像         BitmapDrawable tmpBitDra = (BitmapDrawable) getResources().getDrawable(R.drawable.honeycomb);         Bitmap tmpBit = tmpBitDra.getBitmap();         // 开始处理图像         // 1.获取处理矩阵         // 记录一下初始状态。save()和restore()可以将图像过渡得柔和一些。         // Each save should be balanced with a call to restore().         camera.save();         Matrix matrix = new Matrix();         // rotate         camera.rotateX(rotateX);         camera.rotateY(rotateY);         camera.rotateZ(rotateZ);         // translate         camera.translate(0, 0, translateZ);         camera.getMatrix(matrix);         // 恢复到之前的初始状态。         camera.restore();         // 设置图像处理的中心点         matrix.preTranslate(tmpBit.getWidth() >> 1, tmpBit.getHeight() >> 1);         matrix.preSkew(skewX, skewY);         // matrix.postSkew(skewX, skewY);         // 直接setSkew()，则前面处理的rotate()、translate()等等都将无效。         // matrix.setSkew(skewX, skewY);         // 2.通过矩阵生成新图像(或直接作用于Canvas)         Log.d(“ANDROID_LAB”, “width=” + tmpBit.getWidth() + “ height=” + tmpBit.getHeight());         Bitmap newBit = null;         try {             // 经过矩阵转换后的图像宽高有可能不大于0，此时会抛出IllegalArgumentException             newBit = Bitmap.createBitmap(tmpBit, 0, 0, tmpBit.getWidth(), tmpBit.getHeight(), matrix, true);         } catch (IllegalArgumentException iae) {             iae.printStackTrace();         }         if (newBit != null) {             imgResult.setImageBitmap(newBit);         }     }       @Override     public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {         if (seekBar == seekbarXRotate) {             txtXRotate.setText(progress + “゜”);             rotateX = progress;         } else if (seekBar == seekbarYRotate) {             txtYRotate.setText(progress + “゜”);             rotateY = progress;         } else if (seekBar == seekbarZRotate) {             txtZRotate.setText(progress + “゜”);             rotateZ = progress;         } else if (seekBar == seekbarXSkew) {             skewX = (progress - 100) * 1.0f / 100;             txtXTranslate.setText(String.valueOf(skewX));         } else if (seekBar == seekbarYSkew) {             skewY = (progress - 100) * 1.0f / 100;             txtYTranslate.setText(String.valueOf(skewY));         } else if (seekBar == seekbarZTranslate) {             translateZ = progress - 100;             txtZTranslate.setText(String.valueOf(translateZ));         }         refreshImage();     }       @Override     public void onStartTrackingTouch(SeekBar seekBar) {       }       @Override     public void onStopTrackingTouch(SeekBar seekBar) {       } }</pre>文章出处：    <a href="/misc/goto?guid=4959499212667205168" rel="nofollow">DEVDIV博客</a>    <p></p>