android.graphics.Camera实现图像的旋转、缩放
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。
个人总结Camera与Matrix的一些区别如下：
本文为练习Camera的使用。实现效果图如下：
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
代码如下：
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) { }}