android开发中如何对图片进行处理

package de.hdodenhof.circleimageview; 
import edu.njupt.zhb.main.R; 
import android.content.Context; 
import android.content.res.TypedArray; 
import android.graphics.Bitmap; 
import android.graphics.BitmapShader; 
import android.graphics.Canvas; 
import android.graphics.Color; 
import android.graphics.Matrix; 
import android.graphics.Paint; 
import android.graphics.RectF; 
import android.graphics.Shader; 
import android.graphics.drawable.BitmapDrawable; 
import android.graphics.drawable.ColorDrawable; 
import android.graphics.drawable.Drawable; 
import android.util.AttributeSet; 
import android.widget.ImageView; 
 
public class CircleImageView extends ImageView { 
 
 private static final ScaleType SCALE_TYPE = ScaleType.CENTER_CROP; 
 
 private static final Bitmap.Config BITMAP_CONFIG = Bitmap.Config.ARGB_8888; 
 private static final int COLORDRAWABLE_DIMENSION = 1; 
 
 private static final int DEFAULT_BORDER_WIDTH = 0; 
 private static final int DEFAULT_BORDER_COLOR = Color.BLACK; 
 
 private final RectF mDrawableRect = new RectF(); 
 private final RectF mBorderRect = new RectF(); 
 
 private final Matrix mShaderMatrix = new Matrix(); 
 private final Paint mBitmapPaint = new Paint(); 
 private final Paint mBorderPaint = new Paint(); 
 
 private int mBorderColor = DEFAULT_BORDER_COLOR; 
 private int mBorderWidth = DEFAULT_BORDER_WIDTH; 
 
 private Bitmap mBitmap; 
 private BitmapShader mBitmapShader; 
 private int mBitmapWidth; 
 private int mBitmapHeight; 
 
 private float mDrawableRadius; 
 private float mBorderRadius; 
 
 private boolean mReady; 
 private boolean mSetupPending; 
 
 public CircleImageView(Context context) { 
  super(context); 
 } 
 
 public CircleImageView(Context context, AttributeSet attrs) { 
  this(context, attrs, 0); 
 } 
 
 public CircleImageView(Context context, AttributeSet attrs, int defStyle) { 
  super(context, attrs, defStyle); 
  super.setScaleType(SCALE_TYPE); 
 
  TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.CircleImageView, defStyle, 0); 
 
  mBorderWidth = a.getDimensionPixelSize(R.styleable.CircleImageView_border_width, DEFAULT_BORDER_WIDTH); 
  mBorderColor = a.getColor(R.styleable.CircleImageView_border_color, DEFAULT_BORDER_COLOR); 
 
  a.recycle(); 
 
  mReady = true; 
 
  if (mSetupPending) { 
   setup(); 
   mSetupPending = false; 
  } 
 } 
 
 @Override 
 public ScaleType getScaleType() { 
  return SCALE_TYPE; 
 } 
 
 @Override 
 public void setScaleType(ScaleType scaleType) { 
  if (scaleType != SCALE_TYPE) { 
   throw new IllegalArgumentException(String.format("ScaleType %s not supported.", scaleType)); 
  } 
 } 
 
 @Override 
 protected void onDraw(Canvas canvas) { 
  if (getDrawable() == null) { 
   return; 
  } 
 
  canvas.drawCircle(getWidth() / 2, getHeight() / 2, mDrawableRadius, mBitmapPaint); 
  canvas.drawCircle(getWidth() / 2, getHeight() / 2, mBorderRadius, mBorderPaint); 
 } 
 
 @Override 
 protected void onSizeChanged(int w, int h, int oldw, int oldh) { 
  super.onSizeChanged(w, h, oldw, oldh); 
  setup(); 
 } 
 
 public int getBorderColor() { 
  return mBorderColor; 
 } 
 
 public void setBorderColor(int borderColor) { 
  if (borderColor == mBorderColor) { 
   return; 
  } 
 
  mBorderColor = borderColor; 
  mBorderPaint.setColor(mBorderColor); 
  invalidate(); 
 } 
 
 public int getBorderWidth() { 
  return mBorderWidth; 
 } 
 
 public void setBorderWidth(int borderWidth) { 
  if (borderWidth == mBorderWidth) { 
   return; 
  } 
 
  mBorderWidth = borderWidth; 
  setup(); 
 } 
 
 @Override 
 public void setImageBitmap(Bitmap bm) { 
  super.setImageBitmap(bm); 
  mBitmap = bm; 
  setup(); 
 } 
 
 @Override 
 public void setImageDrawable(Drawable drawable) { 
  super.setImageDrawable(drawable); 
  mBitmap = getBitmapFromDrawable(drawable); 
  setup(); 
 } 
 
 @Override 
 public void setImageResource(int resId) { 
  super.setImageResource(resId); 
  mBitmap = getBitmapFromDrawable(getDrawable()); 
  setup(); 
 } 
 
 private Bitmap getBitmapFromDrawable(Drawable drawable) { 
  if (drawable == null) { 
   return null; 
  } 
 
  if (drawable instanceof BitmapDrawable) { 
   return ((BitmapDrawable) drawable).getBitmap(); 
  } 
 
  try { 
   Bitmap bitmap; 
 
   if (drawable instanceof ColorDrawable) { 
    bitmap = Bitmap.createBitmap(COLORDRAWABLE_DIMENSION, COLORDRAWABLE_DIMENSION, BITMAP_CONFIG); 
   } else { 
    bitmap = Bitmap.createBitmap(drawable.getIntrinsicWidth(), drawable.getIntrinsicHeight(), BITMAP_CONFIG); 
   } 
 
   Canvas canvas = new Canvas(bitmap); 
   drawable.setBounds(0, 0, canvas.getWidth(), canvas.getHeight()); 
   drawable.draw(canvas); 
   return bitmap; 
  } catch (OutOfMemoryError e) { 
   return null; 
  } 
 } 
 
 private void setup() { 
  if (!mReady) { 
   mSetupPending = true; 
   return; 
  } 
 
  if (mBitmap == null) { 
   return; 
  } 
 
  mBitmapShader = new BitmapShader(mBitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP); 
 
  mBitmapPaint.setAntiAlias(true); 
  mBitmapPaint.setShader(mBitmapShader); 
 
  mBorderPaint.setStyle(Paint.Style.STROKE); 
  mBorderPaint.setAntiAlias(true); 
  mBorderPaint.setColor(mBorderColor); 
  mBorderPaint.setStrokeWidth(mBorderWidth); 
 
  mBitmapHeight = mBitmap.getHeight(); 
  mBitmapWidth = mBitmap.getWidth(); 
 
  mBorderRect.set(0, 0, getWidth(), getHeight()); 
  mBorderRadius = Math.min((mBorderRect.height() - mBorderWidth) / 2, (mBorderRect.width() - mBorderWidth) / 2); 
 
  mDrawableRect.set(mBorderWidth, mBorderWidth, mBorderRect.width() - mBorderWidth, mBorderRect.height() - mBorderWidth); 
  mDrawableRadius = Math.min(mDrawableRect.height() / 2, mDrawableRect.width() / 2); 
 
  updateShaderMatrix(); 
  invalidate(); 
 } 
 
 private void updateShaderMatrix() { 
  float scale; 
  float dx = 0; 
  float dy = 0; 
 
  mShaderMatrix.set(null); 
 
  if (mBitmapWidth * mDrawableRect.height() > mDrawableRect.width() * mBitmapHeight) { 
   scale = mDrawableRect.height() / (float) mBitmapHeight; 
   dx = (mDrawableRect.width() - mBitmapWidth * scale) * 0.5f; 
  } else { 
   scale = mDrawableRect.width() / (float) mBitmapWidth; 
   dy = (mDrawableRect.height() - mBitmapHeight * scale) * 0.5f; 
  } 
 
  mShaderMatrix.setScale(scale, scale); 
  mShaderMatrix.postTranslate((int) (dx + 0.5f) + mBorderWidth, (int) (dy + 0.5f) + mBorderWidth); 
 
  mBitmapShader.setLocalMatrix(mShaderMatrix); 
 } 
 
} 

<?xml version="1.0" encoding="utf-8"?>