<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
 android:layout_width="match_parent" 
 android:layout_height="match_parent" 
 android:background="#bbaacc" > 
 
 <ImageView 
 android:src="@drawable/ic_launcher" 
 android:layout_width="wrap_content" 
 android:layout_height="wrap_content" 
 android:background="#aabbcc" /> 
 
</LinearLayout> 

<?xml version="1.0" encoding="utf-8"?> 
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android" 
 android:layout_width="match_parent" 
 android:layout_height="match_parent" 
 android:background="#bbccaa" > 
 
 <TableLayout 
 android:layout_width="match_parent" 
 android:layout_height="wrap_content" 
 android:padding="10dp" > 
 
 <TextView 
 android:layout_width="wrap_content" 
 android:layout_height="wrap_content" 
 android:layout_marginBottom="10dp" 
 android:text="圖片尺寸的寬和高都遠(yuǎn)遠(yuǎn)大于ImageView的尺寸" /> 
 
 <TableRow 
 android:layout_width="match_parent" 
 android:layout_height="wrap_content" > 
 
 <ImageView 
 android:layout_width="300px" 
 android:layout_height="300px" 
 android:background="#aabbcc" 
 android:scaleType="matrix" 
 android:src="@drawable/test" /> 
 
 <ImageView 
 android:layout_width="300px" 
 android:layout_height="300px" 
 android:layout_marginLeft="10dp" 
 android:background="#aabbcc" 
 android:scaleType="fitXY" 
 android:src="@drawable/test" /> 
 
 <ImageView 
 android:layout_width="300px" 
 android:layout_height="300px" 
 android:layout_marginLeft="10dp" 
 android:background="#aabbcc" 
 android:scaleType="fitStart" 
 android:src="@drawable/test" /> 
 
 <ImageView 
 android:layout_width="300px" 
 android:layout_height="300px" 
 android:layout_marginLeft="10dp" 
 android:background="#aabbcc" 
 android:scaleType="fitCenter" 
 android:src="@drawable/test" /> 
 </TableRow> 
 
 <TableRow 
 android:layout_width="match_parent" 
 android:layout_height="wrap_content" 
 android:layout_marginTop="5dp" > 
 
 <TextView 
 android:layout_width="300px" 
 android:layout_height="wrap_content" 
 android:gravity="center" 
 android:text="matrix" /> 
 
 <TextView 
 android:layout_width="300px" 
 android:layout_height="wrap_content" 
 android:gravity="center" 
 android:text="fitXY" /> 
 
 <TextView 
 android:layout_width="300px" 
 android:layout_height="wrap_content" 
 android:gravity="center" 
 android:text="fitStart" /> 
 
 <TextView 
 android:layout_width="300px" 
 android:layout_height="wrap_content" 
 android:gravity="center" 
 android:text="fitCenter" /> 
 </TableRow> 
 
 <TableRow 
 android:layout_width="match_parent" 
 android:layout_height="wrap_content" 
 android:layout_marginTop="10dp" > 
 
 <ImageView 
 android:layout_width="300px" 
 android:layout_height="300px" 
 android:background="#aabbcc" 
 android:scaleType="fitEnd" 
 android:src="@drawable/test" /> 
 
 <ImageView 
 android:layout_width="300px" 
 android:layout_height="300px" 
 android:layout_marginLeft="10dp" 
 android:background="#aabbcc" 
 android:scaleType="center" 
 android:src="@drawable/test" /> 
 
 <ImageView 
 android:layout_width="300px" 
 android:layout_height="300px" 
 android:layout_marginLeft="10dp" 
 android:background="#aabbcc" 
 android:scaleType="centerCrop" 
 android:src="@drawable/test" /> 
 
 <ImageView 
 android:layout_width="300px" 
 android:layout_height="300px" 
 android:layout_marginLeft="10dp" 
 android:background="#aabbcc" 
 android:scaleType="centerInside" 
 android:src="@drawable/test" /> 
 </TableRow> 
 
 <TableRow 
 android:layout_width="match_parent" 
 android:layout_height="wrap_content" 
 android:layout_marginTop="5dp" > 
 
 <TextView 
 android:layout_width="300px" 
 android:layout_height="wrap_content" 
 android:gravity="center" 
 android:text="fitEnd" /> 
 
 <TextView 
 android:layout_width="300px" 
 android:layout_height="wrap_content" 
 android:gravity="center" 
 android:text="center" /> 
 
 <TextView 
 android:layout_width="300px" 
 android:layout_height="wrap_content" 
 android:gravity="center" 
 android:text="centerCrop" /> 
 
 <TextView 
 android:layout_width="300px" 
 android:layout_height="wrap_content" 
 android:gravity="center" 
 android:text="centerInside" /> 
 </TableRow> 
 </TableLayout> 
 
</ScrollView> 

public ImageView(Context context) { 
 super(context); 
 initImageView(); 
} 
 
public ImageView(Context context, AttributeSet attrs) { 
 this(context, attrs, 0); 
} 
 
public ImageView(Context context, AttributeSet attrs, int defStyle) { 
 super(context, attrs, defStyle); 
 initImageView(); 
 
 TypedArray a = context.obtainStyledAttributes(attrs, 
 com.android.internal.R.styleable.ImageView, defStyle, 0); 
 
 Drawable d = a.getDrawable(com.android.internal.R.styleable.ImageView_src); 
 if (d != null) { 
 setImageDrawable(d); 
 } 
 
 ////////////////////////////////////////////////// 
 // 
 // 以下源碼部分屬性初始化不涉及主核心，不再貼出 
 // 
 ////////////////////////////////////////////////// 
 
 
 a.recycle(); 
 
 //need inflate syntax/reader for matrix 
} 

/** 
 * Sets a drawable as the content of this ImageView. 
 * 
 * @param drawable The drawable to set 
 */ 
public void setImageDrawable(Drawable drawable) { 
 if (mDrawable != drawable) { 
 mResource = 0; 
 mUri = null; 
 
 int oldWidth = mDrawableWidth; 
 int oldHeight = mDrawableHeight; 
 
 updateDrawable(drawable); 
 
 if (oldWidth != mDrawableWidth || oldHeight != mDrawableHeight) { 
 requestLayout(); 
 } 
 invalidate(); 
 } 
} 

private void updateDrawable(Drawable d) { 
 if (mDrawable != null) { 
 mDrawable.setCallback(null); 
 unscheduleDrawable(mDrawable); 
 } 
 mDrawable = d; 
 if (d != null) { 
 d.setCallback(this); 
 if (d.isStateful()) { 
 d.setState(getDrawableState()); 
 } 
 d.setLevel(mLevel); 
 mDrawableWidth = d.getIntrinsicWidth(); 
 mDrawableHeight = d.getIntrinsicHeight(); 
 applyColorMod(); 
 configureBounds(); 
 } else { 
 mDrawableWidth = mDrawableHeight = -1; 
 } 
} 

 private void configureBounds() { 
 if (mDrawable == null || !mHaveFrame) { 
 return; 
 } 
 
 
 int dwidth = mDrawableWidth; 
 int dheight = mDrawableHeight; 
 
 
 int vwidth = getWidth() - mPaddingLeft - mPaddingRight; 
 int vheight = getHeight() - mPaddingTop - mPaddingBottom; 
 
 
 boolean fits = (dwidth < 0 || vwidth == dwidth) && 
 (dheight < 0 || vheight == dheight); 
 
 ////////////////////////////////////////代碼塊一//////////////////////////////////////// 
 
 if (dwidth <= 0 || dheight <= 0 || ScaleType.FIT_XY == mScaleType) { 
 /* If the drawable has no intrinsic size, or we're told to 
 scaletofit, then we just fill our entire view. 
 */ 
 mDrawable.setBounds(0, 0, vwidth, vheight); 
 mDrawMatrix = null; 
 
 ////////////////////////////////////////代碼塊二//////////////////////////////////////// 
 
 } else { 
 // We need to do the scaling ourself, so have the drawable 
 // use its native size. 
 mDrawable.setBounds(0, 0, dwidth, dheight); 
 
 
 if (ScaleType.MATRIX == mScaleType) { 
 // Use the specified matrix as-is. 
 if (mMatrix.isIdentity()) { 
 mDrawMatrix = null; 
 } else { 
 mDrawMatrix = mMatrix; 
 } 
 
 ////////////////////////////////////////代碼塊三//////////////////////////////////////// 
 
 } else if (fits) { 
 // The bitmap fits exactly, no transform needed. 
 mDrawMatrix = null; 
 
 ////////////////////////////////////////代碼塊四//////////////////////////////////////// 
 
 } else if (ScaleType.CENTER == mScaleType) { 
 // Center bitmap in view, no scaling. 
 mDrawMatrix = mMatrix; 
 mDrawMatrix.setTranslate((int) ((vwidth - dwidth) * 0.5f + 0.5f), 
  (int) ((vheight - dheight) * 0.5f + 0.5f)); 
 
 ////////////////////////////////////////代碼塊五//////////////////////////////////////// 
 
 } else if (ScaleType.CENTER_CROP == mScaleType) { 
 mDrawMatrix = mMatrix; 
 
 
 float scale; 
 float dx = 0, dy = 0; 
 
 
 if (dwidth * vheight > vwidth * dheight) { 
 scale = (float) vheight / (float) dheight; 
 dx = (vwidth - dwidth * scale) * 0.5f; 
 } else { 
 scale = (float) vwidth / (float) dwidth; 
 dy = (vheight - dheight * scale) * 0.5f; 
 } 
 
 
 mDrawMatrix.setScale(scale, scale); 
 mDrawMatrix.postTranslate((int) (dx + 0.5f), (int) (dy + 0.5f)); 
 
 ////////////////////////////////////////代碼塊六//////////////////////////////////////// 
 
 } else if (ScaleType.CENTER_INSIDE == mScaleType) { 
 mDrawMatrix = mMatrix; 
 float scale; 
 float dx; 
 float dy; 
 
 if (dwidth <= vwidth && dheight <= vheight) { 
 scale = 1.0f; 
 } else { 
 scale = Math.min((float) vwidth / (float) dwidth, 
 (float) vheight / (float) dheight); 
 } 
 
 dx = (int) ((vwidth - dwidth * scale) * 0.5f + 0.5f); 
 dy = (int) ((vheight - dheight * scale) * 0.5f + 0.5f); 
 
 
 mDrawMatrix.setScale(scale, scale); 
 mDrawMatrix.postTranslate(dx, dy); 
 
 ////////////////////////////////////////代碼塊七//////////////////////////////////////// 
 
 } else { 
 // Generate the required transform. 
 mTempSrc.set(0, 0, dwidth, dheight); 
 mTempDst.set(0, 0, vwidth, vheight); 
 
 mDrawMatrix = mMatrix; 
 mDrawMatrix.setRectToRect(mTempSrc, mTempDst, scaleTypeToScaleToFit(mScaleType)); 
 
 ////////////////////////////////////////代碼塊八//////////////////////////////////////// 
 
 } 
 } 
 } 

private void initImageView() { 
 mMatrix = new Matrix(); 
 mScaleType = ScaleType.FIT_CENTER; 
}