android - 如何在 XML 中扩展自定义 View ？

Question

这是我第一次尝试在 XML 中使用自定义 View ，我不确定该怎么做。任何帮助将不胜感激。

我正在使用 Interfuser's coverflow并且需要在我可以以 XML 格式使用它的地方扩展它，以便我可以在 View 中添加其他组件。

希望下面的代码将显示我需要的(尝试做的)。我相信这比我想象的要容易。

感谢

布局:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="horizontal" >

<com.myapp.home.CoverFlow
    android:id="@+id/coverFlow1"
    android:layout_width="wrap_content"
    android:layout_height="10dip" />

</LinearLayout>

CoverFlow.java:

package com.myapp.home;

public class CoverFlow extends Gallery {

/**
 * Graphics Camera used for transforming the matrix of ImageViews
 */
private Camera mCamera = new Camera();

/**
 * The maximum angle the Child ImageView will be rotated by
 */    
private int mMaxRotationAngle = 60;

/**
 * The maximum zoom on the centre Child
 */
private int mMaxZoom = -120;

/**
 * The Centre of the Coverflow 
 */   
private int mCoveflowCenter;

public CoverFlow(Context context) {
super(context);
this.setStaticTransformationsEnabled(true);
}

public CoverFlow(Context context, AttributeSet attrs) {
super(context, attrs);
    this.setStaticTransformationsEnabled(true);
}

public CoverFlow(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
this.setStaticTransformationsEnabled(true);   
}

/**
 * Get the max rotational angle of the image
* @return the mMaxRotationAngle
*/
public int getMaxRotationAngle() {
return mMaxRotationAngle;
}

/**
* Set the max rotational angle of each image
* @param maxRotationAngle the mMaxRotationAngle to set
*/
public void setMaxRotationAngle(int maxRotationAngle) {
mMaxRotationAngle = maxRotationAngle;
}

/**
* Get the Max zoom of the centre image
* @return the mMaxZoom
*/
public int getMaxZoom() {
return mMaxZoom;
}

/**
* Set the max zoom of the centre image
* @param maxZoom the mMaxZoom to set
*/
public void setMaxZoom(int maxZoom) {
mMaxZoom = maxZoom;
}

/**
 * Get the Centre of the Coverflow
 * @return The centre of this Coverflow.
 */
private int getCenterOfCoverflow() {
    return (getWidth() - getPaddingLeft() - getPaddingRight()) / 2 + getPaddingLeft();
}

/**
 * Get the Centre of the View
 * @return The centre of the given view.
 */
private static int getCenterOfView(View view) {
    return view.getLeft() + view.getWidth() / 2;
}  
/**
* {@inheritDoc}
*
* @see #setStaticTransformationsEnabled(boolean) 
*/ 
protected boolean getChildStaticTransformation(View child, Transformation t) {

final int childCenter = getCenterOfView(child);
final int childWidth = child.getWidth() ;
int rotationAngle = 0;

t.clear();
t.setTransformationType(Transformation.TYPE_MATRIX);

    if (childCenter == mCoveflowCenter) {
        transformImageBitmap((ImageView) child, t, 0);
    } else {      
        rotationAngle = (int) (((float) (mCoveflowCenter - childCenter)/ childWidth) *      mMaxRotationAngle);
        if (Math.abs(rotationAngle) > mMaxRotationAngle) {
         rotationAngle = (rotationAngle < 0) ? -mMaxRotationAngle : mMaxRotationAngle;   
        }
        transformImageBitmap((ImageView) child, t, rotationAngle);         
    }    

return true;
}

/**
* This is called during layout when the size of this view has changed. If
* you were just added to the view hierarchy, you're called with the old
* values of 0.
*
* @param w Current width of this view.
* @param h Current height of this view.
* @param oldw Old width of this view.
* @param oldh Old height of this view.
 */
 protected void onSizeChanged(int w, int h, int oldw, int oldh) {
  mCoveflowCenter = getCenterOfCoverflow();
  super.onSizeChanged(w, h, oldw, oldh);
 }

 /**
  * Transform the Image Bitmap by the Angle passed 
  * 
  * @param imageView ImageView the ImageView whose bitmap we want to rotate
  * @param t transformation 
  * @param rotationAngle the Angle by which to rotate the Bitmap
  */
 private void transformImageBitmap(ImageView child, Transformation t, int rotationAngle) {            
  mCamera.save();
  final Matrix imageMatrix = t.getMatrix();;
  final int imageHeight = child.getLayoutParams().height;;
  final int imageWidth = child.getLayoutParams().width;
  final int rotation = Math.abs(rotationAngle);

  mCamera.translate(0.0f, 0.0f, 100.0f);

  //As the angle of the view gets less, zoom in     
  if ( rotation < mMaxRotationAngle ) {
   float zoomAmount = (float) (mMaxZoom +  (rotation * 1.5));
   mCamera.translate(0.0f, 0.0f, zoomAmount);          
  } 

  mCamera.rotateY(rotationAngle);
  mCamera.getMatrix(imageMatrix);               
  imageMatrix.preTranslate(-(imageWidth/2), -(imageHeight/2)); 
  imageMatrix.postTranslate((imageWidth/2), (imageHeight/2));
  mCamera.restore();
}
}

主.java

public class Main extends Activity {

@Override
 public void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);

 requestWindowFeature(Window.FEATURE_NO_TITLE);

 CoverFlow coverFlow;
 coverFlow = new CoverFlow(this);

 coverFlow.setAdapter(new ImageAdapter(this));

 ImageAdapter coverImageAdapter =  new ImageAdapter(this);

 coverImageAdapter.createReflectedImages();

 coverFlow.setAdapter(coverImageAdapter);

 coverFlow.setSpacing(-25);
 coverFlow.setSelection(4, true);
 coverFlow.setAnimationDuration(1000);


 setContentView(R.layout.main);
 }

public class ImageAdapter extends BaseAdapter {
 int mGalleryItemBackground;
 private Context mContext;

 private FileInputStream fis;

 private Integer[] mImageIds = {
   R.drawable.a,
         R.drawable.b,
         R.drawable.c,
         R.drawable.d,
         R.drawable.e,
         R.drawable.f,
         R.drawable.g,
         R.drawable.h,
         R.drawable.i
 };

 private ImageView[] mImages;

 public ImageAdapter(Context c) {
  mContext = c;
  mImages = new ImageView[mImageIds.length];
 }
public boolean createReflectedImages() {
      //The gap we want between the reflection and the original image
      final int reflectionGap = 4;


      int index = 0;
      for (int imageId : mImageIds) {
    Bitmap originalImage = BitmapFactory.decodeResource(getResources(), 
      imageId);
       int width = originalImage.getWidth();
       int height = originalImage.getHeight();


       //This will not scale but will flip on the Y axis
       Matrix matrix = new Matrix();
       matrix.preScale(1, -1);

       //Create a Bitmap with the flip matrix applied to it.
       //We only want the bottom half of the image
       Bitmap reflectionImage = Bitmap.createBitmap(originalImage, 0, height/2, width, height/2, matrix, false);


       //Create a new bitmap with same width but taller to fit reflection
       Bitmap bitmapWithReflection = Bitmap.createBitmap(width 
         , (height + height/2), Config.ARGB_8888);

      //Create a new Canvas with the bitmap that's big enough for
      //the image plus gap plus reflection
      Canvas canvas = new Canvas(bitmapWithReflection);
      //Draw in the original image
      canvas.drawBitmap(originalImage, 0, 0, null);
      //Draw in the gap
      Paint deafaultPaint = new Paint();
      canvas.drawRect(0, height, width, height + reflectionGap, deafaultPaint);
      //Draw in the reflection
      canvas.drawBitmap(reflectionImage,0, height + reflectionGap, null);

      //Create a shader that is a linear gradient that covers the reflection
      Paint paint = new Paint(); 
      LinearGradient shader = new LinearGradient(0, originalImage.getHeight(), 0, 
        bitmapWithReflection.getHeight() + reflectionGap, 0x70ffffff, 0x00ffffff, 
        TileMode.CLAMP); 
      //Set the paint to use this shader (linear gradient)
      paint.setShader(shader); 
      //Set the Transfer mode to be porter duff and destination in
      paint.setXfermode(new PorterDuffXfermode(Mode.DST_IN)); 
      //Draw a rectangle using the paint with our linear gradient
      canvas.drawRect(0, height, width, 
        bitmapWithReflection.getHeight() + reflectionGap, paint); 

      ImageView imageView = new ImageView(mContext);
      imageView.setImageBitmap(bitmapWithReflection);
      imageView.setLayoutParams(new CoverFlow.LayoutParams(120, 180));
      imageView.setScaleType(ScaleType.MATRIX);
      mImages[index++] = imageView;

      }
   return true;
 }

 public int getCount() {
     return mImageIds.length;
 }

 public Object getItem(int position) {
     return position;
 }

 public long getItemId(int position) {
     return position;
 }

 public View getView(int position, View convertView, ViewGroup parent) {

  //Use this code if you want to load from resources
     ImageView i = new ImageView(mContext);
     i.setImageResource(mImageIds[position]);
     i.setLayoutParams(new CoverFlow.LayoutParams(130, 130));
     i.setScaleType(ImageView.ScaleType.CENTER_INSIDE); 

     //Make sure we set anti-aliasing otherwise we get jaggies
     BitmapDrawable drawable = (BitmapDrawable) i.getDrawable();
     drawable.setAntiAlias(true);
     return i;

  //return mImages[position];
 }
 /** Returns the size (0.0f to 1.0f) of the views 
  * depending on the 'offset' to the center. */ 
  public float getScale(boolean focused, int offset) { 
    /* Formula: 1 / (2 ^ offset) */ 
      return Math.max(0, 1.0f / (float)Math.pow(2, Math.abs(offset))); 
  } 

}
}

Answer 1

LayoutInflater inflater = (LayoutInflater) this
 .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
final View v = inflater.inflate(R.layout."layout here", null, false);

并使用，例如

 TextView tv=(TextView)v.findViewById(R,id."id here");