Android下のGallery表示技術分析(三)

前回の記事ではバックグラウンド効果を実現しましたが、3 D効果を実現する方法を見てみましょう.コードの2つに注意してください.

transformImageBitmap:画像の変形;

getChildStaticTransformation:変形後の形状を制御する;

public class Gallery3D extends Gallery {
	//     
	private Camera mCamera = new Camera();
	//       
	private int mMaxRotationAngle = 60;
	//      
	private int mMaxZoom = -120;
	//    
	private int mCoveflowCenter;

	public Gallery3D(Context context) {
		super(context);
		//      ,  getChildStaticTransformation  
		this.setStaticTransformationsEnabled(true);
	}

	public Gallery3D(Context context, AttributeSet attrs) {
		super(context, attrs);
		this.setStaticTransformationsEnabled(true);
	}

	public Gallery3D(Context context, AttributeSet attrs, int defStyle) {
		super(context, attrs, defStyle);
		this.setStaticTransformationsEnabled(true);
	}

//	public int getMaxRotationAngle() {
//		return mMaxRotationAngle;
//	}
//
//	public void setMaxRotationAngle(int maxRotationAngle) {
//		mMaxRotationAngle = maxRotationAngle;
//	}
//
//	public int getMaxZoom() {
//		return mMaxZoom;
//	}
//
//	public void setMaxZoom(int maxZoom) {
//		mMaxZoom = maxZoom;
//	}

	private int getCenterOfCoverflow() {
		return (getWidth() - getPaddingLeft() - getPaddingRight()) / 2
				+ getPaddingLeft();
	}

	private static int getCenterOfView(View view) {
		return view.getLeft() + view.getWidth() / 2;
	}

	/**
	 *   gallery        (   gallery   )
	 */
	@Override
	protected boolean getChildStaticTransformation(View child, Transformation t) {
		//      view    
		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 {
			//      gallery              
			rotationAngle = (int) (((float) (mCoveflowCenter - childCenter) / childWidth) * mMaxRotationAngle);
			//                    （-mMaxRotationAngle mMaxRotationAngle;）
			if (Math.abs(rotationAngle) > mMaxRotationAngle) {
				rotationAngle = (rotationAngle < 0) ? -mMaxRotationAngle
						: mMaxRotationAngle;
			}
			transformImageBitmap((ImageView) child, t, rotationAngle);
		}

		return true;
	}

	@Override
	protected void onSizeChanged(int w, int h, int oldw, int oldh) {
		mCoveflowCenter = getCenterOfCoverflow();
		super.onSizeChanged(w, h, oldw, oldh);
	}

	/**
	 *      
	 * @param child
	 * @param t
	 * @param rotationAngle
	 */
	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);

		//  Z      camera   ，         。   Y    ，       ；X          。
		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);
		}

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