CoverFlow.java

package hong.specialEffects.wight;

import android.content.Context;
import android.graphics.Camera;
import android.graphics.Matrix;
import android.util.AttributeSet;
import android.view.View;
import android.view.animation.Transformation;
import android.widget.Gallery;
import android.widget.ImageView;

public class CoverFlow extends Gallery {
	//mCamera����������3DЧ������,����z�᷽���ϵ�ƽ��,��y�����ת��
	private Camera mCamera = new Camera();
	//��ͼƬ��y�������ת�Ƕ�,Ҳ������Ļ�����������ͼƬ����ת�Ƕ�
	private int mMaxRotationAngle = 50;//60;
	//mMaxZoom��ͼƬ��z��ƽ�Ƶľ���,�Ӿ��Ͽ��������ǷŴ���С��Ч��.
	private int mMaxZoom = -480;//-120;
	private int mCoveflowCenter;
	private boolean mAlphaMode = true;
	private boolean mCircleMode = false;

	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);
	}

	public int getMaxRotationAngle() {
		return mMaxRotationAngle;
	}

	public void setMaxRotationAngle(int maxRotationAngle) {
		mMaxRotationAngle = maxRotationAngle;
	}

	public boolean getCircleMode() {
		return mCircleMode;
	}

	public void setCircleMode(boolean isCircle) {
		mCircleMode = isCircle;
	}

	public boolean getAlphaMode() {
		return mAlphaMode;
	}

	public void setAlphaMode(boolean isAlpha) {
		mAlphaMode = isAlpha;
	}

	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��ͼ���л�ʱ������ô˺���
	 * ����ͼ���λ�ý�ͼ������Ӧλ�õ�����y����ת�󣬼ȵõ�coverflowЧ��
	 */
	@Override
	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;
	}

	/**
	 * �������ν���ڴ�С�IJ���ʱ,��һ�۵��Ѿ������˸ı䡣��� ��ֻ����ӵ���ͼ���,���˽���ɵĹ��� ��ֵ��Ϊ0��
	 * 
	 * @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.
	 */
	@Override
	protected void onSizeChanged(int w, int h, int oldw, int oldh) {
		mCoveflowCenter = getCenterOfCoverflow();
		super.onSizeChanged(w, h, oldw, oldh);
	}

	/**
	 * ��ͼ��λͼ����y����ת
	 * 
	 * @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);

		// ����ͼ�ĽǶȸ���,�Ŵ�
		if (rotation <= mMaxRotationAngle) {
			float zoomAmount = (float) (mMaxZoom + (rotation * 1.5));
			mCamera.translate(0.0f, 0.0f, zoomAmount);
			if (mCircleMode) {
				if (rotation < 40)
					mCamera.translate(0.0f, 155, 0.0f);
				else
					mCamera.translate(0.0f, (255 - rotation * 2.5f), 0.0f);
			}
			if (mAlphaMode) {
				(child).setAlpha((int) (255 - rotation * 2.5));
			}
		}
		mCamera.rotateY(rotationAngle);
		mCamera.getMatrix(imageMatrix);
		imageMatrix.preTranslate(-(imageWidth / 2), -(imageHeight / 2));
		imageMatrix.postTranslate((imageWidth / 2), (imageHeight / 2));
		mCamera.restore();
	}
}