Android实现CoverFlow效果

先上一张效果图：

上代码，看了代码什么都明白

CoverFlow从Gallery继承过来

package com.coverflow;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 {private Camera mCamera = new Camera();private int mMaxRotationAngle = 50;private int mMaxZoom = -380;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;}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;}/** * 这就是所谓的在大小的布局时,这一观点已经发生了改变。如果 你只是添加到视图层次,有人叫你旧的观念 价值观为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);}/** * 把图像位图的角度通过 *  * @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);// 如视图的角度更少,放大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);elsemCamera.translate(0.0f, (255 - rotation * 2.5f), 0.0f);}if (mAlphaMode) {((ImageView) (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();}}

这个就是CoverFlow类，说明几点：
1. 成员函数
mCamera是用来做类3D效果处理,比如z轴方向上的平移,绕y轴的旋转等
mMaxRotationAngle是图片绕y轴最大旋转角度,也就是屏幕最边上那两张图片的旋转角度
mMaxZoom是图片在z轴平移的距离,视觉上看起来就是放大缩小的效果.
其他的变量都可以无视
也就是说把这个属性设成true的时候每次viewGroup(看Gallery的源码就可以看到它是从ViewGroup间接继承过来的)在重新画它的child的时候都会促发getChildStaticTransformation这个函数,所以我们只需要在这个函数里面去加上旋转和放大的操作就可以了
其他的getter和setter函数都可以无视

ImageAdapter适配器：

package com.coverflow;import android.content.Context;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.graphics.Canvas;import android.graphics.LinearGradient;import android.graphics.Matrix;import android.graphics.Paint;import android.graphics.PorterDuffXfermode;import android.graphics.Bitmap.Config;import android.graphics.PorterDuff.Mode;import android.graphics.Shader.TileMode;import android.graphics.drawable.BitmapDrawable;import android.view.View;import android.view.ViewGroup;import android.widget.BaseAdapter;import android.widget.ImageView;import com.gallery.R;public class ImageAdapter extends BaseAdapter {int mGalleryItemBackground;private Context mContext;private Integer[] mImageIds = { R.drawable.a1,R.drawable.a2, R.drawable.a3,R.drawable.a4, R.drawable.a5 };public ImageAdapter(Context c) {mContext = c;}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) {ImageView i = createReflectedImages(mContext,mImageIds[position]);i.setLayoutParams(new CoverFlow.LayoutParams(120, 100));i.setScaleType(ImageView.ScaleType.CENTER_INSIDE);// 设置的抗锯齿BitmapDrawable drawable = (BitmapDrawable) i.getDrawable();drawable.setAntiAlias(true);return i;}public float getScale(boolean focused, int offset) {return Math.max(0, 1.0f / (float) Math.pow(2, Math.abs(offset)));}public ImageView createReflectedImages(Context mContext,int imageId) {Bitmap originalImage = BitmapFactory.decodeResource(mContext.getResources(), imageId);final int reflectionGap = 4;int width = originalImage.getWidth();int height = originalImage.getHeight();Matrix matrix = new Matrix();matrix.preScale(1, -1);Bitmap reflectionImage = Bitmap.createBitmap(originalImage, 0,height / 2, width, height / 2, matrix, false);Bitmap bitmapWithReflection = Bitmap.createBitmap(width,(height + height / 2), Config.ARGB_8888);Canvas canvas = new Canvas(bitmapWithReflection);canvas.drawBitmap(originalImage, 0, 0, null);Paint deafaultPaint = new Paint();canvas.drawRect(0, height, width, height + reflectionGap, deafaultPaint);canvas.drawBitmap(reflectionImage, 0, height + reflectionGap, null);Paint paint = new Paint();LinearGradient shader = new LinearGradient(0, originalImage.getHeight(), 0, bitmapWithReflection.getHeight()+ reflectionGap, 0x70ffffff, 0x00ffffff, TileMode.MIRROR);paint.setShader(shader);paint.setXfermode(new PorterDuffXfermode(Mode.DST_IN));canvas.drawRect(0, height, width, bitmapWithReflection.getHeight()+ reflectionGap, paint);ImageView imageView = new ImageView(mContext);imageView.setImageBitmap(bitmapWithReflection);return imageView;}}

BitmapDrawable drawable = (BitmapDrawable) i.getDrawable();
drawable.setAntiAlias(true);
是保证图片绕Y旋转了以后不会出现锯齿.

下面是Activity：

package com.coverflow;import android.app.Activity;import android.graphics.Color;import android.os.Bundle;import com.gallery.R;public class HelloAndroid extends Activity {/** Called when the activity is first created. */@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);CoverFlow cf = new CoverFlow(this);// cf.setBackgroundResource(R.drawable.shape);cf.setBackgroundColor(Color.BLACK);cf.setAdapter(new ImageAdapter(this));ImageAdapter imageAdapter = new ImageAdapter(this);cf.setAdapter(imageAdapter);// cf.setAlphaMode(false);// cf.setCircleMode(false);cf.setSelection(2, true);cf.setAnimationDuration(1000);setContentView(cf);}}

 

转载：http://my.oschina.net/liux/blog/41925