Android 滑动效果进阶篇（六）—— 倒影效果

上篇介绍了使用Animation实现3D动画旋转翻页效果，现在介绍图片倒影实现，先看效果图

本示例主要通过自定义Gallery和ImageAdapter（继承自BaseAdapter）实现

1、倒影绘制

ImageAdapter继承自BaseAdapter，详细实现可见 Android 滑动效果入门篇（二）—— Gallery 这里重点介绍倒影原理及实现

倒影原理：

倒影效果是主要由原图+间距+倒影三部分组成，高度大约为原图的3/2（原图为1、倒影为1/2）

原图，就是我们看到了最开始的图片

间距，是原图与倒影之间的间隙，如：reflectionGap = 4;

倒影，是原图下半部分1/2高度，通过矩阵变换matrix.preScale(1, -1); 获取倒立图片，然后再加上线性遮罩和阴影实现

倒影实现：

/** 反射倒影 */public boolean createReflectedImages() {final int reflectionGap = 4;int index = 0;for (Map<String, Object> map : list) {Integer id = (Integer) map.get("image");Bitmap originalImage = BitmapFactory.decodeResource(mContext.getResources(), id);// 获取原始图片int width = originalImage.getWidth();int height = originalImage.getHeight();Matrix matrix = new Matrix();matrix.preScale(1, -1);// 图片矩阵变换（从低部向顶部的倒影）Bitmap reflectionImage = Bitmap.createBitmap(originalImage, 0, height/2, width, height/2, matrix, false);// 截取原图下半部分Bitmap bitmapWithReflection = Bitmap.createBitmap(width, (height + height / 2), Config.ARGB_8888);// 创建倒影图片（高度为原图3/2）Canvas canvas = new Canvas(bitmapWithReflection);// 绘制倒影图（原图 + 间距 + 倒影）canvas.drawBitmap(originalImage, 0, 0, null);// 绘制原图Paint paint = new Paint();canvas.drawRect(0, height, width, height + reflectionGap, paint);// 绘制原图与倒影的间距canvas.drawBitmap(reflectionImage, 0, height + reflectionGap, null);// 绘制倒影图paint = new Paint();LinearGradient shader = new LinearGradient(0, originalImage.getHeight(), 0, bitmapWithReflection.getHeight() + reflectionGap, 0x70ffffff, 0x00ffffff, TileMode.CLAMP);paint.setShader(shader);// 线性渐变效果paint.setXfermode(new PorterDuffXfermode(Mode.DST_IN));// 倒影遮罩效果canvas.drawRect(0, height, width, bitmapWithReflection.getHeight() + reflectionGap, paint);// 绘制倒影的阴影效果ImageView imageView = new ImageView(mContext);imageView.setImageBitmap(bitmapWithReflection);// 设置倒影图片imageView.setLayoutParams(new myGallery.LayoutParams(180, 240));imageView.setScaleType(ScaleType.MATRIX);mImages[index++] = imageView;}return true;}

2、myGallery

自定义Gallery来实现倒影图片的浏览与选择

public class myGallery extends Gallery {private Camera mCamera = new Camera();private int mMaxRotationAngle = 60;// 最大旋转角度 60private int mMaxZoom = -120;private int mCoveflowCenter;public myGallery(Context context) {super(context);this.setStaticTransformationsEnabled(true);}public myGallery(Context context, AttributeSet attrs) {super(context, attrs);this.setStaticTransformationsEnabled(true);}public myGallery(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;}/** 获取Gallery的中心x */private int getCenterOfCoverflow() {return (getWidth() - getPaddingLeft() - getPaddingRight()) / 2 + getPaddingLeft();}/** 获取View的中心x */private static int getCenterOfView(View view) {return view.getLeft() + view.getWidth() / 2;}@Overrideprotected void onSizeChanged(int w, int h, int oldw, int oldh) {mCoveflowCenter = getCenterOfCoverflow();super.onSizeChanged(w, h, oldw, oldh);}@Overrideprotected boolean getChildStaticTransformation(View child, Transformation trans) {final int childCenter = getCenterOfView(child);final int childWidth = child.getWidth();int rotationAngle = 0;trans.clear();trans.setTransformationType(Transformation.TYPE_BOTH);// alpha 和 matrix 都变换if (childCenter == mCoveflowCenter) {// 正中间的childViewtransformImageBitmap((ImageView) child, trans, 0);} else {// 两侧的childViewrotationAngle = (int) ( ( (float) (mCoveflowCenter - childCenter) / childWidth ) * mMaxRotationAngle );if (Math.abs(rotationAngle) > mMaxRotationAngle) {rotationAngle = (rotationAngle < 0) ? -mMaxRotationAngle : mMaxRotationAngle;}transformImageBitmap((ImageView) child, trans, rotationAngle);}return true;}private void transformImageBitmap(ImageView child, Transformation trans, int rotationAngle) {mCamera.save();final Matrix imageMatrix = trans.getMatrix();final int imageHeight = child.getLayoutParams().height;final int imageWidth = child.getLayoutParams().width;final int rotation = Math.abs(rotationAngle);// 在Z轴上正向移动camera的视角，实际效果为放大图片; 如果在Y轴上移动，则图片上下移动; X轴上对应图片左右移动。mCamera.translate(0.0f, 0.0f, 100.0f);// As the angle of the view gets less, zoom inif (rotation < mMaxRotationAngle) {float zoomAmount = (float) (mMaxZoom + (rotation * 1.5));mCamera.translate(0.0f, 0.0f, zoomAmount);}mCamera.rotateY(rotationAngle);// rotationAngle 为正，沿y轴向内旋转； 为负，沿y轴向外旋转mCamera.getMatrix(imageMatrix);imageMatrix.preTranslate(-(imageWidth / 2), -(imageHeight / 2));imageMatrix.postTranslate((imageWidth / 2), (imageHeight / 2));mCamera.restore();}}

3、Activity

Activity中，主要实现自定义Gallery的图片填充ImageAdapter、myGallery选择事件监听、点击事件监听

private void initRes(){tvTitle = (TextView) findViewById(R.id.tvTitle);gallery = (myGallery) findViewById(R.id.mygallery);// 获取自定义的myGallery控件adapter = new ImageAdapter(this); adapter.createReflectedImages();// 创建倒影效果gallery.setAdapter(adapter);gallery.setOnItemSelectedListener(new OnItemSelectedListener() {// 设置选择事件监听@Overridepublic void onItemSelected(AdapterView<?> parent, View view, int position, long id) {tvTitle.setText(adapter.titles[position]);}@Overridepublic void onNothingSelected(AdapterView<?> parent) {}});gallery.setOnItemClickListener(new OnItemClickListener() {// 设置点击事件监听@Overridepublic void onItemClick(AdapterView<?> parent, View view, int position, long id) {Toast.makeText(Main.this, "img " + (position+1) + " selected", Toast.LENGTH_SHORT).show();}});}

main.xml布局文件中，通过实现自定义的myGallery，来显示图片集合

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="fill_parent"    android:layout_height="fill_parent"    android:orientation="vertical" >    <TextView        android:id="@+id/tvTitle"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_centerHorizontal="true"        android:textSize="16sp" />        <com.homer.reflect.myGallery        android:id="@+id/mygallery"        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:layout_below="@id/tvTitle"        android:layout_marginTop="10dip" /></RelativeLayout>

源码下载

参考推荐：

Android实现图片的倒影效果

Android中图片倒影、圆角效果重绘