Android(安卓)自定义Gallery浏览图片
16lz
2021-01-25
之前写的《Android ImageSwitcher和Gallery的使用》一文中提到我在教室一下午为实现那个效果找各种资料。期间在网上找了一个个人觉得比较不错的效果，现在贴图上来：
其实这个效果使用的知识点就是图像的获取、创建、缩放、旋转、Matrix类、Canvas类等,另外就是自定义的Gallery控件。
相信大家都期待马上上代码了吧，嘻嘻。（注释比较多，相信大家都能看懂。）
main.xml:
<?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" android:background="@android:color/background_light" > <TextView android:id="@+id/tvTitle" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_centerHorizontal="true" android:textSize="16sp" /> <com.example.demo.GalleryView android:id="@+id/mygallery" android:spacing="20dp" android:layout_width="fill_parent" android:layout_height="fill_parent" android:unselectedAlpha="1.2" android:layout_below="@id/tvTitle" android:layout_marginTop="10dip" /></RelativeLayout>
新建一个GalleryView类：
public class GalleryView extends Gallery { private Camera mCamera = new Camera(); private int mMaxRotationAngle = 60; // 最大旋转角度 60 private int mMaxZoom = -120; private int mCoveflowCenter; @Override public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) { // e1是按下的事件，e2是抬起的事件 int keyCode; if (isScrollingLeft(e1, e2)) { keyCode = KeyEvent.KEYCODE_DPAD_LEFT; } else { keyCode = KeyEvent.KEYCODE_DPAD_RIGHT; } onKeyDown(keyCode, null); return true; } private boolean isScrollingLeft(MotionEvent e1, MotionEvent e2) { return e2.getX() > e1.getX(); } public GalleryView(Context context) { super(context); this.setStaticTransformationsEnabled(true); } public GalleryView(Context context, AttributeSet attrs) { super(context, attrs); this.setStaticTransformationsEnabled(true); } public GalleryView(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; } @Override protected void onSizeChanged(int w, int h, int oldw, int oldh) { mCoveflowCenter = getCenterOfCoverflow(); super.onSizeChanged(w, h, oldw, oldh); } @Override protected 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childView transformImageBitmap((ImageView) child, trans, 0); } else { // 两侧的childView rotationAngle = (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, -20.0f); // As the angle of the view gets less, zoom in if (rotation < mMaxRotationAngle) { float zoomAmount = (float) (mMaxZoom + (rotation * 1.0)); 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(); }}View Code
再新建一个适配器类：ImageAdapter.java（最重要的地方）
public class ImageAdapter extends BaseAdapter { private ImageView[] mImages; // 保存倒影图片的数组 private Context mContext; public List<Map<String, Object>> list; public Integer[] imgs = { R.drawable.image01, R.drawable.image02, R.drawable.image03, R.drawable.image04, R.drawable.image05, R.drawable.image06, R.drawable.image07 }; public String[] titles = { "美图01", "美图02", "美图03", "美图04", "美图05", "美图06", "美图07" }; public ImageAdapter(Context c) { this.mContext = c; list = new ArrayList<Map<String, Object>>(); for (int i = 0; i < imgs.length; i++) { HashMap<String, Object> map = new HashMap<String, Object>(); map.put("image", imgs[i]); list.add(map); } mImages = new ImageView[list.size()]; } /** 反射倒影 */ public boolean createReflectedImages() { final int reflectionGap = 4; final int Height = 300; int index = 0; for (Map<String, Object> map : list) { Integer id = (Integer) map.get("image"); // 根据给定的资源ID从指定的资源中解析、创建Bitmap对象。 Bitmap originalImage = BitmapFactory.decodeResource( mContext.getResources(), id); // 获取原始图片 // 获得实际图片的宽高 int width = originalImage.getWidth(); int height = originalImage.getHeight(); float scale = Height / (float) height; Matrix sMatrix = new Matrix(); // 第一次缩放图片动作 sMatrix.postScale(scale, scale); Bitmap miniBitmap = Bitmap.createBitmap(originalImage, 0, 0, originalImage.getWidth(), originalImage.getHeight(), sMatrix, false); // 获取第一次缩放后的图片的宽高 int mwidth = miniBitmap.getWidth(); int mheight = miniBitmap.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(miniBitmap, 0, mheight/2, mwidth, mheight/2, matrix, false); // 截取原图下半部分 Bitmap bitmapWithReflection = Bitmap.createBitmap(mwidth, mheight+mheight/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(miniBitmap, 0, 0, null); // 绘制原图 Paint paint = new Paint(); canvas.drawRect(0, mheight, mwidth, mheight , paint); // 绘制原图与倒影的间距 canvas.drawBitmap(reflectionImage, 0, mheight , null); // 绘制倒影图,绘制原图与倒影的间距(第四个参数改变) paint = new Paint(); LinearGradient shader = new LinearGradient(0, miniBitmap.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, mheight, mwidth, 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 GalleryView.LayoutParams( (int) (width * scale), (int) (mheight * 3 / 2.0+ reflectionGap))); imageView.setScaleType(ScaleType.MATRIX); mImages[index++] = imageView; } return true; } @Override public int getCount() { return imgs.length; } @Override public Object getItem(int position) { return mImages[position]; } @Override public long getItemId(int position) { return position; } @Override public View getView(int position, View convertView, ViewGroup parent) { return mImages[position]; // 显示倒影图片（当前获取焦点） } public float getScale(boolean focused, int offset) { return Math.max(0, 1.0f / (float) Math.pow(2, Math.abs(offset))); }}View Code
最后就是Main.java（默认Activity）:
public class Main extends Activity { private TextView tvTitle; private GalleryView gallery; private ImageAdapter adapter; @Override public void onCreate(Bundle savedInstanceState) { requestWindowFeature(Window.FEATURE_NO_TITLE); super.onCreate(savedInstanceState); setContentView(R.layout.main); initRes(); } private void initRes(){ tvTitle = (TextView) findViewById(R.id.tvTitle); gallery = (GalleryView) findViewById(R.id.mygallery); 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 @Override public void onItemSelected(AdapterView<?> parent, View view, int position, long id) { tvTitle.setText(adapter.titles[position]); } @Override public void onNothingSelected(AdapterView<?> parent) { } }); gallery.setOnItemClickListener(new OnItemClickListener() { // 设置点击事件监听 @Override public void onItemClick(AdapterView<?> parent, View view, int position, long id) { Toast.makeText(Main.this, "img " + (position+1) + " selected", Toast.LENGTH_SHORT).show(); } }); }}View Code
接下来运行即可。你就能看到上面的运行效果了。
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