Android笔记：图片倒影、ReflectionImage

ReflectionImage类代码:

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.LinearGradient;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.PorterDuff.Mode;
import android.graphics.PorterDuffXfermode;
import android.graphics.Shader.TileMode;
import android.graphics.drawable.BitmapDrawable;
import android.util.AttributeSet;
import android.widget.ImageView;
//图片倒影
public class ReflectionImage extends ImageView
{
    // 是否为Reflection模式
    private boolean mReflectionMode = true;
              
    public ReflectionImage(Context context)
    {
        super(context);
    }
              
    public ReflectionImage(Context context, AttributeSet attrs)
    {
        super(context, attrs);
        // 取得原始图片的bitmap并重画
        BitmapDrawable bd = (BitmapDrawable) this.getDrawable();
        Bitmap originalImage = bd.getBitmap();
        DoReflection(originalImage);
    }
              
    public ReflectionImage(Context context, AttributeSet attrs, int defStyle)
    {
        super(context, attrs, defStyle);
        Bitmap originalImage = ((BitmapDrawable) this.getDrawable()).getBitmap();
        DoReflection(originalImage);
    }
              
    public void setReflectionMode(boolean isRef)
    {
        mReflectionMode = isRef;
    }
              
    public boolean getReflectionMode()
    {
        return mReflectionMode;
    }
              
    // 只重写了setImageResource,和构造函数里面干了同样的事情
    @Override
    public void setImageResource(int resId)
    {
        Bitmap originalImage = BitmapFactory.decodeResource(getResources(), resId);
        DoReflection(originalImage);
        // super.setImageResource(resId);
    }
              
    private void DoReflection(Bitmap originalImage)
    {
        final int reflectionGap = 4; // 原始图片和反射图片中间的间距
        int width = originalImage.getWidth();
        int height = originalImage.getHeight();
                  
        // 反转
        Matrix matrix = new Matrix();
        matrix.preScale(1, -1);
        // reflectionImage就是下面透明的那部分,可以设置它的高度为原始的3/4,这样效果会更好些
        Bitmap reflectionImage = Bitmap.createBitmap(originalImage, 0, 0, width, height, matrix, false);
        // 创建一个新的bitmap,高度为原来的两倍
        Bitmap bitmapWithReflection = Bitmap.createBitmap(width, (height + height), Config.ARGB_8888);
        Canvas canvasRef = new Canvas(bitmapWithReflection);
                  
        // 先画原始的图片
        canvasRef.drawBitmap(originalImage, 0, 0, null);
        // 画间距
        Paint deafaultPaint = new Paint();
        canvasRef.drawRect(0, height, width, height + reflectionGap, deafaultPaint);
                  
        // 画被反转以后的图片
        canvasRef.drawBitmap(reflectionImage, 0, height + reflectionGap, null);
        // 创建一个渐变的蒙版放在下面被反转的图片上面
        Paint paint = new Paint();
        LinearGradient shader = new LinearGradient(0, originalImage.getHeight(), 0, bitmapWithReflection.getHeight() + reflectionGap, 0x80ffffff, 0x00ffffff,
                TileMode.CLAMP);
        // Set the paint to use this shader (linear gradient)
        paint.setShader(shader);
        // Set the Transfer mode to be porter duff and destination in
        paint.setXfermode(new PorterDuffXfermode(Mode.DST_IN));
        // Draw a rectangle using the paint with our linear gradient
        canvasRef.drawRect(0, height, width, bitmapWithReflection.getHeight() + reflectionGap, paint);
        // 调用ImageView中的setImageBitmap
        this.setImageBitmap(bitmapWithReflection);
    }
}