如何利用matrix实现图片倒影效果

2019-12-12 06:20:12

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本文主要内容就是用marix加上渐变色实现图片倒影的效果，步骤如下：

1. 获取需要倒影效果的图片，这里取原图片的一半

2. 添加颜色渐变到倒影图片上

具体的实现如下面代码所述，我们以一种自定义view的形式给出效果图，代码如下：

package com.flection.view;import com.flection.main.R;import android.annotation.SuppressLint;import android.content.Context;import android.graphics.Bitmap;import android.graphics.Bitmap.Config;import android.graphics.BitmapFactory;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.LinearGradient;import android.graphics.Matrix;import android.graphics.Paint;import android.graphics.PorterDuffXfermode;import android.graphics.Shader.TileMode;import android.graphics.drawable.BitmapDrawable;import android.util.AttributeSet;import android.view.View;public class FlectionView extends View {  Context mContext=null;  public FlectionView(Context context) {    super(context);  }  public FlectionView(Context context, AttributeSet attrs) {    super(context, attrs);    this.mContext=context;  }  @SuppressLint("DrawAllocation")  @Override  protected void onDraw(Canvas canvas) {    //设置背景色    this.setBackgroundColor(Color.parseColor("#8B8378"));    Bitmap oldBitmap = BitmapFactory.decodeResource(mContext.getResources(),R.drawable.dropbox);    Bitmap newBitmap = createFlectionBitmap(oldBitmap);    canvas.drawBitmap(newBitmap,newBitmap.getWidth() ,newBitmap.getHeight(), new Paint());    this.invalidate();  }  //获取原图+倒影图的bitmap  private Bitmap createFlectionBitmap(Bitmap oldBitmap) {    int mWidth = oldBitmap.getWidth();    int mHeight = oldBitmap.getHeight();    //原图和倒影图之间的缝隙    int gap = 2;    Matrix matrix = new Matrix();    matrix.preScale(1, -1);    Bitmap flection = Bitmap.createBitmap(oldBitmap, 0, mHeight / 2,        mWidth, mHeight / 2, matrix, false);    Bitmap background = Bitmap.createBitmap(mWidth, mHeight+gap+mHeight/2, Config.ARGB_8888);    Canvas canvas = new Canvas(background);    Paint p1 = new Paint();    //画出原图    canvas.drawBitmap(oldBitmap, 0, 0, p1);    //画出倒影图    canvas.drawBitmap(flection, 0, mHeight+gap, p1);    Paint shaderPaint = new Paint();    LinearGradient shader = new LinearGradient(0, mHeight, 0,        flection.getHeight(), 0x70ffffff, 0x00ffffff, TileMode.MIRROR);    shaderPaint.setShader(shader);    shaderPaint.setXfermode(new PorterDuffXfermode(android.graphics.PorterDuff.Mode.DST_IN));    //画出渐变颜色    canvas.drawRect(0, mHeight+gap, mWidth, background.getHeight(), shaderPaint);    return background;  }}

实现的效果如下图：