如何利用matrix实现图片倒影效果

Vanessa ·

更新时间:2024-11-10

· 978 次阅读

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：