19_Android中图片处理原理篇，关于人脸识别站点，图片载入到内存，图片缩放，图片翻转倒置，网上撕衣服游戏案例编写

1载入图片到内存

（1）.数码相机照片特别是大于3m以上的，内存吃不消，会报OutOfMemoryError,若是想仅仅显示原图片的1/8,能够通过BitmapFactory.Options来实现。详细代码例如以下：

BitmapFactory.Options bmpFactoryOptions = new BitmapFactory.Options();

bmpFactoryOptions.inSampleSize = 8;

Bitmap bmp = BitmapFactory.decodeFile(imageFilePath, bmpFactoryOptions);

imv.setImageBitmap(bmp);

假设图片太大，会出现的以下的问题：

2 依据当前屏幕分辨率的大小，载入图片

Display currentDisplay = getWindowManager().getDefaultDisplay();

int dw = currentDisplay.getWidth();

int dh = currentDisplay.getHeight();

BitmapFactory.Options bmpFactoryOptions = new BitmapFactory.Options();

bmpFactoryOptions.inJustDecodeBounds = true;

Bitmap bmp = BitmapFactory.decodeFile(imageFilePath, bmpFactoryOptions);

//通过以下的代码计算缩放比，那个方向的缩放比大，就依照这把方向的缩放比来缩放。

int heightRatio = (int)Math.ceil(bmpFactoryOptions.outHeight/(float)dh);

int widthRatio = (int)Math.ceil(bmpFactoryOptions.outWidth/(float)dw);

Log.v("HEIGHTRATIO",""+heightRatio);

Log.v("WIDTHRATIO",""+widthRatio);

//推断是否要进行缩放

if (heightRatio > 1 && widthRatio > 1)

{

if (heightRatio > widthRatio)

{

//高度变化大,按高度缩放

bmpFactoryOptions.inSampleSize = heightRatio;

}

else

{

// 宽度变化大,按宽度缩放

bmpFactoryOptions.inSampleSize = widthRatio;

}

}

bmpFactoryOptions.inJustDecodeBounds = false;

bmp = BitmapFactory.decodeFile(imageFilePath, bmpFactoryOptions);

3 获取Exif图片信息

//从文件获取exif信息

ExifInterface ei = new ExifInterface(imageFilePath);

String imageDescription = ei.getAttribute("ImageDescription");

if (imageDescription != null)

{

Log.v("EXIF", imageDescription);

}

//把exif信息写到文件:

ExifInterface ei = new ExifInterface(imageFilePath);

ei.setAttribute("ImageDescription","Something New");

4 从gallery获取一个图片

Intent intent = new Intent(Intent.ACTION_PICK);

intent.setType(“image/*”);

intent.getData() 获取image的uri

Bitmap bmp = BitmapFactory.decodeStream(getContentResolver().

openInputStream(imageFileUri), null, bmpFactoryOptions);

5 创建bitmap拷贝

Bitmap bmp = BitmapFactory.decodeStream(getContentResolver().

openInputStream(imageFileUri), null, bmpFactoryOptions);

Bitmap alteredBitmap = Bitmap.createBitmap(bmp.getWidth(),bmp.getHeight(),

bmp.getConfig());

Canvas canvas = new Canvas(alteredBitmap);

Paint paint = new Paint();

canvas.drawBitmap(bmp, 0, 0, paint);

6 图形缩放

Matrix matrix = new Matrix();

matrix.setValues(new float[] {

1, 0, 0,

0, 1, 0,

0, 0, 1

});

x = 1x + 0y + 0z

y = 0x + 1y + 0z

z = 0x + 0y + 1z

通过canvas.drawBitmap(bmp, matrix, paint);创建bitmap

1.水平缩放0.5

2.垂直拉扯2倍

matrix.setScale(1.5f,1);//水平点放大到1.5f,垂直1

7 图形旋转

Matrix matrix = new Matrix();

matrix.setRotate(15);

canvas.drawBitmap(bmp, matrix, paint);

消除锯齿

paint.setAntiAlias(true);

指定圆心的旋转

matrix.setRotate(15,bmp.getWidth()/2,bmp.getHeight()/2);

Matrix matrix = new Matrix();

matrix.setRotate(15,bmp.getWidth()/2,bmp.getHeight()/2);

alteredBitmap = Bitmap.createBitmap(bmp, 0, 0, bmp.getWidth(), bmp.getHeight(),

matrix, false);

alteredImageView.setImageBitmap(alteredBitmap);

8 图像平移：

setTranslate(1.5f,-10);

9 镜子效果：

matrix.setScale(-1, 1);

matrix.postTranslate(bmp.getWidth(),0);

10 倒影效果：

matrix.setScale(1, -1);

matrix.postTranslate(0, bmp.getHeight());

11 图像颜色处理：

颜色矩阵  ColorMatrix cm = new ColorMatrix();

paint.setColorFilter(new ColorMatrixColorFilter(cm));

1 0 0 0 0

0 1 0 0 0

0 0 1 0 0

0 0 0 1 0

New Red Value = 1*128 + 0*128 + 0*128 + 0*0 + 0

New Blue Value = 0*128 + 1*128 + 0*128 + 0*0 + 0

New Green Value = 0*128 + 0*128 + 1*128 + 0*0 + 0

New Alpha Value = 0*128 + 0*128 + 0*128 + 1*0 + 0

ColorMatrix cm = new ColorMatrix();

cm.set(new float[] {

2, 0, 0, 0, 0,

0, 1, 0, 0, 0,

0, 0, 1, 0, 0,

0, 0, 0, 1, 0

});

paint.setColorFilter(new ColorMatrixColorFilter(cm));

12 变换图像的亮度

ColorMatrix cm = new ColorMatrix();

float contrast = 2;

cm.set(new float[] {

contrast, 0, 0, 0, 0,

0, contrast, 0, 0, 0,

0, 0, contrast, 0, 0,

0, 0, 0, 1, 0 });

paint.setColorFilter(new ColorMatrixColorFilter(cm));

12 变换图像的亮度

ColorMatrix cm = new ColorMatrix();

float contrast = 2;

cm.set(new float[] {

contrast, 0, 0, 0, 0,

0, contrast, 0, 0, 0,

0, 0, contrast, 0, 0,

0, 0, 0, 1, 0 });

paint.setColorFilter(new ColorMatrixColorFilter(cm));

13 更改图片的饱和度：

ColorMatrix cm = new ColorMatrix();

cm.setSaturation(.5f);

paint.setColorFilter(new ColorMatrixColorFilter(cm));

14 图像合成:

Bitmap drawingBitmap = Bitmap.createBitmap(bmp1.getWidth(),bmp1.getHeight(), bmp1.getConfig());

canvas = new Canvas(drawingBitmap);

paint = new Paint();

canvas.drawBitmap(bmp1, 0, 0, paint);

paint.setXfermode(new PorterDuffXfermode(android.graphics.PorterDuff.Mode.MULTIPLY));

canvas.drawBitmap(bmp2, 0, 0, paint);

15 按指定path上绘制文字

Paint paint = new Paint();

paint.setColor(Color.GREEN);

paint.setTextSize(20);

paint.setTypeface(Typeface.DEFAULT);

Path p = new Path();

p.moveTo(20, 20);

p.lineTo(100, 150);

p.lineTo(200, 220);

canvas.drawTextOnPath("Hello this is text on a path", p, 0, 0, paint);

16 人脸识别

FaceDetector detector = new FaceDetector(faceBitmap.getWidth(),

faceBitmap.getHeight(), 3); // 创建识别器

mNumFaces = detector.findFaces(faceBitmap, mFaces);

// 识别

if (mNumFaces > 0) {

for (int i = 0; i < mNumFaces; i++) {

handleFace(mFaces[i]);

//调用函数对人脸画面进行处理

}

}

关于人脸识别部分（站点地址是）：

http://www.faceplusplus.com/

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1  场景：一张图片非常大。放到手机上时须要对图片资源进行压缩以及缩放，编写例如以下界面的案例：

2 操作：当点击载入图片到内存时。图片从自己的手机sd卡中取到并显示。

3 ADT开发时，手机连接上电脑后，在Android开发工具中的”FileExplorer”中的文件位置例如以下：

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4 以下開始编写代码，项目结构例如以下：

5 编写activity_main.xml，代码例如以下：

<LinearLayout ）、手指在一张美女图片上移动时。移动部分的图片会变成成透明。然后显示底部的另外一张图片

（2）、当手指离开的时候播放音乐…

应用效果图：

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1 编写应用，代码结构例如以下：

2、编写布局文件activity_main.xml

<RelativeLayout 、编写MainActivity

package com.itheima.play;

import android.app.Activity;

import android.graphics.Bitmap;

import android.graphics.BitmapFactory;

import android.graphics.Canvas;

import android.graphics.Color;

import android.graphics.Matrix;

import android.graphics.Paint;

import android.media.MediaPlayer;

import android.os.Bundle;

import android.view.MotionEvent;

import android.view.View;

import android.view.View.OnTouchListener;

import android.widget.ImageView;

public class MainActivity extends Activity {

private ImageView iv;

// 能够改动的位图

private Bitmap alertBitmap;

private Canvas canvas;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

iv = (ImageView) findViewById(R.id.iv);

Bitmap bitmap = BitmapFactory.decodeResource(getResources(),

R.drawable.pre);

// 创建一个空白的原图的拷贝

alertBitmap = Bitmap.createBitmap(bitmap.getWidth(),

bitmap.getHeight(), bitmap.getConfig());

canvas = new Canvas(alertBitmap);

Paint paint = new Paint();

paint.setColor(Color.BLACK);

canvas.drawBitmap(bitmap, new Matrix(), paint);

iv.setImageBitmap(alertBitmap);

iv.setOnTouchListener(new OnTouchListener() {

@Override

public boolean onTouch(View v, MotionEvent event) {

switch (event.getAction()) {

case MotionEvent.ACTION_DOWN:// 手指按下屏幕

System.out.println("action down");

break;

case MotionEvent.ACTION_MOVE:// 手指在屏幕上移动

int x = (int) event.getX();

int y = (int) event.getY();

System.out.println("设置("+x+","+y+")透明颜色");

for(int i=-4;i<5;i++){

for(int j=-4;j<5;j++){

try{

alertBitmap.setPixel(x+i, y+j, Color.TRANSPARENT);

} catch (Exception e) {

e.printStackTrace();

}

}

}

iv.setImageBitmap(alertBitmap);

break;

case MotionEvent.ACTION_UP:// 手指离开屏幕

MediaPlayer.create(getApplicationContext(), R.raw.higirl).start();

break;

}

return true;//能够反复循环的处理事件

}

});

}

}

4  Android的清单文件例如以下：

<?xml version="1.0" encoding="utf-8"?

>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

package="com.itheima.play"

android:versionCode="1"

android:versionName="1.0" >

<uses-sdk

android:minSdkVersion="8"

android:targetSdkVersion="19" />

<application

android:allowBackup="true"

android:icon="@drawable/ic_launcher"

android:label="@string/app_name"

android:theme="@style/AppTheme" >

<activity

android:name="com.itheima.play.MainActivity"

android:label="@string/app_name" >

<intent-filter>

<action android:name="android.intent.action.MAIN" />

<category android:name="android.intent.category.LAUNCHER" />

</intent-filter>

</activity>

</application>

</manifest>