[Android] 使用Matrix矩阵类对图像进行缩放、旋转、对比度、亮度处理

前一篇文章讲述了Android拍照、截图、保存并显示在ImageView控件中,该篇文章继续讲述Android图像处理技术,主要操作包括:通过打开相册里的图片,使用Matrix对图像进行缩放、旋转、移动、对比度、亮度、饱和度操作,希望对大家有所帮助.

一. 显示打开图片

首先,设置activity_main.xml布局如下所示：

然后,在Mainctivity.java中public class MainActivity extends Activity函数添加代码如下：

private Button selectBn;private ImageView imageShow;private ImageView imageCreate;private TextView textview1;private TextView textview2;private Bitmap bmp; //原始图片@Overrideprotected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);    selectBn = (Button) findViewById(R.id.button1);    imageShow = (ImageView) findViewById(R.id.imageView1);    imageCreate = (ImageView) findViewById(R.id.imageView2);    textview1 = (TextView) findViewById(R.id.textView1);    textview2 = (TextView) findViewById(R.id.textView2);        //选择图片    selectBn.setOnClickListener(new OnClickListener() {    @Override    public void onClick(View v) {    Intent intent = new Intent(Intent.ACTION_PICK,     android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);    startActivityForResult(intent, 0 );    }    });    if (savedInstanceState == null) {        getFragmentManager().beginTransaction()                .add(R.id.container, new PlaceholderFragment())                .commit();    }}//显示两张图片protected void onActivityResult(int requestCode, int resultCode, Intent data) {  super.onActivityResult(requestCode, resultCode, data);if(resultCode==RESULT_OK) {ShowPhotoByImageView(data);     //显示照片CreatePhotoByImageView();          //创建图片}}

再调用自定义函数实现显示图片：

//自定义函数 显示打开的照片在ImageView1中public void ShowPhotoByImageView(Intent data) {Uri imageFileUri = data.getData();DisplayMetrics dm = new DisplayMetrics();getWindowManager().getDefaultDisplay().getMetrics(dm);int width = dm.widthPixels;    //手机屏幕水平分辨率int height = dm.heightPixels;  //手机屏幕垂直分辨率Log.v("height", ""+height );Log.v("width", ""+width);try {// Load up the image's dimensions not the image itselfBitmapFactory.Options bmpFactoryOptions = new BitmapFactory.Options();bmpFactoryOptions.inJustDecodeBounds = true;bmp = BitmapFactory.decodeStream(getContentResolver().openInputStream(imageFileUri), null, bmpFactoryOptions);int heightRatio = (int)Math.ceil(bmpFactoryOptions.outHeight/(float)height);int widthRatio = (int)Math.ceil(bmpFactoryOptions.outWidth/(float)width);Log.v("bmpheight", ""+bmpFactoryOptions.outHeight);Log.v("bmpheight", ""+bmpFactoryOptions.outWidth);if(heightRatio>1&&widthRatio>1) {if(heightRatio>widthRatio) {bmpFactoryOptions.inSampleSize = heightRatio*2;}else {bmpFactoryOptions.inSampleSize = widthRatio*2;}} //图像真正解码       bmpFactoryOptions.inJustDecodeBounds = false;              bmp = BitmapFactory.decodeStream(getContentResolver().openInputStream(imageFileUri), null, bmpFactoryOptions);      imageShow.setImageBitmap(bmp); //将剪裁后照片显示出来      textview1.setVisibility(View.VISIBLE);} catch(FileNotFoundException e) {e.printStackTrace();}}//创建第二张图片并显示public void CreatePhotoByImageView() {try {    Bitmap createBmp = Bitmap.createBitmap(bmp.getWidth(), bmp.getHeight(), bmp.getConfig());    Canvas canvas = new Canvas(createBmp); //画布 传入位图用于绘制    Paint paint = new Paint(); //画刷 改变颜色 对比度等属性    canvas.drawBitmap(bmp, 0, 0, paint);    //错误:没有图片 因为参数bmp写成createBmp    imageCreate.setImageBitmap(createBmp);    textview2.setVisibility(View.VISIBLE);} catch(Exception e) {e.printStackTrace();}}

显示的效果如下图所示,该图叫莱娜图(Lenna),是图像处理中经常使用的样例图.

二. Matrix操作

然后通过Matrix对图像进行处理操作,在onCreate函数中添加点击事件:

//缩小图片Button button2=(Button)findViewById(R.id.button2);button2.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {SmallPicture();}});//放大图片    Button button3=(Button)findViewById(R.id.button3);    button3.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {BigPicture();}});   //旋转图片Button button4=(Button)findViewById(R.id.button4);button4.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {TurnPicture();}});//图片饱和度改变Button button5=(Button)findViewById(R.id.button5);button5.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {SaturationPicture();}});//图片对比度改变Button button6=(Button)findViewById(R.id.button6);button6.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {ContrastPicture();}});

最后分别自定义函数各操作实现,代码如下：

//缩小图片private void SmallPicture() {Matrix matrix = new Matrix();//缩放区间 0.5-1.0if(smallbig>0.5f)smallbig=smallbig-0.1f;elsesmallbig=0.5f;//x y坐标同时缩放matrix.setScale(smallbig,smallbig,bmp.getWidth()/2,bmp.getHeight()/2); Bitmap createBmp = Bitmap.createBitmap(bmp.getWidth(), bmp.getHeight(), bmp.getConfig());Canvas canvas = new Canvas(createBmp); //画布 传入位图用于绘制Paint paint = new Paint(); //画刷 改变颜色 对比度等属性    canvas.drawBitmap(bmp, matrix, paint);    imageCreate.setBackgroundColor(Color.RED);    imageCreate.setImageBitmap(createBmp);    textview2.setVisibility(View.VISIBLE);    }  //放大图片private void BigPicture() {Matrix matrix = new Matrix();//缩放区间 0.5-1.0if(smallbig<1.5f)smallbig=smallbig+0.1f;elsesmallbig=1.5f;//x y坐标同时缩放matrix.setScale(smallbig,smallbig,bmp.getWidth()/2,bmp.getHeight()/2); Bitmap createBmp = Bitmap.createBitmap(bmp.getWidth(), bmp.getHeight(), bmp.getConfig());Canvas canvas = new Canvas(createBmp); Paint paint = new Paint(); canvas.drawBitmap(bmp, matrix, paint);imageCreate.setBackgroundColor(Color.RED);imageCreate.setImageBitmap(createBmp);textview2.setVisibility(View.VISIBLE);}//旋转图片private void TurnPicture() {Matrix matrix = new Matrix();turnRotate=turnRotate+15;//选择角度 饶(0,0)点选择 正数顺时针 负数逆时针 中心旋转matrix.setRotate(turnRotate,bmp.getWidth()/2,bmp.getHeight()/2); Bitmap createBmp = Bitmap.createBitmap(bmp.getWidth(), bmp.getHeight(), bmp.getConfig());Canvas canvas = new Canvas(createBmp); Paint paint = new Paint(); canvas.drawBitmap(bmp, matrix, paint);imageCreate.setBackgroundColor(Color.RED);imageCreate.setImageBitmap(createBmp);textview2.setVisibility(View.VISIBLE);}//改变图像饱和度private void SaturationPicture() {//设置饱和度 0表示灰度图像 大于1饱和度增加 0-1饱和度减小ColorMatrix cm = new ColorMatrix();cm.setSaturation(saturation);Paint paint = new Paint(); paint.setColorFilter(new ColorMatrixColorFilter(cm));//显示图片Matrix matrix = new Matrix();Bitmap createBmp = Bitmap.createBitmap(bmp.getWidth(), bmp.getHeight(), bmp.getConfig());Canvas canvas = new Canvas(createBmp); canvas.drawBitmap(bmp, matrix, paint);imageCreate.setImageBitmap(createBmp);textview2.setVisibility(View.VISIBLE);saturation=saturation+0.1f;if(saturation>=1.5f) {saturation=0f;}}//设置图片对比度private void ContrastPicture() {ColorMatrix cm = new ColorMatrix();float brightness = -25;  //亮度float contrast = 2;        //对比度cm.set(new float[] {contrast, 0, 0, 0, brightness,0, contrast, 0, 0, brightness,0, 0, contrast, 0, brightness,0, 0, 0, contrast, 0});Paint paint = new Paint(); paint.setColorFilter(new ColorMatrixColorFilter(cm));//显示图片Matrix matrix = new Matrix();Bitmap createBmp = Bitmap.createBitmap(bmp.getWidth(), bmp.getHeight(), bmp.getConfig());Canvas canvas = new Canvas(createBmp); canvas.drawBitmap(bmp, matrix, paint);imageCreate.setImageBitmap(createBmp);textview2.setVisibility(View.VISIBLE);}

同时自定义变量如下：

//图片变换参数private float smallbig=1.0f;   //缩放比例private int turnRotate=0;       //旋转度数private float saturation=0f;    //饱和度

    它的运行结果如下图所示：



    需要指出的是：该项目仅仅讲述处理的过程,并没有考虑很多因素,如:有的图像显示可能超出屏幕,没有载入图片点击处理按钮报错,横竖屏切换导致不显示图片,最下面按钮可能被遮挡,图像放大画布没有变,因为为认为显示一张改变后的图片效果更好,而该工程仅仅是对比.图像缩放移动触屏变换更好,下一篇讲述.
    XML布局推荐：http://www.apkbus.com/forum.php?mod=viewthread&tid=44949
    解决画布跟着图片放大：http://www.eoeandroid.com/thread-3162-1-1.html

三. Matrix处理的原理

    Android中可以通过Matrix和ColorMatrix对图像进行处理.
    1.Matrix
    图像空间变换,包括旋转、剪裁、缩放或移动.Matrix类中每个数字都将应用于图像上每个点的3个坐标x\y\z之一.
    如下代码通过setValues设置值.(1,0,0)表示x坐标转换x=1x+0y+0z,同样y=0x+1y+0z,z=0x+0y+1z.该矩阵不做任何变换.如果第一行改为(.5f,0,0),那么图像在x轴上将图像压缩50%.移动见setTranslate()函数.

Matrix matrix = new Matrix();matrix.setValues(new float[] {        1, 0, 0,        0, 1, 0,        0, 0, 1});

    2.ColorMatrix
    在Canvas(画布)对象上绘制时既可使用Matrix方法,也可使用ColorMatrix来改变在Canvas对象上绘制的Paint(画刷)对象.对图像的像素处理时,每个像素由RGBA值组成(Red Green Blue Alpha).具体方法推荐博文:http://www.cnblogs.com/leon19870907/articles/1978065.html
    最后希望该文章对大家有所帮助,尤其是Android初学者.该文章是讲述Android使用Matrix处理图片的基础文章,如果有不足或错误地方,请见谅~参考资料《Android多媒体开发高级编程著：Shawn Van Every》
    下载地址:http://download.csdn.net/detail/eastmount/8082043
(By:Eastmount 2014-10-26 夜2点 http://blog.csdn.net/eastmount)

一. 显示打开图片

二. Matrix操作

三. Matrix处理的原理

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