[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:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:id="@+id/container" android:layout_width="match_parent" android:layout_height="wrap_content" tools:context="com.example.cangeimagetest.MainActivity" tools:ignore="MergeRootFrame" > <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="vertical" > <Button android:id="@+id/button1" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="选择图片" /> <TextView android:id="@+id/textView1" android:layout_width="match_parent" android:layout_height="wrap_content" android:visibility="invisible" android:text="原图显示" /> <ImageView android:id="@+id/imageView1" android:layout_width="wrap_content" android:layout_gravity="center_horizontal" android:layout_height="wrap_content" /> <TextView android:id="@+id/textView2" android:layout_width="match_parent" android:layout_height="wrap_content" android:visibility="invisible" android:text="变化后的图片" /> <ImageView android:id="@+id/imageView2" android:layout_gravity="center_horizontal" android:layout_marginBottom="20dp" android:layout_width="wrap_content" android:layout_height="wrap_content" /> </LinearLayout> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal" android:layout_alignParentBottom="true" > <Button android:id="@+id/button2" android:layout_width="wrap_content" android:layout_height="match_parent" android:layout_weight="1" android:text="缩小" /> <Button android:id="@+id/button3" android:layout_width="wrap_content" android:layout_height="match_parent" android:layout_weight="1" android:text="放大" /> <Button android:id="@+id/button4" android:layout_width="wrap_content" android:layout_height="match_parent" android:layout_weight="1" android:text="旋转" /> <Button android:id="@+id/button5" android:layout_width="wrap_content" android:layout_height="match_parent" android:layout_weight="1" android:text="饱和" /> <Button android:id="@+id/button6" android:layout_width="wrap_content" android:layout_height="match_parent" android:layout_weight="1" android:text="对比" /> </LinearLayout> </RelativeLayout>
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 @Override protected 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 itself BitmapFactory.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() { @Override public void onClick(View v) { SmallPicture(); } }); //放大图片 Button button3=(Button)findViewById(R.id.button3); button3.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { BigPicture(); } }); //旋转图片 Button button4=(Button)findViewById(R.id.button4); button4.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { TurnPicture(); } }); //图片饱和度改变 Button button5=(Button)findViewById(R.id.button5); button5.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { SaturationPicture(); } }); //图片对比度改变 Button button6=(Button)findViewById(R.id.button6); button6.setOnClickListener(new OnClickListener() { @Override public 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 0.5-1.0 if(smallbig>0.5f) smallbig=smallbig-0.1f; else smallbig=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 0.5-1.0 if(smallbig<1.5f) smallbig=smallbig+0.1f; else smallbig=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》
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(By:Eastmount 2014-10-26 夜2点
http://blog.csdn.net/eastmount)
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