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,主要操作包含:通过打开相冊里的图片,使用Matrix对图像进行缩放、旋转、移动、对照度、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布局例如以下所看到的：
<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="对照" />
</LinearLayout>
</RelativeLayout>
然后,在Mainctivity.java中public class MainActivity extends Activity函数加入代码例如以下：
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
}
}
再调用自己定义函数实现显示图片：
//自己定义函数 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 对照度等属性
canvas.drawBitmap(bmp, 0, 0, paint); //错误:没有图片 由于參数bmp写成createBmp
imageCreate.setImageBitmap(createBmp);
textview2.setVisibility(View.VISIBLE);
} catch(Exception e) {
e.printStackTrace();
}
}
显示的效果例如以下图所看到的,该图叫莱娜图(Lenna),是图像处理中常常使用的例子图.
二. Matrix操作
然后通过Matrix对图像进行处理操作,在onCreate函数中加入点击事件:
//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();
}
});
//图片对照度改变
Button button6=(Button)findViewById(R.id.button6);
button6.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
ContrastPicture();
}
});
最后分别自己定义函数各操作实现,代码例如以下：
//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坐标同一时候缩放
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 对照度等属性
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坐标同一时候缩放
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饱和度添加 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;
}
}
//设置图片对照度
private void ContrastPicture() {
ColorMatrix cm = new ColorMatrix();
float brightness = -25; //亮度
float contrast = 2; //对照度
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);
}
同一时候自己定义变量例如以下：
//图片变换參数 private float smallbig=1.0f; //缩放比例 private int turnRotate=0; //旋转度数 private float saturation=0f; //饱和度
它的执行结果例如以下图所看到的：
须要指出的是：该项目只讲述处理的过程,并没有考虑非常多因素,如:有的图像显示可能超出屏幕,没有加载图片点击处理button报错,横竖屏切换导致不显示图片,最以下button可能被遮挡,图像放大画布没有变,由于为觉得显示一张改变后的图片效果更好,而该project不过对照.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中能够通过Matrix和ColorMatrix对图像进行处理.
1.Matrix
图像空间变换,包含旋转、剪裁、缩放或移动.Matrix类中每一个数字都将应用于图像上每一个点的3个坐标xyz之中的一个.
例如以下代码通过setValues设置值.(1,0,0)表示x坐标转换x=1x+0y+0z,相同y=0x+1y+0z,z=0x+0y+1z.该矩阵不做不论什么变换.假设第一行改为(.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,每一个像素由RGBA值组成(Red Green Blue Alpha).详细方法推荐博文: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刚開始学习的人.该文章是讲述Android使用Matrix处理图片的基础文章,假设有不足或错误地方,请见谅~參考资料《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)