Android项目开发中经常会遇见需要实现圆角或者圆形的图片功能，如果仅仅使用系统自带的ImageView控件显然无法实现此功能，所以通过系列文章的形式由简到繁全方位的介绍一下此功能的实现，巩固一下自身的学习，同时，和广大网友交流分享
本项目源码下载地址：链接：http://pan.baidu.com/s/1sljdvtF 密码：xj85
首先看效果图
首先看一下CircleImageView的主要流程
1. 首先通过setImageXxx()方法设置图片Bitmap；
2. 进入构造函数CircleImageView()获取自定义参数，以及调用setup()函数；
3. 进入setup()函数（非常关键），进行图片画笔边界画笔(Paint)一些重绘参数初始化：构建渲染器BitmapShader用Bitmap来填充绘制区域,设置样式和内外圆半径计算等，以及调用updateShaderMatrix()函数和 invalidate()函数；
4. 进入updateShaderMatrix()函数，计算缩放比例和平移，设置BitmapShader的Matrix参数等；
5. 触发ondraw()函数完成最终的绘制。使用配置好的Paint先画出绘制内圆形来以后再画边界圆形。
下面看具体的代码实现：
attr.xml
<?xml version="1.0" encoding="utf-8"?><resources> <declare-styleable name="roundedimageview"> <attr name="border_thickness" format="dimension" /> <attr name="border_inside_color" format="color" /> <attr name="border_outside_color" format="color"></attr> </declare-styleable></resources>
然后是自定义ImageView的实现类：
RoundImageView.class
**
* 圆形ImageView，可设置最多两个宽度不同且颜色不同的圆形边框。 * 设置颜色在xml布局文件中由自定义属性配置参数指定 */public class RoundImageView extends ImageView { private int mBorderThickness = 0; private Context mContext; private int defaultColor = 0xFFFFFFFF; // 如果只有其中一个有值，则只画一个圆形边框
private int mBorderOutsideColor = 0; private int mBorderInsideColor = 0; // 控件默认长、宽
private int defaultWidth = 0; private int defaultHeight = 0;//构造方法，参数上下文
public RoundImageView(Context context) { super(context);
mContext = context;
} public RoundImageView(Context context, AttributeSet attrs) { super(context, attrs);
mContext = context;
setCustomAttributes(attrs);
} public RoundImageView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle);
mContext = context;
setCustomAttributes(attrs);
} private void setCustomAttributes(AttributeSet attrs) {
TypedArray a = mContext.obtainStyledAttributes(attrs, R.styleable.roundedimageview);
mBorderThickness = a.getDimensionPixelSize(R.styleable.roundedimageview_border_thickness, 0);
mBorderOutsideColor = a.getColor(R.styleable.roundedimageview_border_outside_color, defaultColor);
mBorderInsideColor = a.getColor(R.styleable.roundedimageview_border_inside_color, defaultColor);
}
@Override protected void onDraw(Canvas canvas) {
Drawable drawable = getDrawable(); if (drawable == null) { return;
} if (getWidth() == 0 || getHeight() == 0) { return;
} this.measure(0, 0); if (drawable.getClass() == NinePatchDrawable.class) return;
Bitmap b = ((BitmapDrawable) drawable).getBitmap();
Bitmap bitmap = b.copy(Bitmap.Config.ARGB_8888, true); if (defaultWidth == 0) {
defaultWidth = getWidth();
} if (defaultHeight == 0) {
defaultHeight = getHeight();
} int radius = 0; if (mBorderInsideColor != defaultColor && mBorderOutsideColor != defaultColor) {// 定义画两个边框，分别为外圆边框和内圆边框
radius = (defaultWidth < defaultHeight ? defaultWidth : defaultHeight) / 2 - 2 * mBorderThickness; // 画内圆
drawCircleBorder(canvas, radius + mBorderThickness / 2, mBorderInsideColor); // 画外圆
drawCircleBorder(canvas, radius + mBorderThickness + mBorderThickness / 2, mBorderOutsideColor);
} else if (mBorderInsideColor != defaultColor && mBorderOutsideColor == defaultColor) {// 定义画一个边框
radius = (defaultWidth < defaultHeight ? defaultWidth : defaultHeight) / 2 - mBorderThickness;
drawCircleBorder(canvas, radius + mBorderThickness / 2, mBorderInsideColor);
} else if (mBorderInsideColor == defaultColor && mBorderOutsideColor != defaultColor) {// 定义画一个边框
radius = (defaultWidth < defaultHeight ? defaultWidth : defaultHeight) / 2 - mBorderThickness;
drawCircleBorder(canvas, radius + mBorderThickness / 2, mBorderOutsideColor);
} else {// 没有边框
radius = (defaultWidth < defaultHeight ? defaultWidth : defaultHeight) / 2;
}
Bitmap roundBitmap = getCroppedRoundBitmap(bitmap, radius);
canvas.drawBitmap(roundBitmap, defaultWidth / 2 - radius, defaultHeight / 2 - radius, null);
} /**
* 获取裁剪后的圆形图片
*
* @param
*/// radius半径
public Bitmap getCroppedRoundBitmap(Bitmap bmp, int radius) {
Bitmap scaledSrcBmp; int diameter = radius * 2; // 为了防止宽高不相等，造成圆形图片变形，因此截取长方形中处于中间位置最大的正方形图片
int bmpWidth = bmp.getWidth(); int bmpHeight = bmp.getHeight(); int squareWidth = 0, squareHeight = 0; int x = 0, y = 0;
Bitmap squareBitmap; if (bmpHeight > bmpWidth) {// 高大于宽
squareWidth = squareHeight = bmpWidth;
x = 0;
y = (bmpHeight - bmpWidth) / 2; // 截取正方形图片
squareBitmap = Bitmap.createBitmap(bmp, x, y, squareWidth, squareHeight);
} else if (bmpHeight < bmpWidth) {// 宽大于高
squareWidth = squareHeight = bmpHeight;
x = (bmpWidth - bmpHeight) / 2;
y = 0;
squareBitmap = Bitmap.createBitmap(bmp, x, y, squareWidth, squareHeight);
} else {
squareBitmap = bmp;
} if (squareBitmap.getWidth() != diameter || squareBitmap.getHeight() != diameter) {
scaledSrcBmp = Bitmap.createScaledBitmap(squareBitmap, diameter, diameter, true);
} else {
scaledSrcBmp = squareBitmap;
}
Bitmap output = Bitmap.createBitmap(scaledSrcBmp.getWidth(),
scaledSrcBmp.getHeight(),
Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(output);
Paint paint = new Paint();
Rect rect = new Rect(0, 0, scaledSrcBmp.getWidth(), scaledSrcBmp.getHeight());
paint.setAntiAlias(true);
paint.setFilterBitmap(true);
paint.setDither(true);
canvas.drawARGB(0, 0, 0, 0);
canvas.drawCircle(scaledSrcBmp.getWidth() / 2,
scaledSrcBmp.getHeight() / 2,
scaledSrcBmp.getWidth() / 2,
paint);
paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));
canvas.drawBitmap(scaledSrcBmp, rect, rect, paint);
bmp = null;
squareBitmap = null;
scaledSrcBmp = null; return output;
} /**
* 边缘画圆 */
private void drawCircleBorder(Canvas canvas, int radius, int color) {
Paint paint = new Paint(); /* 去锯齿 */
paint.setAntiAlias(true);
paint.setFilterBitmap(true);
paint.setDither(true);
paint.setColor(color); /* 设置paint的 style 为STROKE：空心 */
paint.setStyle(Paint.Style.STROKE); /* 设置paint的外框宽度 */
paint.setStrokeWidth(mBorderThickness);
canvas.drawCircle(defaultWidth / 2, defaultHeight / 2, radius, paint);
}
}
使用时非常简单，直接在布局中调用自定义的类
activity_main.xml，这里要注意的是，第二个是带有边框的，效果图如上
<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:imagecontrol="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:id="@+id/activity_main" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" android:paddingBottom="@dimen/activity_vertical_margin" android:paddingLeft="@dimen/activity_horizontal_margin" android:paddingRight="@dimen/activity_horizontal_margin" android:paddingTop="@dimen/activity_vertical_margin" tools:context="com.example.ceshi.MainActivity"> <Button android:id="@+id/aaa" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="点击设置头像" /> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal"> <com.example.ceshi.RoundImageView android:id="@+id/image" android:layout_width="0dp" android:layout_weight="1" android:layout_height="wrap_content" /> <!-- border_outside_color 外部圆圈的颜色 --> <!-- border_inside_color 内部部圆圈的颜色 --> <!-- border_thickness 外圆和内圆的宽度 --> <com.example.ceshi.RoundImageView android:id="@+id/img2" android:layout_width="0dp" android:layout_weight="1" android:layout_height="wrap_content" imagecontrol:border_inside_color="#bc0978" imagecontrol:border_outside_color="#ba3456" imagecontrol:border_thickness="1dp" /> </LinearLayout>
打开图库选取图片，截取图片和设置图片在MainActivity.class中实现
MainActivity.class
public class MainActivity extends AppCompatActivity { private Button bt; private static final int PHOTO_REQUEST_GALLERY = 2;// 从相册中选择
private static final int PHOTO_REQUEST_CUT = 3;// 结果
private ImageView photo,photo2; private File tempFile;
@Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
photo= (ImageView) findViewById(R.id.image);
photo2= (ImageView) findViewById(R.id.img2);
bt = (Button) findViewById(R.id.aaa);
bt.setOnClickListener(new View.OnClickListener() {
@Override public void onClick(View v) {// Intent intent=new Intent(Intent.ACTION_PICK);// intent.setType("image/*");// startActivityForResult(intent,PHOTO_REQUEST_GALLERY); // 激活系统图库，选择一张图片
Intent intent = new Intent(Intent.ACTION_PICK);
intent.setType("image/*"); // 开启一个带有返回值的Activity，请求码为PHOTO_REQUEST_GALLERY startActivityForResult(intent, PHOTO_REQUEST_GALLERY);
}
});
} /*
* 剪切图片 */
private void crop(Uri uri) { // 裁剪图片意图
Intent intent = new Intent("com.android.camera.action.CROP");
intent.setDataAndType(uri, "image/*");
intent.putExtra("crop", "true"); // 裁剪框的比例，1：1
intent.putExtra("aspectX", 1);
intent.putExtra("aspectY", 1); // 裁剪后输出图片的尺寸大小
intent.putExtra("outputX", 250);
intent.putExtra("outputY", 250);
intent.putExtra("outputFormat", "JPEG");// 图片格式
intent.putExtra("noFaceDetection", true);// 取消人脸识别
intent.putExtra("return-data", true); // 开启一个带有返回值的Activity，请求码为PHOTO_REQUEST_CUT startActivityForResult(intent, PHOTO_REQUEST_CUT);
}
@Override protected void onActivityResult(int requestCode, int resultCode, Intent data) { super.onActivityResult(requestCode, resultCode, data); if (requestCode == PHOTO_REQUEST_GALLERY) { // 从相册返回的数据
if (data != null) { // 得到图片的全路径
Uri uri = data.getData();
crop(uri);
}
} else if (requestCode == PHOTO_REQUEST_CUT) { // 从剪切图片返回的数据
if (data != null) {
Bitmap bitmap = data.getParcelableExtra("data");
photo.setImageBitmap(bitmap);
photo2.setImageBitmap(bitmap);
} try { // 将临时文件删除 tempFile.delete();
} catch (Exception e) {
e.printStackTrace();
}
} super.onActivityResult(requestCode, resultCode, data);
}
}
以上就可以实现自定义控件，设置圆形头像
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