圆形ImageView

一般来说，圆形ImageView边缘都设置的比较明显，这里，以有边缘为例
1、创建属性文件：attrs.xml，创建路径为—— res/values/attrs.xml，内容如下：

<?xml version="1.0" encoding="utf-8"?>    <resources>        <declare-styleable name="CircleImageView">                <attr name="border_width" format="dimension" />                <attr name="border_color" format="color" />        </declare-styleable>    </resources>

2、新建一个CircleImageView.java文件，将附录中的源码复制进去
3、布局文件

<?xml version="1.0" encoding="utf-8"?><RelativeLayout    xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:app="http://schemas.android.com/apk/res-auto"    android:layout_width="fill_parent"    android:layout_height="fill_parent"    android:orientation="vertical"    >    <com.chen.CircleImageView        android:id="@+id/circle"        android:layout_width="200dp"        android:layout_height="200dp"        android:layout_centerInParent="true"        android:layout_marginTop="50dp"        android:background="#ff0000"        app:border_color="#000000"        app:border_width="2dp"/></RelativeLayout>

4、Java代码中使用

 CircleImageView circle = (CircleImageView) findViewById(R.id.circle);//circle.setBackgroundResource(R.drawable.chen); circle.setImageResource(R.drawable.chen);

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注：
1、如果写了第一步的属性文件，在布局文件中要加上

xmlns:app="http://schemas.android.com/apk/res-auto"

这样才能在属性中使用自定义的属性
2、在Java代码中调用的时候，使用

circle.setBackgroundResource(R.drawable.chen);

方法，最后展示效果是图片原有的形状。如果原图是方图，就展示放图。这是因为，在自定义的CircleImageView中，只有以下3中加载、处理图片的方法

附录：
1、原图

2、效果图

3、CircleImageView.java源码：

package com.chen;import android.content.Context;import android.content.res.TypedArray;import android.graphics.Bitmap;import android.graphics.BitmapShader;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Matrix;import android.graphics.Paint;import android.graphics.RectF;import android.graphics.Shader;import android.graphics.drawable.BitmapDrawable;import android.graphics.drawable.ColorDrawable;import android.graphics.drawable.Drawable;import android.util.AttributeSet;import android.widget.ImageView;public class CircleImageView extends ImageView {    private static final ScaleType SCALE_TYPE = ScaleType.CENTER_CROP;    private static final Bitmap.Config BITMAP_CONFIG = Bitmap.Config.ARGB_8888;    private static final int COLORDRAWABLE_DIMENSION = 1;    private static final int DEFAULT_BORDER_WIDTH = 0;    private static final int DEFAULT_BORDER_COLOR = Color.BLACK;    private final RectF mDrawableRect = new RectF();    private final RectF mBorderRect = new RectF();    private final Matrix mShaderMatrix = new Matrix();    private final Paint mBitmapPaint = new Paint();    private final Paint mBorderPaint = new Paint();    private int mBorderColor = DEFAULT_BORDER_COLOR;    private int mBorderWidth = DEFAULT_BORDER_WIDTH;    private Bitmap mBitmap;    private BitmapShader mBitmapShader;    private int mBitmapWidth;    private int mBitmapHeight;    private float mDrawableRadius;    private float mBorderRadius;    private boolean mReady;    private boolean mSetupPending;    public CircleImageView(Context context) {        super(context);    }    public CircleImageView(Context context, AttributeSet attrs) {        this(context, attrs, 0);    }    public CircleImageView(Context context, AttributeSet attrs, int defStyle) {        super(context, attrs, defStyle);        super.setScaleType(SCALE_TYPE);        TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.CircleImageView, defStyle, 0);        mBorderWidth = a.getDimensionPixelSize(R.styleable.CircleImageView_border_width, DEFAULT_BORDER_WIDTH);        mBorderColor = a.getColor(R.styleable.CircleImageView_border_color, DEFAULT_BORDER_COLOR);        a.recycle();        mReady = true;        if (mSetupPending) {            setup();            mSetupPending = false;        }    }    @Override    public ScaleType getScaleType() {        return SCALE_TYPE;    }    @Override    public void setScaleType(ScaleType scaleType) {        if (scaleType != SCALE_TYPE) {            throw new IllegalArgumentException(String.format("ScaleType %s not supported.", scaleType));        }    }    @Override    protected void onDraw(Canvas canvas) {        if (getDrawable() == null) {            return;        }        canvas.drawCircle(getWidth() / 2, getHeight() / 2, mDrawableRadius, mBitmapPaint);        if (mBorderWidth != 0) {            canvas.drawCircle(getWidth() / 2, getHeight() / 2, mBorderRadius, mBorderPaint);        }    }    @Override    protected void onSizeChanged(int w, int h, int oldw, int oldh) {        super.onSizeChanged(w, h, oldw, oldh);        setup();    }    public int getBorderColor() {        return mBorderColor;    }    public void setBorderColor(int borderColor) {        if (borderColor == mBorderColor) {            return;        }        mBorderColor = borderColor;        mBorderPaint.setColor(mBorderColor);        invalidate();    }    public int getBorderWidth() {        return mBorderWidth;    }    public void setBorderWidth(int borderWidth) {        if (borderWidth == mBorderWidth) {            return;        }        mBorderWidth = borderWidth;        setup();    }    @Override    public void setImageBitmap(Bitmap bm) {        super.setImageBitmap(bm);        mBitmap = bm;        setup();    }    @Override    public void setImageDrawable(Drawable drawable) {        super.setImageDrawable(drawable);        mBitmap = getBitmapFromDrawable(drawable);        setup();    }    @Override    public void setImageResource(int resId) {        super.setImageResource(resId);        mBitmap = getBitmapFromDrawable(getDrawable());        setup();    }    private Bitmap getBitmapFromDrawable(Drawable drawable) {        if (drawable == null) {            return null;        }        if (drawable instanceof BitmapDrawable) {            return ((BitmapDrawable) drawable).getBitmap();        }        try {            Bitmap bitmap;            if (drawable instanceof ColorDrawable) {                bitmap = Bitmap.createBitmap(COLORDRAWABLE_DIMENSION, COLORDRAWABLE_DIMENSION, BITMAP_CONFIG);            } else {                bitmap = Bitmap.createBitmap(drawable.getIntrinsicWidth(), drawable.getIntrinsicHeight(), BITMAP_CONFIG);            }            Canvas canvas = new Canvas(bitmap);            drawable.setBounds(0, 0, canvas.getWidth(), canvas.getHeight());            drawable.draw(canvas);            return bitmap;        } catch (OutOfMemoryError e) {            return null;        }    }    private void setup() {        if (!mReady) {            mSetupPending = true;            return;        }        if (mBitmap == null) {            return;        }        mBitmapShader = new BitmapShader(mBitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);        mBitmapPaint.setAntiAlias(true);        mBitmapPaint.setShader(mBitmapShader);        mBorderPaint.setStyle(Paint.Style.STROKE);        mBorderPaint.setAntiAlias(true);        mBorderPaint.setColor(mBorderColor);        mBorderPaint.setStrokeWidth(mBorderWidth);        mBitmapHeight = mBitmap.getHeight();        mBitmapWidth = mBitmap.getWidth();        mBorderRect.set(0, 0, getWidth(), getHeight());        mBorderRadius = Math.min((mBorderRect.height() - mBorderWidth) / 2, (mBorderRect.width() - mBorderWidth) / 2);        mDrawableRect.set(mBorderWidth, mBorderWidth, mBorderRect.width() - mBorderWidth, mBorderRect.height() - mBorderWidth);        mDrawableRadius = Math.min(mDrawableRect.height() / 2, mDrawableRect.width() / 2);        updateShaderMatrix();        invalidate();    }    private void updateShaderMatrix() {        float scale;        float dx = 0;        float dy = 0;        mShaderMatrix.set(null);        if (mBitmapWidth * mDrawableRect.height() > mDrawableRect.width() * mBitmapHeight) {            scale = mDrawableRect.height() / (float) mBitmapHeight;            dx = (mDrawableRect.width() - mBitmapWidth * scale) * 0.5f;        } else {            scale = mDrawableRect.width() / (float) mBitmapWidth;            dy = (mDrawableRect.height() - mBitmapHeight * scale) * 0.5f;        }        mShaderMatrix.setScale(scale, scale);        mShaderMatrix.postTranslate((int) (dx + 0.5f) + mBorderWidth, (int) (dy + 0.5f) + mBorderWidth);        mBitmapShader.setLocalMatrix(mShaderMatrix);    }}