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.net.Uri;
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 static final int CircleImageView_border_width = 0;public static final int CircleImageView_border_color = 1;public static final int[] CircleImageView = { 0x7f010000, 0x7f010001 };public CircleImageView(Context context) {super(context);init();}public CircleImageView(Context context, AttributeSet attrs) {this(context, attrs, 0);}public CircleImageView(Context context, AttributeSet attrs, int defStyle) {super(context, attrs, defStyle);TypedArray a = context.obtainStyledAttributes(attrs, CircleImageView,defStyle, 0);mBorderWidth = a.getDimensionPixelSize(0, DEFAULT_BORDER_WIDTH);mBorderColor = a.getColor(CircleImageView_border_color,DEFAULT_BORDER_COLOR);a.recycle();init();}private void init() {super.setScaleType(SCALE_TYPE);mReady = true;if (mSetupPending) {setup();mSetupPending = false;}}@Overrideprotected 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);}}@Overrideprotected 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();}@Overridepublic void setImageBitmap(Bitmap bm) {super.setImageBitmap(bm);mBitmap = bm;setup();}@Overridepublic void setBackgroundResource(int resid) {super.setBackgroundResource(resid);mBitmap = getBitmapFromDrawable(getDrawable());setup();}@Overridepublic void setImageDrawable(Drawable drawable) {super.setImageDrawable(drawable);mBitmap = getBitmapFromDrawable(drawable);setup();}@Overridepublic void setImageResource(int resId) {super.setImageResource(resId);mBitmap = getBitmapFromDrawable(getDrawable());setup();}@Overridepublic void setImageURI(Uri uri) {super.setImageURI(uri);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);}
}

2.绘制现有图片

<span style="white-space:pre">   </span>private Bitmap cicleImage(int id) {// 加载现有图片Bitmap bitmap = BitmapFactory.decodeResource(getResources(), id);int width = bitmap.getWidth();int height = bitmap.getHeight();// 构造新图纸Bitmap output = Bitmap.createBitmap(width, height,Bitmap.Config.ARGB_8888);Canvas canvas = new Canvas(output);Paint paint = new Paint();paint.setAntiAlias(true); // 抗锯齿canvas.drawARGB(0, 0, 0, 0); // 将背景绘制成黑色// 画一个灰色的实心园paint.setColor(0xff424242);canvas.drawCircle(width / 2, height / 2, width / 2, paint);/* [Sa * Da, Sc * Da] */// 取两层绘制交集，显示上层，本例下层是刚绘制的实心园，上层是即将绘制// 的图片，两者的交集就是个园，显示上层，就把图片中的园形部分显示出来了paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));// 绘制现有图片Rect src = new Rect(0, 0, width, width);Rect dst = new Rect(0, 0, width, height);//Rect src: 是对图片进行裁截，若是空null则显示整个图片//Rect dst：是图片在Canvas画布中显示的区域，大于src则把src的裁截区放大， 小于src则把src的裁截区缩小。canvas.drawBitmap(bitmap, src, dst, paint);return output;}