制作圆形图片

 //第一种方案（直接画）

private Bitmap toRoundCorner(Bitmap bitmap,int pixels){
        Bitmap roundConcernBitmap=Bitmap.createBitmap(bitmap.getWidth(),bitmap.getHeight(), Bitmap.Config.ARGB_8888);
        Canvas canvas=new Canvas(roundConcernBitmap);
        int color=0xff424242;
        Paint paint=new Paint();
        paint.setColor(color);
        paint.setAntiAlias(true);
        //可以设置此处改成圆形
        Rect rect=new Rect(0,0,bitmap.getWidth(),bitmap.getHeight());
        RectF rectF=new RectF(rect);
        //清屏
        canvas.drawARGB(0,0,0,0);
        canvas.drawRoundRect(rectF,pixels,pixels,paint);
        //设置两张图片的交互模式（即控制重叠部分）
        paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));
        canvas.drawBitmap(bitmap,rect,rect,paint);
        return roundConcernBitmap;
    }


//第二种方案（github里面剪切的，并没有仔细研究..）

//xml代码，attr

<?xml version="1.0" encoding="UTF-8"?>

-<resources>

-<declare-styleable name="CircleImageView">

</declare-styleable>

</resources>

//java代码

/*
* Copyright 2014 - 2016 Henning Dodenhof
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.example.administrator.android_07_25;

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.ColorFilter;
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.support.annotation.ColorInt;
import android.support.annotation.ColorRes;
import android.support.annotation.DrawableRes;
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 = 2;

private static final int DEFAULT_BORDER_WIDTH = 0;
private static final int DEFAULT_BORDER_COLOR = Color.BLACK;
private static final int DEFAULT_FILL_COLOR = Color.TRANSPARENT;
private static final boolean DEFAULT_BORDER_OVERLAY = false;

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 final Paint mFillPaint = new Paint();

private int mBorderColor = DEFAULT_BORDER_COLOR;
private int mBorderWidth = DEFAULT_BORDER_WIDTH;
private int mFillColor = DEFAULT_FILL_COLOR;

private Bitmap mBitmap;
private BitmapShader mBitmapShader;
private int mBitmapWidth;
private int mBitmapHeight;

private float mDrawableRadius;
private float mBorderRadius;

private ColorFilter mColorFilter;

private boolean mReady;
private boolean mSetupPending;
private boolean mBorderOverlay;
private boolean mDisableCircularTransformation;

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, R.styleable.CircleImageView, defStyle, 0);

mBorderWidth = a.getDimensionPixelSize(R.styleable.CircleImageView_civ_border_width, DEFAULT_BORDER_WIDTH);
mBorderColor = a.getColor(R.styleable.CircleImageView_civ_border_color, DEFAULT_BORDER_COLOR);
mBorderOverlay = a.getBoolean(R.styleable.CircleImageView_civ_border_overlay, DEFAULT_BORDER_OVERLAY);
mFillColor = a.getColor(R.styleable.CircleImageView_civ_fill_color, DEFAULT_FILL_COLOR);

a.recycle();

init();
}

private void init() {
super.setScaleType(SCALE_TYPE);
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
public void setAdjustViewBounds(boolean adjustViewBounds) {
if (adjustViewBounds) {
throw new IllegalArgumentException("adjustViewBounds not supported.");
}
}

@Override
protected void onDraw(Canvas canvas) {
if (mDisableCircularTransformation) {
super.onDraw(canvas);
return;
}

if (mBitmap == null) {
return;
}

if (mFillColor != Color.TRANSPARENT) {
canvas.drawCircle(mDrawableRect.centerX(), mDrawableRect.centerY(), mDrawableRadius, mFillPaint);
}
canvas.drawCircle(mDrawableRect.centerX(), mDrawableRect.centerY(), mDrawableRadius, mBitmapPaint);
if (mBorderWidth > 0) {
canvas.drawCircle(mBorderRect.centerX(), mBorderRect.centerY(), mBorderRadius, mBorderPaint);
}
}

@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
setup();
}

@Override
public void setPadding(int left, int top, int right, int bottom) {
super.setPadding(left, top, right, bottom);
setup();
}

@Override
public void setPaddingRelative(int start, int top, int end, int bottom) {
super.setPaddingRelative(start, top, end, bottom);
setup();
}

public int getBorderColor() {
return mBorderColor;
}

public void setBorderColor(@ColorInt int borderColor) {
if (borderColor == mBorderColor) {
return;
}

mBorderColor = borderColor;
mBorderPaint.setColor(mBorderColor);
invalidate();
}

/**
* @deprecated Use {@link #setBorderColor(int)} instead
*/
@Deprecated
public void setBorderColorResource(@ColorRes int borderColorRes) {
setBorderColor(getContext().getResources().getColor(borderColorRes));
}

/**
* Return the color drawn behind the circle-shaped drawable.
*
* @return The color drawn behind the drawable
*
* @deprecated Fill color support is going to be removed in the future
*/
@Deprecated
public int getFillColor() {
return mFillColor;
}

/**
* Set a color to be drawn behind the circle-shaped drawable. Note that
* this has no effect if the drawable is opaque or no drawable is set.
*
* @param fillColor The color to be drawn behind the drawable
*
* @deprecated Fill color support is going to be removed in the future
*/
@Deprecated
public void setFillColor(@ColorInt int fillColor) {
if (fillColor == mFillColor) {
return;
}

mFillColor = fillColor;
mFillPaint.setColor(fillColor);
invalidate();
}

/**
* Set a color to be drawn behind the circle-shaped drawable. Note that
* this has no effect if the drawable is opaque or no drawable is set.
*
* @param fillColorRes The color resource to be resolved to a color and
* drawn behind the drawable
*
* @deprecated Fill color support is going to be removed in the future
*/
@Deprecated
public void setFillColorResource(@ColorRes int fillColorRes) {
setFillColor(getContext().getResources().getColor(fillColorRes));
}

public int getBorderWidth() {
return mBorderWidth;
}

public void setBorderWidth(int borderWidth) {
if (borderWidth == mBorderWidth) {
return;
}

mBorderWidth = borderWidth;
setup();
}

public boolean isBorderOverlay() {
return mBorderOverlay;
}

public void setBorderOverlay(boolean borderOverlay) {
if (borderOverlay == mBorderOverlay) {
return;
}

mBorderOverlay = borderOverlay;
setup();
}

public boolean isDisableCircularTransformation() {
return mDisableCircularTransformation;
}

public void setDisableCircularTransformation(boolean disableCircularTransformation) {
if (mDisableCircularTransformation == disableCircularTransformation) {
return;
}

mDisableCircularTransformation = disableCircularTransformation;
initializeBitmap();
}

@Override
public void setImageBitmap(Bitmap bm) {
super.setImageBitmap(bm);
initializeBitmap();
}

@Override
public void setImageDrawable(Drawable drawable) {
super.setImageDrawable(drawable);
initializeBitmap();
}

@Override
public void setImageResource(@DrawableRes int resId) {
super.setImageResource(resId);
initializeBitmap();
}

@Override
public void setImageURI(Uri uri) {
super.setImageURI(uri);
initializeBitmap();
}

@Override
public void setColorFilter(ColorFilter cf) {
if (cf == mColorFilter) {
return;
}

mColorFilter = cf;
applyColorFilter();
invalidate();
}

@Override
public ColorFilter getColorFilter() {
return mColorFilter;
}

private void applyColorFilter() {
if (mBitmapPaint != null) {
mBitmapPaint.setColorFilter(mColorFilter);
}
}

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 (Exception e) {
e.printStackTrace();
return null;
}
}

private void initializeBitmap() {
if (mDisableCircularTransformation) {
mBitmap = null;
} else {
mBitmap = getBitmapFromDrawable(getDrawable());
}
setup();
}

private void setup() {
if (!mReady) {
mSetupPending = true;
return;
}

if (getWidth() == 0 && getHeight() == 0) {
return;
}

if (mBitmap == null) {
invalidate();
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);

mFillPaint.setStyle(Paint.Style.FILL);
mFillPaint.setAntiAlias(true);
mFillPaint.setColor(mFillColor);

mBitmapHeight = mBitmap.getHeight();
mBitmapWidth = mBitmap.getWidth();

mBorderRect.set(calculateBounds());
mBorderRadius = Math.min((mBorderRect.height() - mBorderWidth) / 2.0f, (mBorderRect.width() - mBorderWidth) / 2.0f);

mDrawableRect.set(mBorderRect);
if (!mBorderOverlay && mBorderWidth > 0) {
mDrawableRect.inset(mBorderWidth - 1.0f, mBorderWidth - 1.0f);
}
mDrawableRadius = Math.min(mDrawableRect.height() / 2.0f, mDrawableRect.width() / 2.0f);

applyColorFilter();
updateShaderMatrix();
invalidate();
}

private RectF calculateBounds() {
int availableWidth = getWidth() - getPaddingLeft() - getPaddingRight();
int availableHeight = getHeight() - getPaddingTop() - getPaddingBottom();

int sideLength = Math.min(availableWidth, availableHeight);

float left = getPaddingLeft() + (availableWidth - sideLength) / 2f;
float top = getPaddingTop() + (availableHeight - sideLength) / 2f;

return new RectF(left, top, left + sideLength, top + sideLength);
}

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) + mDrawableRect.left, (int) (dy + 0.5f) + mDrawableRect.top);

mBitmapShader.setLocalMatrix(mShaderMatrix);
}

}