android中怎么通过自定义imageview实现圆角图片

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（1）在activity_main.xml文件布局，非常简单

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" android:orientation="vertical" android:layout_width="match_parent" android:layout_height="match_parent"> <com.example.administrator.testz.CircleImageView  android:layout_width="160dp"  android:layout_marginLeft="20dp"  android:layout_marginTop="20dp"  android:layout_height="160dp"  android:layout_centerInParent="true"  android:src="@mipmap/icon"  app:civ_border_width="2dp"  app:civ_border_color="@color/colorAccent" /></LinearLayout>

2.1注意添加attrs文件，设置图片的属性，然后在java代码中引用属性，在xml文件使用相关属性

<?xml version="1.0" encoding="utf-8"?><resources> <declare-styleable name="CircleImageView">  <attr name="civ_border_width" format="dimension" />  <attr name="civ_border_color" format="color" />  <attr name="civ_border_overlay" format="boolean" />  <attr name="civ_fill_color" format="color" />  <attr name="civ_circle_background_color" format="color" /> </declare-styleable></resources>

（2）MainActivity直接导入上面的布局即可，无需其他操作，如果要写监听或者其他操作，需要特别处理，这里仅仅提供显示

（3）开源的工具类，图片圆角转换工具类

package com.example.administrator.testz;  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.Outline;  import android.graphics.Paint;  import android.graphics.Rect;  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.os.Build;  import android.support.annotation.ColorInt;  import android.support.annotation.ColorRes;  import android.support.annotation.DrawableRes;  import android.support.annotation.RequiresApi;  import android.util.AttributeSet;  import android.view.MotionEvent;  import android.view.View;  import android.view.ViewOutlineProvider;  import android.widget.ImageView;public class CircleImageView extends ImageView { //参考网址:https://github.com/hdodenhof/CircleImageView 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_CIRCLE_BACKGROUND_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 mCircleBackgroundPaint = new Paint(); private int mBorderColor = DEFAULT_BORDER_COLOR; private int mBorderWidth = DEFAULT_BORDER_WIDTH; private int mCircleBackgroundColor = DEFAULT_CIRCLE_BACKGROUND_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);  // Look for deprecated civ_fill_color if civ_circle_background_color is not set  if (a.hasValue(R.styleable.CircleImageView_civ_circle_background_color)) {   mCircleBackgroundColor = a.getColor(R.styleable.CircleImageView_civ_circle_background_color,     DEFAULT_CIRCLE_BACKGROUND_COLOR);  } else if (a.hasValue(R.styleable.CircleImageView_civ_fill_color)) {   mCircleBackgroundColor = a.getColor(R.styleable.CircleImageView_civ_fill_color,     DEFAULT_CIRCLE_BACKGROUND_COLOR);  }  a.recycle();  init(); } private void init() {  super.setScaleType(SCALE_TYPE);  mReady = true;  if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {   setOutlineProvider(new OutlineProvider());  }  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 (mCircleBackgroundColor != Color.TRANSPARENT) {   canvas.drawCircle(mDrawableRect.centerX(), mDrawableRect.centerY(), mDrawableRadius, mCircleBackgroundPaint);  }  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)); } public int getCircleBackgroundColor() {  return mCircleBackgroundColor; } public void setCircleBackgroundColor(@ColorInt int circleBackgroundColor) {  if (circleBackgroundColor == mCircleBackgroundColor) {   return;  }  mCircleBackgroundColor = circleBackgroundColor;  mCircleBackgroundPaint.setColor(circleBackgroundColor);  invalidate(); } public void setCircleBackgroundColorResource(@ColorRes int circleBackgroundRes) {  setCircleBackgroundColor(getContext().getResources().getColor(circleBackgroundRes)); } /**  * Return the color drawn behind the circle-shaped drawable.  *  * @return The color drawn behind the drawable  *  * @deprecated Use {@link #getCircleBackgroundColor()} instead.  */ @Deprecated public int getFillColor() {  return getCircleBackgroundColor(); } /**  * 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 Use {@link #setCircleBackgroundColor(int)} instead.  */ @Deprecated public void setFillColor(@ColorInt int fillColor) {  setCircleBackgroundColor(fillColor); } /**  * 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 Use {@link #setCircleBackgroundColorResource(int)} instead.  */ @Deprecated public void setFillColorResource(@ColorRes int fillColorRes) {  setCircleBackgroundColorResource(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);  mCircleBackgroundPaint.setStyle(Paint.Style.FILL);  mCircleBackgroundPaint.setAntiAlias(true);  mCircleBackgroundPaint.setColor(mCircleBackgroundColor);  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); } @Override public boolean onTouchEvent(MotionEvent event) {  return inTouchableArea(event.getX(), event.getY()) && super.onTouchEvent(event); } private boolean inTouchableArea(float x, float y) {  return Math.pow(x - mBorderRect.centerX(), 2) + Math.pow(y - mBorderRect.centerY(), 2) <= Math.pow(mBorderRadius, 2); } @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP) private class OutlineProvider extends ViewOutlineProvider {  @Override  public void getOutline(View view, Outline outline) {   Rect bounds = new Rect();   mBorderRect.roundOut(bounds);   outline.setRoundRect(bounds, bounds.width() / 2.0f);  } }}

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