Android实现圆形图片的两种方式

在项目中，我们经常会用到圆形图片，但是android本身又没有提供，那我只能我们自己来完成。

第一种方式，自定义CircleImageView:

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; 

 // 圆形边框的厚度默认值。
 // 如果是0，则没有天蓝色渐变的边框。
 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;
 private final Paint mFlagBackgroundPaint = new Paint();
 private final TextPaint mFlagTextPaint = new TextPaint();
 private String mFlagText;
 private boolean mShowFlag = false;
 private Rect mFlagTextBounds = new Rect(); 

 Shader mSweepGradient = null; 

 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); 

  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 (getDrawable() == null) {
   return;
  } 

  canvas.drawCircle(getWidth() / 2, getHeight() / 2, mDrawableRadius,
    mBitmapPaint);
  if (mBorderWidth != 0) {
   canvas.save();
   canvas.rotate(20, getWidth() / 2, getHeight() / 2);
   canvas.drawCircle(getWidth() / 2, getHeight() / 2, mBorderRadius,
     mBorderPaint);
   canvas.restore();
  } 

  if (mShowFlag && mFlagText != null) {
   canvas.drawArc(mBorderRect, 40, 100, false, mFlagBackgroundPaint);
   mFlagTextPaint.getTextBounds(mFlagText, 0, mFlagText.length(),
     mFlagTextBounds);
   canvas.drawText(mFlagText, getWidth() / 2,
     (float) ((3 + Math.cos((float) (Math.PI * 5 / 18)))
            * getHeight() / 4 + mFlagTextBounds.height() / 3),
     mFlagTextPaint); 

  } 

 } 

 @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;
 } 

 /**
  * @param borderWidth
  *   圆形的边框厚度。
  */
 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();
 } 

 @Override
 public 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); 

  mFlagBackgroundPaint.setColor(Color.BLACK & 0x66FFFFFF);
  mFlagBackgroundPaint.setFlags(TextPaint.ANTI_ALIAS_FLAG); 

  mFlagTextPaint.setFlags(TextPaint.ANTI_ALIAS_FLAG);
  mFlagTextPaint.setTextAlign(Align.CENTER);
  mFlagTextPaint.setColor(Color.WHITE);
  mFlagTextPaint
    .setTextSize(getResources().getDisplayMetrics().density * 18); 

  mSweepGradient = new SweepGradient(getWidth() / 2, getHeight() / 2,
    new int[] { Color.rgb(255, 255, 255), Color.rgb(1, 209, 255) },
    null); 

  mBorderPaint.setShader(mSweepGradient); 

  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);
 } 

 public void setShowFlag(boolean show) {
  mShowFlag = show;
  invalidate();
 } 

 public void setFlagText(String text) {
  mFlagText = text;
  invalidate();
 }
}

使用的时候，切记不要引用成V4报下的CircleImageView！！

另一篇文章分享的第二种方式：把图片修剪为圆形，这样给我们视觉上的效果是一样

我们时常会用到圆形图片，那么，是对图片进行裁剪，还是自定义圆形的ImageView，如果没有特殊要求的话，我们肯定选择前者，原因很简单，因为简单！！直接上源码，就是这么粗暴任性~~~

/**
  * 将图片剪裁为圆形
  */
 public static Bitmap createCircleImage(Bitmap source) {
  int length = source.getWidth() < source.getHeight() ? source.getWidth() : source.getHeight();
  Paint paint = new Paint();
  paint.setAntiAlias(true);
  Bitmap target = Bitmap.createBitmap(length, length, Bitmap.Config.ARGB_8888);
  Canvas canvas = new Canvas(target);
  canvas.drawCircle(length / 2, length / 2, length / 2, paint);
  paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));
  canvas.drawBitmap(source, 0, 0, paint);
  return target;
 }

只需要输入bitmap，然后就给你返回圆形的bitmap，然后设置到ImageView中，是不是很简单。

这里另外提一点，如果从ImageView中拿出来bitmap，只需要一行代码：

//从ImageView中获取bitmap
  Bitmap bm =((BitmapDrawable) ( imageView).getDrawable()).getBitmap();

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持我们。