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查字典教程网。