Android应用自定义圆角图片RoundImageView
Android开发中图片控件ImageView默认的样子是矩形，方方正正的。在我们实际的项目中，有时候这些方正的图片显得有些呆板，我们就需要其它样式的图片，比较圆形图片（The rounded picture）， 常见的就是app中用户头像等。要得到圆形图片有很多方式，比如draw一个circle，也可以用切好的圆形图片做背景或者写一个xml实现圆角功能等 等。不过在项目中，如果我们有多个地方要把图片展示出圆形的，而且图片是从网络上取的，这种情况还一个个处理就麻烦了，我们可以定义个圆形图片组件 RoundImageView，然后在要用的地方把RoundImageView 当成ImageView一样使用就行了。我在最近做的项目中也用到了圆形图片，所以做个笔记，方便下次使用！
首先看我们定义的RoundImageView:
public class RoundImageView extends ImageView { private int mBorderThickness = 0; private Context mContext; private int defaultColor = 0xFFFFFFFF; // 如果只有其中一个有值，则只画一个圆形边框 private int mBorderOutsideColor = 0; private int mBorderInsideColor = 0; // 控件默认长、宽 private int defaultWidth = 0; private int defaultHeight = 0; public RoundImageView(Context context) { super(context); mContext = context; } public RoundImageView(Context context, AttributeSet attrs) { super(context, attrs); mContext = context; setCustomAttributes(attrs); } public RoundImageView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); mContext = context; setCustomAttributes(attrs); } private void setCustomAttributes(AttributeSet attrs) {//这里要用到自定义属性 TypedArray a = mContext.obtainStyledAttributes(attrs, R.styleable.RoundImageView); mBorderThickness = a.getDimensionPixelSize( R.styleable.RoundImageView_border_thickness, 0); mBorderOutsideColor = a .getColor(R.styleable.RoundImageView_border_outside_color, defaultColor); mBorderInsideColor = a.getColor( R.styleable.RoundImageView_border_inside_color, defaultColor); } @Override protected void onDraw(Canvas canvas) { Drawable drawable = getDrawable(); if (drawable == null) { return; } if (getWidth() == 0 || getHeight() == 0) { return; } if (drawable.getClass() == NinePatchDrawable.class) return; Bitmap b = ((BitmapDrawable) drawable).getBitmap(); Bitmap bitmap = b.copy(Bitmap.Config.ARGB_8888, true); if (defaultWidth == 0) { defaultWidth = getWidth(); } if (defaultHeight == 0) { defaultHeight = getHeight(); } int radius = 0; if (mBorderInsideColor != defaultColor && mBorderOutsideColor != defaultColor) {// 定义画两个边框，分别为外圆边框和内圆边框 radius = (defaultWidth < defaultHeight ? defaultWidth : defaultHeight) / 2 - 2 * mBorderThickness; // 画内圆 drawCircleBorder(canvas, radius + mBorderThickness / 2, mBorderInsideColor); // 画外圆 drawCircleBorder(canvas, radius + mBorderThickness + mBorderThickness / 2, mBorderOutsideColor); } else if (mBorderInsideColor != defaultColor && mBorderOutsideColor == defaultColor) {// 定义画一个边框 radius = (defaultWidth < defaultHeight ? defaultWidth : defaultHeight) / 2 - mBorderThickness; drawCircleBorder(canvas, radius + mBorderThickness / 2, mBorderInsideColor); } else if (mBorderInsideColor == defaultColor && mBorderOutsideColor != defaultColor) {// 定义画一个边框 radius = (defaultWidth < defaultHeight ? defaultWidth : defaultHeight) / 2 - mBorderThickness; drawCircleBorder(canvas, radius + mBorderThickness / 2, mBorderOutsideColor); } else {// 没有边框 radius = (defaultWidth < defaultHeight ? defaultWidth : defaultHeight) / 2; } Bitmap roundBitmap = getCroppedRoundBitmap(bitmap, radius); bitmap = null; canvas.drawBitmap(roundBitmap, defaultWidth / 2 - radius, defaultHeight / 2 - radius, null); } /** * 获取裁剪后的圆形图片 */ public Bitmap getCroppedRoundBitmap(Bitmap bmp, int radius) { Bitmap scaledSrcBmp; int diameter = radius * 2; // 为了防止宽高不相等，造成圆形图片变形，因此截取长方形中处于中间位置最大的正方形图片 int bmpWidth = bmp.getWidth(); int bmpHeight = bmp.getHeight(); int squareWidth = 0, squareHeight = 0; int x = 0, y = 0; Bitmap squareBitmap; if (bmpHeight > bmpWidth) {// 高大于宽 squareWidth = squareHeight = bmpWidth; x = 0; y = (bmpHeight - bmpWidth) / 2; // 截取正方形图片 squareBitmap = Bitmap.createBitmap(bmp, x, y, squareWidth, squareHeight); } else if (bmpHeight < bmpWidth) {// 宽大于高 squareWidth = squareHeight = bmpHeight; x = (bmpWidth - bmpHeight) / 2; y = 0; squareBitmap = Bitmap.createBitmap(bmp, x, y, squareWidth, squareHeight); } else { squareBitmap = bmp; } if (squareBitmap.getWidth() != diameter || squareBitmap.getHeight() != diameter) { scaledSrcBmp = Bitmap.createScaledBitmap(squareBitmap, diameter, diameter, true); } else { scaledSrcBmp = squareBitmap; } Bitmap output = Bitmap.createBitmap(scaledSrcBmp.getWidth(), scaledSrcBmp.getHeight(), Config.ARGB_8888); Canvas canvas = new Canvas(output); Paint paint = new Paint(); Rect rect = new Rect(0, 0, scaledSrcBmp.getWidth(), scaledSrcBmp.getHeight()); paint.setAntiAlias(true); paint.setFilterBitmap(true); paint.setDither(true); canvas.drawARGB(0, 0, 0, 0); canvas.drawCircle(scaledSrcBmp.getWidth() / 2, scaledSrcBmp.getHeight() / 2, scaledSrcBmp.getWidth() / 2, paint); paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN)); canvas.drawBitmap(scaledSrcBmp, rect, rect, paint); // bitmap回收(recycle导致在布局文件XML看不到效果) // bmp.recycle(); // squareBitmap.recycle(); // scaledSrcBmp.recycle(); squareBitmap = null; scaledSrcBmp = null; return output; } /** * 边缘画圆 */ private void drawCircleBorder(Canvas canvas, int radius, int color) { Paint paint = new Paint(); /* 去锯齿 */ paint.setAntiAlias(true); paint.setFilterBitmap(true); paint.setDither(true); paint.setColor(color); /* 设置paint的 style 为STROKE：空心 */ paint.setStyle(Paint.Style.STROKE); /* 设置paint的外框宽度 */ paint.setStrokeWidth(mBorderThickness); canvas.drawCircle(defaultWidth / 2, defaultHeight / 2, radius, paint); } }
在res/values建一个attrs.xml文件，加入自定义属性字段
<?xml version="1.0" encoding="utf-8"?> <resources> <declare-styleable name="RoundImageView"> <attr name="border_thickness" format="dimension" /> <attr name="border_outside_color" format="color" /> <attr name="border_inside_color" format="color" /> </declare-styleable> </resources>
最后就直接把这个RoundImageView看作ImageView在你需要用的地方用就可以了。