Android應用自定義圓角圖片RoundImageView

Android開發中圖片控件ImageView默認的樣子是矩形，方方正正的。在我們實際的項目中，有時候這些方正的圖片顯得有些呆板，我們就需要其它樣式的圖片，比較圓形圖片（The rounded picture），常見的就是app中用戶頭像等。要得到圓形圖片有很多方式，比如draw一個circle，也可以用切好的圓形圖片做背景或者寫一個xml實現圓角功能等等。不過在項目中，如果我們有多個地方要把圖片展示出圓形的，而且圖片是從網絡上取的，這種情況還一個個處理就麻煩了，我們可以定義個圓形圖片組件RoundImageView，然後在要用的地方把RoundImageView 當成ImageView一樣使用就行了。我在最近做的項目中也用到了圓形圖片，所以做個筆記，方便下次使用！

首先看我們定義的RoundImageView:

public class RoundImageView extends ImageView {
private int mBorderThickness = 0;
private Context mContext;
private int defaultColor = 0xFFFFFFFF;
// 如果只有其中一個有值，則只畫一個圓形邊框
private int mBorderOutsideColor = 0;
private int mBorderInsideColor = 0;
// 控件默認長、寬
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) {//這裡要用到自定義屬性
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) {// 定義畫兩個邊框，分別為外圓邊框和內圓邊框
radius = (defaultWidth < defaultHeight ? defaultWidth
: defaultHeight) / 2 - 2 * mBorderThickness;
// 畫內圓
drawCircleBorder(canvas, radius + mBorderThickness / 2,
mBorderInsideColor);
// 畫外圓
drawCircleBorder(canvas, radius + mBorderThickness
+ mBorderThickness / 2, mBorderOutsideColor);
} else if (mBorderInsideColor != defaultColor
&& mBorderOutsideColor == defaultColor) {// 定義畫一個邊框
radius = (defaultWidth < defaultHeight ? defaultWidth
: defaultHeight) / 2 - mBorderThickness;
drawCircleBorder(canvas, radius + mBorderThickness / 2,
mBorderInsideColor);
} else if (mBorderInsideColor == defaultColor
&& mBorderOutsideColor != defaultColor) {// 定義畫一個邊框
radius = (defaultWidth < defaultHeight ? defaultWidth
: defaultHeight) / 2 - mBorderThickness;
drawCircleBorder(canvas, radius + mBorderThickness / 2,
mBorderOutsideColor);
} else {// 沒有邊框
radius = (defaultWidth < defaultHeight ? defaultWidth
: defaultHeight) / 2;
}
Bitmap roundBitmap = getCroppedRoundBitmap(bitmap, radius);
bitmap = null;
canvas.drawBitmap(roundBitmap, defaultWidth / 2 - radius, defaultHeight
/ 2 - radius, null);
}


/**
* 獲取裁剪後的圓形圖片
*/
public Bitmap getCroppedRoundBitmap(Bitmap bmp, int radius) {
Bitmap scaledSrcBmp;
int diameter = radius * 2;


// 為了防止寬高不相等，造成圓形圖片變形，因此截取長方形中處於中間位置最大的正方形圖片
int bmpWidth = bmp.getWidth();
int bmpHeight = bmp.getHeight();
int squareWidth = 0, squareHeight = 0;
int x = 0, y = 0;
Bitmap squareBitmap;
if (bmpHeight > bmpWidth) {// 高大於寬
squareWidth = squareHeight = bmpWidth;
x = 0;
y = (bmpHeight - bmpWidth) / 2;
// 截取正方形圖片
squareBitmap = Bitmap.createBitmap(bmp, x, y, squareWidth,
squareHeight);
} else if (bmpHeight < bmpWidth) {// 寬大於高
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導致在布局文件XML看不到效果)
// bmp.recycle();
// squareBitmap.recycle();
// scaledSrcBmp.recycle();
squareBitmap = null;
scaledSrcBmp = null;
return output;
}


/**
* 邊緣畫圓
*/
private void drawCircleBorder(Canvas canvas, int radius, int color) {
Paint paint = new Paint();
/* 去鋸齒 */
paint.setAntiAlias(true);
paint.setFilterBitmap(true);
paint.setDither(true);
paint.setColor(color);
/* 設置paint的　style　為STROKE：空心 */
paint.setStyle(Paint.Style.STROKE);
/* 設置paint的外框寬度 */
paint.setStrokeWidth(mBorderThickness);
canvas.drawCircle(defaultWidth / 2, defaultHeight / 2, radius, paint);
}
}

在res/values建一個attrs.xml文件，加入自定義屬性字段

最後就直接把這個RoundImageView看作ImageView在你需要用的地方用就可以了。