Android自己定義圓角ImageView

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我們常常看到一些app中能夠顯示圓角圖片。比方qq的連絡人表徵圖等等，實現圓角圖片一種辦法是直接使用圓角圖片資源，當然假設沒有圓角圖片資源。我們也能夠自己通過程式實現的，以下介紹一個自己定義圓角ImageView的方法：

package com.yulongfei.imageview;import android.content.Context;import android.content.res.TypedArray;import android.graphics.Bitmap;import android.graphics.Bitmap.Config;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Paint;import android.graphics.Path;import android.graphics.PorterDuff;import android.graphics.PorterDuffXfermode;import android.graphics.RectF;import android.util.AttributeSet;import android.widget.ImageView;public class RoundAngleImageView extends ImageView {private int roundWidth = 13;private int roundHeight = 13;public RoundAngleImageView(Context context) {super(context);init(context, null);}public RoundAngleImageView(Context context, AttributeSet attrs, int defStyle) {super(context, attrs, defStyle);init(context, attrs);}public RoundAngleImageView(Context context, AttributeSet attrs) {super(context, attrs);init(context, attrs);}private void init(Context context, AttributeSet attrs) {if (attrs != null) {TypedArray a = context.obtainStyledAttributes(attrs,R.styleable.RoundAngleImageView);roundWidth = a.getDimensionPixelSize(R.styleable.RoundAngleImageView_roundWidth, roundWidth);roundHeight = a.getDimensionPixelSize(R.styleable.RoundAngleImageView_roundHeight, roundHeight);a.recycle();} else {float density = context.getResources().getDisplayMetrics().density;roundWidth = (int)(roundWidth * density);roundHeight = (int)(roundHeight * density);}}/** 重寫draw() */@Overridepublic void draw(Canvas canvas) {//執行個體化一個和ImageView一樣大小的bitmapBitmap bitmap = Bitmap.createBitmap(getWidth(), getHeight(),Config.ARGB_8888);//執行個體化一個canvas，這個canvas相應的記憶體為上面的bitmapCanvas canvas2 = new Canvas(bitmap);if (bitmap.isRecycled()) {bitmap = Bitmap.createBitmap(getWidth(), getHeight(),Config.ARGB_8888);canvas2 = new Canvas(bitmap);}//將imageView自己繪製到canvas2上，這個導致bitmap裡面存放了imageViewsuper.draw(canvas2);//利用canvas畫一個圓角矩形，這個會改動bitmap的資料drawRoundAngle(canvas2);//將裁剪好的bitmap繪製到系統當前canvas上，這樣裁剪好的imageview就能顯示到螢幕上Paint paint = new Paint();paint.setXfermode(null);canvas.drawBitmap(bitmap, 0, 0, paint);bitmap.recycle();}public void setRoundWidth(int roundWidth, int roundHeight) {this.roundWidth = roundWidth;this.roundHeight = roundHeight;}private void drawRoundAngle(Canvas canvas){Paint maskPaint = new Paint();        maskPaint.setAntiAlias(true);maskPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));        Path maskPath = new Path();          maskPath.addRoundRect(new RectF(0.0F, 0.0F, getWidth(), getHeight()), roundWidth, roundHeight, Path.Direction.CW);                //這是設定了填充模式。很關鍵        maskPath.setFillType(Path.FillType.INVERSE_WINDING);        canvas.drawPath(maskPath, maskPaint);}}

Android自己定義圓角ImageView