Android中的ImageView只能显示矩形的图片，为了用户体验更多，Android实现圆角矩形，圆形或者椭圆等图形，一般通过自定义ImageView来实现，首先获取到图片的Bitmap，然后通过Paint和onDraw（）进行圆形图片显示。
代码：
1 activity_image.xml
2 <?xml version="1.0" encoding="utf-8"?>
3 <LinearLayoutxmlns:android="http://schemas.android.com/apk/res/android"
4 android:layout_width="match_parent"
5 android:layout_height="match_parent"
6 android:orientation="vertical">
7
8 <com.example.imageviewdrawdemo.ZQImageViewRoundOval
9 android:id="@+id/cicle"
10 android:layout_width="100dp"
11 android:layout_height="100dp"
12 android:src="@drawable/qie">
13 </com.example.imageviewdrawdemo.ZQImageViewRoundOval>
14
15 <com.example.imageviewdrawdemo.ZQImageViewRoundOval
16 android:id="@+id/roundRect"
17 android:layout_width="286dp"
18 android:layout_height="190dp"
19 android:layout_marginTop="10dp"
20 android:src="@drawable/l1">
21 </com.example.imageviewdrawdemo.ZQImageViewRoundOval>
22
23 <com.example.imageviewdrawdemo.ZQImageViewRoundOval
24 android:id="@+id/oval"
25 android:layout_width="wrap_content"
26 android:layout_height="wrap_content"
27 android:layout_marginTop="20dp"
28 android:src="@drawable/l2">
29 </com.example.imageviewdrawdemo.ZQImageViewRoundOval>
30
31 </LinearLayout>
1 /**
2 * 实现圆形、圆角，椭圆等自定义图片View。
3 * @author zq
4 *
5 */
6 public class ZQImageViewRoundOval extends ImageView {
7
8 private Paint mPaint;
9
10 private int mWidth;
11
12 private int mHeight;
13
14 private int mRadius;//圆半径
15
16 private RectF mRect;//矩形凹行大小
17
18 private int mRoundRadius;//圆角大小
19
20 private BitmapShader mBitmapShader;//图形渲染
21
22 private Matrix mMatrix;
23
24 private int mType;//记录是圆形还是圆角矩形
25
26 public static final int TYPE_CIRCLE = 0;//圆形
27 public static final int TYPE_ROUND = 1;//圆角矩形
28 public static final int TYPE_OVAL = 2;//椭圆形
29 public static final int DEFAUT_ROUND_RADIUS = 10;//默认圆角大小
30
31 public ZQImageViewRoundOval(Context context) {
32 this(context, null);
33 // TODOAuto-generated constructor stub
34 }
35
36 public ZQImageViewRoundOval(Context context, AttributeSet attrs) {
37 this(context,attrs, 0);
38 // TODOAuto-generated constructor stub
39 }
40
41 public ZQImageViewRoundOval(Context context, AttributeSet attrs,int defStyle){
42 super(context,attrs, defStyle);
43 initView();
44 }
45
46 private void initView() {
47 mPaint = new Paint();
48 mPaint.setAntiAlias(true);
49 mMatrix = new Matrix();
50 mRoundRadius = DEFAUT_ROUND_RADIUS;
51 }
52
53 @Override
54 protected void onMeasure(int widthMeasureSpec,intheightMeasureSpec) {
55 // TODOAuto-generated method stub
56 super.onMeasure(widthMeasureSpec,heightMeasureSpec);
57 // 如果是绘制圆形，则强制宽高大小一致
58 if (mType ==TYPE_CIRCLE) {
59 mWidth = Math.min(getMeasuredWidth(),getMeasuredHeight());
60 mRadius = mWidth / 2;
61 setMeasuredDimension(mWidth, mWidth);
62 }
63
64 }
65
66 @Override
67 protected void onDraw(Canvas canvas) {
68
69 if (null ==getDrawable()) {
70 return;
71 }
72 setBitmapShader();
73 if (mType ==TYPE_CIRCLE) {
74 canvas.drawCircle(mRadius, mRadius, mRadius, mPaint);
75 } else if (mType == TYPE_ROUND) {
76 mPaint.setColor(Color.RED);
77 canvas.drawRoundRect(mRect, mRoundRadius, mRoundRadius, mPaint);
78 }else if(mType == TYPE_OVAL){
79 canvas.drawOval(mRect, mPaint);
80 }
81 }
82
83 @Override
84 protected void onSizeChanged(int w,int h, int oldw,int oldh) {
85 // TODOAuto-generated method stub
86 super.onSizeChanged(w,h, oldw, oldh);
87 mRect = new RectF(0,0, getWidth(), getHeight());
88 }
89
90 /**
91 * 设置BitmapShader
92 */
93 private void setBitmapShader() {
94 Drawable drawable = getDrawable();
95 if (null ==drawable) {
96 return;
97 }
98 Bitmap bitmap = drawableToBitmap(drawable);
99 // 将bitmap作为着色器来创建一个BitmapShader
100 mBitmapShader = newBitmapShader(bitmap, TileMode.CLAMP, TileMode.CLAMP);
101 float scale =1.0f;
102 if (mType ==TYPE_CIRCLE) {
103 // 拿到bitmap宽或高的小值
104 int bSize =Math.min(bitmap.getWidth(), bitmap.getHeight());
105 scale = mWidth * 1.0f /bSize;
106
107 } else if (mType == TYPE_ROUND ||mType == TYPE_OVAL) {
108 // 如果图片的宽或者高与view的宽高不匹配，计算出需要缩放的比例；缩放后的图片的宽高，一定要大于我们view的宽高；所以我们这里取大值；
109 scale = Math.max(getWidth() * 1.0f/ bitmap.getWidth(), getHeight() * 1.0f / bitmap.getHeight());
110 }
111 // shader的变换矩阵，我们这里主要用于放大或者缩小
112 mMatrix.setScale(scale,scale);
113 // 设置变换矩阵
114 mBitmapShader.setLocalMatrix(mMatrix);
115 mPaint.setShader(mBitmapShader);
116
117 }
118
119 /**
120 * drawable转bitmap
121 *
122 * @paramdrawable
123 * @return
124 */
125 private Bitmap drawableToBitmap(Drawable drawable) {
126 if (drawableinstanceof BitmapDrawable) {
127 BitmapDrawable bitmapDrawable =(BitmapDrawable) drawable;
128 returnbitmapDrawable.getBitmap();
129 }
130 int w =drawable.getIntrinsicWidth();
131 int h =drawable.getIntrinsicHeight();
132 Bitmap bitmap = Bitmap.createBitmap(w,h, Config.ARGB_8888);
133 Canvas canvas = newCanvas(bitmap);
134 drawable.setBounds(0, 0, w, h);
135 drawable.draw(canvas);
136 return bitmap;
137 }
138 /**
139 * 单位dp转单位px
140 */
141 public int dpTodx(int dp){
142
143 return (int)TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP,
144 dp,getResources().getDisplayMetrics());
145 }
146
147 public int getType(){
148 return mType;
149 }
150 /**
151 * 设置图片类型：圆形、圆角矩形、椭圆形
152 * @param mType
153 */
154 public void setType(int mType) {
155 if(this.mType !=mType){
156 this.mType = mType;
157 invalidate();
158 }
159
160 }
161 public int getRoundRadius() {
162 return mRoundRadius;
163 }
164 /**
165 * 设置圆角大小
166 * @parammRoundRadius
167 */
168 public void setRoundRadius(int mRoundRadius) {
169 if(this.mRoundRadius !=mRoundRadius){
170 this.mRoundRadius =mRoundRadius;
171 invalidate();
172 }
173
174 }
175 }
1 MainActivity类
2 /****
3 *
4 * 自定义ImageView实现圆形图片，圆角矩形图片 椭圆图片
5 *
6 * @authorzq
7 *
8 */
9 public class MainActivity extends Activity {
10
11
12 private ZQImageViewRoundOvaliv_circle;//圆形图片
13 private ZQImageViewRoundOvaliv_roundRect;//圆角矩形图片
14 private ZQImageViewRoundOvaliv_oval;//椭圆图片
15 @Override
16 protected void onCreate(Bundle savedInstanceState) {
17 super.onCreate(savedInstanceState);
18 setContentView(R.layout.activity_image);
19 initViews();
20 }
21 /**
22 * 初始化Views
23 */
24 private void initViews(){
25 iv_circle =(ZQImageViewRoundOval)findViewById(R.id.cicle);
26 iv_roundRect =(ZQImageViewRoundOval)findViewById(R.id.roundRect);
27 iv_oval =(ZQImageViewRoundOval)findViewById(R.id.oval);
28
29
30 iv_roundRect.setType(ZQImageViewRoundOval.TYPE_ROUND);
31 iv_roundRect.setRoundRadius(6);//矩形凹行大小
32
33 iv_oval.setType(ZQImageViewRoundOval.TYPE_OVAL);
34 iv_oval.setRoundRadius(45);//圆角大小
35 }
36 }
源码下载：
Eclipse下载：http://download.csdn.net/detail/dickyqie/9621330
AndroidStudio下载：https://github.com/DickyQie/android-imageview
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