自定义控件之圆形 / 圆角 ImageView

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自定义控件之圆形 / 圆角 ImageView

一、问题在哪里？

问题来源于app开发中一个很常见的场景——用户头像要展示成圆的：

二、怎么搞？

机智的我，第一想法就是，切一张中间圆形透明、四周与底色相同、尺寸与头像相同的蒙板图片，盖在头像上不就完事了嘛，哈哈哈！

在背景纯色的前提下，这的确能简单解决问题，但是如果背景没有这么简单呢？

在这种不规则背景下，有两个问题：

1)　　背景图常常是适应手机宽度缩放，而头像的尺寸又是固定宽高DP的，所以固定的蒙板图片是没法保证在不同机型上都和背景图案吻合的。

2)　　在这种非纯色背景下，哪天想调整一下头像位置就得重新换图片蒙板，实在是太难维护了……

所以呢，既然头像图片肯定是方的，那就就让ImageView圆起来吧。

[转载请保留本文地址：http://www.cnblogs.com/snser/p/5159126.html]

三、开始干活

基本思路是，自定义一个ImageView，通过重写onDraw方法画出一个圆形的图片来：

 1 public class ImageViewPlus extends ImageView{ 2     private Paint mPaintBitmap = new Paint(Paint.ANTI_ALIAS_FLAG); 3     private Bitmap mRawBitmap; 4     private BitmapShader mShader; 5     private Matrix mMatrix = new Matrix(); 6      7     public ImageViewPlus(Context context, AttributeSet attrs) { 8         super(context, attrs); 9     }10     11     @Override12     protected void onDraw(Canvas canvas) {13         Bitmap rawBitmap = getBitmap(getDrawable());14         if (rawBitmap != null){15             int viewWidth = getWidth();16             int viewHeight = getHeight();17             int viewMinSize = Math.min(viewWidth, viewHeight);18             float dstWidth = viewMinSize;19             float dstHeight = viewMinSize;20             if (mShader == null || !rawBitmap.equals(mRawBitmap)){21                 mRawBitmap = rawBitmap;22                 mShader = new BitmapShader(mRawBitmap, TileMode.CLAMP, TileMode.CLAMP);23             }24             if (mShader != null){25                 mMatrix.setScale(dstWidth / rawBitmap.getWidth(), dstHeight / rawBitmap.getHeight());26                 mShader.setLocalMatrix(mMatrix);27             }28             mPaintBitmap.setShader(mShader);29             float radius = viewMinSize / 2.0f;30             canvas.drawCircle(radius, radius, radius, mPaintBitmap);31         } else {32             super.onDraw(canvas);33         }34     }35 36     private Bitmap getBitmap(Drawable drawable){37         if (drawable instanceof BitmapDrawable){38             return ((BitmapDrawable)drawable).getBitmap();39         } else if (drawable instanceof ColorDrawable){40             Rect rect = drawable.getBounds();41             int width = rect.right - rect.left;42             int height = rect.bottom - rect.top;43             int color = ((ColorDrawable)drawable).getColor();44             Bitmap bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);45             Canvas canvas = new Canvas(bitmap);46             canvas.drawARGB(Color.alpha(color), Color.red(color), Color.green(color), Color.blue(color));47             return bitmap;48         } else {49             return null;50         }51     }52 }

分析一下代码：

canvas.drawCircle 决定了画出来的形状是圆形，而圆形的内容则是通过 mPaintBitmap.setShader 搞定的。

其中，BitmapShader需要设置Bitmap填充ImageView的方式(CLAMP：拉伸边缘, MIRROR：镜像, REPEAT：整图重复)。

这里其实设成什么不重要，因为我们实际需要的是将Bitmap按比例缩放成跟ImageView一样大，而不是预置的三种效果。

所以，别忘了 mMatrix.setScale 和 mShader.setLocalMatrix 一起用，将图片缩放一下。

[转载请保留本文地址：http://www.cnblogs.com/snser/p/5159126.html]

四、更多玩法 —— 支持边框

看下面的效果图，如果想给圆形的头像上加一个边框，该怎么搞呢？

 1 public class ImageViewPlus extends ImageView{ 2     private Paint mPaintBitmap = new Paint(Paint.ANTI_ALIAS_FLAG); 3     private Paint mPaintBorder = new Paint(Paint.ANTI_ALIAS_FLAG); 4     private Bitmap mRawBitmap; 5     private BitmapShader mShader; 6     private Matrix mMatrix = new Matrix(); 7     private float mBorderWidth = dip2px(15); 8     private int mBorderColor = 0xFF0080FF; 9     10     public ImageViewPlus(Context context, AttributeSet attrs) {11         super(context, attrs);12     }13     14     @Override15     protected void onDraw(Canvas canvas) {16         Bitmap rawBitmap = getBitmap(getDrawable());17         if (rawBitmap != null){18             int viewWidth = getWidth();19             int viewHeight = getHeight();20             int viewMinSize = Math.min(viewWidth, viewHeight);21             float dstWidth = viewMinSize;22             float dstHeight = viewMinSize;23             if (mShader == null || !rawBitmap.equals(mRawBitmap)){24                 mRawBitmap = rawBitmap;25                 mShader = new BitmapShader(mRawBitmap, TileMode.CLAMP, TileMode.CLAMP);26             }27             if (mShader != null){28                 mMatrix.setScale((dstWidth - mBorderWidth * 2) / rawBitmap.getWidth(), (dstHeight - mBorderWidth * 2) / rawBitmap.getHeight());29                 mShader.setLocalMatrix(mMatrix);30             }31             mPaintBitmap.setShader(mShader);32             mPaintBorder.setStyle(Paint.Style.STROKE);33             mPaintBorder.setStrokeWidth(mBorderWidth);34             mPaintBorder.setColor(mBorderColor);35             float radius = viewMinSize / 2.0f;36             canvas.drawCircle(radius, radius, radius - mBorderWidth / 2.0f, mPaintBorder);37             canvas.translate(mBorderWidth, mBorderWidth);38             canvas.drawCircle(radius - mBorderWidth, radius - mBorderWidth, radius - mBorderWidth, mPaintBitmap);39         } else {40             super.onDraw(canvas);41         }42     }43 44     private Bitmap getBitmap(Drawable drawable){45         if (drawable instanceof BitmapDrawable){46             return ((BitmapDrawable)drawable).getBitmap();47         } else if (drawable instanceof ColorDrawable){48             Rect rect = drawable.getBounds();49             int width = rect.right - rect.left;50             int height = rect.bottom - rect.top;51             int color = ((ColorDrawable)drawable).getColor();52             Bitmap bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);53             Canvas canvas = new Canvas(bitmap);54             canvas.drawARGB(Color.alpha(color), Color.red(color), Color.green(color), Color.blue(color));55             return bitmap;56         } else {57             return null;58         }59     }60     61     private int dip2px(int dipVal)62     {63         float scale = getResources().getDisplayMetrics().density;64         return (int)(dipVal * scale + 0.5f);65     }66 }

看代码中，加边框实际上就是用实心纯色的 Paint 画了一个圆边，在此基础上画上原来的头像即可。

需要的注意的地方有三个：

1)　　圆框的半径不是 radius ，而应该是 radius - mBorderWidth / 2.0f 。想象着拿着笔去画线，线其实是画在右图中白色圈的位置，只不过它很粗。

2)　　在ImageView大小不变的基础上，头像的实际大小要比没有边框的时候小了，所以 mMatrix.setScale 的时候要把边框的宽度去掉。

3)　　画头像Bitmap的时候不能直接 canvas.drawCircle(radius, radius, radius - mBorderWidth, mPaintBitmap) ，这样你会发现头像的右侧和下方边缘被拉伸了（右图）

　　为什么呢？因为 Paint 默认是以左上角为基准开始绘制的，此时头像的实际区域是右图中的红框，而超过红框的部分（圆形的右侧和下方），自然被 TileMode.CLAMP效果沿边缘拉伸了。

　　所以，需要通过挪动坐标系的位置和调整圆心，才能把头像画在正确的区域（右图绿框）中。

[转载请保留本文地址：http://www.cnblogs.com/snser/p/5159126.html]

五、更多玩法 —— 支持xml配置

既然有了边框，那如果想配置边框的宽度和颜色该如何是好呢？

基本上两个思路：

1)　　给ImageViewPlus加上set接口，设置完成之后通过 invalidate(); 重绘一下即可；

2)　　在xml里就支持配置一些自定义属性，这样用起来会方便很多。

这里重点说一下支持xml配置自定义属性。

自定义控件要支持xml配置自定义属性的话，首先需要在 \res\values 里去定义属性：

 1 <?xml version="1.0" encoding="utf-8"?>   2 <resources>   3     <attr name="borderColor" format="color" /> 4     <attr name="borderWidth" format="dimension" /> 5  6     <declare-styleable name="ImageViewPlus">   7         <attr name="borderColor" /> 8         <attr name="borderWidth" /> 9     </declare-styleable>  10 </resources>  

然后在ImageViewPlus的构造函数中去读取这些自定义属性：

 1     private static final int DEFAULT_BORDER_COLOR = Color.TRANSPARENT; 2     private static final int DEFAULT_BORDER_WIDTH = 0; 3      4     public ImageViewPlus(Context context, AttributeSet attrs) { 5         super(context, attrs); 6         //取xml文件中设定的参数 7         TypedArray ta = context.obtainStyledAttributes(attrs, R.styleable.ImageViewPlus); 8         mBorderColor = ta.getColor(R.styleable.ImageViewPlus_borderColor, DEFAULT_BORDER_COLOR); 9         mBorderWidth = ta.getDimensionPixelSize(R.styleable.ImageViewPlus_borderWidth, dip2px(DEFAULT_BORDER_WIDTH));10         ta.recycle();11     }

在xml布局中使用自定义属性：

 1 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 2     xmlns:tools="http://schemas.android.com/tools" 3     xmlns:snser="http://schemas.android.com/apk/res/cc.snser.imageviewplus" 4     android:layout_width="match_parent" 5     android:layout_height="match_parent" 6     android:background="@drawable/wallpaper" 7     android:orientation="vertical" 8     tools:context="${relativePackage}.${activityClass}" > 9     10     <cc.snser.imageviewplus.ImageViewPlus11         android:id="@+id/imgplus"12         android:layout_width="200dp"13         android:layout_height="300dp"14         android:layout_marginBottom="50dp"15         android:layout_centerHorizontal="true"16         android:layout_alignParentBottom="true"17         android:src="@drawable/img_square"18         snser:borderColor="#FF0080FF"19         snser:borderWidth="15dp" />20     21 </RelativeLayout>

[转载请保留本文地址：http://www.cnblogs.com/snser/p/5159126.html]

六、更多玩法 —— 圆角ImageView

搞定了圆形ImageView以及对应的边框，那如何实现下面这种圆角的ImageView呢？

其实原理上一样，把 canvas.drawCircle 对应改成 canvas.drawRoundRect 就OK了，直接贴代码吧：

  1 public class ImageViewPlus extends ImageView{  2     /**  3      * android.widget.ImageView  4      */  5     public static final int TYPE_NONE = 0;  6     /**  7      * 圆形  8      */  9     public static final int TYPE_CIRCLE = 1; 10     /** 11      * 圆角矩形 12      */ 13     public static final int TYPE_ROUNDED_RECT = 2;     14      15     private static final int DEFAULT_TYPE = TYPE_NONE; 16     private static final int DEFAULT_BORDER_COLOR = Color.TRANSPARENT; 17     private static final int DEFAULT_BORDER_WIDTH = 0; 18     private static final int DEFAULT_RECT_ROUND_RADIUS = 0; 19      20     private int mType; 21     private int mBorderColor; 22     private int mBorderWidth; 23     private int mRectRoundRadius; 24      25     private Paint mPaintBitmap = new Paint(Paint.ANTI_ALIAS_FLAG); 26     private Paint mPaintBorder = new Paint(Paint.ANTI_ALIAS_FLAG); 27      28     private RectF mRectBorder = new RectF(); 29     private RectF mRectBitmap = new RectF(); 30      31     private Bitmap mRawBitmap; 32     private BitmapShader mShader; 33     private Matrix mMatrix = new Matrix(); 34      35     public ImageViewPlus(Context context, AttributeSet attrs) { 36         super(context, attrs); 37         //取xml文件中设定的参数 38         TypedArray ta = context.obtainStyledAttributes(attrs, R.styleable.ImageViewPlus); 39         mType = ta.getInt(R.styleable.ImageViewPlus_type, DEFAULT_TYPE); 40         mBorderColor = ta.getColor(R.styleable.ImageViewPlus_borderColor, DEFAULT_BORDER_COLOR); 41         mBorderWidth = ta.getDimensionPixelSize(R.styleable.ImageViewPlus_borderWidth, dip2px(DEFAULT_BORDER_WIDTH)); 42         mRectRoundRadius = ta.getDimensionPixelSize(R.styleable.ImageViewPlus_rectRoundRadius, dip2px(DEFAULT_RECT_ROUND_RADIUS)); 43         ta.recycle(); 44     } 45      46     @Override 47     protected void onDraw(Canvas canvas) { 48         Bitmap rawBitmap = getBitmap(getDrawable()); 49          50         if (rawBitmap != null && mType != TYPE_NONE){ 51             int viewWidth = getWidth(); 52             int viewHeight = getHeight(); 53             int viewMinSize = Math.min(viewWidth, viewHeight); 54             float dstWidth = mType == TYPE_CIRCLE ? viewMinSize : viewWidth; 55             float dstHeight = mType == TYPE_CIRCLE ? viewMinSize : viewHeight; 56             float halfBorderWidth = mBorderWidth / 2.0f; 57             float doubleBorderWidth = mBorderWidth * 2; 58              59             if (mShader == null || !rawBitmap.equals(mRawBitmap)){ 60                 mRawBitmap = rawBitmap; 61                 mShader = new BitmapShader(mRawBitmap, TileMode.CLAMP, TileMode.CLAMP); 62             } 63             if (mShader != null){ 64                 mMatrix.setScale((dstWidth - doubleBorderWidth) / rawBitmap.getWidth(), (dstHeight - doubleBorderWidth) / rawBitmap.getHeight()); 65                 mShader.setLocalMatrix(mMatrix); 66             } 67              68             mPaintBitmap.setShader(mShader); 69             mPaintBorder.setStyle(Paint.Style.STROKE); 70             mPaintBorder.setStrokeWidth(mBorderWidth); 71             mPaintBorder.setColor(mBorderWidth > 0 ? mBorderColor : Color.TRANSPARENT); 72              73             if (mType == TYPE_CIRCLE){ 74                 float radius = viewMinSize / 2.0f; 75                 canvas.drawCircle(radius, radius, radius - halfBorderWidth, mPaintBorder); 76                 canvas.translate(mBorderWidth, mBorderWidth); 77                 canvas.drawCircle(radius - mBorderWidth, radius - mBorderWidth, radius - mBorderWidth, mPaintBitmap); 78             } else if (mType == TYPE_ROUNDED_RECT){ 79                 mRectBorder.set(halfBorderWidth, halfBorderWidth, dstWidth - halfBorderWidth, dstHeight - halfBorderWidth); 80                 mRectBitmap.set(0.0f, 0.0f, dstWidth - doubleBorderWidth, dstHeight - doubleBorderWidth); 81                 float borderRadius = mRectRoundRadius - halfBorderWidth > 0.0f ? mRectRoundRadius - halfBorderWidth : 0.0f; 82                 float bitmapRadius = mRectRoundRadius - mBorderWidth > 0.0f ? mRectRoundRadius - mBorderWidth : 0.0f; 83                 canvas.drawRoundRect(mRectBorder, borderRadius, borderRadius, mPaintBorder); 84                 canvas.translate(mBorderWidth, mBorderWidth); 85                 canvas.drawRoundRect(mRectBitmap, bitmapRadius, bitmapRadius, mPaintBitmap); 86             } 87         } else { 88             super.onDraw(canvas); 89         } 90     } 91  92     private int dip2px(int dipVal) 93     { 94         float scale = getResources().getDisplayMetrics().density; 95         return (int)(dipVal * scale + 0.5f); 96     } 97      98     private Bitmap getBitmap(Drawable drawable){ 99         if (drawable instanceof BitmapDrawable){100             return ((BitmapDrawable)drawable).getBitmap();101         } else if (drawable instanceof ColorDrawable){102             Rect rect = drawable.getBounds();103             int width = rect.right - rect.left;104             int height = rect.bottom - rect.top;105             int color = ((ColorDrawable)drawable).getColor();106             Bitmap bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);107             Canvas canvas = new Canvas(bitmap);108             canvas.drawARGB(Color.alpha(color), Color.red(color), Color.green(color), Color.blue(color));109             return bitmap;110         } else {111             return null;112         }113     }114 }

 1 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 2     xmlns:tools="http://schemas.android.com/tools" 3     xmlns:snser="http://schemas.android.com/apk/res/cc.snser.imageviewplus" 4     android:layout_width="match_parent" 5     android:layout_height="match_parent" 6     android:background="@drawable/wallpaper" 7     android:orientation="vertical" 8     tools:context="${relativePackage}.${activityClass}" > 9     10     <cc.snser.imageviewplus.ImageViewPlus11         android:id="@+id/imgplus"12         android:layout_width="200dp"13         android:layout_height="300dp"14         android:layout_marginBottom="50dp"15         android:layout_centerHorizontal="true"16         android:layout_alignParentBottom="true"17         android:src="@drawable/img_rectangle"18         snser:type="rounded_rect"19         snser:borderColor="#FF0080FF"20         snser:borderWidth="10dp"21         snser:rectRoundRadius="30dp" />22     23 </RelativeLayout>

 1 <?xml version="1.0" encoding="utf-8"?>   2 <resources>   3     <attr name="type">   4         <enum name="none" value="0" />   5         <enum name="circle" value="1" />   6         <enum name="rounded_rect" value="2" /> 7     </attr> 8     <attr name="borderColor" format="color" /> 9     <attr name="borderWidth" format="dimension" />10     <attr name="rectRoundRadius" format="dimension" />11 12     <declare-styleable name="ImageViewPlus">  13         <attr name="type" />14         <attr name="borderColor" />15         <attr name="borderWidth" />16         <attr name="rectRoundRadius" />17     </declare-styleable>18 </resources>  

[转载请保留本文地址：http://www.cnblogs.com/snser/p/5159126.html]

七、Demo源码

保存下面的图片，扩展名改成zip后解压即可。

[转载请保留本文地址：http://www.cnblogs.com/snser/p/5159126.html]

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自定义控件之 圆形 / 圆角 ImageView

自定义控件之 圆形 / 圆角 ImageView

自定义控件之圆形 / 圆角 ImageView

自定义控件之圆形 / 圆角 ImageView