Android 圆角圆形ImageView(超简单实现)

前言：今天偶然看到我之前写过的一篇博客 Android项目中遇到的坑之（Android圆角圆形图 一），我在想，这不就是在模仿ImageView么，我为什么要模仿，直接拿来用不是更好么？我能直接在ImageView的源码上去改改代码？ 于是就有了下面这篇文章了。

先上一张效果图：

效果还是很不错的，代码更简单哦～～～

但凡搞过android的童鞋一定都知道ImageView,既然ImageView已经处理好了各种缩放问题，然后兼容性就更不用说了是吧，好歹别人也是一个系统组件，那显示图片等一系列的任务ImageView都帮我们实现好了，我们无非就是在它的基础上添加一个显示圆角圆形的功能，所以我们看看它的源码..

其它的源码我们就不看了，我们重点看它的onDraw方法：

@Overrideprotected void onDraw(Canvas canvas) {super.onDraw(canvas);if (mDrawable == null) {return; // couldn't resolve the URI}if (mDrawableWidth == 0 || mDrawableHeight == 0) {return;// nothing to draw (empty bounds)}if (mDrawMatrix == null && mPaddingTop == 0 && mPaddingLeft == 0) {mDrawable.draw(canvas);} else {final int saveCount = canvas.getSaveCount();canvas.save();if (mCropToPadding) {final int scrollX = mScrollX;final int scrollY = mScrollY;canvas.clipRect(scrollX + mPaddingLeft, scrollY + mPaddingTop,scrollX + mRight - mLeft - mPaddingRight,scrollY + mBottom - mTop - mPaddingBottom);}canvas.translate(mPaddingLeft, mPaddingTop);if (mDrawMatrix != null) {canvas.concat(mDrawMatrix);}mDrawable.draw(canvas);canvas.restoreToCount(saveCount);}}

代码还是很简单的，相比小伙伴都看得懂，我简单的说一下，当我们设置了ImageView的scaleType后，imageview会通过算法依据我们传递的scaletype类型转换成Matrix对象，我们可以看到这么一段代码：

if (mDrawMatrix != null) {canvas.concat(mDrawMatrix);}

转换成Matrix对象后，直接设给了当前画布，然后把我们传递给ImageView的图片显示出来：

mDrawable.draw(canvas);canvas.restoreToCount(saveCount);

是的，没错就是这么简单～～～

然后我们需要做什么呢？

首先定一个attrs文件：

<?xml version="1.0" encoding="utf-8"?><resources><declare-styleable name="RoundImageView"><attr name="type" format="enum"><enum name="circle" value="1"/><enum name="round" value="2"/></attr><attr name="radius" format="dimension"/>ssss</declare-styleable></resources>

首先我们定义一个view叫RoundImageView,然后继承ImageView,重写其构造方法：

public class RoundImageView extends ImageView {/*** 圆形模式*/private static final int MODE_CIRCLE = 1;/*** 普通模式*/private static final int MODE_NONE = 0;/*** 圆角模式*/private static final int MODE_ROUND = 2;private Paint mPaint;private int currMode = 0;/*** 圆角半径*/private int currRound = dp2px(10);public RoundImageView(Context context) {super(context);initViews();}public RoundImageView(Context context, AttributeSet attrs) {this(context, attrs, 0);}public RoundImageView(Context context, AttributeSet attrs, int defStyleAttr) {super(context, attrs, defStyleAttr);obtainStyledAttrs(context, attrs, defStyleAttr);initViews();}private void obtainStyledAttrs(Context context, AttributeSet attrs, int defStyleAttr) {TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.RoundImageView, defStyleAttr, 0);currMode = a.hasValue(R.styleable.RoundImageView_type) ? a.getInt(R.styleable.RoundImageView_type, MODE_NONE) : MODE_NONE;currRound = a.hasValue(R.styleable.RoundImageView_radius) ? a.getDimensionPixelSize(R.styleable.RoundImageView_radius, currRound) : currRound;a.recycle();}｝

然后就是重写onMeasure方法了，我要处理的就是当模式为圆形的时候强制把控件的宽高保持一致：

@Overrideprotected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {/*** 当模式为圆形模式的时候，我们强制让宽高一致*/if (currMode == MODE_CIRCLE) {super.onMeasure(widthMeasureSpec, heightMeasureSpec);int result = Math.min(getMeasuredHeight(), getMeasuredWidth());setMeasuredDimension(result, result);} else {super.onMeasure(widthMeasureSpec, heightMeasureSpec);}}

好了，然后就是重写我们的onDraw方法了，我们直接把ImageView的代码拷贝过来，然后稍稍改一下：

@Overrideprotected void onDraw(Canvas canvas) {Drawable mDrawable = getDrawable();Matrix mDrawMatrix = getImageMatrix();if (mDrawable == null) {return; // couldn't resolve the URI}if (mDrawable.getIntrinsicWidth() == 0 || mDrawable.getIntrinsicHeight() == 0) {return;// nothing to draw (empty bounds)}if (mDrawMatrix == null && getPaddingTop() == 0 && getPaddingLeft() == 0) {mDrawable.draw(canvas);} else {final int saveCount = canvas.getSaveCount();canvas.save();if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {if (getCropToPadding()) {final int scrollX = getScrollX();final int scrollY = getScrollY();canvas.clipRect(scrollX + getPaddingLeft(), scrollY + getPaddingTop(),scrollX + getRight() - getLeft() - getPaddingRight(),scrollY + getBottom() - getTop() - getPaddingBottom());}}canvas.translate(getPaddingLeft(), getPaddingTop());if (currMode == MODE_CIRCLE) {//当为圆形模式的时候Bitmap bitmap = drawable2Bitmap(mDrawable);mPaint.setShader(new BitmapShader(bitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP));canvas.drawCircle(getWidth() / 2, getHeight() / 2, getWidth() / 2, mPaint);} else if (currMode == MODE_ROUND) {//当为圆角模式的时候Bitmap bitmap = drawable2Bitmap(mDrawable);mPaint.setShader(new BitmapShader(bitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP));canvas.drawRoundRect(new RectF(getPaddingLeft(), getPaddingTop(), getWidth() - getPaddingRight(), getHeight() - getPaddingBottom()),currRound, currRound, mPaint);} else {if (mDrawMatrix != null) {canvas.concat(mDrawMatrix);}mDrawable.draw(canvas);}canvas.restoreToCount(saveCount);}}

好啦～～ 因为我们写到的代码就只有几行：

if (currMode == MODE_CIRCLE) {//当为圆形模式的时候Bitmap bitmap = drawable2Bitmap(mDrawable);mPaint.setShader(new BitmapShader(bitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP));canvas.drawCircle(getWidth() / 2, getHeight() / 2, getWidth() / 2, mPaint);} else if (currMode == MODE_ROUND) {//当为圆角模式的时候Bitmap bitmap = drawable2Bitmap(mDrawable);mPaint.setShader(new BitmapShader(bitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP));canvas.drawRoundRect(new RectF(getPaddingLeft(), getPaddingTop(), getWidth() - getPaddingRight(), getHeight() - getPaddingBottom()),currRound, currRound, mPaint);}

就是当模式为circle跟round的时候，给画笔设置一个bitmapshader（bitmapshader不懂的童鞋自己上api或网上看看其用法）然后用当前canvas画一个圆或者圆角矩形。

然后你就可以用起来了：

<?xml version="1.0" encoding="utf-8"?><LinearLayoutxmlns:android="/apk/res/android"xmlns:tools="/tools"xmlns:app="/apk/res-auto"android:id="@+id/activity_main"android:layout_width="match_parent"android:layout_height="match_parent"android:paddingLeft="@dimen/activity_horizontal_margin"android:paddingRight="@dimen/activity_horizontal_margin"android:paddingTop="@dimen/activity_vertical_margin"android:paddingBottom="@dimen/activity_vertical_margin"tools:context="com.yasin.roundimageview.MainActivity"android:orientation="vertical"><com.yasin.roundimageview.RoundImageViewandroid:layout_width="100dp"android:layout_height="100dp"android:src="@mipmap/test"android:scaleType="fitXY"/><com.yasin.roundimageview.RoundImageViewandroid:layout_marginTop="10dp"android:layout_width="100dp"android:layout_height="100dp"android:src="@mipmap/test"android:scaleType="centerCrop"app:type="round"/><com.yasin.roundimageview.RoundImageViewandroid:layout_marginTop="10dp"android:layout_width="100dp"android:layout_height="100dp"android:src="@mipmap/test"app:type="circle"android:scaleType="fitXY"/><LinearLayoutandroid:layout_width="match_parent"android:layout_height="wrap_content"android:orientation="horizontal"android:layout_marginTop="10dp"><com.yasin.roundimageview.RoundImageViewandroid:layout_width="50dp"android:layout_height="50dp"android:src="@color/colorAccent"/><com.yasin.roundimageview.RoundImageViewandroid:layout_marginLeft="10dp"android:layout_width="50dp"android:layout_height="50dp"android:src="@color/colorAccent"app:type="round"/><com.yasin.roundimageview.RoundImageViewandroid:layout_marginLeft="10dp"android:layout_width="50dp"android:layout_height="50dp"android:src="@color/colorAccent"app:type="circle"/></LinearLayout></LinearLayout>

好啦～～！！ 是不是觉得soeasy呢？？

最后贴上RoundImageView全部代码：

package com.yasin.roundimageview;import android.content.Context;import android.content.res.TypedArray;import android.graphics.Bitmap;import android.graphics.BitmapShader;import android.graphics.Canvas;import android.graphics.Matrix;import android.graphics.Paint;import android.graphics.RectF;import android.graphics.Shader;import android.graphics.drawable.Drawable;import android.os.Build;import android.util.AttributeSet;import android.util.TypedValue;import android.widget.ImageView;/*** Created by leo on 17/3/14.*/public class RoundImageView extends ImageView {/*** 圆形模式*/private static final int MODE_CIRCLE = 1;/*** 普通模式*/private static final int MODE_NONE = 0;/*** 圆角模式*/private static final int MODE_ROUND = 2;private Paint mPaint;private int currMode = 0;/*** 圆角半径*/private int currRound = dp2px(10);public RoundImageView(Context context) {super(context);initViews();}public RoundImageView(Context context, AttributeSet attrs) {this(context, attrs, 0);}public RoundImageView(Context context, AttributeSet attrs, int defStyleAttr) {super(context, attrs, defStyleAttr);obtainStyledAttrs(context, attrs, defStyleAttr);initViews();}private void obtainStyledAttrs(Context context, AttributeSet attrs, int defStyleAttr) {TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.RoundImageView, defStyleAttr, 0);currMode = a.hasValue(R.styleable.RoundImageView_type) ? a.getInt(R.styleable.RoundImageView_type, MODE_NONE) : MODE_NONE;currRound = a.hasValue(R.styleable.RoundImageView_radius) ? a.getDimensionPixelSize(R.styleable.RoundImageView_radius, currRound) : currRound;a.recycle();}private void initViews() {mPaint = new Paint(Paint.ANTI_ALIAS_FLAG | Paint.DITHER_FLAG);}@Overrideprotected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {/*** 当模式为圆形模式的时候，我们强制让宽高一致*/if (currMode == MODE_CIRCLE) {super.onMeasure(widthMeasureSpec, heightMeasureSpec);int result = Math.min(getMeasuredHeight(), getMeasuredWidth());setMeasuredDimension(result, result);} else {super.onMeasure(widthMeasureSpec, heightMeasureSpec);}}@Overrideprotected void onDraw(Canvas canvas) {Drawable mDrawable = getDrawable();Matrix mDrawMatrix = getImageMatrix();if (mDrawable == null) {return; // couldn't resolve the URI}if (mDrawable.getIntrinsicWidth() == 0 || mDrawable.getIntrinsicHeight() == 0) {return;// nothing to draw (empty bounds)}if (mDrawMatrix == null && getPaddingTop() == 0 && getPaddingLeft() == 0) {mDrawable.draw(canvas);} else {final int saveCount = canvas.getSaveCount();canvas.save();if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {if (getCropToPadding()) {final int scrollX = getScrollX();final int scrollY = getScrollY();canvas.clipRect(scrollX + getPaddingLeft(), scrollY + getPaddingTop(),scrollX + getRight() - getLeft() - getPaddingRight(),scrollY + getBottom() - getTop() - getPaddingBottom());}}canvas.translate(getPaddingLeft(), getPaddingTop());if (currMode == MODE_CIRCLE) {//当为圆形模式的时候Bitmap bitmap = drawable2Bitmap(mDrawable);mPaint.setShader(new BitmapShader(bitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP));canvas.drawCircle(getWidth() / 2, getHeight() / 2, getWidth() / 2, mPaint);} else if (currMode == MODE_ROUND) {//当为圆角模式的时候Bitmap bitmap = drawable2Bitmap(mDrawable);mPaint.setShader(new BitmapShader(bitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP));canvas.drawRoundRect(new RectF(getPaddingLeft(), getPaddingTop(), getWidth() - getPaddingRight(), getHeight() - getPaddingBottom()),currRound, currRound, mPaint);} else {if (mDrawMatrix != null) {canvas.concat(mDrawMatrix);}mDrawable.draw(canvas);}canvas.restoreToCount(saveCount);}}/*** drawable转换成bitmap*/private Bitmap drawable2Bitmap(Drawable drawable) {if (drawable == null) {return null;}Bitmap bitmap = Bitmap.createBitmap(getWidth(), getHeight(), Bitmap.Config.ARGB_8888);Canvas canvas = new Canvas(bitmap);//根据传递的scaletype获取matrix对象，设置给bitmapMatrix matrix = getImageMatrix();if (matrix != null) {canvas.concat(matrix);}drawable.draw(canvas);return bitmap;}private int dp2px(float value) {return (int) TypedValue.applyDimension(PLEX_UNIT_DIP, value, getResources().getDisplayMetrics());}}