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：

@Override
protected 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：

@Override
protected 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：

@Override
protected 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"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:app="http://schemas.android.com/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.RoundImageView
android:layout_width="100dp"
android:layout_height="100dp"
android:src="@mipmap/test"
android:scaleType="fitXY"
/>
<com.yasin.roundimageview.RoundImageView
android:layout_marginTop="10dp"
android:layout_width="100dp"
android:layout_height="100dp"
android:src="@mipmap/test"
android:scaleType="centerCrop"
app:type="round"
/>
<com.yasin.roundimageview.RoundImageView
android:layout_marginTop="10dp"
android:layout_width="100dp"
android:layout_height="100dp"
android:src="@mipmap/test"
app:type="circle"
android:scaleType="fitXY"
/>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:layout_marginTop="10dp"
>
<com.yasin.roundimageview.RoundImageView
android:layout_width="50dp"
android:layout_height="50dp"
android:src="@color/colorAccent"
/>
<com.yasin.roundimageview.RoundImageView
android:layout_marginLeft="10dp"
android:layout_width="50dp"
android:layout_height="50dp"
android:src="@color/colorAccent"
app:type="round"
/>
<com.yasin.roundimageview.RoundImageView
android: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);
}

@Override
protected 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);
}
}

@Override
protected 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bitmap
Matrix matrix = getImageMatrix();
if (matrix != null) {
canvas.concat(matrix);
}
drawable.draw(canvas);
return bitmap;
}

private int dp2px(float value) {
return (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, value, getResources().getDisplayMetrics());
}
}