Android(安卓)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"?>"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"        />    "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"            />

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());    }}

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