Android实现图片圆角显示的几种方式_android 圆角图片

在实际开发中我们经常会对图片进行圆角处理，这里做一个小总结，文章结尾还有一个不到100行实现的，支持圆形，圆角和TransitionDrawable的ImageView。

首先是效果图：

实现这种效果有两种方式：

在图片上做

把图片裁剪成圆角图片

优点：节约内存

public Bitmap getRoundRectBitmap(Bitmap bitmap, int radius) {
    Paint paint = new Paint();
    paint.setAntiAlias(true);
    paint.setFilterBitmap(true);
 
    int bmWidth = bitmap.getWidth();
    int bmHeight = bitmap.getHeight();
    final RectF rectF = new RectF(0, 0, width, height);
 
    Canvas canvas = new Canvas(bitmap);
 
    paint.setXfermode(null);
    canvas.drawRoundRect(rectF, radius, radius, paint);
    paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
    canvas.drawBitmap(bitmap, rect, rectF, paint);
 
    return bitmap;
}

控件绘制的时候，控制显示区域在控件上做

优点：方便省事，适合各种图片框架

ImageView

@Override
protected void onDraw(Canvas canvas) {
    int saveCount = canvas.getSaveCount();
    canvas.save();
    super.onDraw(canvas);
 
    mPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_IN));
    canvas.drawRoundRect(rectF, radius, radius, mPaint);
 
    canvas.restoreToCount(saveCount);
}

支持圆形 圆角矩形ShapedImageView

• 支持TransitionDrawable

public class MainActivity extends Activity {
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }
 
}

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:test="http://schemas.android.com/apk/res/com.example.shapeimage"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:gravity="center" >
 
    <com.example.shapeimage.ShapedImageView
        android:id="@+id/image1"
        android:layout_width="200dp"
        android:layout_height="200dp"
        android:layout_centerInParent="true"
        android:src="@drawable/an"
        test:shape_mode="circle" />
 
    <com.example.shapeimage.ShapedImageView
        android:id="@+id/image1"
        android:layout_width="200dp"
        android:layout_height="200dp"
        android:layout_marginTop="20dp"
        android:layout_centerInParent="true"
        test:round_radius="20dp"
        android:src="@drawable/an"
        test:shape_mode="round_rect" />
 
</LinearLayout>

一个属性资源文件attrs.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
 
    <declare-styleable name="ShapedImageView">
        <attr name="shape_mode" format="enum">
            <enum name="round_rect" value="1" />
            <enum name="circle" value="2" />
        </attr>
        <attr name="round_radius" format="dimension" />
    </declare-styleable>
 
</resources>

最重要的就是ShapedImageView.java这个类

import java.util.Arrays;
 
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.PorterDuffXfermode;
import android.graphics.PorterDuff;
import android.graphics.drawable.shapes.RoundRectShape;
import android.graphics.drawable.shapes.Shape;
import android.os.Build;
import android.util.AttributeSet;
import android.widget.ImageView;
 
public class ShapedImageView extends ImageView {
 
    private static final int SHAPE_MODE_ROUND_RECT = 1;
    private static final int SHAPE_MODE_CIRCLE = 2;
 
    private int mShapeMode = 0;
    private float mRadius = 0;
    private Shape mShape;
    private Paint mPaint;
 
    public ShapedImageView(Context context) {
        super(context);
        init(null);
    }
 
    public ShapedImageView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init(attrs);
    }
 
    public ShapedImageView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init(attrs);
    }
 
    private void init(AttributeSet attrs) {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
            setLayerType(LAYER_TYPE_HARDWARE, null);
        }
        if (attrs != null) {
            TypedArray a = getContext().obtainStyledAttributes(attrs, R.styleable.ShapedImageView);
            mShapeMode = a.getInt(R.styleable.ShapedImageView_shape_mode, 0);
            mRadius = a.getDimension(R.styleable.ShapedImageView_round_radius, 0);
            a.recycle();
        }
        mPaint = new Paint();
        mPaint.setAntiAlias(true);
        mPaint.setFilterBitmap(true);
        mPaint.setColor(Color.BLACK);
        mPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_IN));
    }
 
    @Override
    protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
        super.onLayout(changed, left, top, right, bottom);
        if (changed) {
            switch (mShapeMode) {
                case SHAPE_MODE_ROUND_RECT:
                    break;
                case SHAPE_MODE_CIRCLE:
                    int min = Math.min(getWidth(), getHeight());
                    mRadius = (float) min / 2;
                    break;
            }
            if (mShape == null) {
                float[] radius = new float[8];
                Arrays.fill(radius, mRadius);
                mShape = new RoundRectShape(radius, null, null);
            }
            mShape.resize(getWidth(), getHeight());
        }
    }
 
    @Override
    protected void onDraw(Canvas canvas) {
        int saveCount = canvas.getSaveCount();
        canvas.save();
        super.onDraw(canvas);
        switch (mShapeMode) {
            case SHAPE_MODE_ROUND_RECT:
            case SHAPE_MODE_CIRCLE:
                if (mShape != null) {
                    mShape.draw(canvas, mPaint);
                }
                break;
        }
        canvas.restoreToCount(saveCount);
    }
 
}

如果图片展示出来不全或者变形，可以参考<ImageView的Scaletype的属性>这篇文章去根据自己的需要设置响应的值(推荐使用scaleType="centerCrop")。

好了，基本到这里就实现我们要的效果了，最后放上源码下载地址：

首先是github上面的项目源码地址：点击跳转到项目源码地址

然后是Eclipse工程格式的demo下载地址: 点击下载demo