Android 添加GridView中图片的圆角样式

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目录

问题引入

解决方案

问题引入

        在写GridView的时候想把里面的头像修成圆角图片，如图中方形粉色头像

        据我分析，想在一个界面里添加圆角样式就应该在该界面的Activity里，用findViewById找到头像然后对它一顿操作，但是GridView的部分是单独在一个Xml里的，没有属于他自己的Activity，也就没有操作空间。。

        后来看见了别人的这个重写Image的方法：解决方案

解决方案

 可以通过重写ImageView的方法，重写完了直接到Xml布局文件里引入。

重写部分

RoundRectImageView.java

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapShader;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.PixelFormat;
import android.graphics.Rect;
import android.graphics.RectF;
import android.graphics.Shader;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.widget.ImageView;
 
 
 
public class RoundRectImageView extends ImageView {
 
    private Paint paint;
 
    public RoundRectImageView(Context context) {
        this(context,null);
    }
 
    public RoundRectImageView(Context context, AttributeSet attrs) {
        this(context, attrs,0);
    }
 
    public RoundRectImageView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        paint = new Paint();
    }
 
    
    @Override
    protected void onDraw(Canvas canvas) {
        Drawable drawable = getDrawable();
        if (null != drawable) {
            Bitmap bitmap = getBitmapFromDrawable(drawable);
//   Bitmap bitmap = ((BitmapDrawable) drawable).getBitmap();
            Bitmap b = getRoundBitmapByShader(bitmap,getWidth(),getHeight(), 32,5);
            final Rect rectSrc = new Rect(0, 0, b.getWidth(), b.getHeight());
            final Rect rectDest = new Rect(0,0,getWidth(),getHeight());
            paint.reset();
            canvas.drawBitmap(b, rectSrc, rectDest, paint);
 
        } else {
            super.onDraw(canvas);
        }
    }
 
    
    public static Bitmap getBitmapFromDrawable(Drawable drawable) {
        int width = drawable.getIntrinsicWidth();
        int height = drawable.getIntrinsicHeight();
        Bitmap bitmap = Bitmap.createBitmap(width, height, drawable
                .getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888
                : Bitmap.Config.RGB_565);
        Canvas canvas = new Canvas(bitmap);
        //drawable.setBounds(-4, -4, width + 4, height + 4);
        drawable.draw(canvas);
        return bitmap;
    }
 
    public static Bitmap getRoundBitmapByShader(Bitmap bitmap, int outWidth, int outHeight, int radius, int boarder) {
        if (bitmap == null) {
            return null;
        }
        int width = bitmap.getWidth();
        int height = bitmap.getHeight();
        float widthScale = outWidth * 1f / width;
        float heightScale = outHeight * 1f / height;
 
        Matrix matrix = new Matrix();
        matrix.setScale(widthScale, heightScale);
        //创建输出的bitmap
        Bitmap desBitmap = Bitmap.createBitmap(outWidth, outHeight, Bitmap.Config.ARGB_8888);
        //创建canvas并传入desBitmap，这样绘制的内容都会在desBitmap上
        Canvas canvas = new Canvas(desBitmap);
        Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
        //创建着色器
        BitmapShader bitmapShader = new BitmapShader(bitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
        //给着色器配置matrix
        bitmapShader.setLocalMatrix(matrix);
        paint.setShader(bitmapShader);
        //创建矩形区域并且预留出border
        RectF rect = new RectF(boarder, boarder, outWidth - boarder, outHeight - boarder);
        //把传入的bitmap绘制到圆角矩形区域内
        canvas.drawRoundRect(rect, radius, radius, paint);
 
        if (boarder > 0) {
            //绘制boarder
            Paint boarderPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
            boarderPaint.setColor(Color.GREEN);
            boarderPaint.setStyle(Paint.Style.STROKE);
            boarderPaint.setStrokeWidth(boarder);
            canvas.drawRoundRect(rect, radius, radius, boarderPaint);
        }
        return desBitmap;
    }
 
}

引入部分

实现结果

 结束！