Android中图片圆角三种实现方法

android 开发中，经常需要对图片进行二次处理，比如添加圆角效果 或 显示圆形图片；

方法一

通过第三方框架 glide 设置圆角效果；

写法1：

requestoptions options = new requestoptions().error(r.drawable.img_load_failure).bitmaptransform(new roundedcorners(30));//图片圆角为30
glide.with(this).load(url) //图片地址
                .apply(options)
                .into(imagview);

写法2：

requestoptions requestoptions = new requestoptions();
requestoptions.placeholder(r.drawable.ic_launcher_background);
requestoptions.circlecroptransform();
requestoptions.transforms( new roundedcorners(30));
glide.with(this).load(url) //图片地址
                .apply(options)
                .into(imagview);

写法3：

requestoptions options = new requestoptions().centercrop() .transform(new roundtransform(this,30)); 
glide.with(this).load(url) //图片地址
                .apply(options)
                .into(imagview);

public class roundtransform extends bitmaptransformation { 
    private static float radius = 0f; 
    public roundtransform(context context) { 
        this(context, 4); 
    } 
   
    public roundtransform(context context, int dp) { 
        super(context); 
        this.radius = resources.getsystem().getdisplaymetrics().density * dp; 
    } 
   
    @override 
    protected bitmap transform(bitmappool pool, bitmap totransform, int outwidth, int outheight) { 
        bitmap bitmap = transformationutils.centercrop(pool, totransform, outwidth, outheight); 
        return roundcrop(pool, bitmap); 
    } 
   
    private static bitmap roundcrop(bitmappool pool, bitmap source) { 
        if (source == null) return null; 
        bitmap result = pool.get(source.getwidth(), source.getheight(), bitmap.config.argb_8888); 
        if (result == null) { 
            result = bitmap.createbitmap(source.getwidth(), source.getheight(), bitmap.config.argb_8888); 
        } 
   
        canvas canvas = new canvas(result); 
        paint paint = new paint(); 
        paint.setshader(new bitmapshader(source, bitmapshader.tilemode.clamp, bitmapshader.tilemode.clamp)); 
        paint.setantialias(true); 
        rectf rectf = new rectf(0f, 0f, source.getwidth(), source.getheight()); 
        canvas.drawroundrect(rectf, radius, radius, paint); 
        return result; 
    } 
   
    public string getid() { 
        return getclass().getname() + math.round(radius); 
    } 
   
    @override 
    public void updatediskcachekey(messagedigest messagedigest) { 
   
    }
}

方法二

自定义imageview 设置圆角效果；

<imageview
        android:id="@+id/iv"
        android:layout_width="300dp"
        android:layout_height="300dp"
        android:layout_centerhorizontal="true"
        />

imageview iv = findviewbyid(r.id.iv); 
bitmap bitmap =bitmapfactory.decoderesource(getresources(), r.drawable.fengjing);
        bitmap outbitmap =getroundbitmapbyshader(bitmap, 500,300,20, 3);
        iv.setimagebitmap(outbitmap);

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();
    }
 
    /**
     * 绘制圆角矩形图片
     */
    @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(), 50,0);
            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);
        }
    }
 
    /**
     * 把资源图片转换成bitmap
     * @param drawable
     * 资源图片
     * @return 位图
     */
    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;
    }
 
}

方法三

对图片进行处理，还可以加边框；

/**
 * 通过bitmapshader实现圆形边框
 * @param bitmap 
 * @param outwidth 输出的图片宽度
 * @param outheight 输出的图片高度
 * @param radius 圆角大小
 * @param boarder 边框宽度
 */
public static bitmap getroundbitmapbyshader(bitmap bitmap, int outwidth, int outheight, int radius, int boarder) {
    if (bitmap == null) {
        return null;
    }
    int height = bitmap.getheight();
    int width = bitmap.getwidth();
    
    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;
}

实现圆形和边框：

/**
 * 通过bitmapshader实现圆形边框
 * @param bitmap 
 * @param outwidth 输出的图片宽度
 * @param outheight 输出的图片高度
 * @param boarder 边框大小
 */
public static bitmap getcirclebitmapbyshader(bitmap bitmap, int outwidth, int outheight, int boarder) {
int radius;
int width = bitmap.getwidth();
int height = bitmap.getheight();
float widthscale = outwidth * 1f / width;
float heightscale = outheight * 1f / height;
 
bitmap desbitmap = bitmap.createbitmap(outwidth, outheight, bitmap.config.argb_8888);
if (outheight > outwidth) {
    radius = outwidth / 2;
} else {
    radius = outheight / 2;
}
//创建canvas
canvas canvas = new canvas(desbitmap);
paint paint = new paint(paint.anti_alias_flag);
bitmapshader bitmapshader = new bitmapshader(bitmap, shader.tilemode.clamp, shader.tilemode.clamp);
matrix matrix = new matrix();
matrix.setscale(widthscale, heightscale);
bitmapshader.setlocalmatrix(matrix);
paint.setshader(bitmapshader);
canvas.drawcircle(outwidth / 2, outheight / 2, radius - boarder, 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.drawcircle(outwidth / 2, outheight / 2, radius - boarder, boarderpaint);
}
return desbitmap;
}

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