自定义圆形Drawable

一个自定义的drawable

主要做的工作是将一张正常的图片转化成为一个椭圆形或者圆形的图片。达到所要的效果。

这里的这段代码来自于https://github.com/venshine/RoundImageView
我只是对其不清楚的地方做了一些注释，方便自己看，可以说是一篇推介文章吧。

import android.graphics.Bitmap;import android.graphics.BitmapShader;import android.graphics.Canvas;import android.graphics.ColorFilter;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.support.annotation.IntRange;import android.support.annotation.NonNull;import android.support.annotation.Nullable;/** * Created by panyunyi on 2017/5/26. */public class MyRoundVIew extends Drawable{    /*    * 边框颜色    * */    private static final int BORDER_COLOR=0x00000000;    /*    * 边框宽度    *    * */    private static final int BORDER_WIDTH=0;    private final Paint mPaint;    private final Paint  mBorderPaint;    private final RectF mRectF;    private final RectF mBorderRectF;    private int mBitmapWidth;    private int mBitmapHeight;    private final int mBorderWidth;    private final boolean mIsCircle;    public MyRoundVIew(Bitmap bitmap){        this(bitmap,BORDER_COLOR,BORDER_WIDTH,false);    }    public MyRoundVIew(Bitmap bitmap,int borderColor,int borderWidth,boolean isCircle){        if(bitmap==null){            throw new IllegalArgumentException("bitmap cannot be null");        }        //bitmap        mBitmapHeight =bitmap.getHeight();        mBitmapWidth=bitmap.getWidth();        mIsCircle=isCircle;        mBorderWidth=borderWidth;        mRectF=new RectF();        mBorderRectF=new RectF();        Bitmap bm=null;        /*        * 如果图片需要是圆形时，需要先将其转化成为一个正方形。        * */        if(mIsCircle){            bm=getSquareBitmap(bitmap);        }        //初始化paint        mPaint=new Paint();        mPaint.setAntiAlias(true);//使用抗锯齿        mPaint.setDither(true);//使用抖动处理        BitmapShader shader=new BitmapShader(bm==null?bitmap:bm, Shader.TileMode.CLAMP,Shader.TileMode.CLAMP);        mPaint.setShader(shader);        mBorderPaint=new Paint();        mBorderPaint.setDither(true);        mBorderPaint.setAntiAlias(true);        mBorderPaint.setStyle(Paint.Style.STROKE);        mBorderPaint.setColor(borderColor);        mBorderPaint.setStrokeWidth(borderWidth);    }    private Bitmap getSquareBitmap(Bitmap bitmap) {        Bitmap bm;        if (mBitmapWidth > mBitmapHeight) {            /*            *            * createBitmap                    added in API level 1                    Bitmap createBitmap (Bitmap source,                                    int x,                                    int y,                                    int width,                                    int height)                    Returns an immutable bitmap from the specified subset of the source bitmap. The new bitmap may be the same object as source, or a copy may have been made. It is initialized with the same density and color space as the original bitmap.                    Parameters                    source  Bitmap: The bitmap we are subsetting                    x   int: The x coordinate of the first pixel in source                    y   int: The y coordinate of the first pixel in source                    width   int: The number of pixels in each row                    height  int: The number of rows            *            * */            bm = Bitmap.createBitmap(bitmap, (mBitmapWidth - mBitmapHeight) / 2, 0, mBitmapHeight, mBitmapHeight);            mBitmapWidth= mBitmapHeight;        }else if(mBitmapWidth< mBitmapHeight){            bm=Bitmap.createBitmap(bitmap,0,(mBitmapHeight -mBitmapWidth)/2,mBitmapWidth, mBitmapWidth);            mBitmapHeight =mBitmapWidth;        }else{            bm=bitmap;        }        return bm;    }    @Override    public void draw(@NonNull Canvas canvas) {        if(mIsCircle){            /*            * void drawCircle (float cx,                float cy,                float radius,                Paint paint)            Draw the specified circle using the specified paint. If radius is <= 0, then nothing will be drawn. The circle will be filled or framed based on the Style in the paint.                Parameters                cx  float: The x-coordinate of the center of the cirle to be drawn                cy  float: The y-coordinate of the center of the cirle to be drawn                radius  float: The radius of the cirle to be drawn                paint   Paint: The paint used to draw the circle            *            * */            canvas.drawCircle(mRectF.centerX(),mRectF.centerY(),mRectF.centerX(),mPaint);            canvas.drawCircle(mBorderRectF.centerX(),mBorderRectF.centerY(),mBorderRectF.centerX()-mBorderWidth/2.0f,mBorderPaint);        }else{            /*            * void drawOval (float left,                float top,                float right,                float bottom,                Paint paint)            Draw the specified oval using the specified paint. The oval will be filled or framed based on the Style in the paint.                Parameters                left    float                top float                right   float                bottom  float                paint   Paint            *            * */            canvas.drawOval(mRectF,mPaint);            canvas.drawOval(mBorderRectF,mBorderPaint);        }    }    @Override    protected void onBoundsChange(Rect bounds) {        super.onBoundsChange(bounds);        mRectF.set(bounds);        bounds.inset(mBorderWidth / 2, mBorderWidth / 2);   // FIXME fine tuning, [bounds.inset(mBorderWidth,        // mBorderWidth);]        mBorderRectF.set(bounds);    }    @Override    public void setAlpha(@IntRange(from = 0, to = 255) int alpha) {        if(mPaint.getAlpha()!=alpha){            mPaint.setAlpha(alpha);            invalidateSelf();        }    }    @Override    public void setColorFilter(@Nullable ColorFilter colorFilter) {        mPaint.setColorFilter(colorFilter);    }    @Override    public int getOpacity() {        return PixelFormat.TRANSLUCENT;    }    @Override    public int getIntrinsicWidth() {        return mBitmapWidth;    }    @Override    public int getIntrinsicHeight() {        return mBitmapHeight;    }    public void setAntiAlias(boolean aa) {        mPaint.setAntiAlias(aa);        invalidateSelf();    }    @Override    public void setFilterBitmap(boolean filter) {        mPaint.setFilterBitmap(filter);        invalidateSelf();    }    @Override    public void setDither(boolean dither) {        mPaint.setDither(dither);        invalidateSelf();    }}