カスタム円形Drawable

カスタムdrawable
主な仕事は、正常な画像を楕円形や円形の画像に変換することです.所望の効果を達成する.
このコードはhttps://github.com/venshine/RoundImageView私はただそのはっきりしないところに注釈をつけただけで、自分で読むのに便利で、推薦文と言えるでしょう.

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{
    /*
    *     
    * */
    private static final int BORDER_COLOR=0x00000000;
    /*
    *     
    *
    * */

    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;
        /*
        *           ，              。
        * */
        if(mIsCircle){
            bm=getSquareBitmap(bitmap);

        }


        //   paint

        mPaint=new Paint();
        mPaint.setAntiAlias(true);//     
        mPaint.setDither(true);//      
        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();
    }
}