自定义圆形图片

官方推荐使用AppCompatImageView来实现自定义ImagView。

public class AppCompatImageView extends ImageView 
    implements 
  TintableBackgroundView, TintableImageSourceView 

import android.annotation.SuppressLint;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapShader;
import android.graphics.Canvas;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.Shader;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import androidx.annotation.Nullable;
import androidx.appcompat.widget.AppCompatImageView;

/**
 * @author luxi
 * @email luxi2@mychery.com
 * @date 2023/5/11 15:12
 */
public class CircleImageView extends AppCompatImageView {
    /**
     * 画笔；mPaint
     * 图片半径；mRadius
     * 缩放比例：mScale
     */
    private Paint mPaint;

    private int mRadius;

    private float mScale;

    public CircleImageView(Context context) {
        super(context);
    }

    public CircleImageView(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
    }

    public CircleImageView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        //因为是圆形图片，所以应该让宽高保持一致
        int size = Math.min(getMeasuredWidth(), getMeasuredHeight());
        mRadius = size / 2;
        //存储合适的宽高
        setMeasuredDimension(size, size);
    }

    @SuppressLint("DrawAllocation")
    @Override
    protected void onDraw(Canvas canvas) {
        mPaint = new Paint();
        Bitmap bitmap = drawableToBitmap(getDrawable());
        //初始化BitmapShader，传入bitmap对象
        @SuppressLint("DrawAllocation") BitmapShader bitmapShader=new BitmapShader(bitmap, Shader.TileMode.CLAMP,Shader.TileMode.CLAMP);

        //计算缩放比例
        mScale=(mRadius*2.0f)/Math.min(bitmap.getHeight(),bitmap.getWidth());

        Matrix matrix=new Matrix();
        matrix.setScale(mScale,mScale);
        bitmapShader.setLocalMatrix(matrix);


        mPaint.setShader(bitmapShader);

        //画圆形，指定好中心点坐标、半径、画笔
        canvas.drawCircle(mRadius,mRadius,mRadius,mPaint);
    }


    /**
     * 将drawable转化成bitmap
     *
     * @param drawable drawable
     * @author luxi
     * @date 2023/5/11 15:30
     */
    private Bitmap drawableToBitmap(Drawable drawable) {
        if (drawable instanceof BitmapDrawable) {
            BitmapDrawable bd = (BitmapDrawable) drawable;
            return bd.getBitmap();
        }
        int w = drawable.getIntrinsicWidth();
        int h = drawable.getIntrinsicHeight();
        Bitmap bitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(bitmap);
        drawable.setBounds(0, 0, w, h);
        drawable.draw(canvas);
        return bitmap;
    }
}