Android笔记之RoundedImageView

参考项目：GcsSloop/rclayout

实现1，利用Canvas.clipPath来实现，适用于任何View（无法去除锯齿效果）

package com.bu_ish.blog;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Path;
import android.util.AttributeSet;

import androidx.appcompat.widget.AppCompatImageView;

public class RoundedImageView extends AppCompatImageView {
    private int cornerRadius = 12;
    private Path path;

    public RoundedImageView(Context context, AttributeSet attrs) {
        super(context, attrs);
        path = new Path();
    }

    @Override
    protected void onDraw(Canvas canvas) {
        ViewUtils.clipRoundedPathForCanvas(this, canvas, path, cornerRadius);
        super.onDraw(canvas);
    }

    public void setCornerRadius(int radius) {
        cornerRadius = radius;
        invalidate();
    }
}

package com.bu_ish.blog;

import android.graphics.Canvas;
import android.graphics.Path;
import android.view.View;

public class ViewUtils {
    public static void clipRoundedPathForCanvas(View view, Canvas canvas, Path path, int cornerRadius) {
        makePathRounded(view, path, cornerRadius);
        canvas.clipPath(path);
    }

    private static void makePathRounded(View view, Path path, int cornerRadius) {
        int width = view.getWidth(), height = view.getHeight();
        path.moveTo(cornerRadius, 0);
        path.lineTo(width - cornerRadius, 0);
        path.quadTo(width, 0, width, cornerRadius);
        path.lineTo(width, height - cornerRadius);
        path.quadTo(width, height, width - cornerRadius, height);
        path.lineTo(cornerRadius, height);
        path.quadTo(0, height, 0, height - cornerRadius);
        path.lineTo(0, cornerRadius);
        path.quadTo(0, 0, cornerRadius, 0);
    }
}

实现2，利用Canvas.drawPath实现，可抗锯齿，适用于任何View（但是在AS中无法预览圆角效果）

package com.bu_ish.blog;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.PorterDuff;
import android.graphics.PorterDuffXfermode;
import android.graphics.RectF;
import android.util.AttributeSet;

import androidx.appcompat.widget.AppCompatImageView;

public class RoundedImageView extends AppCompatImageView {
    private final Path roundedPath, pathToDraw;
    private final RectF rect;
    private final Paint paint;
    private int cornerRadius = 50;

    public RoundedImageView(Context context, AttributeSet attrs) {
        super(context, attrs);
        roundedPath = new Path();
        pathToDraw = new Path();
        rect = new RectF();
        paint = new Paint();
        initializePaint();
    }

    @Override
    protected void onDraw(Canvas canvas) {
        canvas.saveLayer(null, null, Canvas.ALL_SAVE_FLAG);
        super.onDraw(canvas);
        addRoundRectToRoundedPath();
        preparePathToDraw();
        canvas.drawPath(pathToDraw, paint);
        canvas.restore();
    }

    private void initializePaint() {
        paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_OUT));
        paint.setStyle(Paint.Style.FILL);
        paint.setAntiAlias(true);
    }

    private void addRoundRectToRoundedPath() {
        rect.left = 0;
        rect.top = 0;
        rect.right = getWidth();
        rect.bottom = getHeight();
　　　　 roundedPath.reset();
        roundedPath.addRoundRect(rect, cornerRadius, cornerRadius, Path.Direction.CW);
    }

    private void preparePathToDraw() {
        pathToDraw.reset();
        pathToDraw.addRect(0, 0, getWidth(), getHeight(), Path.Direction.CW);
        pathToDraw.op(roundedPath, Path.Op.DIFFERENCE);
    }

    public void setCornerRadius(int radius) {
        cornerRadius = radius;
        invalidate();
    }
}

实现3，使用BitmapShader实现，仅适用于ImageView，参考Demo：https://pan.baidu.com/s/1WFyZkgmwckNSVMqdLLxymw，提取码：nvb8

一个比较好的开源项目

vinc3m1/RoundedImageView: A fast ImageView that supports rounded corners, ovals, and circles.