ImageView圆角处理one

最新推荐文章于 2020-09-16 16:39:34 发布

原创最新推荐文章于 2020-09-16 16:39:34 发布 · 267 阅读

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#imageview

本文介绍了一种自定义Android ImageView的方法，使其能够显示圆角矩形图像。通过创建XCRoundRectImageView类并覆盖onDraw方法，实现了图像的圆角效果。文章详细展示了如何通过Canvas和Paint对象操作Bitmap来实现这一功能。

package com.example.day08_drawerlayou;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.RectF;
import android.graphics.PorterDuff.Mode;
import android.graphics.PorterDuffXfermode;
import android.graphics.Rect;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.util.Log;
import android.widget.ImageView;

public class XCRoundRectImageView extends ImageView {
private Paint paint;
    public XCRoundRectImageView(Context context) {
        this(context,null);
    }
    public XCRoundRectImageView(Context context, AttributeSet attrs) {
        this(context, attrs,0);
    }
    public XCRoundRectImageView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        paint = new Paint();
    }
    /**
     * 绘制圆角矩形图片
     * @author caizhiming
     */
    @Override
    protected void onDraw(Canvas canvas) {
        Drawable drawable = getDrawable();
        if (null != drawable) {
            Bitmap bitmap = ((BitmapDrawable) drawable).getBitmap();
            Bitmap b = getRoundBitmap(bitmap, 20);
            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);
        }
    }
    /**
     * 获取圆角矩形图片方法
     * @param bitmap
     * @param roundPx,一般设置成14
     * @return Bitmap
     * @author caizhiming
     */
    private Bitmap getRoundBitmap(Bitmap bitmap, int roundPx) {
        Bitmap output = Bitmap.createBitmap(
          bitmap.getWidth(),
                bitmap.getHeight(),
                Config.ARGB_8888);
        Log.i("TAG", bitmap.getWidth()+"/"+bitmap.getHeight());
        Canvas canvas = new Canvas(output);
        final int color = 0xff424242;
        final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());
        final RectF rectF = new RectF(rect);
        paint.setAntiAlias(true);
        canvas.drawARGB(0, 0, 0, 0);
        paint.setColor(color);
        int x = bitmap.getWidth();
        canvas.drawRoundRect(rectF, bitmap.getWidth(), bitmap.getHeight(), paint);
        //设置相交模式(留下相交)
        paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
        canvas.drawBitmap(bitmap, rect, rect, paint);
        return output;
    }
}

这里需要注意,我们写的是一个自己定义的类,用的时候只需要报名.类名写到xml文件代替ImageView就可以了使用的时候和ImageView 一样