圆角矩形ImageView

最新推荐文章于 2021-05-28 15:37:32 发布

翻译最新推荐文章于 2021-05-28 15:37:32 发布 · 734 阅读

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本文介绍了一种自定义Android ImageView的方法，通过继承ImageView并重写onDraw方法来实现圆角图片显示效果。该实现利用了Canvas和Paint等组件，并提供了设置圆角角度的功能。

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1、自定义View

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

public class XCRoundRectImageView extends ImageView {
    private Paint paint;
    private int jiaodu = 0;
    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();
    }
    public void setJiaodu(int jiaodu) {
        this.jiaodu = jiaodu;
        invalidate();
    }
    /**
     * 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, jiaodu);
            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,圆角的弧度
     * @return Bitmap
     * @author caizhiming
     */
    private Bitmap getRoundBitmap(Bitmap bitmap, int roundPx) {
        Bitmap output = Bitmap.createBitmap(bitmap.getWidth(),
                bitmap.getHeight(), Bitmap.Config.ARGB_8888);
        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, roundPx, roundPx, paint);
        paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
        canvas.drawBitmap(bitmap, rect, rect, paint);
        return output;
    }
}

2、布局文件

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    >
    <com.chen.mydemo.XCRoundRectImageView
        android:id="@+id/roundRectImageView"
        android:layout_width="200dp"
        android:layout_height="200dp"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="50dp"
        android:src="@mipmap/ch"
        />
</RelativeLayout>

3、Java代码中使用

XCRoundRectImageView roundRectImageView = (XCRoundRectImageView) findViewById(R.id.roundRectImageView);
//以50度的角度为例
roundRectImageView.setJiaodu(50);