使用BitmapShader-实现圆角和圆形Bitmap

导读

有时候，我们需求上需要实现圆角图片的展示。有很多种处理思路。但所有思路无非就是把Bitmap修饰成圆角或者圆形。然后显示出来。
BitmapShader就帮我们快速的处理了。
接下来介绍的这种方式，充分体现了Drawable First的思想。

Drawable First

自定义Drawable，相比View来说，Drawable属于轻量级的、使用也很简单。以后自定义实现一个效果的时候，可以改变View first的思想，尝试下Drawable first。

先上效果图

image.png image.png

1.圆角

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.Shader.TileMode;
import android.graphics.drawable.Drawable;

public class CircleImageDrawable extends Drawable
{

    private Paint mPaint;
    private int mWidth;
    private Bitmap mBitmap ; 

    public CircleImageDrawable(Bitmap bitmap)
    {
        mBitmap = bitmap ; 
        BitmapShader bitmapShader = new BitmapShader(bitmap, TileMode.CLAMP,
                TileMode.CLAMP);
        mPaint = new Paint();
        mPaint.setAntiAlias(true);
        mPaint.setShader(bitmapShader);
        mWidth = Math.min(mBitmap.getWidth(), mBitmap.getHeight());
    }

    @Override
    public void draw(Canvas canvas)
    {
        canvas.drawCircle(mWidth / 2, mWidth / 2, mWidth / 2, mPaint);
    }

    @Override
    public int getIntrinsicWidth()
    {
        return mWidth;
    }

    @Override
    public int getIntrinsicHeight()
    {
        return mWidth;
    }

    @Override
    public void setAlpha(int alpha)
    {
        mPaint.setAlpha(alpha);
    }

    @Override
    public void setColorFilter(ColorFilter cf)
    {
        mPaint.setColorFilter(cf);
    }

    @Override
    public int getOpacity()
    {
        return PixelFormat.TRANSLUCENT;
    }

}

使用方法：

Bitmap bitmap = BitmapFactory.decodeResource(getResources(),
                R.drawable.mv);
ImageView iv = (ImageView) findViewById(R.id.id_one);
iv.setImageDrawable(new CircleImageDrawable(bitmap));
iv = (ImageView) findViewById(R.id.id_two);
iv.setImageDrawable(new CircleImageDrawable(bitmap))

把Bitmap作为参数传给CircleImageDrawable，就好了！

2.圆形

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.RectF;
import android.graphics.Shader.TileMode;
import android.graphics.drawable.Drawable;

public class RoundImageDrawable extends Drawable
{

    private Paint mPaint;
    private Bitmap mBitmap;

    private RectF rectF;

    public RoundImageDrawable(Bitmap bitmap)
    {
        mBitmap = bitmap;
        BitmapShader bitmapShader = new BitmapShader(bitmap, TileMode.CLAMP,
                TileMode.CLAMP);
        mPaint = new Paint();
        mPaint.setAntiAlias(true);
        mPaint.setShader(bitmapShader);
    }

    @Override
    public void setBounds(int left, int top, int right, int bottom)
    {
        super.setBounds(left, top, right, bottom);
        rectF = new RectF(left, top, right, bottom);
    }

    @Override
    public void draw(Canvas canvas)
    {
        canvas.drawRoundRect(rectF, 30, 30, mPaint);
    }

    @Override
    public int getIntrinsicWidth()
    {
        return mBitmap.getWidth();
    }

    @Override
    public int getIntrinsicHeight()
    {
        return mBitmap.getHeight();
    }

    @Override
    public void setAlpha(int alpha)
    {
        mPaint.setAlpha(alpha);
    }

    @Override
    public void setColorFilter(ColorFilter cf)
    {
        mPaint.setColorFilter(cf);
    }

    @Override
    public int getOpacity()
    {
        return PixelFormat.TRANSLUCENT;
    }

}

使用方法：

Bitmap bitmap = BitmapFactory.decodeResource(getResources(),
                R.drawable.mv);
ImageView iv = (ImageView) findViewById(R.id.id_one);
iv.setImageDrawable(new RoundImageDrawable(bitmap));
iv = (ImageView) findViewById(R.id.id_two);
iv.setImageDrawable(new RoundImageDrawable(bitmap));

源码参考我的github地址

参考文章

http://blog.csdn.net/lmj623565791/article/details/43752383