Android 自定义View 开发 入门与实践5 Bitmap

10.1 Bitmap

Bitmap.ARGB_8888  最好啥也有 ,内存大

Bitmap.ARGB_565  没有透明需求就用这个,内存 小一半

创建:

BitmapFactory:

Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.dog);

裁剪

原图

要个狗鼻子

   Bitmap bitmapSrc = BitmapFactory.decodeResource(getResources(), R.drawable.dog);
        //裁剪图片的一部分  从/2这个点开始  截取一个 宽高为原图/3的
        Bitmap bitmapCut = Bitmap.createBitmap(bitmapSrc, bitmapSrc.getWidth() / 2, bitmapSrc.getHeight() / 2,
                bitmapSrc.getWidth() / 3, bitmapSrc.getHeight() / 3);

        mViewBinding.iv.setImageBitmap(bitmapCut);

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图片缩放

 Bitmap bitmapSrc = BitmapFactory.decodeResource(getResources(), R.drawable.dog);
        Matrix matrix = new Matrix();

        matrix.setScale(2, 1);
        //裁剪图片的一部分  从/2这个点开始  截取一个 宽高为原图/3的
        Bitmap bitmapCut = Bitmap.createBitmap(bitmapSrc, bitmapSrc.getWidth() / 2, bitmapSrc.getHeight() / 2,
                bitmapSrc.getWidth() / 3, bitmapSrc.getHeight() / 3, matrix, true);

        mViewBinding.iv.setImageBitmap(bitmapCut);

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指定色彩创建图像

简单的纯色

 Bitmap bitmap = Bitmap.createBitmap(300, 300, Bitmap.Config.ARGB_8888);
        bitmap.eraseColor(Color.BLUE);
        mViewBinding.iv.setImageBitmap(bitmap);

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                                                                                                                                                                                                                      加上模糊

 

   Bitmap bitmap = Bitmap.createBitmap(300, 300, Bitmap.Config.ARGB_8888);
        bitmap.eraseColor(Color.WHITE);
        Glide.with(this)
                .load(bitmap)
                // radius 最大25  sampling 默认1
                .apply(RequestOptions.bitmapTransform(new BlurTransformation(20, 10)))
                .into(mViewBinding.iv);

没有看出那种毛玻璃的效果

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extractAlpha()

            

  Bitmap src = BitmapFactory.decodeResource(getResources(), R.drawable.bikabika);
        Bitmap bitmap = Bitmap.createBitmap(src.getWidth(), src.getHeight(), Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(bitmap);
        Paint paint = new Paint();
        paint.setColor(Color.GRAY);
        canvas.drawBitmap(src.extractAlpha(), 0, 0, paint);

        mViewBinding.iv.setImageBitmap(bitmap);

        src.recycle();

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发光

 Bitmap src = BitmapFactory.decodeResource(getResources(), R.drawable.bikabika);
        //获取AlphaPaint
        Paint alphaPaint = new Paint();
        BlurMaskFilter blurMaskFilter = new BlurMaskFilter(20, BlurMaskFilter.Blur.NORMAL);
        alphaPaint.setMaskFilter(blurMaskFilter);

        int[] offserXY = new int[2];
        Bitmap alphaBitmap = src.extractAlpha(alphaPaint, offserXY);

        //创建Bitmap
        Bitmap bitmap = Bitmap.createBitmap(alphaBitmap.getWidth(), alphaBitmap.getHeight(), Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(bitmap);

        Paint mPaint = new Paint();
        mPaint.setColor(Color.GRAY);
        canvas.drawBitmap(alphaBitmap, 0, 0, mPaint);
        //绘制源图像
        canvas.drawBitmap(src, -offserXY[0], -offserXY[1], null);
        //设置图像并回收没用的图像资源
        mViewBinding.iv.setImageBitmap(bitmap);

        src.recycle();

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回收图片内存的写法:

if(bmp != null  && bmp.isRecycler()){

bmp.recycle();

bmp = null;

system.gc();

}

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图片水印效果

public Bitmap creatWaterBitmap(Bitmap src, Bitmap watermark) {
        if (src == null) {
            return null;
        }
        int w = src.getWidth();
        int h = src.getHeight();

        int ww = watermark.getWidth();
        int wh = watermark.getHeight();


        //创建空白图像
        //创建一个新的和src长度,宽度一样的bitmap
        Bitmap newBitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(newBitmap);
        //画原图  从0,0 坐标画入
        canvas.drawBitmap(src, 0, 0, null);

        //在src的右下角画入水印
        canvas.drawBitmap(watermark, w - ww + 6, h - wh + 6, null);
        return newBitmap;
    }

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