2018-03-18 图片处理(二)----图片缩放

笔记如下

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如图
2018-03-18_085026.png

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• 实现步骤:
  1.首先动态获取图片
  2.画图片

1.准备画纸(大小参照原图)

Bitmap copyBitmap = Bitmap.createBitmap(srcBitmap.getWidth(),srcBitmap.getHeight(),srcBitmap.getConfig());

2.准备画板,将画纸放到画板上

Canvas canvas = new Canvas(copyBitmap);

3.准备画笔

Paint paint = new Paint();

4.按照一定规则,矩阵规则,缩放,位移规则在这里

Matrix matrix = new Matrix();
//缩放一半
matrix.setScale(0.5f,0.5f);

5.按照规则将图像画到画纸上

canvas.drawBitmap(srcBitmap,matrix,paint);

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完整源码:按钮的点击

    public void opts(View v){

        String path = "storage/emulated/0/6.jpg";
        Bitmap srcBitmap = BitmapFactory.decodeFile(path);
        iv_src.setImageBitmap(srcBitmap);

        //1.准备画纸(大小参照原图)
        Bitmap copyBitmap = Bitmap.createBitmap(srcBitmap.getWidth(),srcBitmap.getHeight(),srcBitmap.getConfig());

        //2.准备画板,将画纸放到画板上
        Canvas canvas = new Canvas(copyBitmap);

        //3.准备画笔
        Paint paint = new Paint();

        //4.按照一定规则,矩阵规则,缩放,位移规则在这里
        Matrix matrix = new Matrix();

        matrix.setScale(0.5f,0.5f);


        //5.按照规则将图像画到画纸上
        canvas.drawBitmap(srcBitmap,matrix,paint);
        iv_dest.setImageBitmap(copyBitmap);

    }