Android canvas与drawBitmap()

1.Bitmap准确缩放到制定大小尺寸

//mBitmap(要缩放的Bitmap图片)，Width，Height（自定义值，缩放到指定大小宽高）
Bitmap scaledBitmap = Bitmap.createScaledBitmap(mBitmap, 100, 100, true);

2.在canvas指定位置上放图标

 Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.mipmap.icon_un);
                        Bitmap scaledBitmap = Bitmap.createScaledBitmap(bitmap, 13, 13, true);
                        canvas.drawBitmap(scaledBitmap, x, y, textbgpaint);

效果如图：

 canvas.drawRect(x , y , x + text_width , y + text_height, textbgpaint);
                       

3.Rect描述矩形，是一个常用的绘画工具类。其中，四个参数如图所示定义。

4.人脸的四角边框

            /**
             * 左上角的竖线
             */
            canvas.drawLine(left, top, left, top + scaleLine, boxPaints[colorID]);
            /**
             * 左上角的横线
             */
            canvas.drawLine(left, top, left + scaleLine, top, boxPaints[colorID]);
            /**
             * 右上角的竖线
             */
            canvas.drawLine(right, top, right - scaleLine, top, boxPaints[colorID]);
            /**
             * 右上角的横线
             */
            canvas.drawLine(right, top, right, top + scaleLine, boxPaints[colorID]);
            /**
             * 左下角的竖线
             */
            canvas.drawLine(left, bottom, left, bottom - scaleLine, boxPaints[colorID]);
            /**
             * 左下角的横线
             */
            canvas.drawLine(left, bottom, left + scaleLine, bottom, boxPaints[colorID]);
            /**
             * 右下角的竖线
             */
            canvas.drawLine(right, bottom, right, bottom - scaleLine, boxPaints[colorID]);
            /**
             * 右下角的横线
             */
            canvas.drawLine(right, bottom, right - scaleLine, bottom, boxPaints[colorID]);