英语作文 ：投诉信 急急急！！！

Posted 2023-04-18

你买了M牌的电脑，使用时间不长，却发现总是自动关机，你对此表示不满，向经理写投诉信，要求退货。
内容：自己买产品的时间及产品描述：产品的故障：自己的不满及退货意愿
120字

To: ABC computer company
Attention: manager, sales department

Re: request for refund of computer

Dear Sir,

I bought a M brand computer from your store on 30th Sep 2009 at 6pm. It is a laptop computer, model 15TL50, with dual core processor, 2GB memory, 500 GB harddisk, and it is loaded with Window 7. Since the computer has been bought, I hardly use it. However, when I use it for more than 1 hour, it always turns off by itself without giving any indication. I have called your company hotline for help but they cannot offer me any solution. I am a student and I need the computer to work on a school project very soon. The condition of the computer is totally unacceptable to me. I am writing this letter to you, to request for a refund of the computer. This will enable me to get another one to work on the school project. Please grant me my request, otherwise I will approach the Consumer Association for assistance.

Pleae find attahced a copy of the sale receipt, and records of fault report for reference.

Please kindly reply as soon as possible.

Thank you.

Yours sincerely,

xxx 参考技术A Dear
xxx,
I
bought
one
xxx
mobile
phone
from
your
site
on
June
1st.And
you
promised
that
the
phone
was
the
best
in
your
shop
with
the
latest
functions.You
also
guaranteed
that
it
had
one
year
warranty.But
you
know
what?The
phone
didn't
work
one
week
later
without
any
damages.
I
don't
want
to
complain
too
much
here.What
I
want
is
a
new
replacement.
Wait
for
your
quick
and
proper
response.
Thanks
and
regards,
xxx

Qt 绘图问题，急急急！

请问如何在一个QWidget子类原有区域画一条直线而不擦除该区域。好实现么？

参考技术A

为了能够使用Qt开发图形绘制软件，首先应该掌握Qt的坐标系统。在Qt中，通过QPainter类来控制它的坐标系统。连同QPaintDevice类与QPaintEngine类，QPainter类构成了Qt绘图系统的基础。其中，QPainter用于执行绘图的操作；QPaintDevice是对一块二维空间的抽象，在这块空间上，我们可以使用QPainter进行图形的绘制；QPaintEngine提供了在不同的设备上进行绘图的接口。

QPaintDevice类是能够进行绘图的对象的基类，QWidget，QPixmap，QPicture，QImage，以及QPrinter类继承了QPaintEngine类的绘图能力。绘图设备的缺省坐标系统是以左上角作为原点，x坐标向右递增，y坐标向下递增。单位对于不同的设备是不同的，在基于像素的设备上，以一个像素作为缺省单位，而在打印机上，以1/72英寸作为缺省单位。

在编写图形绘制软件时，我们需要进行逻辑坐标与物理坐标之间的转换，这部分功能由QPainter的转换矩阵，视口，以及窗口来实现。缺省情况下，逻辑坐标与物理坐标是一致的。QPainter也支持平移与旋转这样的坐标变换。

图元的尺寸（宽度与高度）总是对应于它的数学模型，并且会忽略它所使用的笔的宽度。下图是通过两个点来实现矩形和直线的例子，用到的代码为：

追问

大哥，你不累吗？

追答

发错了吗？

参考技术B 用双缓存机制。本回答被提问者采纳 参考技术C 不很明白你的意思，在QWidget的子类上画图，如果你事先不擦除，它就是在上面覆盖的呀