C#:重写 ProgressBar 上的 OnPaint 不起作用?
我认为创建一个在其自身上绘制一些文本的 ProgressBar
应该非常容易。但是,我不太确定这里发生了什么...
我添加了以下两个覆盖:
protected override void OnPaintBackground(PaintEventArgs pevent)
{
base.OnPaintBackground(pevent);
var flags = TextFormatFlags.VerticalCenter | TextFormatFlags.HorizontalCenter | TextFormatFlags.SingleLine | TextFormatFlags.WordEllipsis;
TextRenderer.DrawText(pevent.Graphics, "Hello", Font, Bounds, Color.Black, flags);
}
protected override void OnPaint(PaintEventArgs e)
{
base.OnPaint(e);
var flags = TextFormatFlags.VerticalCenter | TextFormatFlags.HorizontalCenter | TextFormatFlags.SingleLine | TextFormatFlags.WordEllipsis;
TextRenderer.DrawText(e.Graphics, "Hello", Font, Bounds, Color.Black, flags);
}
但是,我没有收到任何文本,并且这些方法似乎没有被调用。这是怎么回事?
更新:感谢到目前为止的两个答案,我已经通过使用 SetStyle(ControlStyles.UserPaint, true)
实际调用了 OnPaint
,并且我已经通过发送 new Rectangle(0, 0, Width, Height)
而不是 Bounds
来在正确的位置绘制文本。
我现在确实收到了文本,但是 ProgressBar
消失了……重点是将文本放在 ProgressBar
之上。知道我该如何解决这个问题吗?
Was thinking it should be pretty easy to create a ProgressBar
that drew some text upon itself. However, I am not quite sure what is happening here...
I added the following two overrides:
protected override void OnPaintBackground(PaintEventArgs pevent)
{
base.OnPaintBackground(pevent);
var flags = TextFormatFlags.VerticalCenter | TextFormatFlags.HorizontalCenter | TextFormatFlags.SingleLine | TextFormatFlags.WordEllipsis;
TextRenderer.DrawText(pevent.Graphics, "Hello", Font, Bounds, Color.Black, flags);
}
protected override void OnPaint(PaintEventArgs e)
{
base.OnPaint(e);
var flags = TextFormatFlags.VerticalCenter | TextFormatFlags.HorizontalCenter | TextFormatFlags.SingleLine | TextFormatFlags.WordEllipsis;
TextRenderer.DrawText(e.Graphics, "Hello", Font, Bounds, Color.Black, flags);
}
However, I get no text, and the methods doesn't even seem to be called. What is going on here?
Update: Thanks to the two answers so far, I have gotten it to actually call the OnPaint
by using SetStyle(ControlStyles.UserPaint, true)
, and I have gotten it to draw the text in the right place by sending in new Rectangle(0, 0, Width, Height)
instead of Bounds
.
I do get text now, but the ProgressBar
is gone... and the point was kind of to have the text on top of the ProgressBar
. Any idea how I can solve this?
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看来,如果您调用“SetStyle(ControlStyles.UserPaint, true)”,则无法调用为 ProgressBar 实现的标准 OnPaint 方法(使用 base.OnPaint(e) 根本不起作用)。最奇怪的是,即使你实际上创建了一个 UserControl,并尝试在进度条上绘制一些文本......它似乎也不起作用......当然你可以在它上面放置一个标签。 ..但我认为这实际上并不是您想要实现的目标。
好吧,看来我已经成功解决了这个问题。虽然有点复杂。首先,您需要创建一个透明的 Label 控件。代码如下:
第二件事是创建 UserControl,在其上放置一个 ProgressBar (Dock=Fill) - 这将是我们将使用的控件,而不是标准的 ProgressBar。代码:
ProgressBar 的奇怪之处在于它“过度绘制”了放置在其上的控件,因此需要将进度条发送到后面,并将标签控件带到后面正面。目前我还没有找到更优雅的解决方案。
这有效,标签显示在进度条上,标签控件的背景是透明的,所以我认为它看起来像您想要的样子:)
如果您愿意,我可以分享我的示例代码...
哦,顺便说一句。我提到的 ProgressBar 控件的这种奇怪行为导致无法使用 Graphics 对象在派生自 ProgressBar 的控件上绘制任何内容。文本(或使用 Graphics 对象绘制的任何内容)实际上正在绘制,但是......在 ProgressBar 控件后面(如果您仔细观察,您可能会看到当 ProgressBar 的值发生变化时,该用户绘制的东西会闪烁,并且需要重新粉刷自己)。
It seems that if you call 'SetStyle(ControlStyles.UserPaint, true)' the standard OnPaint method implemented for ProgressBar could not be invoked (using base.OnPaint(e) does not work at all). The strangest thing is that even if you actually create a UserControl, and try to draw draw some text upon the progress bar... it doesn't seem to work too... Of course you may place a Label on top of it... but I suppose it is not actually what you wanted to achieve.
Ok, it seems that I have managed to solve this problem. It is although a little complicated. First you need to create a transparent Label control. Code below:
Second thing is to create UserControl, place a ProgressBar on it (Dock=Fill) - this will be the control that we will use instead of standard ProgressBar. Code:
The strange thing with ProgressBar is that it 'overdraws' the controls that are being placed upon it, so it is needed to send progressbar to back, and bring the label control to front. I haven't found more elegant solution at the moment.
This works, the label is being displayed on the progressbar, the background of the label control is transparent, so I think it looks like you wanted it to look :)
I may share my sample code if you wish...
Oh, btw. this strange behaviour of ProgressBar control that I have mentioned, is responsible for that it is not possible to use Graphics object to draw anything on a control that derives from ProgressBar. The text (or whatever you draw using Graphics object) is actually being drawn but... behind the ProgressBar control (if you take a closer look, you may see this user drawn things flickering when the Value of the ProgressBar changes and it need to repaint itself).
这是另一个解决方案以及其他人的建议。我对进度条控件进行了子类化以使其工作。为此,我混合并匹配了来自不同地方的代码。油漆事件可以更干净,但那是你要做的;)
Here's another solution along with other people's suggestions. I subclassed the progressbar control to make this work. I mixed and matched codes from various places for this. The paint event could be cleaner, but that's for you to do ;)
您可以重写 WndProc 并捕获 WmPaint 消息。
下面的示例在其中心绘制进度条的 Text 属性。
You could override WndProc and catch the WmPaint message.
The example below paints the Text property of the progressbar in its center.
我需要自己做这件事,我想我会发布我的解决方案的简化示例,因为我找不到任何示例。如果您使用 ProgressBarRenderer 类,实际上非常简单:
I needed to do this myself and I thought that I would post a simplified example of my solution since I could not find any examples. It is actually pretty simple if you use the ProgressBarRenderer class:
您的问题是您将
Bounds
作为 Rectangle 参数传递。 Bounds 包含控件的高度和宽度,这是您想要的,但它还包含控件相对于父窗体的 Top 和 Left 属性,因此您的“Hello”在控件上偏移了多少控件在其父窗体上偏移。将
Bounds
替换为new Rectangle(0, 0, this.Width, this.Height)
,您应该会看到“Hello”。Your problem is that you're passing in
Bounds
as your Rectangle parameter. Bounds contains the Height and Width of your control, which is what you want, but it also contains the Top and Left properties of your control, relative to the parent form, so your "Hello" is being offset on the control by however much your control is offset on its parent form.Replace
Bounds
withnew Rectangle(0, 0, this.Width, this.Height)
and you should see your "Hello".