动态数据显示 - WPF - 需要将文本添加到画布 - C#
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Dynamic Data Display - WPF - Need to add text to canvas - C#
提问by Harsha
I am using the dynamic data display WPF chart. I have a requirement to display a label next to every point on the curves plotted on the chart.
我正在使用动态数据显示 WPF 图表。我需要在图表上绘制的曲线上的每个点旁边显示一个标签。
The exact functionality is as follows:
具体功能如下：
Every curve has a an object that holds its data and a description that inculdes color, marker shape etc. It also tell me whether the labels must be visible for that particular curve.
There is also an option using a checkbox to hide/show the labels for all points on all the curves on the plot.
There is a third option where a user can left click on the marker and see a label next to it.
每条曲线都有一个保存其数据的对象和一个包含颜色、标记形状等的描述。它还告诉我该特定曲线的标签是否必须可见。
还有一个选项使用复选框来隐藏/显示绘图上所有曲线上所有点的标签。
还有第三个选项，用户可以左键单击标记并查看其旁边的标签。
Now, I previously implemented it by adding labels along with the ElementMarkerPointGraph for each point and setting the visibility of the labels. I know there is a massive performance hit with this approach.
现在，我之前通过为每个点添加标签和 ElementMarkerPointGraph 并设置标签的可见性来实现它。我知道这种方法会对性能造成巨大影响。
I am now looking to create a solution where I can render text directly to the canvas at a location that I provide. I also need help with the removing the text from the canvas.
我现在正在寻找一个解决方案，我可以在我提供的位置将文本直接渲染到画布上。我还需要帮助从画布中删除文本。
Is there a way of adding text natively to the canvas? What is the most efficient way to do so?
有没有办法将文本本地添加到画布？这样做的最有效方法是什么？
EDIT: I need to move the text around as the plotter zooms. I already know when the plotter zooms, I need to be able to move the text to the appropriate location.
编辑：我需要在绘图仪缩放时四处移动文本。我已经知道绘图仪何时缩放，我需要能够将文本移动到适当的位置。
回答by hridya pv
I'm not sure whether this will give you the zooming purpose but the code below can be used to add text inside a canvas..I got it from a site while googling.
我不确定这是否会给你缩放目的，但下面的代码可用于在画布中添加文本......我在谷歌搜索时从网站上得到它。
private void Text(double x, double y, string text, Color color)
{
TextBlock textBlock = new TextBlock();
textBlock.Text = text;
textBlock.Foreground = new SolidColorBrush(color);
Canvas.SetLeft(textBlock, x);
Canvas.SetTop(textBlock, y);
canvasObj.Children.Add(textBlock);
}
回答by Harsha
OK. My exact implementation can't be put up here. But I can provide some idea of how to do it.
好的。我的具体实现不能放在这里。但我可以提供一些关于如何做到这一点的想法。
So create a simple user control that derives from Canvas.
因此，创建一个源自 Canvas 的简单用户控件。
class CustomCanvas : Canvas
{
protected override void OnRender(DrawingContext dc)
{
FormattedText someFormattedText = new FormattedText(someText, System.Globalization.CultureInfo.CurrentCulture, FlowDirection.LeftToRight,
someTypeFace, someFontSize, someColor);
dc.DrawText(someFormattedText, new Point(15, 15));
}
}
You can seal the class, if you do not want it subclassed/overriden further.
如果您不希望它进一步被子类化/覆盖，您可以密封该类。
That's about it. You can check out the other methods available with the drawing context to do some other stuff. :)
就是这样。您可以查看绘图上下文中可用的其他方法来执行其他一些操作。:)
回答by Harsha
I figured it out myself. I'll be overriding the OnRender method to handle this. I can draw text using the drawing context.
我自己想通了。我将覆盖 OnRender 方法来处理这个问题。我可以使用绘图上下文绘制文本。
