如何将rectenge从一个事件函数传递给另一个事件函数？
问题描述：
我想将矩形从一个函数传递给第二个函数
由于某种原因，rectangel读取事件函数为null
我该怎么做？
I want to to pass a rectangle from one function to a second function
For some reason the rectangel read to the event function as null
How can I do this?
private Point startpoint;
private Rectangle rect;
private void canvas1_MouseRightButtonDown(object sender, MouseButtonEventArgs e)
{
startpoint = Mouse.GetPosition(canvas1);
// the rectengle that i creat and i what to pass him to the canvas1_MouseMove Event function
Rectangle rect = new Rectangle();
rect.Stroke = Brushes.Black;
rect.StrokeThickness = 1;
canvas1.Children.Add(rect);
}
private void canvas1_MouseMove(object sender, MouseEventArgs e)
{
//to here i want to pass the rectangle
// when i debug the code the rect value is null!
// so i cant control his Properties
rect.Width = 5;// her i got excsption
//"Object reference not set to an instance of an object."
rect.Height = 6;
}
答
这是最简单的方法。
This is the simplest way to do it.
private Point startpoint;
// "rect" is declared at Class level so both canvas1_MouseRightButtonDown and canvas1_MouseMove can access
private Rectangle rect;
private void canvas1_MouseRightButtonDown(object sender, MouseButtonEventArgs e)
{
startpoint = Mouse.GetPosition(canvas1);
rect = new Rectangle(); // Changed declaration and assignment to just assignment
rect.Stroke = Brushes.Black;
rect.StrokeThickness = 1;
canvas1.Children.Add(rect);
}
private void canvas1_MouseMove(object sender, MouseEventArgs e)
{
if (rect != null) // Check to be sure rect is OK. Mouse will move before right-click.
{
rect.Width = 5;
rect.Height = 6;
}
}