C#更改矩形类型列表中元素的值
C#更改矩形类型列表中元素的值
提问于 2012-04-15 10:58:37
我很难在列表中的特定索引中将元素的值设置为新值。
列表的类型是对象矩形，当我尝试更改列表中矩形的任何值时，我会得到以下错误。
不能将
属性或索引器'System.Drawing.Rectangle.Bottom‘分配给--它是只读的
我尝试将列表转换为数组，但仍然遇到相同的问题，即值是只读的。
基本上，该应用程序接收用户定义的矩形数，并绘制具有不同宽度和高度的矩形，但沿相同的基线绘制。试图实现的代码需要将这些矩形从底部向上垂直重新绘制，同时保持相同数量的矩形，并保持与以前创建的矩形相同的外部形状。
代码：
public void RotateRectangles(List<Rectangle> Rectangles, int startPositionX, int userInput, Graphics DrawingSurface)
{
Graphics RectangleGraphics = DrawingSurface;
try
{
// loop in reverse to compare one rectangle to all the other rectangles in the vector
for (int i = Rectangles.Count - 1; i > -1; --i)
{
bool mustChange = true;
for (int t = Rectangles.Count - 1; t > -1; --t)
{
// only compare if the current position in the vector A if different to the position in vector B.
if (i > t)
{
if (mustChange == true)
{
// If the top Y coordinate of RECT at Position i in vector A is bigger than Y coordinate
// at Position t in vector B
if (Rectangles[i].Top >= Rectangles[t].Top)
{
//adjusting points accordingly
Rectangles[i].Left = (Rectangles[t].Left);
Rectangles[t].Bottom = (Rectangles[i].Top);
}
else
{
// If the Y coordinate is not bigger, then we need to stop checking
mustChange = false;
}
}
}
}
}
// loop forward to compare one rectangle to all the other rectangles in the vector
for (int i = 0; i < Rectangles.Count; ++i)
{
bool forwardChange = true;
for (int t = 0; t < Rectangles.Count; ++t)
{
// If the top Y coordinate of RECT at Position i in vector A is bigger than Y coordinate at Position t
// in vector B AND the two rectangales touch
if (i < t && Rectangles[i].Top <= Rectangles[t].Bottom)
{
if (forwardChange == true)
{
// If the top Y coordinate of RECT at Position i in vector A is bigger than Y coordinate at Position t
// in vector B
if (Rectangles[i].Top > Rectangles[t].Top)
{
//adjusting points accordingly
Rectangles[i].Right = (Rectangles[t].Right);
Rectangles[t].Bottom = (Rectangles[i].Top);
}
else
{
// If the Y coordinate is not bigger, then we need to stop checking
forwardChange = false;
// Addjust the Y position of each rectangle so it does not overlap with the first drawing
for (int z = 0; z < Rectangles.Count; ++z)
{
Rectangles[z].Top = (250 - Rectangles[z].Top);
Rectangles[z].Bottom = (250 - Rectangles[z].Bottom);
}
}
}
}
}
}
for (int z = 0; z < Rectangles.Count; ++z)
{
Rectangle DrawRec = myRectangleClass.MyRectangle(Rectangles[z].Left, Rectangles[z].Top, Rectangles[z].Right, Rectangles[z].Bottom);
RectangleGraphics.DrawRectangle(Pen, DrawRec);
ReadWrite.writeOutput(Rectangles[z].Left, Rectangles[z].Top, Rectangles[z].Right, Rectangles[z].Bottom);
}
}
catch (Exception e)
{
}
}造成错误的部分是：
Rectangles[i].Left = (Rectangles[t].Left);
Rectangles[t].Bottom = (Rectangles[i].Top);
Rectangles[i].Right = (Rectangles[t].Right);
Rectangles[t].Bottom = (Rectangles[i].Top);
Rectangles[z].Top = (250 - Rectangles[z].Top);
Rectangles[z].Bottom = (250 - Rectangles[z].Bottom);请有人帮我一下，或者至少把我引向正确的方向。
回答 3
Stack Overflow用户
回答已采纳
发布于 2012-04-15 11:05:22
右、左、顶、底的属性是只读的。可以使用偏移和充气方法以及属性位置、大小、宽度和高度来调整矩形的位置和大小，也可以用新创建的矩形替换现有的矩形。
例如：
Rectangle ri = Rectangles[i];
Rectangle rt = Rectangles[t];
Rectangle[i] = new Rectangle( rt.Left, ri.Bottom, rt.Height, rt.Width );Stack Overflow用户
发布于 2012-04-15 13:20:43
问题不是矩形的值类型，而是List[]操作符返回一个新的值对象。
List<Rectangle> a;
a[4].X += 4; // does the same like the following code:
var r = a[4]
r.X += 4; // will change r, but not a[4] 因此，您需要将矩形值存储在列表中。
Stack Overflow用户
发布于 2012-04-15 11:05:24
Rectangles[i] = new Rectangle(Rectangles[t].Left, Rectangles[i].Top, Rectangles[i].Width, Rectangles[i].Height);将一个新矩形分配给所需的索引。
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/10161400
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