带底部边框的文本框 [英] TextBox with bottom border

问题描述

我想要带有下边框的 TextBox ，但是为 TextBox 绘制的图形在调整大小时会失真/损坏，因为 Color.Transparent 。

使用我发现的代码，我能够创建带下划线的TextBox（Drawn Rectangle with透明的顶部，左侧，右侧）。问题是当我调整窗体/窗口的大小时：当我调整到较小的尺寸时，再次调整大小以扩展它，绘制的图形失真。 ？任何修复该

下面是照片：第二张照片已被调整小，然后再返回到更大的尺寸。

以下是代码：

  [DllImport（user32）] 
 private static extern IntPtr GetWindowDC（IntPtr hwnd）; 
 struct RECT {
 public int left，top，right，bottom; 
} 
 struct NCCALSIZE_PARAMS {
 public RECT newWindow; 
 public RECT oldWindow; 
 public RECT clientWindow; 
 IntPtr windowPos; 
} 
 
 float clientPadding = 0; 
 int actualBorderWidth = 2; 
颜色borderColor = Color.Black; 
 protected override void WndProc（ref Message m）{
 //我们必须改变客户端的大小来为边界
腾出空间//如果没有的话，边界会有多厚。 
 if（m.Msg == 0x83）{// WM_NCCALCSIZE 
 if（m.WParam == IntPtr.Zero）{
 RECT rect =（RECT）Marshal.PtrToStructure（m.LParam ，typeof（RECT））; 
 rect.left + = 2; 
 rect.right  -  = 2; 
 rect.top + = 0; 
 rect.bottom  -  = 0; //（int）clientPadding; 
 Marshal.StructureToPtr（rect，m.LParam，false）; 
} else {
 NCCALSIZE_PARAMS rects =（NCCALSIZE_PARAMS）Marshal.PtrToStructure（m.LParam，typeof（NCCALSIZE_PARAMS））; 
 rects.newWindow.left + =（int）clientPadding; 
 rects.newWindow.right  -  =（int）clientPadding; 
 rects.newWindow.top + =（int）clientPadding; 
 rects.newWindow.bottom  -  = 2; 
 Marshal.StructureToPtr（rects，m.LParam，false）; 
} 
} 
如果（m.Msg == 0x85）{// WM_NCPAINT 
 IntPtr的WDC = GetWindowDC（手柄）; 
 using（Graphics g = Graphics.FromHdc（wDC））{
 ControlPaint.DrawBorder（g，new Rectangle（0，0，Size.Width，Size.Height），
 Color.Transparent ，1，ButtonBorderStyle.Solid，
 Color.Transparent，1，ButtonBorderStyle.Solid，
 Color.Transparent，1，ButtonBorderStyle.Solid，
 borderColor，actualBorderWidth，ButtonBorderStyle.Solid）; 
} 
 return; 
} 
 base.WndProc（ref m）; 
 
  

编辑：

我已经找到问题，这是因为 Color.Transparent 我通过将其更改为Color.White来修复它，因为我有一个白色背景。但是，情况并非总是如此，在使用Color.Transparent时，如何防止闪烁/撕裂？

解决方案

要使用底部边框创建 TextBox ，我可以提供的最简单的解决方法是将1像素高度的标签（或其他控件）到文本框的底部：

 使用System.Drawing中; 
使用System.Windows.Forms; 
 public class MyTextBox：TextBox 
 {
 public MyTextBox（）
 {
 BorderStyle = System.Windows.Forms.BorderStyle.None; 
 AutoSize = false; //允许你改变高度以使底部填充
 Controls.Add（new Label（）
 {Height = 1，Dock = DockStyle.Bottom，BackColor = Color.Black}）; 
} 
} 
  

I want to have TextBox with bottom border but Graphics drawn for TextBox is distorted/broken on resize because of Color.Transparent.

Using an code I found, I was able to create a underlined TextBox (Drawn Rectangle with tranparent top, left, right). The problem is when I resize the form/window: when I resize it to smaller, then resize again to expand it, the graphics drawn is distorted. Any fix for this?

Here are photos: The second photo has been already resized smaller, then back to a larger size.

Here's the code:

[DllImport("user32")]
    private static extern IntPtr GetWindowDC(IntPtr hwnd);
    struct RECT {
        public int left, top, right, bottom;
    }
    struct NCCALSIZE_PARAMS {
        public RECT newWindow;
        public RECT oldWindow;
        public RECT clientWindow;
        IntPtr windowPos;
    }

    float clientPadding = 0;
    int actualBorderWidth = 2;
    Color borderColor = Color.Black;
    protected override void WndProc(ref Message m) {
        //We have to change the clientsize to make room for borders
        //if not, the border is limited in how thick it is.
        if (m.Msg == 0x83) { //WM_NCCALCSIZE 
            if (m.WParam == IntPtr.Zero) {
                RECT rect = (RECT)Marshal.PtrToStructure(m.LParam, typeof(RECT));
                rect.left += 2;
                rect.right -= 2;
                rect.top += 0;
                rect.bottom -= 0;// (int)clientPadding;
                Marshal.StructureToPtr(rect, m.LParam, false);
            } else {
                NCCALSIZE_PARAMS rects = (NCCALSIZE_PARAMS)Marshal.PtrToStructure(m.LParam, typeof(NCCALSIZE_PARAMS));
                rects.newWindow.left += (int)clientPadding;
                rects.newWindow.right -= (int)clientPadding;
                rects.newWindow.top += (int)clientPadding;
                rects.newWindow.bottom -= 2;
                Marshal.StructureToPtr(rects, m.LParam, false);
            }
        }
        if (m.Msg == 0x85) {//WM_NCPAINT    
            IntPtr wDC = GetWindowDC(Handle);
            using (Graphics g = Graphics.FromHdc(wDC)) {
                ControlPaint.DrawBorder(g, new Rectangle(0, 0, Size.Width, Size.Height),
                    Color.Transparent, 1, ButtonBorderStyle.Solid,
                    Color.Transparent, 1, ButtonBorderStyle.Solid,
                    Color.Transparent, 1, ButtonBorderStyle.Solid,
                    borderColor, actualBorderWidth, ButtonBorderStyle.Solid);
            }
            return;
        }
        base.WndProc(ref m);
    }

EDIT :

I already found the issue, it's because of the Color.Transparent I fixed it by changing it to Color.White, since I have a white background. But then, that would not always be the case, how would I prevent that "Flickering/Tearing" while using Color.Transparent?

解决方案

To have a TextBox with bottom border, The most simple workaround that I can offer is docking a 1 pixel height lable (or other control) to bottom of the TextBox:

using System.Drawing;
using System.Windows.Forms;
public class MyTextBox : TextBox
{
    public MyTextBox()
    {
        BorderStyle = System.Windows.Forms.BorderStyle.None;
        AutoSize = false; //Allows you to change height to have bottom padding
        Controls.Add(new Label()
                    { Height = 1, Dock = DockStyle.Bottom, BackColor = Color.Black });
    }
}

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