如何更改组合框下拉按钮的颜色

Posted 2023-04-11

【中文标题】如何更改组合框下拉按钮的颜色

【英文标题】：How to change the ComboBox dropdown button color

【发布时间】：2021-01-31 06:05:13

【问题描述】：

如何更改滑动按钮的颜色？ 不是边框颜色，也不是幻灯片项目颜色。

我已经更改了幻灯片项目的颜色

有什么办法可以改变颜色吗？

【问题讨论】：

***.com/questions/6468024/…

这不是我的麻烦。我想改变▾这个按钮的背景颜色

也许在这个线程上为自定义控件添加一个标签？ =)

【参考方案1】：

Flat ComboBox - 更改边框颜色和下拉按钮颜色

您需要自己处理WM_PAINT 并绘制边框和下拉矩形。这就是 .Net Framework 内部 ComboBox.FlatComboAdapter 类的工作方式。

在这篇文章中，我创建了一个FlatComboBox，它以平面样式绘制边框和下拉菜单，具有以下附加属性：

BorderColor：用于边框和下拉箭头 ButtonColor：用于下拉区域颜色。

代码如下：

using System;
using System.ComponentModel;
using System.Drawing;
using System.Runtime.InteropServices;
using System.Windows.Forms;
public class FlatComboBox : ComboBox

    private Color borderColor = Color.Gray;
    [DefaultValue(typeof(Color), "Gray")]
    public Color BorderColor
    
        get  return borderColor; 
        set
        
            if (borderColor != value)
            
                borderColor = value;
                Invalidate();
            
        
    
    private Color buttonColor = Color.LightGray;
    [DefaultValue(typeof(Color), "LightGray")]
    public Color ButtonColor
    
        get  return buttonColor; 
        set
        
            if (buttonColor != value)
            
                buttonColor = value;
                Invalidate();
            
        
    
    protected override void WndProc(ref Message m)
    
        if (m.Msg == WM_PAINT && DropDownStyle != ComboBoxStyle.Simple)
        
            var clientRect = ClientRectangle;
            var dropDownButtonWidth = SystemInformation.HorizontalScrollBarArrowWidth;
            var outerBorder = new Rectangle(clientRect.Location,
                new Size(clientRect.Width - 1, clientRect.Height - 1));
            var innerBorder = new Rectangle(outerBorder.X + 1, outerBorder.Y + 1,
                outerBorder.Width - dropDownButtonWidth - 2, outerBorder.Height - 2);
            var innerInnerBorder = new Rectangle(innerBorder.X + 1, innerBorder.Y + 1,
                innerBorder.Width - 2, innerBorder.Height - 2);
            var dropDownRect = new Rectangle(innerBorder.Right + 1, innerBorder.Y,
                dropDownButtonWidth, innerBorder.Height + 1);
            if (RightToLeft == RightToLeft.Yes)
            
                innerBorder.X = clientRect.Width - innerBorder.Right;
                innerInnerBorder.X = clientRect.Width - innerInnerBorder.Right;
                dropDownRect.X = clientRect.Width - dropDownRect.Right;
                dropDownRect.Width += 1;
            
            var innerBorderColor = Enabled ? BackColor : SystemColors.Control;
            var outerBorderColor = Enabled ? BorderColor : SystemColors.ControlDark;
            var buttonColor = Enabled ? ButtonColor : SystemColors.Control;
            var middle = new Point(dropDownRect.Left + dropDownRect.Width / 2,
                dropDownRect.Top + dropDownRect.Height / 2);
            var arrow = new Point[]
            
                new Point(middle.X - 3, middle.Y - 2),
                new Point(middle.X + 4, middle.Y - 2),
                new Point(middle.X, middle.Y + 2)
            ;
            var ps = new PAINTSTRUCT();
            bool shoulEndPaint = false;
            IntPtr dc;
            if (m.WParam == IntPtr.Zero)
            
                dc = BeginPaint(Handle, ref ps);
                m.WParam = dc;
                shoulEndPaint = true;
            
            else
            
                dc = m.WParam;
            
            var rgn = CreateRectRgn(innerInnerBorder.Left, innerInnerBorder.Top, 
                innerInnerBorder.Right, innerInnerBorder.Bottom);
            SelectClipRgn(dc, rgn);
            DefWndProc(ref m);
            DeleteObject(rgn);
            rgn = CreateRectRgn(clientRect.Left, clientRect.Top, 
                clientRect.Right, clientRect.Bottom);
            SelectClipRgn(dc, rgn);
            using (var g = Graphics.FromHdc(dc))
            
                using (var b = new SolidBrush(buttonColor))
                
                    g.FillRectangle(b, dropDownRect);
                
                using (var b = new SolidBrush(outerBorderColor))
                
                    g.FillPolygon(b, arrow);
                
                using (var p = new Pen(innerBorderColor))
                
                    g.DrawRectangle(p, innerBorder);
                    g.DrawRectangle(p, innerInnerBorder);
                
                                    using (var p = new Pen(outerBorderColor))
                
                    g.DrawRectangle(p, outerBorder);
                
            
            if (shoulEndPaint)
                EndPaint(Handle, ref ps);
            DeleteObject(rgn);
        
        else
            base.WndProc(ref m);
    

    private const int WM_PAINT = 0xF;
    [StructLayout(LayoutKind.Sequential)]
    public struct RECT
    
        public int L, T, R, B;
    
    [StructLayout(LayoutKind.Sequential)]
    public struct PAINTSTRUCT
    
        public IntPtr hdc;
        public bool fErase;
        public int rcPaint_left;
        public int rcPaint_top;
        public int rcPaint_right;
        public int rcPaint_bottom;
        public bool fRestore;
        public bool fIncUpdate;
        public int reserved1;
        public int reserved2;
        public int reserved3;
        public int reserved4;
        public int reserved5;
        public int reserved6;
        public int reserved7;
        public int reserved8;
    
    [DllImport("user32.dll")]
    private static extern IntPtr BeginPaint(IntPtr hWnd,
        [In, Out] ref PAINTSTRUCT lpPaint);

    [DllImport("user32.dll")]
    private static extern bool EndPaint(IntPtr hWnd, ref PAINTSTRUCT lpPaint);

    [DllImport("gdi32.dll")]
    public static extern int SelectClipRgn(IntPtr hDC, IntPtr hRgn);

    [DllImport("user32.dll")]
    public static extern int GetUpdateRgn(IntPtr hwnd, IntPtr hrgn, bool fErase);
    public enum RegionFlags
    
        ERROR = 0,
        NULLREGION = 1,
        SIMPLEREGION = 2,
        COMPLEXREGION = 3,
    
    [DllImport("gdi32.dll")]
    internal static extern bool DeleteObject(IntPtr hObject);

    [DllImport("gdi32.dll")]
    private static extern IntPtr CreateRectRgn(int x1, int y1, int x2, int y2);

【讨论】：

我建议您反转您的流量控制。无需在每条 Windows 消息（包括您不关心的消息）上运行所有这些。您可以通过执行类似if (!youCareAboutThisMessage) base.WndProc(ref m); return;

的操作来短路

@Zer0 有道理，我没有反转控制流，但我将声明移到了 if 块中。就像一个侧节点：这是一个非常快速的实现，我假设未来的读者自己关心性能。在为生产环境实施某些东西时，应该考虑很多因素。我会留给未来的读者做更多的优化/修正。

@mr.G 您可能对FlatNumericUpdown 和TextBox with BorderColor 感兴趣。

@RezaAghaei 非常感谢 :) ，但代码中存在一些问题如果我使用下拉样式 dropdownList，combobox1.text 不可见

@mr.G 我会看看并更新答案。