ContextMenuStrip向上或向下滚动按钮

Question

我目前正在开发一个Windows touch应用程序。一些winForm代码仍然存在。正如您所看到的，滚动/箭头按钮高度的高度对于触摸按钮来说实际上太小了。有没有办法将高度增加到35/40像素？

以下链接是VS2012 c＃示例项目下载页面。 download example here

谢谢。

Answer 1

此解决方案枚举ContextMenuStrip的子窗口。可能会发生两个子窗口（滚动按钮）或零子窗口。

用于滚动按钮的控件是标签，默认使用小的9x5图像。图像更新为更大的图像（使用Marlett字体），然后AutoSize设置为true，这会导致标签自行调整大小。

修改：将实施更改为扩展方法以获得更好的灵活性

using System;
using System.Collections;
using System.Collections.Generic;
using System.Drawing;
using System.Runtime.InteropServices;
using System.Windows.Forms;

namespace Opulos.Core.UI {

///<summary>Extension class to increase the size of the scroll up-down arrows on a drop down context menu or tool strip menu. The default up-down arrows are only 5 pixels high.</summary>
public static class ToolStripEx {

    private static Hashtable htData = new Hashtable();

    private class Data {
        public bool needsUpdate = true;
        public bool disposeLastImage = false;
        public ToolStrip toolStrip = null;
        public List<Image> currentImages = new List<Image>();
    }

    public static void BigButtons(this ToolStrip toolStrip) {
        htData[toolStrip] = new Data() { toolStrip = toolStrip };
        toolStrip.VisibleChanged += toolStrip_VisibleChanged;
        toolStrip.ForeColorChanged += toolStrip_ForeColorChanged;
        toolStrip.Disposed += toolStrip_Disposed;
    }

    static void toolStrip_Disposed(object sender, EventArgs e) {
        Data d = (Data) htData[sender];
        if (d != null && d.currentImages != null) {
            foreach (var img in d.currentImages)
                img.Dispose();
            d.currentImages = null;
            htData.Remove(sender);
        }
    }

    static void toolStrip_ForeColorChanged(object sender, EventArgs e) {
        Data d = (Data) htData[sender];
        d.needsUpdate = true;
        UpdateImages(d);
    }

    static void toolStrip_VisibleChanged(object sender, EventArgs e) {
        Data d = (Data) htData[sender];
        UpdateImages(d);
    }

    private static void UpdateImages(Data d) {
        if (!d.needsUpdate)
            return;

        d.toolStrip.BeginInvoke((Action) delegate {
            try {
                var list = GetChildWindows(d.toolStrip.Handle);
                if (list.Count == 0)
                    return;

                List<Image> newImages = new List<Image>();
                int k = 0;

                foreach (var i in list) {
                    var c = Control.FromHandle(i) as Label;
                    if (c != null && d.needsUpdate) {
                        String glyph = (k == 0 ? "t" : "u");
                        using (Font f = new System.Drawing.Font("Marlett", 20f)) {
                            Size s = TextRenderer.MeasureText("t", f);
                            var oldImage = c.Image;
                            c.Image = new Bitmap(s.Width, s.Height);
                            newImages.Add(c.Image);
                            // avoid disposing the default image
                            // might cause problems, not sure
                            if (d.disposeLastImage)
                                oldImage.Dispose();
                            using (Graphics g = Graphics.FromImage(c.Image)) {
                                using (Brush b = new SolidBrush(d.toolStrip.ForeColor))
                                    g.DrawString(glyph, f, b, 0, 0);
                            }
                            c.AutoSize = true;
                        }
                        k++;
                    }
                }
                if (newImages.Count > 0) {
                    d.needsUpdate = false;
                    d.disposeLastImage = true;
                    d.currentImages = newImages;
                }
            } catch {} // protect against crash (just in case)
        });
    }

    private static List<IntPtr> GetChildWindows(IntPtr parent) {
        List<IntPtr> result = new List<IntPtr>();
        GCHandle listHandle = GCHandle.Alloc(result);
        try {
            EnumChildWindows(parent, enumProc, GCHandle.ToIntPtr(listHandle));
        } finally {
            if (listHandle.IsAllocated)
                listHandle.Free();
        }
        return result;
    }

    private delegate bool EnumChildProc(IntPtr hWnd, IntPtr lParam);
    private static EnumChildProc enumProc = new EnumChildProc(CallChildEnumProc);
    private static bool CallChildEnumProc(IntPtr hWnd, IntPtr lParam) {
        GCHandle gch = GCHandle.FromIntPtr(lParam);
        List<IntPtr> list = gch.Target as List<IntPtr>;
        if (list == null)
            throw new InvalidCastException("GCHandle Target could not be cast as List<IntPtr>");

        list.Add(hWnd);
        return true;
    }

    [DllImport("user32.dll")]
    private static extern bool EnumChildWindows(IntPtr hWndParent, EnumChildProc lpEnumFunc, IntPtr lParam);
}
}

        [STAThread]
        static void Main() {
            Application.EnableVisualStyles();
            var cms = new ContextMenuStrip();
            cms.BigButtons();
            for (int i = 0; i < 20; i++)
                cms.Items.Add(new ToolStripMenuItem("Item " + i));
            cms.MaximumSize = new Size(200, 400);
            Form f = new Form();
            f.ContextMenuStrip = cms;
            Application.Run(f);
        }