为什么响应WM_NCCALCSIZE后我的表单越来越小? [英] Why my form is getting smaller and smaller after responding to WM_NCCALCSIZE?

问题描述

我想自己绘制标题栏，但标题栏的高度与系统的高度不同，要增加标题栏的高度，然后我响应WM_NCCALCSIZE
但是，如果我不断地最大化和还原，形式将变得越来越小
发生了什么事?
希望有人能回答，谢谢！

I would like to paint the title bar by myself, but my title bar height is not the same as the system''s, to increase the height of the title bar, I then respond to WM_NCCALCSIZE
But if i constantly maximize and restore,the form will become increasingly smaller
what happended?
Hope someone can answer, thank you!

using System;
using System.Runtime.InteropServices;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        [DllImport("user32")]
        public static extern int GetSystemMetrics(int nIndex);
        private const int SM_CYCAPTION = 4;
        private const int SM_CXFRAME = 32;
        private const int SM_CYFRAME = 33;
        private const int WM_NCCALCSIZE = 0x83;

        [StructLayout(LayoutKind.Sequential)]
        public struct RECT
        {
            public int Left;
            public int Top;
            public int Right;
            public int Bottom;
        }

        [StructLayout(LayoutKind.Sequential)]
        public struct PWINDOWPOS
        {
            public IntPtr hwnd;
            public IntPtr hwndInsertAfter;
            public int x;
            public int y;
            public int cx;
            public int cy;
            public uint flags;
        }

        [StructLayout(LayoutKind.Sequential)]
        public struct NCCALCSIZE_PARAMS
        {
            [MarshalAs(UnmanagedType.ByValArray, SizeConst = 3)]
            public RECT[] rgrc;
            public PWINDOWPOS lppos;
        }

        protected override void WndProc(ref Message m)
        {
            if (m.Msg == WM_NCCALCSIZE && m.WParam != IntPtr.Zero)
            {
                NCCALCSIZE_PARAMS Params;
                Params = (NCCALCSIZE_PARAMS)m.GetLParam(typeof(NCCALCSIZE_PARAMS));
                Params.rgrc[0].Top += 40 - (GetSystemMetrics(SM_CYCAPTION) + GetSystemMetrics(SM_CYFRAME)); //caption height
                Marshal.StructureToPtr(Params, m.LParam, false);
            }
            base.WndProc(ref m);
        }
    }
}

推荐答案

在进行计算时，您必须考虑Windows主题，以免将40之类的硬编码数字添加到Top属性中. br/>
请看以下链接，了解有关其完成方式的示例:在Codeplex上的CustomBorderForm

You have to take into account the windows themes when doing your calculations so you can''t hard code numbers like 40 into the Top property.

Take a look at the following link for samples on how it''s done : CustomBorderForm on codeplex

好吧，也许我找到了答案?

well,maybe i have found the answer?

protected override void SetBoundsCore(int x, int y, int width, int height, BoundsSpecified specified)
{
    base.SetBoundsCore(x, y, width, height + 40 - (GetSystemMetrics(SM_CYCAPTION) + GetSystemMetrics(SM_CYFRAME)), specified);
}

但是什么是SetBoundsCore?

but what is SetBoundsCore?

这篇关于为什么响应WM_NCCALCSIZE后我的表单越来越小?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！