很长一段时间以来,我一直在尝试找到解决“per-appllication cleartype fonts”问题的方法。
我想为 a 或 a 或任何其他非自定义/库存控件实现TextBox
cleartypeButton
字体ComboBox
。
好吧,我知道有一种简单的方法可以实现这一点,那就是覆盖 OnPaint 方法:
protected override void OnPaint(PaintEventArgs pevent)
{
pevent.Graphics.TextRenderingHint = TextRenderingHint.ClearTypeGridFit;
base.OnPaint(pevent);
}
这工作得很好,但问题是我想在不继承任何这些控件的情况下做到这一点,并以某种方式从类外部更改字体属性。
到目前为止,我使用的方法没有多大成功,是安装一个“挂钩程序”并监听发送到控件的消息。下面的代码是以下代码的一部分Form1 class
:
// the delegate with the same signature as the callback function
private delegate int HookMessages(int nCode, IntPtr wParam, IntPtr lParam);
// when the Load event of the Form takes place the controls are created
// and the method that sets the hooks is called
private void Form1_Load(object sender, EventArgs e)
{
Button btn = new Button();
btn.Name = "btn";
btn.Parent = this;
btn.Size = new Size(this.ClientRectangle.Width - 10, 20);
btn.Location = new Point(5, tbx.Top + tbx.Height + 10);
btn.BackColor = Color.FromArgb(100, 1, 1, 1);
btn.Text = "Click ME";
HookControlMessages();
}
// the hook that monitors control's events is set for the current thread
private void HookControlMessages()
{
if (hookWndHandle == 0)
{
HookWndProcedure = new HookMessages(HookWndProcMessages);
hookWndHandle = SetWindowsHookEx(
WindowHookTypes.WH_CALLWNDPROC,
HookWndProcedure,
IntPtr.Zero,
(int)GetCurrentThreadId());
if (hookWndHandle == 0)
{
MessageBox.Show("Window`s messages hooking failed.");
return;
}
}
}
// the callback function
private static int HookWndProcMessages(int nCode, IntPtr wParam, IntPtr lParam)
{
int nextHook = 0;
try
{
if (nCode >= 0)
{
CWPSTRUCT m = (CWPSTRUCT)Marshal.PtrToStructure(lParam, typeof(CWPSTRUCT));
_thisInstance.CheckWndProcMsgs(m);
}
nextHook = CallNextHookEx(hookWndHandle, nCode, wParam, lParam);
}
catch
{
nextHook = 0;
}
return nextHook;
}
private void CheckWndProcMsgs(CWPSTRUCT m)
{
if (m.hwnd == ((this.Controls.Find("btn", true) as Control[])[0] as Button).Handle)
{
#region BUTTON
switch (m.message)
{
case (int)WindowsMessages.WM_CREATE:
{
// when the handle of the control is created also a new font is created
// and a WM_SETFONT message sent along with the specification that a redraw must be performed
Rect rc = new Rect(new Rectangle(0, 0, ((this.Controls.Find("btn", true) as Control[])[0] as UButton).Width, ((this.Controls.Find("btn", true) as Control[])[0] as UButton).Height));
hFontNew = CreateFont(
25, 5, 2, 0, 900, 0, 0, 0,
(byte)FontCharSet.OEM_CHARSET,
(byte)FontPrecision.OUT_DEFAULT_PRECIS,
(byte)FontClipPrecision.CLIP_DEFAULT_PRECIS,
(byte)FontQuality.DEFAULT_QUALITY,
(byte)(FontPitchAndFamily.DEFAULT_PITCH | FontPitchAndFamily.FF_DONTCARE),
"Verdana");
SendMessage(m.hwnd, (uint)WindowsMessages.WM_SETFONT, hFontNew, (IntPtr)1);
}
break;
case (int)WindowsMessages.WM_SETFONT:
{
// the purpose of this block is to verify if the new font is set correct
LOGFONT lf = new LOGFONT();
IntPtr lf0 = Marshal.AllocCoTaskMem(Marshal.SizeOf(lf));
GetObject((IntPtr)m.wparam, Marshal.SizeOf(lf), lf0);
lf = (LOGFONT)Marshal.PtrToStructure(lf0, lf.GetType());
Marshal.FreeCoTaskMem(lf0);
}
break;
case (int)WindowsMessages.WM_DESTROY:
{
// when the control is destroyed the new font is also deleted
if (hFontNew != IntPtr.Zero)
{
DeleteObject(hFontNew);
}
}
break;
}
#endregion
}
}
这件作品非常适用于使用 CreateWindow/CreateWindowEx 函数创建的窗口,或者如果Paint event
将由用户处理自定义绘画,但我希望将所有绘画留给系统,只更改字体而无需任何其他干预到控制。
这种方法应该有效吗?如果没有,有人可以解释我为什么吗?我知道当系统绘制控件时,它使用由Control.Font
类的属性设置的字体,但是,它不应该也使用窗口消息中的字体呈现吗?当类在方法中处理系统消息时,它不是在绘画WndProc
时传递进来的数据Message.WParam & Message.LParam
吗?WndProc
例如。绘制文本时,系统不应该使用 WM_GETFONT 来使用适当的字体吗?我不知道任何将字体渲染设置在类之外的 Control 属性。
这个问题还有其他解决方案吗?