SetBkColor 和 SetTextColor 不设置 DrawText 的背景和文本颜色

Question

使用以下代码将字符串写入 DesktopWindow 的设备上下文是可行的，但背景颜色和文本颜色保持不变（蓝底白字）：

Private Sub writeToScreen(txt As String)
Declare Function GetDesktopWindow Lib "user32" () As Integer
Declare Function DrawTextW Lib "user32" (hdc As Integer, lpStr As WString, nCount As Integer, _
     ByRef lpRect As RECT, wFormat As Integer) As Integer
Declare Function CreateDCA Lib "gdi32" (lpDriverName As CString, lpDeviceName As Integer, _
     lpOutput As Integer, lpInitData As Integer) As Integer
Declare Function DeleteDC Lib "gdi32" (hdc As Integer) As Integer
Declare Function GetTextColor Lib "gdi32" (hdc As Integer) As Color
Declare Function SetTextColor Lib "gdi32" (hdc As Integer,  crColor As Color) As Color
Declare Function GetBkColor Lib "gdi32" (hdc As Integer) As Color
Declare Function SetBkColor  Lib "gdi32" (hdc As Integer,  crColor As Color) As Color

Const DT_MULTILINE = &H00000001
Const DT_NOCLIP = &H100
Const INVALID_COLOR = &hFFFFFFFF

Dim tFormat As Integer = DT_MULTILINE Or DT_NOCLIP
Dim hdc As Integer = CreateDCA("DISPLAY", 0, 0, 0)
Dim tRect As RECT   //The RECT structure is defined elsewhere
Dim textCol, backColor As Color

tR.Left = 200
tR.Top = 250
tR.Right = 600
tR.Bottom = 350
textCol = SetTextColor(hdc, &cFF8040)
backColor = SetBkColor(hdc, &c000000)

If DrawTextW(hdc, txt, Len(txt), tR, tFormat) = 0 Then
  System.DebugLog("Text Draw Error")
End If

Call SetTextColor(hdc, textCol)
Call SetBkColor(hdc, backColor)
Call DeleteDC(hdc)  
End Sub

我做错了什么？文字写得很好，但颜色很难看。

Answer 1

首先使用 SetBkMode() (http://msdn.microsoft.com/en-us/library/dd162965%28v=vs.85%29.aspx) 将 DC 设置为不绘制背景。

SetTextColor() 仅用于 TextOut()，而不用于 DrawText()，IIRC - MSDN 对此不明确。尝试在 DC 中选择不同的 HBRUSH，这可能会满足您的要求。