Question

VB怎样在透明窗体上显示PNG图片

Answer 1

'模块modMain.bas
Attribute VB_Name = "modMain"
Option Explicit

Public Declare Function GdipCreateFromHDC Lib "gdiplus" (ByVal hdc As Long, graphics As Long) As GpStatus
Public Declare Function GdipCreateFromHWND Lib "gdiplus" (ByVal hwnd As Long, graphics As Long) As GpStatus
Public Declare Function GdipDeleteGraphics Lib "gdiplus" (ByVal graphics As Long) As GpStatus
Public Declare Function GdipGetDC Lib "gdiplus" (ByVal graphics As Long, hdc As Long) As GpStatus
Public Declare Function GdipReleaseDC Lib "gdiplus" (ByVal graphics As Long, ByVal hdc As Long) As GpStatus
Public Declare Function GdipDrawImageRect Lib "gdiplus" (ByVal graphics As Long, ByVal image As Long, ByVal x As Single, ByVal y As Single, ByVal Width As Single, ByVal Height As Single) As GpStatus
Public Declare Function GdipLoadImageFromFile Lib "gdiplus" (ByVal filename As String, image As Long) As GpStatus
Public Declare Function GdipCloneImage Lib "gdiplus" (ByVal image As Long, cloneImage As Long) As GpStatus
Public Declare Function GdipGetImageWidth Lib "gdiplus" (ByVal image As Long, Width As Long) As GpStatus
Public Declare Function GdipGetImageHeight Lib "gdiplus" (ByVal image As Long, Height As Long) As GpStatus
Public Declare Function GdipCreateBitmapFromHBITMAP Lib "gdiplus" (ByVal hbm As Long, ByVal hpal As Long, bitmap As Long) As GpStatus
Public Declare Function GdipBitmapGetPixel Lib "gdiplus" (ByVal bitmap As Long, ByVal x As Long, ByVal y As Long, color As Long) As GpStatus
Public Declare Function GdipBitmapSetPixel Lib "gdiplus" (ByVal bitmap As Long, ByVal x As Long, ByVal y As Long, ByVal color As Long) As GpStatus
Public Declare Function GdipDisposeImage Lib "gdiplus" (ByVal image As Long) As GpStatus
Public Declare Function GdipCreateBitmapFromFile Lib "gdiplus" (ByVal filename As Long, bitmap As Long) As GpStatus

Public Declare Function ReleaseCapture Lib "user32" () As Long
Public Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long

Public Const HTCAPTION = 2
Public Const WM_NCLBUTTONDOWN = &HA1
Public Const WM_SYSCOMMAND = &H112

Public Type GdiplusStartupInput
GdiplusVersion As Long
DebugEventCallback As Long
SuppressBackgroundThread As Long
SuppressExternalCodecs As Long
End Type

Public Declare Function GdiplusStartup Lib "gdiplus" (token As Long, inputbuf As GdiplusStartupInput, Optional ByVal outputbuf As Long = 0) As GpStatus
Public Declare Sub GdiplusShutdown Lib "gdiplus" (ByVal token As Long)

Public Enum GpStatus
Ok = 0
GenericError = 1
InvalidParameter = 2
OutOfMemory = 3
ObjectBusy = 4
InsufficientBuffer = 5
NotImplemented = 6
Win32Error = 7
WrongState = 8
Aborted = 9
FileNotFound = 10
ValueOverflow = 11
AccessDenied = 12
UnknownImageFormat = 13
FontFamilyNotFound = 14
FontStyleNotFound = 15
NotTrueTypeFont = 16
UnsupportedGdiplusVersion = 17
GdiplusNotInitialized = 18
PropertyNotFound = 19
PropertyNotSupported = 20
End Enum

'窗体Form1
VERSION 5.00
Begin VB.Form Form1
AutoRedraw = -1 'True
BorderStyle = 0 'None
Caption = "Form1"
ClientHeight = 7500
ClientLeft = 0
ClientTop = 0
ClientWidth = 9000
LinkTopic = "Form1"
ScaleHeight = 500
ScaleMode = 3 'Pixel
ScaleWidth = 600
ShowInTaskbar = 0 'False
StartUpPosition = 2 '屏幕中心
End
Attribute VB_Name = "Form1"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Option Explicit

Private Const ULW_OPAQUE = &H4
Private Const ULW_COLORKEY = &H1
Private Const ULW_ALPHA = &H2
Private Const BI_RGB As Long = 0&
Private Const DIB_RGB_COLORS As Long = 0
Private Const AC_SRC_ALPHA As Long = &H1
Private Const AC_SRC_OVER = &H0
Private Const WS_EX_LAYERED = &H80000
Private Const GWL_STYLE As Long = -16
Private Const GWL_EXSTYLE As Long = -20
Private Const HWND_TOPMOST As Long = -1
Private Const SWP_NOMOVE As Long = &H2
Private Const SWP_NOSIZE As Long = &H1

Private Type BLENDFUNCTION
BlendOp As Byte
BlendFlags As Byte
SourceConstantAlpha As Byte
AlphaFormat As Byte
End Type

Private Type Size
cx As Long
cy As Long
End Type

Private Type POINTAPI
x As Long
y As Long
End Type

Private Type RGBQUAD
rgbBlue As Byte
rgbGreen As Byte
rgbRed As Byte
rgbReserved As Byte
End Type

Private Type BITMAPINFOHEADER
biSize As Long
biWidth As Long
biHeight As Long
biPlanes As Integer
biBitCount As Integer
biCompression As Long
biSizeImage As Long
biXPelsPerMeter As Long
biYPelsPerMeter As Long
biClrUsed As Long
biClrImportant As Long
End Type

Private Type BITMAPINFO
bmiHeader As BITMAPINFOHEADER
bmiColors As RGBQUAD
End Type

Private Declare Function BitBlt Lib "gdi32.dll" (ByVal hDestDC As Long, ByVal x As Long, ByVal y As Long, ByVal nWidth As Long, ByVal nHeight As Long, ByVal hSrcDC As Long, ByVal xSrc As Long, ByVal ySrc As Long, ByVal dwRop As Long) As Long
Private Declare Function DeleteObject Lib "gdi32" (ByVal hObject As Long) As Long
Private Declare Function SetWindowLong Lib "user32" Alias "SetWindowLongA" (ByVal hwnd As Long, ByVal nIndex As Long, ByVal dwNewLong As Long) As Long
Private Declare Function AlphaBlend Lib "Msimg32.dll" (ByVal hdcDest As Long, ByVal nXOriginDest As Long, ByVal lnYOriginDest As Long, ByVal nWidthDest As Long, ByVal nHeightDest As Long, ByVal hdcSrc As Long, ByVal nXOriginSrc As Long, ByVal nYOriginSrc As Long, ByVal nWidthSrc As Long, ByVal nHeightSrc As Long, ByVal bf As Long) As Boolean
Private Declare Function UpdateLayeredWindow Lib "user32.dll" (ByVal hwnd As Long, ByVal hdcDst As Long, pptDst As Any, psize As Any, ByVal hdcSrc As Long, pptSrc As Any, ByVal crKey As Long, ByRef pblend As BLENDFUNCTION, ByVal dwFlags As Long) As Long
Private Declare Function CreateDIBSection Lib "gdi32.dll" (ByVal hdc As Long, pBitmapInfo As BITMAPINFO, ByVal un As Long, ByRef lplpVoid As Any, ByVal handle As Long, ByVal dw As Long) As Long
Private Declare Function GetDIBits Lib "gdi32.dll" (ByVal aHDC As Long, ByVal hBitmap As Long, ByVal nStartScan As Long, ByVal nNumScans As Long, lpBits As Any, lpBI As BITMAPINFO, ByVal wUsage As Long) As Long
Private Declare Function SetDIBits Lib "gdi32.dll" (ByVal hdc As Long, ByVal hBitmap As Long, ByVal nStartScan As Long, ByVal nNumScans As Long, lpBits As Any, lpBI As BITMAPINFO, ByVal wUsage As Long) As Long
Private Declare Function CreateCompatibleDC Lib "gdi32.dll" (ByVal hdc As Long) As Long
Private Declare Function SelectObject Lib "gdi32.dll" (ByVal hdc As Long, ByVal hObject As Long) As Long
Private Declare Function DeleteDC Lib "gdi32.dll" (ByVal hdc As Long) As Long
Private Declare Sub CopyMemory Lib "kernel32.dll" Alias "RtlMoveMemory" (Destination As Any, Source As Any, ByVal Length As Long)
Private Declare Function SetWindowPos Lib "user32.dll" (ByVal hwnd As Long, ByVal hWndInsertAfter As Long, ByVal x As Long, ByVal y As Long, ByVal cx As Long, ByVal cy As Long, ByVal wFlags As Long) As Long
Private Declare Function GetWindowLong Lib "user32.dll" Alias "GetWindowLongA" (ByVal hwnd As Long, ByVal nIndex As Long) As Long
Private Declare Function GetDC Lib "user32.dll" (ByVal hwnd As Long) As Long

Dim mDC As Long
Dim mainBitmap As Long
Dim blendFunc32bpp As BLENDFUNCTION
Dim token As Long
Dim oldBitmap As Long

Private Sub Form_DblClick()

Unload Me

End Sub

Private Sub Form_Load()

Dim GpInput As GdiplusStartupInput
GpInput.GdiplusVersion = 1

If GdiplusStartup(token, GpInput) <> 0 Then
MsgBox "Fehler bem laden von GDI+!", vbCritical
Unload Me
End If

MakeTrans (App.Path & "\splash.png")

End Sub

Private Sub Form_MouseDown(Button As Integer, Shift As Integer, x As Single, y As Single)

Call ReleaseCapture
SendMessage Me.hwnd, WM_NCLBUTTONDOWN, HTCAPTION, 0&

End Sub

Private Sub Form_Unload(Cancel As Integer)

Call GdiplusShutdown(token)
SelectObject mDC, oldBitmap
DeleteObject mainBitmap
DeleteObject oldBitmap
DeleteDC mDC

End Sub

Private Function MakeTrans(pngPath As String) As Boolean

Dim tempBI As BITMAPINFO
Dim tempBlend As BLENDFUNCTION
Dim lngHeight As Long, lngWidth As Long
Dim curWinLong As Long
Dim img As Long
Dim graphics As Long
Dim winSize As Size
Dim srcPoint As POINTAPI

With tempBI.bmiHeader
.biSize = Len(tempBI.bmiHeader)
.biBitCount = 32
.biHeight = Me.ScaleHeight
.biWidth = Me.ScaleWidth
.biPlanes = 1
.biSizeImage = .biWidth * .biHeight * (.biBitCount / 8)
End With
mDC = CreateCompatibleDC(Me.hdc)
mainBitmap = CreateDIBSection(mDC, tempBI, DIB_RGB_COLORS, ByVal 0, 0, 0)
oldBitmap = SelectObject(mDC, mainBitmap)

Call GdipCreateFromHDC(mDC, graphics)
Call GdipLoadImageFromFile(StrConv(pngPath, vbUnicode), img)
Call GdipGetImageHeight(img, lngHeight)
Call GdipGetImageWidth(img, lngWidth)
Call GdipDrawImageRect(graphics, img, 0, 0, lngWidth, lngHeight)

curWinLong = GetWindowLong(Me.hwnd, GWL_EXSTYLE)

SetWindowLong Me.hwnd, GWL_EXSTYLE, curWinLong Or WS_EX_LAYERED
SetWindowPos Me.hwnd, HWND_TOPMOST, 0, 0, 0, 0, SWP_NOMOVE Or SWP_NOSIZE

srcPoint.x = 0
srcPoint.y = 0
winSize.cx = Me.ScaleWidth
winSize.cy = Me.ScaleHeight

With blendFunc32bpp
.AlphaFormat = AC_SRC_ALPHA
.BlendFlags = 0
.BlendOp = AC_SRC_OVER
.SourceConstantAlpha = 255
End With

Call GdipDisposeImage(img)
Call GdipDeleteGraphics(graphics)
Call UpdateLayeredWindow(Me.hwnd, Me.hdc, ByVal 0&, winSize, mDC, srcPoint, 0, blendFunc32bpp, ULW_ALPHA)

End Function