如何用VB6将PNG（图像）文件打开为RGB数组，或R、G、B数组

Question

如何用VB6打开PNG格式的图像文件？理想情况下，我（即我的客户）希望打开 PNG 文件并将其放入单独的 R(ed)、G(reen) 和 B(lue) 数组中。

VB6 不是我选择的工具（因为缺乏知识），如果有人能为我指明 VB6 解决方案的正确方向，我会很高兴。

Answer 1

您可以尝试开源 FreeImage 项目。

Answer 2

'1 form with :
'    1 picturebox : name=Picture1
'    1 commandbutton : name=Command1
Option Explicit

Private Type BITMAP
  bmType As Long
  bmWidth As Long
  bmHeight As Long
  bmWidthBytes As Long
  bmPlanes As Integer
  bmBitsPixel As Integer
  bmBits As Long
End Type

Private Declare Function GetObject Lib "gdi32" Alias "GetObjectA" (ByVal hObject As Long, ByVal nCount As Long, ByRef lpObject As Any) As Long
Private Declare Function GetBitmapBits Lib "gdi32" (ByVal hBitmap As Long, ByVal dwCount As Long, ByRef lpBits As Any) As Long
Private Declare Function SetBitmapBits Lib "gdi32" (ByVal hBitmap As Long, ByVal dwCount As Long, ByRef lpBits As Any) As Long

Private mbmpBits() As Byte
Private mudtBmp As BITMAP

Private Sub Command1_Click()
  ShowRed
'  ShowGreen
'  ShowBlue
End Sub

Private Sub Form_Load()
  Picture1.Picture = LoadPicture("c:\temp\pic.bmp")
End Sub

Private Sub Form_Unload(Cancel As Integer)
  Set Form1 = Nothing
End Sub

Private Sub ShowRed()
  Dim lngX As Long, lngY As Long
  ReadBits
  For lngX = 0 To mudtBmp.bmWidth - 1
    For lngY = 0 To mudtBmp.bmHeight - 1
      mbmpBits(0, lngX, lngY) = 0
      mbmpBits(1, lngX, lngY) = 0
    Next lngY
  Next lngX
  ShowBits
End Sub

Private Sub ShowGreen()
  Dim lngX As Long, lngY As Long
  ReadBits
  For lngX = 0 To mudtBmp.bmWidth - 1
    For lngY = 0 To mudtBmp.bmHeight - 1
      mbmpBits(0, lngX, lngY) = 0
      mbmpBits(2, lngX, lngY) = 0
    Next lngY
  Next lngX
  ShowBits
End Sub

Private Sub ShowBlue()
  Dim lngX As Long, lngY As Long
  ReadBits
  For lngX = 0 To mudtBmp.bmWidth - 1
    For lngY = 0 To mudtBmp.bmHeight - 1
      mbmpBits(1, lngX, lngY) = 0
      mbmpBits(2, lngX, lngY) = 0
    Next lngY
  Next lngX
  ShowBits
End Sub

Private Sub ReadBits()
  GetObject Picture1.Picture.Handle, Len(mudtBmp), mudtBmp
  With mudtBmp
    ReDim mbmpBits(0 To (.bmBitsPixel \ 8) - 1, 0 To .bmWidth - 1, 0 To .bmHeight - 1) As Byte
    GetBitmapBits Picture1.Picture.Handle, .bmWidthBytes * .bmHeight, mbmpBits(0, 0, 0)
  End With 'mudtBmp
End Sub

Private Sub ShowBits()
  SetBitmapBits Picture1.Picture.Handle, mudtBmp.bmWidthBytes * mudtBmp.bmHeight, mbmpBits(0, 0, 0)
  Erase mbmpBits
  Picture1.Refresh
End Sub