vb)利用GetBitmapBits,SetBitmapBits加速图像处理 (不知道前面有没有人写过这个,这里主要是最近写
些心得体会,希望对大家有用.久未写东西,会有堆毛病,将就着吧.)最近发现了两个好东东,SetBitmapBits,GetBitmapBits,能极大
提高某些图像处理速度.引用别人
话\"SetBitmapBits:
vb声明: Declare Function SetBitmapBits Lib \"gdi32\" (ByVal hBitmap As Long, ByVal dwCount As Long, lpBits As Any) As Long
作用: \"将来自缓冲区
2进制位复制到幅位图\"参数: hBitmap Long
位图句柄 dwCount Long
欲复制字节数量 lpBits Any
指向个缓冲区指针
这个缓冲区包含了为位图正确格式化位图位 GetBitmapBits:
vb声明: Declare Function GetBitmapBits Lib \"gdi32\" (ByVal hBitmap As Long, ByVal dwCount As Long, lpBits As Any) As Long
作用: \"将来自位图
2进制位复制到个缓冲区\"参数: hBitmap Long
位图句柄 dwCount Long
欲复制字节数如设为零表示取得位图中字节数 lpBits Any
指向容纳位图位个缓冲区指针注意事先将缓冲区至少
化成dwCount个字节 \"举
个例子,将图片旋转90度,下面是我写顺时针旋转90度
.假设目标图像
宽等于源图长,目标图像长等于源图宽,两图颜色值占用位数相等.参数: hSrcBmp,源图位图
句柄,vb中对应是Picture.HandlehDestBmp,目标位图
句柄其中用到
GetObject,CopyMemory和BITMAP类型,声明如下Declare Function GetObject Lib \"gdi32\" Alias \"GetObjectA\" (ByVal hObject As Long, ByVal nCount As Long, lpObject As Any) As Long
Declare Sub CopyMemory Lib \"kernel32\" Alias \"RtlMoveMemory\" (pDest As Any, pSrc As Any, ByVal ByteLen As Long)
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
\'顺时针旋转90度
:Public Function TurnBmp(hSrcBmp As Long, hDestBmp As Long) As Boolean
Dim X As Long, Y As Long
Dim BytesPixel As Long
Dim tSBmpInfo As BITMAP, tDBmpInfo As BITMAP
Dim sBits
As Byte, dBits As Byte\'获得位图信息
Call GetObject(hSrcBmp, Len(tSBmpInfo), tSBmpInfo)
Call GetObject(hDestBmp, Len(tDBmpInfo), tDBmpInfo)
\'申请空间
ReDim sBits(1 To tSBmpInfo.bmWidthBytes, 1 To tSBmpInfo.bmHeight)
ReDim dBits(1 To tDBmpInfo.bmWidthBytes, 1 To tDBmpInfo.bmHeight)
\'获得源图和目标图 2进制位
Call GetBitmapBits(hSrcBmp, tSBmpInfo.bmWidthBytes * tSBmpInfo.bmHeight, sBits(1, 1))
Call GetBitmapBits(hDestBmp, tDBmpInfo.bmWidthBytes * tDBmpInfo.bmHeight, dBits(1, 1))
\'计算颜色值占用多少字节
BytesPixel = tSBmpInfo.bmBitsPixel / 8
\'旋转
For Y = 1 To tSBmpInfo.bmHeight
For X = 1 To tSBmpInfo.bmWidth
Call CopyMemory(dBits((tSBmpInfo.bmHeight - Y) * BytesPixel + 1, X), sBits((X - 1) * BytesPixel + 1, Y), BytesPixel)
Next X
Next Y
\'将旋转
结果复制到目标位图Call SetBitmapBits(hDestBmp, tDBmpInfo.bmWidthBytes * tDBmpInfo.bmHeight, dBits(1, 1))
End Function
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