VB中给圆填充颜色的算法如何写

2013-11-08

VB中给圆填充颜色的算法怎么写本帖最后由 bcrun 于 2013-10-28 10:20:29 编辑这是我画的一个圆Dim a As Si

VB中给圆填充颜色的算法怎么写
本帖最后由 bcrun 于 2013-10-28 10:20:29 编辑这是我画的一个圆

 Dim a As Single
   Dim b As Single

Private Sub picdraw_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single)
   a = X
   b = Y
End Sub

Private Sub picdraw_MouseMove(Button As Integer, Shift As Integer, X As Single, Y As Single)
    If Button = 1 Then
    Picdraw.Cls
    Picdraw.Circle ((a + X) / 2, (b + Y) / 2), (((a - X) ^ 2 + (b - Y) ^ 2) ^ 0.5) / 2, RGB(0, 0, 0)
    End If
  
End Sub

[解决办法]
建个工程，添加如下代码，你什么都明白了。
Private Sub Form_Paint()
'这段代码演示了如何使用VB的Circle方法绘制各种各样的圆。
Form1.ScaleMode = vbPixels  ' 设置绘图单位为像素
Form1.Circle (60, 60), 40, vbRed '画一个圆心(60,60)半径40的红色的圆（默认空心）
Form1.FillStyle = 0 '设定填充模式为实心
Form1.FillColor = vbBlue '设定填充色蓝色
Form1.Circle (190, 60), 40, vbRed '下来画出来的就是填充了实心蓝色的圆了
Form1.DrawWidth = 3 '设定边框宽度为3
Form1.Circle (60, 190), 40, vbRed '这次绘制出来的圆边框粗细为3
Form1.DrawStyle = 5 '设定边框不可见
Form1.FillColor = vbRed '设定填充色红色
Form1.Circle (190, 190), 40 '这次绘制出来一个无边框、填充颜色是红色的圆
End Sub
[解决办法]
    Picdraw.Cls
    Picdraw.FillColor = RGB(0, 0, 0)
    Picdraw.FillStyle = vbSolid
    Picdraw.Circle ((a + X) / 2, (b + Y) / 2), (((a - X) ^ 2 + (b - Y) ^ 2) ^ 0.5) / 2, RGB(0, 0, 0)

[解决办法]
FloodFill
The FloodFill function fills an area of the display surface with the current brush. The area is assumed to be bounded as specified by the crFill parameter.

Note  The FloodFill function is included only for compatibility with 16-bit versions of Windows. For Win32-based applications, use the ExtFloodFill function with FLOODFILLBORDER specified.

BOOL FloodFill(
  HDC hdc,          // handle to device context
  int nXStart,      // x-coordinate, where fill begins
  int nYStart,      // y-coordinate, where fill begins
  COLORREF crFill   // fill color
);

Parameters
hdc
Handle to a device context.
nXStart
Specifies the logical x-coordinate of the point where filling is to begin.
nYStart
Specifies the logical y-coordinate of the point where filling is to begin.
crFill
Specifies the color of the boundary or of the area to be filled.
Return Values
If the function succeeds, the return value is nonzero.

If the function fails, the return value is zero.

Windows NT: To get extended error information, callGetLastError.

Remarks
Following are reasons this function might fail:

The fill could not be completed.
The given point has the boundary color specified by the crFill parameter.
The given point lies outside the current clipping region — that is, it is not visible on the device.
See Also
Bitmaps Overview, Bitmap Functions, ExtFloodFill

[解决办法]
ExtFloodFill
The ExtFloodFill function fills an area of the display surface with the current brush.

BOOL ExtFloodFill(
  HDC hdc,          // handle to device context

  int nXStart,      // x-coordinate where filling begins
  int nYStart,      // y-coordinate where filling begins
  COLORREF crColor, // fill color
  UINT fuFillType   // fill type
);

Parameters
hdc
Handle to a device context.
nXStart
Specifies the logical x-coordinate of the point where filling is to begin.
nYStart
Specifies the logical y-coordinate of the point where filling is to begin.
crColor
Specifies the color of the boundary or of the area to be filled. The interpretation of crColor depends on the value of the fuFillType parameter.
fuFillType
Specifies the type of fill operation to be performed. It must be one of the following values: Value Meaning
FLOODFILLBORDER The fill area is bounded by the color specified by the crColor parameter. This style is identical to the filling performed by the FloodFill function.
FLOODFILLSURFACE The fill area is defined by the color that is specified by crColor. Filling continues outward in all directions as long as the color is encountered. This style is useful for filling areas with multicolored boundaries.

Return Values
If the function succeeds, the return value is nonzero.

If the function fails, the return value is zero.

Windows NT: To get extended error information, callGetLastError.

Remarks
Following are some of the reasons this function might fail:

The filling could not be completed.
The specified point has the boundary color specified by the crColor parameter (if FLOODFILLBORDER was requested).
The specified point does not have the color specified by crColor (if FLOODFILLSURFACE was requested).
The point is outside the clipping region — that is, it is not visible on the device.
If the fuFillType parameter is FLOODFILLBORDER, the system assumes that the area to be filled is completely bounded by the color specified by the crColor parameter. The function begins filling at the point specified by the nXStart and nYStart parameters and continues in all directions until it reaches the boundary.

If fuFillType is FLOODFILLSURFACE, the system assumes that the area to be filled is a single color. The function begins to fill the area at the point specified by nXStart and nYStart and continues in all directions, filling all adjacent regions containing the color specified by crColor.

Only memory device contexts and devices that support raster-display operations support the ExtFloodFill function. To determine whether a device supports this technology, use the GetDeviceCaps function.

QuickInfo
  Windows NT: Requires version 3.1 or later.
  Windows: Requires Windows 95 or later.
  Windows CE: Unsupported.
  Header: Declared in wingdi.h.
  Import Library: Use gdi32.lib.

See Also
Bitmaps Overview, Bitmap Functions, FloodFill, GetDeviceCaps

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