If a relatively simple animation effect is achieved in VB, many people will use Timer controls, in fact, there is a linedda in the API function, and the simple animation effect is not bad with this function. Because it is an API function, it is generally, so many languages can use it to achieve simple animation.
The prototype of this function is as follows:
Bool Linedda (int NXStart, int NYSTART, INT NXEND, INT NYEND, LINEDDAPROC LPLINEFUNC, LPARAM LPDATA);
The parameters are as follows:
NxStart: X value of the starting point
NYSTART: The y value of the starting point
NXEND: X value of the end point
NYEND: Y value of the end point
LPLINEFUNC: Address of the callback function
LPDATA: User-defined parameters (this parameter is passed to the callback function)
This function and animation are actually nothing. Its function is to calculate the coordinates of each screen pixel on two-point line segment. The coordinates of these two points have been given in the first four parameters of the function. Each time a coordinate is calculated, the function calls the callback function referred to in the fifth parameter, we can complete some simple operations in the callback function to achieve the animation effect.
The prototype of the callback function is: Void Callback LinedDaproc (int X, int y, lparam lpdata);
The first two parameters are the coordinates of the point, and the third parameter is the custom parameters passed by LINEDDA, which is specified by our own, and what is all. :)
The statement of the LINEDDA function in VB is:
Public Declare Function Linedda Lib "GDi32.dll" (Byval N1 As Long, Byval N3 As Long, Byval N4 As Long, BYVAL LPAR LPAR AS Long
Its callback function prototype is:
Public Sub LinedDaproc (byval x as long, byval y as long, byval lpdata as long
In VB, the callback function must be placed in the standard module, use the Addressof operator when the function address is transferred, and the function name is connected.
The VB source program is as follows:
Form module:
Option expedition
Private submmand1_click ()
'Circulating the LinedDa function, implement simple animation in its designated callback
DIM I as long
DIM POINT (9) as PointApi
For i = 0 to Ubound (Point) - 1
Point (i 1) .x = Point (i) .x 50
IF Point (i) .y = 0 THEN POINT (i 1) .y = 50 else Point (i 1) .y = 0
Linedda Point (i) .X, Point (i) .y, Point (i 1) .x, Point (i 1) .y, addressof lineddaproc, me.hdc
Next i
End Sub
Standard module:
Option expedition
'API function declaration
Public Declare Function LineDDA Lib "gdi32.dll" (ByVal n1 As Long, ByVal n2 As Long, ByVal n3 As Long, ByVal n4 As Long, ByVal lpLineDDAProc As Long, ByVal lParam As Long) As LongPublic Declare Function DrawText Lib "user32. DLL "Alias" DrawTexta "(Byval HDC As Long, Byval Ncount As Long, LPRECT AS RECT, BYVAL WFORMAT AS long) As long
Public Declare Sub Sleep Lib "kernel32.dll" (Byval dwmilliseconds as ring)
'API type declaration
Public Type Rect
LEFT As Long
Top as long
Right As long
Bottom as long
End Type
Public Type PointApi
X as long
Y as long
End Type
'API constant statement
Private const dt_center = & h1
Private const dt_vcenter = & h4
The callback function of 'Linedda function
'Parameters: x, y is point coordinates, LPDATA is custom parameters
Public Sub LinedDaproc (byval x as long, byval y as long, byval lpdata as long
DIM RCT AS Rect
IF x MOD 10 = 0 THEN
Rct.Left = X
Rct.right = rct.Left 18
Rct.top = Y
Rct.bottom = rct.top 18
DrawText LPDATA, "LPP", -1, RCT, DT_Center OR DT_VCENTER
Sleep (100)
Doevents
END IF
End Sub
The result of the above program is to display some text on the form, add a commandbutton to the form, and copy the code above. In fact, in the famous PGP encryption software, when the password enters an error, the window will be jitter, this effect can be implemented using the LINEDDA function, the key is to see our imagination. : D
This is the above source download address: http://9cbsgoodname008.51.net/LINEDDA.ZIP
* ------------------------------------------- *
* Please inform the author and indicate the source, 9CBS welcomes you! *
* Author: Lu Peipei (goodname008) *
* Email: GoodName008@163.com *
* Column: http://blog.9cbs.net/goodname008 *
* ------------------------------------------- *
