Progress bar made by Pb

 

PowerBuilder is recognized as one of the best Database Front-end development tools. However, PB is monotonous in user interface processing for a long time. The most obvious example is, all window controls do not support transparent colors, that is, transparent. In versions earlier than PowerBuilder 7, the progress bar is not provided, so most programmers always use two Rectangle controls in the program to program the progress. In this way, the Progress percentage in the progress bar is lost. If a static text is added as the percentage, the percentage of the progress bar cannot overlap with the progress bar because the statictext control has no transparent color, you have to place a statictext control outside the progress bar to display the progress, which wastes space and is not beautiful. I have also seen the solution on the Internet. It mainly utilizes the features that can be transparently processed by controls in the data window. However, I always feel that the data window is a heavy-duty control, if you need to occupy a large amount of system resources, can you use other simpler methods to solve the above problems? The key to the above problems lies in the transparency of the text output background. We know that Windows provides a large number of underlying API functions for upper-layer applications to call, text output is the most basic, so Windows must be able to solve the problem of transparent text background output. Find the API help carefully and find the relevant functions, so the problem is solved. The main statements and main program sections of object implementation are listed below: Create a new visual Custom User object uo_progressbar, and place two rectangular controls (Rectangle) in it, named r_back and r_front respectively. The instance variables are defined as follows: Ulong iul_ihDC // Save the DC handle of the Custom User object Real ir_step // The step value calculated based on the object width Integer ii_x, ii_y // The text output location calculated based on the object width and height Declare Local external functions as follows: Function ulong GetDC (ulong hWnd) Library "USER32.DLL" Function boolean TextOut (ulong hdcr, integer stx, Integer sty, ref string lpString, long nCount) Library "GDI32.DLL" Alias for "TextOutA" Function int SetBkMode (ulong hdcr, integer mode) Library "GDI32.DLL" Enter the following code in the constructor event of the object: Integer li_width, li_height // Calculate the width and height based on the object change box Choose case this. BorderStyle CASE StyleLowered !, StyleRaised! Li_width = this. width-PixelsToUnits (4, XPixelsToUnits !) Li_height = this. height-PixelsToUnits (4, YPixelsToUnits !) CASE StyleBox !, StyleShadowBox! Li_width = this. width-PixelsToUnits (2, XPixelsToUnits !) Li_height = this. height-PixelsToUnits (2, XPixelsToUnits !) CASE Else Li_width = this. width Li_height = this. height END CHOOSE R_back.width = li_width R_front.height = li_height R_front.width = 0 R_back.height = li_height // Calculate the percentage text output position so that it is centered horizontally and vertically. Ii_x = UnitsToPixels (li_width, XUnitsToPixels !) /2-16 Ii_y = (UnitsToPixels (li_height, YUnitsToPixels !) -16)/2 Ir_step = li_width/100 // calculate the step value Iul_ihDC = GetDC (handle (this )) // Obtain the DC handle of the object for API call SetBkMode (iul_ihdc, 1) // set the text output background color to transparent Return 0 Write a function for the object: of_setposition, // Function: display the progress of Parameter Changes // Parameter: integer ai_percent // Return: None String ls_msg Integer li_x If ai_percent <= 100 and ai_percent <0 then SetRedraw (FALSE) li_x = "ai_percent * ir_step" r_back.x = "li_x" r_front.width = "li_x" ls_msg = "string (" ai_percent) + "%" SetRedraw (True) TextOut (iul_ihdc, ii_x, ii_y, Ls_msg, len (ls_msg) End If Of course, you can also write a function to change the foreground color and text color in the progress bar.