C # create a special form/Control Using winform

The idea of creating a special form or control is generally to generate a region and then set it to the specified window or control. There are many ways to generate region. The most common method is to generate a region from an image. The transparent part of the image is "hidden", and the rest is used as a region. You can use setmediawrgn API to set the region of a window or control. However, the. NET Framework encapsulates this operation. in C #, you only need to assign values to the region attribute of the window or control. Next I will implement the core of the special form in C #. Code Post it for you to see if you have any comments. Despite mentioning it, we are welcome. J is a method for generating region based on Bitmap objects: /// <summary> /// obtain the area of the non-transparent part of the image. /// </Summary> /// <Param name = "picture"> obtain the image of the region. </Param> /// <Param name = "transparentcolor"> transparent color. </Param> // <returns> private region BMP RGn (Bitmap Picture, color transparentcolor) {int nwidth = picture. width; int nheight = picture. height; region RGN = new region (); RGN. makeempty (); bool istransrgn; // whether the previous vertex is in the transparent area color curcolor; // The current vertex color rectangle currect = new rectangle (); currect. height = 1; int x = 0, y = 0; // scan the image pixel by pixel to locate and merge the areas with non-transparent colors. For (y = 0; y <nheight; ++ y) {istransrgn = true; For (x = 0; x <nwidth; ++ X) {curcolor = picture. getpixel (x, y); If (curcolor = transparentcolor | x = nwidth-1) // if there is a transparent color or line tail {If (istransrgn = false) // exit the valid area {currect. width = x-currect. x; RGN. union (currect) ;}} else // non-transparent color {If (istransrgn = true) // enter the valid area {currect. X = x; currect. y = y ;}// if curcolor istransrgn = curcolor = transparentcol Or;} // for x} // For y return RGN;} the principle is very simple, that is, to scan the image row by row, merge the non-transparent rectangles (only one pixel height) in each row into a region object. When a complete image is scanned, what we get is the desired region. This Algorithm In many Article . With region, the following is simple: This. region = BMP RGn (New Bitmap ("D: \ a.bmp"), color. fromargb (0, 0, 0); the above Code uses the outline of D: \ a.bmp as the region of the main window. Assume that the background of the image is black (color. fromargb (0, 0, 0 )). In fact, it is not just form. Any control can use this method to set region and create a special control.