c++ - how can i do a transparent form?

[Cambalinho]

i continue with problems for make the form transparent
see these code:

SetWindowLong(hwnd, GWL_EXSTYLE, GetWindowLong(hwnd, GWL_EXSTYLE) | WS_EX_LAYERED);
                    SetLayeredWindowAttributes(hwnd, clrBackColor, NULL, LWA_COLORKEY);

heres how i create the form:

hwnd = CreateWindowEx(WS_EX_CLIENTEDGE|CS_HREDRAW | CS_VREDRAW , classname, strCaption.c_str(), WS_OVERLAPPEDWINDOW | BS_NOTIFY,
                                  CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, parent, NULL, mod, this);

the form can be transparent, but, in same cases, i can lose the events form...i don't understand why... can anyone explain more about it, please?

[Igor Vartanov]

WS_EX_CLIENTEDGE|CS_HREDRAW | CS_VREDRAW

This is definitely not what you think it is. Here you need only Extended Window Styles. You need CS_ styles in your windows class registration only. And this is the place where you should use WS_EX_LAYERED.

WS_OVERLAPPEDWINDOW | BS_NOTIFY

Again, only Window Class Styles expected here, and button styles must be used only with button controls.

Please read MSDN articles carefully prior to putting any API in use. Now it looks like you play a sort of programming casino throwing dice and waiting for a jackpot.

[Cambalinho]

WS_EX_CLIENTEDGE|CS_HREDRAW | CS_VREDRAW

This is definitely not what you think it is. Here you need only Extended Window Styles. You need CS_ styles in your windows class registration only. And this is the place where you should use WS_EX_LAYERED.

WS_OVERLAPPEDWINDOW | BS_NOTIFY

Again, only Window Class Styles expected here, and button styles must be used only with button controls.

Please read MSDN articles carefully prior to putting any API in use. Now it looks like you play a sort of programming casino throwing dice and waiting for a jackpot.

true.. thanks for correct me:

hwnd = CreateWindowEx(WS_EX_OVERLAPPEDWINDOW, classname, strCaption.c_str(), WS_OVERLAPPEDWINDOW|CS_HREDRAW | CS_VREDRAW,
                                CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, parent, NULL, mod, this);

if i create the form with WS_EX_LAYERED , the form is showed invisible.
but i continue with some strange effects
see how i put the form transparent:

property<color> BackColor
        {
            Get(color)
            {
                return clrBackColor;
            },
            Set(color clrColor)
            {


                if(clrBackColor!=clrColor && clrColor==-1)//if the color is changed and '-1'(transparent)
                {
                    SetWindowLong(hwnd, GWL_EXSTYLE, GetWindowLong(hwnd, GWL_EXSTYLE) | WS_EX_LAYERED);
                    SetLayeredWindowAttributes(hwnd, clrBackColor, Opacy, LWA_COLORKEY|LWA_ALPHA);
                    UpdateWindow(hwnd);
                    clrBackColor=-1;
                }
                else if(clrBackColor!=clrColor) //if the color is changed
                {
                    SetWindowLong(hwnd, GWL_EXSTYLE, GetWindowLong(hwnd, GWL_EXSTYLE) |(~ WS_EX_LAYERED));
                    SetLayeredWindowAttributes(hwnd, -1, Opacy, LWA_COLORKEY | LWA_ALPHA);
                    UpdateWindow(hwnd);
                    SetClassLongPtr(hwnd,GCLP_HBRBACKGROUND, (LONG)CreateSolidBrush(clrBackColor));
                    InvalidateRect(hwnd,NULL,true);
                }

            }
        };

is these code correct for add and take of the WS_EX_LAYERED style?
i'm getting only black color

[Cambalinho]

now i understand why, when i create the form with WS_EX_LAYERED, i get the form invisible
by defauld, the opacy is '0'(zero).. so i did these:

hwnd = CreateWindowEx(WS_EX_APPWINDOW | WS_EX_LAYERED, classname, strCaption.c_str(), WS_OVERLAPPEDWINDOW | CS_HREDRAW | CS_VREDRAW ,
                                  CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, parent, NULL, mod, this);

                SetLayeredWindowAttributes(hwnd, NULL, 255, LWA_ALPHA);

now the form is showed with WS_EX_LAYERED style.
now i must see why i only get 1 color(black) on backcolor

[Cambalinho]

before i could change the backcolor with these code:

SetClassLongPtr(hwnd,GCLP_HBRBACKGROUND, (LONG)CreateSolidBrush(clrBackColor));

now i only recive the black color and not red\green
why these visual error?

[Cambalinho]

now i found the error:

property<color> BackColor
        {
            Get(color)
            {
                return clrBackColor;
            },
            Set(color clrColor)
            {
                if(clrBackColor!=clrColor && clrColor==-1)//if the color is changed and '-1'(transparent)
                {
                    SetLayeredWindowAttributes(hwnd, clrBackColor, Opacy, LWA_COLORKEY|LWA_ALPHA);
                    clrBackColor=-1;
                }
                else if(clrBackColor!=clrColor) //if the color is changed
                {
                    SetClassLongPtr(hwnd,GCLP_HBRBACKGROUND, (LONG)CreateSolidBrush(clrColor));
                    InvalidateRect(hwnd,NULL,true);
                    clrBackColor=clrColor;
                }
            }
        };

i wasn't change the clrBackColor value and not use the clrColor variable. now works fine

[Cambalinho]

for finish, i have 1 question: why, when i maximizate the form, i lose the caption bar and borders actions?(like resize the caption menu and that 3 buttons on form)

[Igor Vartanov]

I have to admit that I fail to understand your question. But whatever effect you run into, this would definitely have nothing to do with layered window transparency.

[Cambalinho]

I have to admit that I fail to understand your question. But whatever effect you run into, this would definitely have nothing to do with layered window transparency.

just test yourself:
1 - put the form transparent;
2 - now maximize the form;
3 - can you click:
- on close button?('X');
- on icon menu?;
- and the others 2 buttons?
the caption bar is showed, but without any action activated.