In my main program I have a dialg box that contains many controls.
One of them is a static control in witch I want to draw an image with a text on and some transparency effect.
Can any one help ?
You should consider deriving your own class from CStatic. You should define the static control with the SS_OWNERDRAW style, so you will be able to handle its rendering in CStatic::DrawItem. When DrawItem is called, you will receive a pointer to the DrawItemStruct, which has embedded in it, a handle to the control's DC that you can use to render into the control.
I'd also suggest looking at this implementation: http://www.codeproject.com/Articles/9064/Yet-Another-Transparent-Static-Control
Related
Single Document, the simplest MFC app.
The idea is that default CDC pDC is edited(colored) in some way from onDraw() function. When a user clicks on a number I want it to be displayed using colors from pDC.
If I use the default handler function OnKeyDown for WM_KEYPRESS I don't get a pointer for my edited pDC.
My question is how to access the edited pDC?
I am sure that there is a simple solution that I am missing, please help.
I am not 100% sure I understand the question correctly, but let me try....
The usual and recommended way in MFC to do what I think you want would be to handle all drawing in onDraw() only.
So, in the onKeyDown() handler, you would store the pressed key to a member variable (or maybe even push it to a vector or list of keys to be drawn) and then call Invalidate(false). That causes Windows to generate a WM_PAINT message to your window, which ends up being handled in onDraw(), where you can now draw the correct things based on your current member variable values.
It is also possible to create a CPaintDC outside of onDraw() and draw on that. But as said, usually in MFC applications, all drawing is kept in one place. Windows may request your app to redraw at any time and it does that with a WM_PAINT message.
Looking for some code/project examples on how to draw a pulse waveform with certain width/frequency in a MFC control. Which control would be the best to use for this purpose?. I am very new to this. Have already done some online search and definitely can use some expert ideas. I am lost.
The MFC CStatic class represents a picture control. You can derive a class from CStatic and paint whatever you like in its OnPaint member function. For examples search codeproject.com and codeguru.com for "CStatic", like this one:
http://www.codeguru.com/cpp/controls/controls/chartingandanaloguecontrols/article.php/c5219/Simple-Graph-Control.htm
I'm updating an MFC dialog with a number of buttons on it.
At present, the dialog has a Picture control covering the whole dialog providing a patterned background. On top of that, each button is a CBitmapButton using (opaque) images carefully generated to match the area of background they cover.
It would obviously be much easier if the images could be created as mostly transparent, so the background shows through automatically. However, I can't work out how to get MFC to render transparent images correctly in this case.
I understand that I might want a different class to CBitmapButton, or need to write a custom subclass; that's fine, but I don't know where to start. It would be nice to support 32-bit BMP or PNG with alpha channel, but I'd settle for the "specified colour should be transparent" type.
It may not be the best way to do it, but what I'd do is create a custom CButton derived class (assuming that you're actually using the rest of the CButton functionality), then override the DrawItem function to put your custom draw code in.
For the image itself I'd use a Bitmap GDI+ object (which will allow you to load either BMPs or PNGs with alpha channels) then use the regular DrawImage function to draw the bitmap.
If you're going to put PNGs into your resource file then you need to put them in as a "PNG" type. Make sure when you look in the resource file code that the entry looks like
IDB_PNG1 PNG "C:\temp\test.png"
and doesn't try to treat it as a BITMAP resource otherwise you'll have problems loading them.
Edit
Putting my response here so I can post code. Yes, I meant to derive a custom class from CButton, then add a Gdiplus::Bitmap member variable. Here is roughly what you'll need to do to get it to work, though I haven't checked that the code actually compiles and works, but hopefully you'll get the idea. It's not the most efficient way to do it, but if you've not done much custom drawing before then it does have the advantage of being simple!
void CMyButton::LoadImage(const int resourceID)
{
m_pBitmap = Gdiplus::Bitmap::FromResource(NULL, MAKEINTRESOURCE(resourceID));
ASSERT(m_pBitmap);
}
void CMyButton::DrawItem(LPDRAWITEMSTRUCT lpDrawItemStruct)
{
ASSERT(lpDrawItemStruct->CtlType == ODT_BUTTON);
CRect rcClient;
GetClientRect(&rcClient);
if (lpDrawItemStruct->itemState & ODS_SELECTED)
{
// If you want to do anything special when the button is pressed, do it here
// Maybe offset the rect to give the impression of the button being pressed?
rcClient.OffsetRect(1,1);
}
Graphics gr(lpDrawItemStruct->hDC);
gr.DrawImage(m_pBitmap, rcClient.left, rcClient.top);
}
I am trying to create a custom CStatic control in vc++ and have a few problems.
I originally was just using a CStatic control with the SS_BLACKRECT style. This was good for the situation until I needed to display an image over the control on demand.
I figured out all the logistics behind actually drawing the image onto the control but I cant seem to figure out how to do so without interfering with other things.
Basically I want the control to function as a normal CStatic with the SS_BLACKRECT style most of the time.
Then I need to be able to call a method that will cause it to draw an image over the control instead. I am doing the drawing using GDI and have tried it both in the OnPaint() method and the DrawItem() method without success. I can get it to draw in the OnPaint() but when I call the base CStatic::OnPaint() it draws over my image.
I need to be able to allow it to draw like normal but then just throw an image in on top. When I tried to do it in the DrawItem() method I had a problem because obviously it was not drawing using the SS_BLACKRECT style but waiting for me to draw the control like its supposed to.
I guess what I think I'm looking for is one of three things. A way to draw using GDI after the base OnPaint() method finishes. A way to have the control draw the default SS_BLACKRECT style and then OWNERDRAW the image afterwards. Or the code to mimic the drawing of SS_BLACKRECT.
The last one might be the easiest but I just don't know all the things I need to set up to draw a CStatic control like the default DrawItem.
Try calling Default() in your OnPaint() handler.
Then, depending on whether you're drawing your image, you can then draw over the top of the standard CStatic control.
Here's a couple ideas:
If CStatic::OnPaint() draws over your image, then try calling it first and drawing your image afterwards.
Otherwise, from what little I've seen of SS_BLACKRECT, you should be able to replicate it's drawing simply be calling CDC::FillSolidRect() passing the rectangle of your control obtained through GetClientRect() and using the color returned by GetSysColor(COLOR_WINDOWFRAME)
How Would I go about placing text on the windows desktop? I've been told that GetDesktopWindow() is what I need but I need an example.
I'm assuming your ultimate goal is displaying some sort of status information on the desktop.
You will have to do either:
Inject a DLL into Explorer's process and subclass the desktop window (the SysListView32 at the bottom of the Progman window's hierarchy) to paint your text directly onto it.
Create a nonactivatable window whose background is painted using PaintDesktop and paint your text on it.
First solution is the most intrusive, and quite hard to code, so I would not recommend it.
Second solution allows the most flexibility. No "undocumented" or reliance on a specific implementation of Explorer, or even of just having Explorer as a shell.
In order to prevent a window from being brought to the top when clicked, you can use the extended window style WS_EX_NOACTIVATE on Windows 2000 and up. On downlevel systems, you can handle the WM_MOUSEACTIVATE message and return MA_NOACTIVATE.
You can get away with the PaintDesktop call if you need true transparency by using layered windows, but the concept stays the same. I wrote another answer detailing how to properly do layered windows with alpha using GDI+.
Why not just draw the text in the desktop wallpaper image file?
This solution would be feasible if you don't have to update the information too often and if you have a wallpaper image.
One can easily use CImage class to load the wallpaper image, CImage::GetDC() to obtain a device context to draw into, then save the new image, and finally update the desktop wallpaper to the new image.
i haven't tried but i assume you could do the following:
use GetDesktopWindow to retrieve the handle of the desktop window
use SetWindowLong to point the windows message handler to your own procedure
in your proc, process the WM_PAINT message (or whatever) and draw what you need.
in your proc, call the original message handler (as returned by SetWindowLong).
not 100% sure it will work, but seems like it should as this is the normal way to subclass a window.
-don
If your intent is to produce something like the Sidebar, you probably just want to create one or more layered windows. That will also allow you to process mouse clicks and other normal sources of input, and if you supply the alpha channel information, Windows will make sure that your window is drawn properly at all times. If you don't want the window to be interactive, use appropriate styles (such as WS_EX_NOACTIVATE) like Koro suggests.