I am using SetLayeredWindowAttributer to make a particular color of layered window transparent.
This works fine on Windows XP,VISTA . But when I use the same on Windows 7 its not working.
SetLayeredWindowAttributes(hWnd, RGB(0xff,0xff,0xff), 0, LWA_COLORKEY);
When I use LWA_ALPHA then also it works.
Problem is that I am not able to make a particular color transparent in Windows 7.
The following statement works on Windows 7
SetLayeredWindowAttributes(hWnd,RGB(0xff,0xff,0xff), 100, LWA_ALPHA);
Is it possible that the rendered color values not matching the color value in SetLayeredWindowAttributes?
You should avoid using 0xff,0xff,0xff (white) with LWA_COLORKEY. Any other value should be fine (e.g. 0xff,0xff,0xfe).
For more control over your layered window I suggest you consider using UpdateLayeredWindowIndirect. I wrote an article that describes in detail how it can be used with both GDI and Direct2D.
http://msdn.microsoft.com/en-us/magazine/ee819134.aspx
Related
I'm making this app in Haxe which compiles to C++ code. I'm using the SetLayeredWindowAttributes() function to set the background of the window to be fully transparent. The problem is that this works completely fine only on certain monitors, but not on others.
If I launch the app on my main monitor, which I believe to be 32-bit (if that matters), the background doesn't change at all, or will flicker and then completely disappear until I focus another window.
However, if I connect another monitor and run the app on that one, the background does become transparent, and the transparency persists even if I move it back to my main monitor. Even with the 2nd monitor connected at the same time. If I launch it on the main one, transparency fails.
I have tried changing the color values between 0xFFffffff/0xffffff, etc, but no combination of these work.
This same problem occurs even on a completely different machine with different hardware than mine. My hardware: Lenovo Ideapad L340-15IRH, i5-9300H, Gpu(s) Gtx 1650, Intel HD 630.
Please help me, what am I doing wrong?
Code to enable transparency, using windows.h inside a C++ function:
HWND hWnd = GetActiveWindow();
res = SetWindowLong(hWnd, GWL_EXSTYLE, GetWindowLong(hWnd, GWL_EXSTYLE) | WS_EX_LAYERED);
SetLayeredWindowAttributes(hWnd, RGB(255, 255, 255), 0, LWA_COLORKEY);
Code which creates the transparent background, in main haxe code:
transparentsquare = new FlxSprite(0, 0).makeGraphic(screenW, screenH, FlxColor.WHITE);
add(transparentsquare);
It doesn't matter if I enable transparency before everything has loaded, I can enable it by pressing a key at any time and it still fails if I enable it after the app has fully loaded. Also, obviously graphics are not drawn in the C++ function but in the haxe code, so I can't use any fancy DirectX APIs and what-not.
I am trying to create a simple transparent window where I can draw with Direct2D.
So far what I have done:
Created window
Set style to WS_EX_LAYERED
Set alpha color key as #FFF
Draw using Windows Graphics a white rectangle
Now window is transparent with per-pixel alpha
Then make a target out of the window and draw using Direct2D
Make ALPHA _PREMULIPLIED target
Clear with #FFF with 0.0f alpha
Window is now black
I just don't know how to make window to transparent. If you can point out my mistake, I would be obliged
Here how it's achievable using DirectComposition API
Russian: http://www.oszone.net/25395/
English: https://msdn.microsoft.com/magazine/dn745861.aspx
Basically what author does is
Sets WS_EX_NOREDIRECTIONBITMAP extended style to remove redirection bitmap of DWM. Content of window is now empty.
Creates DirectComposition device
Creates Composition SwapChain (and not hwnd swapchain)
Places one visual with SwapChain as content as root visual.
Renders into SwapChain using Direct2D API.
It also works well with WS_EX_TRANSPARENT | WS_EX_LAYERED | WS_EX_TOPMOST for creating event-transparent overlays.
I don't think it's possible with directX. However GDI does work.
Take a look at the source here to see how it's done: http://pastebin.com/NJf8wi2V
In the source you can see that there is an option to attempt to use directx/opengl. However as you can see from running they do not work.
I'm currently developing an application with OpenCV to do visual recognition of elements on the screen.
While a visual representation of the process is not needed, it would be very useful for debugging purposes if I could find a way to draw circles, lines and possibly text directly on the screen, without having an app window.
There are certain applications that, for instance, draw HUDs over the screen. How do they go about doing that?
I need a way for my drawing to always be at the front. In general, all the ways I managed to find involve painting on a window (WinAPI, Direct2D, OpenGL). Is there a workaround to make it appear like it's simply a layover on the desktop (including all open windows)?
for the purpose of debugging, just literally draw on the screen. IIRC GetDC(0) will get you a device context for the screen, but check out that whole family of functions. in Windows 7 it doesn't even foul up other applications' displays, and reportedly it's likewise "safe" on the mac.
for example, this draws an ellipse in the upper left of the screen:
#include <windows.h>
int main()
{
HDC const dc = GetDC( 0 );
Ellipse( dc, 10, 10, 200, 200 );
}
the graphic disappears if it's on top of a window and that window is moved.
You can achieve the device context (DC) of the screen, and draw in that DC as usual. The output will be directed to the screen. To achieve that, call WinApi GetDC("DISPLAY"), if i'm not mistaken.
I'm displaying a bitmap using GDI+. After loading the bitmap from a DLL resource I set the background colour (blue - #0000FF) to transparent using TransparentBlt. On Windows Vista and later this works as expected.
However, on a Windows XP system we're testing on this only works when any tooltip (e.g. the "title" property in IE, or Windows Explorer's tooltip shown when hovering the mouse over a file, etc) is displayed. The rest of the time the background colour is still blue.
Has anyone encountered this before, or know of a way to stop this occurring and for the blue to be properly made transparent?
Edit: After further investigation I found that setting colour depth in Windows XP to 16 bit colours instead of 32 bit colours caused TransparentBlt to start working normally again. Obviously this isn't an ideal solution, specifying what colour depth must be used, but does this give any hint to what might be happening?
Edit2: Code sample included.
m_pGDIBitmap = new Gdiplus::Bitmap(_Module.m_hInst, MAKEINTRESOURCE(lImageResource));
m_hMemDC = CreateCompatibleDC(hdc);
Gdiplus::Graphics myGraphics(m_hMemDC);
myGraphics.DrawImage(m_pGDIBitmap,
Gdiplus::Rect(0, 0, m_pGDIBitmap->GetWidth(), m_pGDIBitmap->GetHeight()),
0,
0,
m_pGDIBitmap->GetWidth(),
m_pGDIBitmap->GetHeight(),
Gdiplus::UnitPixel, &imAtt);
SetStretchBltMode(hdc, HALFTONE);
SetBrushOrgEx(hdc, rcBounds.left, rcBounds.top, NULL);
TransparentBlt(hdc, rcBounds.left, rcBounds.top, iScaledWidth, iScaledHeight, m_hMemDC, 0, 0, iBitmapWidth, iBitmapHeight, GetPixel(m_hMemDC, 0, 0));
You must show some sample code - the code that loads the bitmap and the code that blits it to display.
From the symptoms that you describe, my guess is that you load the bitmap not in its native format, but in the current display format. This means, that when the bit depth of the bitmap differs from the bit depth of the display, an automatic color space conversion is made. When this happens, the color that you provide to TransparentBlt is actually different from the color in the bitmap.
Possible alternative solutions:
Make sure that the bitmap is loaded in its native format without conversion.
Allow the conversion to take place, but instead of providing a hardcoded color value to TransparentBlt, make a GetPixel of a known "transparent" pixel of the bitmap (like top-left), and provide this value to the TransparentBlt.
What I ended up doing was more of a workaround, but it did work. I changed the background colour to black and added the following code before the DrawImage call:
Gdiplus::ImageAttributes imAtt;
imAtt.SetColorKey(Gdiplus::Color(0, 0, 0), Gdiplus::Color(0, 0, 0), Gdiplus::ColorAdjustTypeBitmap);
For some reason using this with blue as the background didn't work and using TransparentBlt on its own with either colour didn't work, but the combination applied the transparency correctly on the various OSes and colour depths that I tried.
If I had access to a paint program that supported bitmap files with an alpha channel, i.e. 32 bit bitmaps, I suspect making the background explicitly transparent and then using AlphaBlend would have worked as well but I didn't have the ability to try that at the time.
Windows 7 taskbar buttons are drawn on a shaded background. The color shade somehow reacts on where the mouse is over the button.
I'd like to use such buttons in my application. How can i do that ?
Perhaps try
DrawThemeBackground
http://msdn.microsoft.com/en-us/library/bb773289(VS.85).aspx
Give it the BS_PUSHBUTTON constant. I've used this in Windows XP to draw the plush blue XP themed controls, but not in Aero, but it's worth a try.
The effect is called "Color Hot-track". It does not seem that there is a dedicated API for that. There are some notes in a developer blog about it:
I found some source code from Rudi Grobler though doing a similar thing:
Make your WPF buttons color hot-track!
I believe they're implemented as shader programs on the GPU. Just a simple program which takes the cursor position, and computes a brightness for each pixel based on the distance from that position.
It uses the new animation api (Some of it exists in Vista, extended in 7) There is no magic style to set, you still need to do the drawing on your own