It's a while since I've done this, but I'm trying to add a custom button graphic to a windows button, with some transparent areas. I've tried various schemes but can't seem to get the transparent areas to show. Here's my code:
hbmpUpDisabled = LoadImage(instance,MAKEINTRESOURCE(IDB_UPARROWDISABLED), IMAGE_BITMAP, 0, 0, LR_DEFAULTSIZE | LR_LOADTRANSPARENT | LR_LOADMAP3DCOLORS );
SendMessage(GetDlgItem(hWndDlg, IDC_MOVEUP),BM_SETIMAGE,(WPARAM)IMAGE_BITMAP,(LPARAM)hbmpUpDisabled);
Does anyone notice any problems here? It works if my bitmap is a 1-bit bitmap. I couldn't get a 32 bit bitmap to work, and I'm not sure how to setup a 24 bit or 8 bit bitmap to do it.... I tried a custom 255,0,255 color (which IIRC is a default transparent value), but so far no joy....
LR_LOADMAP3DCOLORS should map grey - in the source image - to to the current button face color. Buttons do not use AlphaBlt or TransparentBlt so there is no way to actually (short of custom painting) set a bitmap with transparent or alpha'd areas onto a button and expect it to work. You just have to pre-prepare the bitmap with the correct button color in its background areas.
That said - I suspect that some of these restrictions may be lifted for buttons implemented by common controls v6. Add commctl 6 as a dependend assembly to your exe and see if the behaviour changes.
Related
I need a way to display a PNG image with transparent background on a background with gradient color.
I have tried this:
CImage img;
CBitmap bmp;
img.Load(_T(".\\res\\foo.png"));
bmp.Attach(img.Detach());
CDC dcStatus;
dcStatus.CreateCompatibleDC(&dc);
dcStatus.SelectObject(&bmp);
dcStatus.SetBkColor(TRANSPARENT);
dc.BitBlt(rectText.left + 250, rectText.top, 14, 14, &dcStatus, 0, 0, SRCCOPY);
bmp.DeleteObject();
but foo.png gets black background wherever it is transparent in original image.
I did try to do a new bitmap that was painted with transparent color and did all possible operations on it, but that didn't help. Sample of one permutation:
CImage img;
CBitmap bmp;
img.Load(_T(".\\res\\foo.png"));
bmp.Attach(img.Detach());
CBitmap bmpMaska;
bmpMaska.CreateBitmap(14, 14, 1, 1, NULL);
CDC dcStatus;
dcStatus.CreateCompatibleDC(&dc);
dcStatus.SelectObject(&bmp);
CDC dcMaska;
dcMaska.CreateCompatibleDC(&dc);
dcMaska.SelectObject(&bmpMaska);
dcMaska.SetBkColor(dcStatus.GetPixel(0, 0));
//TODO: Bitmap ni transparent
dc.BitBlt(rectText.left + 250, rectText.top, 14, 14, &dcMaska, 0, 0, SRCCOPY);
dc.BitBlt(rectText.left + 250, rectText.top, 14, 14, &dcStatus, 0, 0, SRCAND);
bmp.DeleteObject();
bmpMaska.DeleteObject();
This did not do the trick. Either, there was all black square on the screen, or the result was the same as original.
I have also checked AlphaBlend API, but my code must be pure MFC + C++ witthout any additional APIs.
[Edit]: Company policy is as little APIs as possible. The code is supposed to run on embedded windows systems in real time.
[Edit 2]: I am not bound to PNG image format, meaning, anything that will display as transparent, goes.
Please, tell me what am I doing wrong?
Convert the png to a 32 bit bmp file. Google 'AlphaConv' and use that. PNG's are a PITA to work with - several API's claim to support them but actually don't, or only partially, or only on some platforms etc.
Load your 32-bit bmp using CBitmap::LoadBitmap (from resources - this is by far the easiest)
Then use CDC::AlphaBlend() to draw your bitmap. TransparentBlt() doesn't work with an alpha channel - it's just either draw the pixel or not. AlphaBlend is part of the win32 API, and you could still investigate CImage::AlphaBlend if you'd like, but that has a bug somewhere (I forgot what exactly) so I always use the raw ::AlphaBlend.
But beware - you need to premultipy the alpha channel for correct display. See my answer on How to draw 32-bit alpha channel bitmaps? .
No variation of what you described will work. You need another API to get this to work. Or, you could use GetDIBits and do your own version of ::AlphaBlend() :)
Based on what you're asking for (simply some set of pixels being transparent) it's probably easiest to use a 24- or 32-bit BMP, and simply pick a color to treat as transparent. Pre-process your picture to take any pixel that precisely matches your transparent color and increase change the least significant bit of one of the channels.
Given 8 bits per channel, this won't normally cause a visible change. Then draw the pixels you want transparent in one exact color. This is easy to do in something like a paint program.
You can then draw that to your DC using TransparentBlt. That lets you specify the color you want to treat as transparent.
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've implemented a owner draw button into my win32 app (no MFC). The button is a normal 20x20 bitmap (round icon with transparency). The problem is that the button is positioned on a solid background and i can see the buttons gray background (since the bitmap is round). I've tried responding to WM_CTLCOLORBTN with NULL_BRUSH but no luck.. I've tried displaying the button using a bitmap and a ico file but wont budge.. Does anyone know how to solve this problem?
This is my problem, the settings icon should be transparent at the edges (not white/gray)
It sounds like you're trying to make a non-rectangular control.
You could call SetWindowRgn to tell Windows that your control is non-rectangular.
In addition to what #joel's answer, if you want to make some area transperant put a unique color in the area where you want to have transperancy using some image editors (RGB(0xFF,0x00,0xFF)) is mostly used Then use TransperantBlt
You say it's a solid background but your image shows some kind of orange-yellow gradient as a background. If it really was a standard windows button solid color you can load the bitmap with LoadImage using the LR_LOADMAP3DCOLORS or LR_LOADTRANSPARENT. Since you have a gradient you'll have to use a more complicated technique to mask out the bitmap.
http://www.winprog.org/tutorial/transparency.html
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.
I'm creating a non-intrusive popup window to notify the user when processing a time-consuming operation. At the moment I'm setting its transparency by calling SetLayeredWindowAttributes which gives me a reasonable result:
alt text http://img6.imageshack.us/img6/3144/transparentn.jpg
However I'd like the text and close button to appear opaque (it doesn't quite look right with white text) while keeping the background transparent - is there a way of doing this?
In order to do "proper" alpha in a layered window you need to supply the window manager with a PARGB bitmap by a call to UpdateLayeredWindow.
The cleanest way to achieve this that I know of is the following:
Create a GDI+ Bitmap object with the PixelFormat32bppPARGB pixel format.
Create a Graphics object to draw in this Bitmap object.
Do all your drawing into this object using GDI+.
Destroy the Graphics object created in step 2.
Call the GetHBITMAP method on the Bitmap object to get a Windows HBITMAP.
Destroy the Bitmap object.
Create a memory DC using CreateCompatibleDC and select the HBITMAP from step 5 into it.
Call UpdateLayeredWindow using the memory DC as a source.
Select previous bitmap and delete the memory DC.
Destroy the HBITMAP created in step 5.
This method should allow you to control the alpha channel of everything that is drawn: transparent for the background, opaque for the text and button.
Also, since you are going to be outputting text, I recommend that you call SystemParametersInfo to get the default antialiasing setting (SPI_GETFONTSMOOTHING), and then the SetTextRenderingHint on the Graphics object to set the antialiasing type to the same type that is configured by the user, for a nicer look.
I suspect you'll need two top level windows rather than one - one that has the alpha blend and a second that is display above the first with the opaque text and button but with a transparent background. To accomplish this with a single window you'll need to use the UpdateLayeredWindow API call, but using this will cause your buttons to not redraw when they are interacted with (hover highlights, focus etc.)
It is possible that if this application is for Vista only there is a new API call that you can use, but I do not believe it is available in XP or earlier.
I can't say for sure, you'll need to try it, but since everything is a window, you could try setting the layered attributes for your button to make it opaque.
As for the text, you may be able to put that in its own frame with a set background and foreground color, and modify its layered attributes to make the background color transparent...
But since these are child windows and not the top-level window, I really don't know that it'll work.