I have a window on which I call DwmExtendFrameIntoClientArea(),
the window hosts other child windows, I use Direct2D to paint on one of the child windows,
When a bitmap is loaded which has a black region on it, that region becomes blurred.
I wish to clear everything in the child window and paint it again on WM_PAINT, however I cannot seem to clear the contents.
I have tried to clear it using
m_pRenderTarget->Clear(D2D1::ColorF(D2D1::ColorF::Black))
This makes the child window region black, it erases all previous drawing, but no transparency.
I have tried to draw a bitmap which is just a black bar over the client area
m_pRenderTarget->DrawBitmap(m_pBkgrnd,D2D1::Rect<float> (0.f,0.f,GetWidth(),GetHeight()))
This makes whatever that had appeared before it, in black.
Tried the old GDI way of painting a black region over the entire child window,
RECT rc;
GetClientRect(m_hwnd, &rc);
HBRUSH brush = CreateSolidBrush(RGB(0,0,0));
HDC hc=GetDC(m_hwnd);
FillRect(hc, &rc, brush);
ReleaseDC(m_hwnd,hc);
DeleteObject(brush);
Doesn't work.
However if I don't do any of this and I try to resize the main window, it works right i.e. the previous painting dissappears.
Is there any API call or any way to clear the window manually before I draw it again?
How are you initializing your render target? Make sure you specify Premultipled Alpha, and not Straight or Ignore. Then, to clear everything to transparent, use ID2D1RenderTarget::Clear(D2D1::ColorF(0, 0, 0, 0)). You cannot use something like FillRectangle to draw with a transparent color, as that will blend the transparent color into what's already there and that is a no-op.
Related
I'm new to X and Linux programming in general. It's pretty easy to suppress a window background repaint (to reduce flicker when the window is resized) using VC++ and Windows. However the architecture and difficulty in finding comprehensive documentation for X is a different game altogether.
You can create a pixmap which will serve as an offscreen temporary buffer, draw into it, and after all drawing operations have been completed update the window background only once:
Pixmap pixmap = XCreatePixmap(display,
rootWindow,
width,
height,
XDefaultDepthOfScreen(screen));
// Draw into pixmap
// ...
// ...
// And update window background after that
XSetWindowBackgroundPixmap(display, window, pixmap);
XClearWindow(display, window);
This question was generated by a response to another question: Common Controls on a Transparent Window?.
Apparently, there is a way to only paint the background without a control painting itself again This would solve the problem of having common control buttons on a transparent background.
So my question is, how do I paint only the background around a common control after the common control has painted itself?
About how to redraw visible borders.
The rounded rectangle drawn by RoundRect is used as representative
The FrameRgn function draws a border around the specified region by using the specified brush.
Simple code demonstration：
HRGN hRegion = ::CreateRoundRectRgn (0, 0, ClientWidth, ClientHeight,12,12);
Canvas->Brush->Style = bsSolid;
Canvas->Brush->Color = RGB(96, 96, 96);
::FrameRgn(Canvas->Handle, hRegion, Canvas->Brush->Handle, 2, 2);
::DeleteObject(hRegion); // Don't leak a GDI object
Link you need: Redraw Border
I'm hoping I can get away with communicating the issue I'm having clearly without posting a ton of source code. The source is all ASM and while most would understand it, it's still not their primary "thing."
I have a layered window which is working perfectly - up to the point of resizing it. The window is all per-pixel alpha. There are no transparent pixels. The borders and caption are opaque (255 alpha); the client area is something like 128 alpha or whatever I put it at. So no transparent pixels.
I have a function that handles redraws - it's actually geared toward rebuilding the frame for a new window size. GetWindowDC is called on the layered window. CreateCompatibleDC creates off of that DC. The bitmap is a DIB section. The bitmap is properly sent to UpdateLayeredWindow. Again, everything works perfectly as long as the window is not in active resize (border drag).
I have tried using DefWindowProc to handle border drags, as well as completely handling all aspects of that functionality myself. The results are the same: massive flicker but ONLY beyond the window boundaries that existed before border drag began, and then the window size does not ultimately change - sort of. The original window area remains displayed without issue. No flicker there. However if (for example) I'm dragging the right border to the right, everything right of the original window right edge flickers rapidly then vanishes. When I release the left mouse button, the display remains at the original size (the size the window was before dragging the border). I've verified the bitmap is correctly rebuilt to the new size. It seems like the DC for the layered window doesn't want to resize because the entire area of original window size is completely stable, but any new area appearing post-resize flickers then hides.
I've even tried removing the ws_ex_layered style before resizing the window in my manual handling (I've tried both MoveWindow and SetWindowPos) then resetting the ex style after SetWindowPos / MoveWindow but before dragging.
When I let DefWindowProc handle the updates, I got the exact same result. So indications are that something is wrong with my repainting. But I even whittled that process down (commenting out oodles of code for test) and just filled the bitmap with 0xFF0000FF (arbitrary test value, blue, full opacity) then jumped straight to UpdateLayeredWindow. Same result.
The bitmap used for UpdateLayeredWindow is deleted before calling the "rebuild" function and within the function that bitmap is recreated to the new size. I have verified the new size extensively - I can see the new bitmap as it high-speed flickers and it's all good. The DC is GetWindowDC from the layered window. The compatible DC creates off that DC. The bitmap is selected into the compatible DC, and that compatible DC is passed to UpdateLayeredWindow. If any of these things were off, I would never see the new bitmap displayed. It's there - it just flickers at high speed ONLY beyond the window bounds that existed before resize began. DefWindowProc yields the same results. Within that original area, my caption buttons slide off to the right as I drag the right border to the right, further verifying everything is good.
I'm at a loss. Any input would be welcome.
Hi I want to clear out the DrawText() and I don't know how to do it properly. I could simply SetTextColor to the color of my background but this is not elegant way to do it I think. I dont know maybe I could do something with a rectangle rc that holds my text.
I draw by case WM_PAINT and in it:
hdc=BeginPaint(hwnd, &paint);
.... //some other code here
DrawText(hdc, TEXT("some text"), -1, &rc, DT_SINGLELINE);
....//some other code here
EndPaint(hwnd, &paint);
and one more thing. I don't have DeleteDC(hdc); or ReleaseDC(hdc); in my WM_PAINT is that ok, or I should have them after or before EndPaint(hwnd, &paint);?
There's no way to "clear" text that you've drawn other than to draw something else over the top. If your background is a solid color then just draw a rectangle of that color (you can work out how big it needs to be by using the DT_CALCRECT flag with DrawText). If your background is an image then you need to blit the appropriate area of the image.
Note that drawing the text over the top of itself using the background color (as you suggest) may not work because of ClearType/anti-aliasing.
To answer your second question, no - the DC returned by BeginPaint is effectively deleted by the call to EndPaint and so you don't need to (and mustn't) delete it separately.
I am implementing a border control in win32, and I have implemented various styles for that border. I am using simple MoveTo() and LineTo() commands for drawing the border.
My problem is, when i select some new style for my border, it starts painting over the currently drawn border. I understand i need to refresh/repaint my window inorder to have a fresh canvas. I am using InvalidateRect() for now to achieve this purpose. But I am concerned, If i have other windows associated with my border control window (as child windows), how will this effect the child windows?i will need to repaint everything on this window, correct?
Secondly, Is there anyway I can draw lines inside a GDI Region (HRGN)? So far, all i have come across is how to fill up that HRGN with some fill color. Is there anyway i can retrieve HDC associated with that particular HRGN object??
This is not a concern, anything you draw is automatically clipped by the child window rectangles. No extra code is required. The underlying window style flag is WS_CLIPCHILDREN.
You cannot draw lines in a region nor are they associated with a device context. Other than by drawing the region and then drawing the lines in your paint message handler. You are probably interested in paths. The MSDN docs start here.