I'm trying to use the method described here to use a QPainter and GDI calls on the same widget.
Unfortunately this tutorial seem to have been written on an earlier version of Qt and now it does not work.
I set the WA_PaintOnScreen flag and reimplement paintEngine() to return NULL.
Then on the paintEvent() I create a QPainter, use it and then use some GDI calls to paint a bitmap. The GDI calls work fine but the QPainter does nothing. I get the following error on the console:
QPainter::begin: Paint device returned engine == 0, type: 1
Is this simply not supported anymore? how can I do it?
I've also tried creating an additional widget on top of the GDI-painting widget but that didn't go well as well since the top widget appears black and blocks the GDI widget.
I got this working in QT 4.7-beta 2 as follows
In the constructor call setAttribute(Qt::WA_PaintOnScreen,true);
Do NOT reimplement paintEngine() to return NULL;
Use the following code in the paintEvent();
QPainter painter(this);
HDC hdc = painter.paintEngine()->getDC(); // THIS IS THE CRITICAL STEP!
HWND hwnd = winID();
// From this point on it is all regular GDI
QString text("Test GDI Paint");
RECT rect;
GetClientRect(hwnd, &rect);
HBRUSH hbrRed = CreateSolidBrush(RGB(255,0,0));
FillRect(hdc, &rect, hbrRed);
HBRUSH hbrBlue = CreateSolidBrush(RGB(40,40,255));
HPEN bpenGreen = CreatePen(PS_SOLID, 4, RGB(0,255,0));
SelectObject(hdc,bpenGreen);
SelectObject(hdc,hbrBlue);
Ellipse(hdc,10,10,rect.right-20,rect.bottom-20);
SetTextAlign(hdc, TA_CENTER | TA_BASELINE);
TextOutW(hdc, width() / 2, height() / 2, text.utf16(), text.size());
ReleaseDC(hwnd, hdc);
This worked with Qt 4.0 and 4.1, but stopped working in either 4.2 or 4.3, when Trolltech reimplemented the Windows paint engine. In the second edition of the Qt 4 book, we added the sentence:
"For this to work, we must also reimplement QPaintDevice::paintEngine() to return a null pointer and set the Qt::WA_PaintOnScreen attribute in the widget's constructor."
I haven't tested it using later versions of Qt (I'm no longer at Trolltech/Nokia and have no Windows machine) but I hope it will still work.
Related
I'm an experienced programmer specialized in Computer Graphics, mainly using Direct3D 9.0c, OpenGL and general algorithms. Currently, I am evaluating Direct2D as rendering technology for a professional application dealing with medical image data. As for rendering, it is a x64 desktop application in windowed mode (not fullscreen).
Already with my very initial steps I struggle with a task I thought would be a no-brainer: Rendering a single-channel bitmap on screen.
Running on a Windows 8.1 machine, I create an ID2D1DeviceContext with a Direct3D swap chain buffer surface as render target. The swap chain is created from a HWND and buffer format DXGI_FORMAT_B8G8R8A8_UNORM. Note: See also the code snippets at the end.
Afterwards, I create a bitmap with pixel format DXGI_FORMAT_R8_UNORM and alpha mode D2d1_ALPHA_MODE_IGNORE. When calling DrawBitmap(...) on the device context, a debug break point is triggered with the debug message "D2d DEBUG ERROR - This operation is not compatible with the pixel format of the bitmap".
I know that this output is quite clear. Also, when changing the pixel format to DXGI_FORMAT_R8G8B8A8_UNORM with DXGI_ALPHA_MODE_IGNORE everything works well and I see the bitmap rendered. However, I simply cannot believe that! Graphics cards support single-channel textures ever since - every 3D graphics application can use them without thinking twice. This goes without speaking.
I tried to find anything here and at Google, without success. The only hint I could find was the MSDN Direct2D page with the (supported pixel formats). The documentation suggests - by not mentioning it - that DXGI_FORMAT_R8_UNORM is indeed not supported as bitmap format. I also find posts talking about alpha masks (using DXGI_FORMAT_A8_UNORM), but that's not what I'm after.
What am I missing that I can't convince Direct2D to create and draw a grayscale bitmap? Or is it really true that Direct2D doesn't support drawing of R8 or R16 bitmaps??
Any help is really appreciated as I don't know how to solve this. If I can't get this trivial basics to work, I think I'd have to stop digging deeper into Direct2D :-(.
And here is the code snippets of relevance. Please note that they might not compile since I ported this on the fly from my C++/CLI code to plain C++. Also, I threw away all error checking and other noise:
Device, Device Context and Swap Chain Creation (D3D and Direct2D):
// Direct2D factory creation
D2D1_FACTORY_OPTIONS options = {};
options.debugLevel = D2D1_DEBUG_LEVEL_INFORMATION;
ID2D1Factory1* d2dFactory;
D2D1CreateFactory(D2D1_FACTORY_TYPE_MULTI_THREADED, options, &d2dFactory);
// Direct3D device creation
const auto type = D3D_DRIVER_TYPE_HARDWARE;
const auto flags = D3D11_CREATE_DEVICE_BGRA_SUPPORT;
ID3D11Device* d3dDevice;
D3D11CreateDevice(nullptr, type, nullptr, flags, nullptr, 0, D3D11_SDK_VERSION, &d3dDevice, nullptr, nullptr);
// Direct2D device creation
IDXGIDevice* dxgiDevice;
d3dDevice->QueryInterface(__uuidof(IDXGIDevice), reinterpret_cast<void**>(&dxgiDevice));
ID2D1Device* d2dDevice;
d2dFactory->CreateDevice(dxgiDevice, &d2dDevice);
// Swap chain creation
DXGI_SWAP_CHAIN_DESC1 desc = {};
desc.Format = DXGI_FORMAT_B8G8R8A8_UNORM;
desc.SampleDesc.Count = 1;
desc.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT;
desc.BufferCount = 2;
IDXGIAdapter* dxgiAdapter;
dxgiDevice->GetAdapter(&dxgiAdapter);
IDXGIFactory2* dxgiFactory;
dxgiAdapter->GetParent(__uuidof(IDXGIFactory), reinterpret_cast<void **>(&dxgiFactory));
IDXGISwapChain1* swapChain;
dxgiFactory->CreateSwapChainForHwnd(d3dDevice, hwnd, &swapChainDesc, nullptr, nullptr, &swapChain);
// Direct2D device context creation
const auto options = D2D1_DEVICE_CONTEXT_OPTIONS_NONE;
ID2D1DeviceContext* deviceContext;
d2dDevice->CreateDeviceContext(options, &deviceContext);
// create render target bitmap from swap chain
IDXGISurface* swapChainSurface;
swapChain->GetBuffer(0, __uuidof(swapChainSurface), reinterpret_cast<void **>(&swapChainSurface));
D2D1_BITMAP_PROPERTIES1 bitmapProperties;
bitmapProperties.dpiX = 0.0f;
bitmapProperties.dpiY = 0.0f;
bitmapProperties.bitmapOptions = D2D1_BITMAP_OPTIONS_TARGET | D2D1_BITMAP_OPTIONS_CANNOT_DRAW;
bitmapProperties.pixelFormat.format = DXGI_FORMAT_B8G8R8A8_UNORM;
bitmapProperties.pixelFormat.alphaMode = D2D1_ALPHA_MODE_IGNORE;
bitmapProperties.colorContext = nullptr;
ID2D1Bitmap1* swapChainBitmap = nullptr;
deviceContext->CreateBitmapFromDxgiSurface(swapChainSurface, &bitmapProperties, &swapChainBitmap);
// set swap chain bitmap as render target of D2D device context
deviceContext->SetTarget(swapChainBitmap);
D2D single-channel Bitmap Creation:
const D2D1_SIZE_U size = { 512, 512 };
const UINT32 pitch = 512;
D2D1_BITMAP_PROPERTIES1 d2dProperties;
ZeroMemory(&d2dProperties, sizeof(D2D1_BITMAP_PROPERTIES1));
d2dProperties.pixelFormat.alphaMode = D2D1_ALPHA_MODE_IGNORE;
d2dProperties.pixelFormat.format = DXGI_FORMAT_R8_UNORM;
char* sourceData = new char[512*512];
ID2D1Bitmap1* d2dBitmap;
deviceContext->DeviceContextPointer->CreateBitmap(size, sourceData, pitch, d2dProperties, &d2dBitmap);
Bitmap drawing (FAILING):
deviceContext->BeginDraw();
D2D1_COLOR_F d2dColor = {};
deviceContext->Clear(d2dColor);
// THIS LINE FAILS WITH THE DEBUG BREAKPOINT IF SINGLE CHANNELED
deviceContext->DrawBitmap(bitmap, nullptr, 1.0f, D2D1_INTERPOLATION_MODE_LINEAR, nullptr);
swapChain->Present(1, 0);
deviceContext->EndDraw();
From my little experience, Direct2D seems very limited, indeed.
Have you tried Direct2D effects (ID2D1Effect)? You can write your own [it seems comparatively complicated], or use one of the built-in effects [which is rather simple].
There is one called Color matrix effect (CLSID_D2D1ColorMatrix). It might work to have your DXGI_FORMAT_R8_UNORM (or DXGI_FORMAT_A8_UNORM, any single-channel would do) as input (inputs to effects are ID2D1Image, and ID2D1Bitmap inherits from ID2D1Image). Then set the D2D1_COLORMATRIX_PROP_COLOR_MATRIX for copying the input channel to all output channels. Have not tried it, though.
I have a problem with off-screen rendering with OpenGL.
I searched for a lot about FBO and PBO but nothing was helpful for me.
I guess the matter was from memDC which was made by CreateCompatibleDC.
Here is a part of my code
void COpenGLWnd::ShowinWnd(int ID)
{
m_hDC = ::GetDC(m_hWnd);
memDC = CreateCompatibleDC(m_hDC);
SetDCPixelFormat(memDC);
m_hRC = wglCreateContext(memDC);
VERIFY(wglMakeCurrent(memDC, m_hRC));
m_isitStart = 0;
GLuint pbo;
glGenBuffersARB(1,&pbo);
glBindBufferARB(GL_PIXEL_PACK_BUFFER_ARB, pbo);
glBufferDataARB(GL_PIXEL_PACK_BUFFER_ARB, (m_WndWidth * 3 + 3) / 4 * 4 * m_WndHeight, NULL, GL_STREAM_READ);
glBindBufferARB(GL_PIXEL_PACK_BUFFER_ARB, pbo);
switch(ID)
{
case T_FADEIN:
GLFadeinRender();
break;
case T_PARANORAMAL:
GLParanormalRender();
break;
case T_3DCUBE:
GL3DcubeRender();
break;
default:
break;
}
glBindBufferARB(GL_PIXEL_PACK_BUFFER_ARB, pbo);
glReadBuffer(GL_BACK);
glReadPixels(0,0,m_WndWidth,m_WndHeight,GL_BGR_EXT,GL_UNSIGNED_BYTE, 0);
BYTE* data = (BYTE*) glMapBufferARB(GL_PIXEL_PACK_BUFFER_ARB, GL_READ_ONLY_ARB);
if(data)
{
SaveBitmapToDirectFile(data); //this makes bitmap file with pixel BYTE array, "data".
glUnmapBufferARB(GL_PIXEL_PACK_BUFFER_ARB);
}
glBindFramebuffer(GL_PIXEL_PACK_BUFFER_ARB,0);
SwapBuffers(memDC);
glDeleteBuffers(1,&pbo);
wglMakeCurrent(memDC, NULL);
wglDeleteContext(m_hRC);
DeleteDC(memDC);
::ReleaseDC(m_hWnd, m_hDC);
}
If I run this programm without memDC and CreateContext on m_hDC, nothing was matter. Well rendered on window, well written bitmap file. But I want to render in off-screen and only saving bitmap files. How can I handle this?
MemDCs will automatically drop you back to the old, OpenGL-1.1 software rasterizer. This rasterizer is very limited, does not support any kind of modern features, like FBOs, PBuffers and so on.
If you want a GPU accelerated OpenGL context you need to create this on a regular window (or a PBuffer DC, but to get a PBuffer DC you need a window first). You need the window just for getting the context, you don't have to render there and the window can stay hidden all the time (omit the ShowWindow call of the creation process). With a valid pixelformat set for the window create the OpenGL context on its HDC.
Since you already have a window, just go with that then.
With the OpenGL context from a regular window you can then use FBOs for off-screen rendering.
I followed this tutorial (there's a bit more than what's listed here because in my code I get a window via mouse click) for grabbing a window as a bitmap and then rendering that bitmap in a different window.
My question:
When that window is minimized or hidden (SW_HIDE) my screen capture doesn't work, so is it possible to capture a window when it is minimized or hidden?
The PrintWindow api works well, I use it for capturing thumbnails for hidden windows. Despite the name, it is different than WM_PRINT and WM_PRINTCLIENT, it works with pretty much every window except for Direct X / WPF windows.
I added some code (C#) but after reviewing how I used the code, I realized that the window isn't actually hidden when I capture its bitmap, its just off screen so this may not work for your case. Could you show the window off screen, do a print and then hide it again?
public static Bitmap PrintWindow(IntPtr hwnd)
{
RECT rc;
WinUserApi.GetWindowRect(hwnd, out rc);
Bitmap bmp = new Bitmap(rc.Width, rc.Height, PixelFormat.Format32bppArgb);
Graphics gfxBmp = Graphics.FromImage(bmp);
IntPtr hdcBitmap = gfxBmp.GetHdc();
bool succeeded = WinUserApi.PrintWindow(hwnd, hdcBitmap, 0);
gfxBmp.ReleaseHdc(hdcBitmap);
if (!succeeded)
{
gfxBmp.FillRectangle(new SolidBrush(Color.Gray), new Rectangle(Point.Empty, bmp.Size));
}
IntPtr hRgn = WinGdiApi.CreateRectRgn(0, 0, 0, 0);
WinUserApi.GetWindowRgn(hwnd, hRgn);
Region region = Region.FromHrgn(hRgn);
if (!region.IsEmpty(gfxBmp))
{
gfxBmp.ExcludeClip(region);
gfxBmp.Clear(Color.Transparent);
}
gfxBmp.Dispose();
return bmp;
}
There are WM_PRINT and WM_PRINTCLIENT messages you can send to the window, which cause its contents to be rendered into the HDC of your choice.
However, these aren't perfect: while the standard Win32 controls handle these correctly, any custom controls in the app might not.
I am trying to get the bitmap of partially hidden controls.
I used code before that did the drawing, but included windows overlapping it. So.. maybe you want to try this.
The WM_PRINTCLIENT should (in my understanding) redraw all inside the control, even if it is not really visible.
const int WM_PRINT = 0x317, WM_PRINTCLIENT = 0x318, PRF_CLIENT = 4,
PRF_CHILDREN = 0x10, PRF_NON_CLIENT = 2,
COMBINED_PRINTFLAGS = PRF_CLIENT | PRF_CHILDREN | PRF_NON_CLIENT;
SendMessage(handle, WM_PRINTCLIENT, (int)hdc, COMBINED_PRINTFLAGS);
//GDIStuff.BitBlt(hdc, 0, 0, width, height, hdcControl, 0, 0, (int)GDIStuff.TernaryRasterOperations.SRCCOPY);
The before code is commented out now. It is based on the code found here: Pocket PC: Draw control to bitmap (accepted answer). It is basically the same as Tim Robinson suggests in this thread.
Also, have a look here
http://www.tcx.be/blog/2004/paint-control-onto-graphics/
I'm completely new to win32. I have been working on it the last 48 hours.
I'm trying to build a "grid", and I got examples of a List-View control and a Header control on msdn.microsoft.com .
The first one calls the InitCommonControls() function (besides I read this function is obsolete).
HWND DoCreateHeader(HWND hwndParent, HINSTANCE hInst)
{
HWND hwndHeader;
RECT rcParent;
HDLAYOUT hdl;
WINDOWPOS wp;
// Ensure that the common control DLL is loaded, and then create
// the header control.
InitCommonControls();
// ...
// hwndHeader = CreateWindowEx(0, WC_HEADER, ...
}
The second one calls the InitCommonControlsEx() function.
HWND CreateListView (HWND hwndParent, HINSTANCE hInst)
{
RECT rcl;
INITCOMMONCONTROLSEX icex;
// Ensure that the common control DLL is loaded.
icex.dwSize = sizeof(INITCOMMONCONTROLSEX);
icex.dwICC = ICC_LISTVIEW_CLASSES;
InitCommonControlsEx(&icex);
// ...
// HWND hWndListView = CreateWindow(WC_LISTVIEW ...
}
Seems these functions need comctl32.lib library, but download it is a mess.
Furthermore I have noticed that if I remove these functions, everything keeps working well. Then, are they necessary?
Thanks!
Yes it is necessary. They are required to get the window classes for those custom controls registered. Odds are, some other component in your code is loading them. I'm not sure, but I think if you have support for comctl v6 (XP and up visual styles) in your manifest, you get commctl32.dll automatically.
More info on what InitCommonControlsEx does is here.
Not sure what you mean by downloading comctl32.lib, it is present on every Windows platform since NT 4 and Windows 95 so you don't need to redistribute it.
I have a chart (in bitmap format) that I'm trying to render to a printer using StretchBlt. When drawing to the screen, StretchBlt works fine. When drawing to a CutePDF printer, it returns 0, sets the last error to ERROR_INVALID_HANDLE, and works anyway. When drawing to a PDF995 printer or a physical HP printer, it returns 0, sets the last error to ERROR_INVALID_HANDLE, and fails to draw anything.
What would cause StretchBlt to fail for certain devices? I've verified that the source bitmap is a DIB and that the destination supports StretchBlt by calling GetDeviceCaps.
Here's my code, in case it's relevant: (It's written in C++Builder, so it uses Delphi's VCL; TCanvas wraps an HDC, and TBitmap wraps an HBITMAP. VCL provides its own StretchDraw function which does not support HALFTONE; I'm getting the same problems with it.)
void PrettyStretchDraw(TCanvas *dest, const TRect& rect, TGraphic *source)
{
if (dynamic_cast<Graphics::TBitmap*>(source) && !source->Transparent) {
POINT pt;
GetBrushOrgEx(dest->Handle, &pt);
SetStretchBltMode(dest->Handle, HALFTONE);
SetBrushOrgEx(dest->Handle, pt.x, pt.y, NULL);
StretchBlt(
dest->Handle,
rect.Left,
rect.Top,
rect.Width(),
rect.Height(),
dynamic_cast<Graphics::TBitmap*>(source)->Canvas->Handle,
0,
0,
source->Width,
source->Height,
SRCCOPY);
} else {
DrawItSomeOtherWay(dest, rect, source);
}
}
StretchBlt is broken on some printer drivers (PDF995 is notable example).
I once encontered this error happening on Windows 2003 Server only (it worked on XP).
Try to reproduce the problem on other OS, and it it does not, consider it OS specific and use StretchDIBits instead on this OS.