As the title says.
Even with CPaintDC in the derived class the GDI drawing is not cut off.
Thanks in advance.
void CGraph::OnPaint ()
{
CPaintDC dc(this);
dc.SetViewportOrg (0, 400);
dc.SetMapMode(MM_ISOTROPIC);
dc.SetWindowExt(1000, 800);
dc.SetViewportExt(1000, -800);
// MessageBox(L"OnPaint");
ProcessData ();
DrawCoordinateSystem (&dc);
DrawGrid (&dc);
DrawGraph (&dc);
}
So, your CGraph is derived from CStatic, and the drawing code you show draws outside of the CStatic control, onto the dialog it is on? That's impossible, a control can only draw on itself. Are you sure the control isn't bigger than you think it is, and what you think is off-control actually isn't? Use spy++ to select your cstatic, it'll show you the border of the window.
Maybe what you are seeing is improper invalidation. Try dragging another window over your control, see what that does.
Otherwise, the methods to restrict the drawing area are
You manually track where to draw. Tedious.
Use SetClipRgn() to set the area to which to restrict drawing.
Not quite the same, but symptoms sometimes look similar: check the WS_CLIPSIBLINGS and WS_CLIPCHILDREN flags of your control and the dialog it's on.
Here is the way I solved the problem
CDC* pDC = GetDC();
CRect rClient(0,0,1000,800);
//GetClientRect(rClient);
CRgn ClipRgn;
if (ClipRgn.CreateRectRgnIndirect(&rClient))
{
pDC->SelectClipRgn(&ClipRgn);
}
pDC->SelectObject (PenBlack);
pDC->MoveTo (-leftMargin*zoomWidth, setPointsCorrected);
pDC->LineTo (1000*zoomWidth, setPointsCorrected);
pDC->SelectClipRgn(NULL);
ReleaseDC(pDC);
Related
I'm currently trying to draw something outside OnPaint function. I know there are many duplicate questions on the internet, however, I failed to get any of them to work. This is entirely because of my lack of understanding of MFC.
What works inside OnPaint:
CDC* pDC = GetDC();
HDC hDC = pDC->GetSafeHdc();
CRect lDisplayRect;
GetDlgItem(IDC_DISPLAYPOS)->GetClientRect(&lDisplayRect);
GetDlgItem(IDC_DISPLAYPOS)->ClientToScreen(&lDisplayRect);
ScreenToClient(&lDisplayRect);
pDC->FillSolidRect(&lDisplayRect, GetSysColor(COLOR_3DDKSHADOW));
pDC->TextOutW(300, 300, TEXT("test"));
It fills the area of the button control I have with a defined colour.
And it prints out the "test" string without any issue.
But it won't work outside OnPaint.
I've seen numerous suggestions such as using CmemDC,CPaintDC, etc
But none of them worked outside OnPaint.
For example,
CClientDC dc(this);
dc.rectangle( ....);
does not work.
Please note that this is a temporary test code and what I am eventually trying to do is draw incoming frames from a frame grabber within my display thread (a separate thread from the main UI thread) on the DisplayPos area and my dlg object(the dialog) owns an instance of the DisplayThread class. And I'm passing HWND and displayrect upon creating the member mDisplayThread so I can draw stuff within the display thread and that's the reason why I need to be able to draw to DC outside OnPaint (DisplayThread class does not have OnPaint or inherit any class that has it).
I'm in dire need of help...Please help!
Added: I have overridden PreTranslateMessage(MSG* pMsg) and made it return without calling the default function just in case WM_ERASE msg is erasing everything, but this approach didn't work either.
For example:
void CMFCApplicationDlg::OnLButtonDown(UINT nFlags, CPoint point)
{
// TODO: Add your message handler code here and/or call default
HDC hdc = ::GetDC(m_hWnd);
Ellipse(hdc, point.x - 10, point.y - 10, point.x + 10, point.y + 10);
::ReleaseDC(m_hWnd, hdc);
CDialogEx::OnLButtonDown(nFlags, point);
}
Two important suggestions:
Do not draw outside of OnPaint. The content may be erased or painted over at the direction of OS.
Do not draw on the dialog surface. First, it is not designed for that. It may be affected by other controls or by theming, skinning, etc. Just create a window with your own window procedure, so you are in control.
I would store the information needed for drawing in you frame grabber, and cause an immediate window painting by calling RedrawWindow
I'm programming an MFC application. I created a CStatic derived control on my Form dialog, so that I see the form directly when starting the program. I'm now drawing in this control with the OnPaint() Method in the derived class. So far, everything works.
However, strangely the drawings aren't clipped outside of the control. Instead,the whole form is painted if I draw really big things. In my understanding, only the control should be painted.
Thanks in advance
Andreas D.
#dlb Got it now.
CDC* pDC = GetDC();
CRect rClient();
GetClientRect(rClient);
CRgn ClipRgn;
if (ClipRgn.CreateRectRgnIndirect(&rClient))
{
pDC->SelectClipRgn(&ClipRgn);
}
// Drawing content
pDC->SelectClipRgn(NULL);
ReleaseDC(pDC);
Thanks for your answer
Check if your control is using the 'Unclipped Device Context' option. You can check this by getting the control flags.
You can also call IsOptimizedDraw() and if that return true then your drawing can draw outside the control.
I am quite desperate to resolve this very annoying issue :(
I am trying to display a child window on parent window. Some time the window need to be resized. But for some reason, when I using MoveWindow function it leaves blank space on the top of the parent window. I would like to present a picture here but I can not post a picture.
Here is the code example:
HWND hwnd // Comes from external function. Was defined as WS_CHILD previously
HWND hwndParent = ::GetParent(hwnd);
RECT parentRect = {0,0,0,0};
RECT childRect = {0,0,0,0};
::GetClientRect(hwndParent, &parentRect); // Suppose it returns {0,0,600,300}
BOOL ok = ::MoveWindow(hwnd, 0, 0, 600, 300, true);
::GetClientRect(hwnd, &childRect); // Will return {0,0,584,297}
WHY ?????
What am I doing wrong? Did I forgot some flags with window initialization?!
Rather than use GetClientRect, use GetWindowRect and MapWindowPoints(NULL,hwndParent,&parentRect,2) to adjust it to the parent window coordinates. GetWindowRect will include the non-client area that MoveWindow requires.
Edit: If you want a window that doesn't have a non-client area so the window rect and the client rect are the same size, you need to trim the window styles that you apply to the window. Avoid the WS_BORDER, WS_CAPTION, WS_DLGFRAME, WS_OVERLAPPED, WS_SIZEBOX, and WS_THICKFRAME styles.
MoveWindow updates window position, while GetClientRect gets a client-area part of the window, which does not have to be the same. If your window has non-client area, then everything is fine and works as expected.
If you are still under impression that child window does not fully cover parent's client area, then the spacing belongs to the child control/window, and you need to look for ways to remove it there (control flags, parameters etc).
MoveWindow operates on window coordinates -- including non-client area (borders, title bar, etc).
GetClientRect gets the area of the client portion of the window, ignoring borders, title bar, etc.
This is where the mismatch is. If you want to MoveWindow to a desired client size, you need to just AdjustWindowRect to try and predict what to pass into MoveWindow. Note that it's not always possible, and not always accurate. For example minimum / maximum sizes of windows, menus (which can wrap to multiple lines), etc.
The problem was WS_POPUP flag to the parent window.
Very strange. As far as I know it was not suppose to have such an effect.
Thanks for everyone!
I'm writing a control that may have some of its parts transparent or semitransparent. Basically this control shows a png image (with alpha channel). The control's parent window has some graphics on it. Therefore, to make the png control render correctly it needs to get image of what the parent window would draw beneath it. Parent dialog might have WS_CLIPCHILDREN flag set, that means that the the parent window won't draw anything under the the png control and in this case png control won't work properly.
This control has to work on Windows Mobile also, so it can't have WS_EX_TRANSPARENT
Funny you should ask. I just wrote code to do this yesterday. It's in the code base for Project Resistance. Look at how ResistorView (which has a PNG with transparency) interacts with MainForm (which has the background image).
I'm not doing c#, so I don't think that could be helpful. I tried to look into your code and I don't see anything that can solve my problem even though you accomplish the same task as me.
To give more details, my control also supports gif animation and I also used the same IImage load from stream as you do in your project. From my experience, that IImage load from stream is unbelievable junk code, it's extremely slow. I have no idea how that possibly could be so slow. Loading 32x32 gif with 31 frames takes like 1.5secods using that junk IImage stuff. I wrote my own loader (using some opensource gif library) and without any optimization entire decoding/loading of the gif frames takes less than 100ms. I'm using TouchPro2... I can't imagine how badly this code would perform on a low end device.
As a quick alternative here's a possible solution to my question:
in the WM_PAINT handler of the child control that draws images (gif or png) I do the following:
first, I call SetRedraw(false) on self and on parent window.
then I hide the child control, and send WM_PAINT to parent window with optional HDC (as wParam). The parent window renders everything to the offscreen bitmap (passed via hdc to WM_PAINT) and after WM_PAINT successfully returns I take relevant part of the offscreen bitmap.
Then I enable show the child window and call SetRedraw(true) on both child and the parent window. That trick works but has some disadvantages obviously (I need to createa huge offscreen bitmap to capture entire screen area even though I need 32x32 pixel from the middle of parent window).
the code is below:
bool pic_control::get_parent_bg(MyBitmap & bg)
{
CWindow parent = GetParent();
CClientDC dc(parent);
bool is_visible = IsWindowVisible() && parent.IsWindowVisible();
if(!is_visible){
return false;
}
parent.SetRedraw(false);
SetRedraw(false);
CRect rect;
parent.GetClientRect(rect);
MyBitmap bmp;
bmp.create(rect.Width(), rect.Height());
ShowWindow(SW_HIDE);
parent.SendMessage(WM_PAINT, (WPARAM)(HDC)bmp.dc());
ShowWindow(SW_SHOW);
GetWindowRect(rect);
parent.ScreenToClient(rect);
bg.create(rect.Width(), rect.Height());
bg.dc().BitBlt(0, 0, rect.Width(), rect.Height(), bmp.dc(), rect.left, rect.top, SRCCOPY);
IF_DEBUG SAL::saveHBITMAPToJpeg(bg.GetBitmap(), "frames/BG.jpg", 100);
SetRedraw(true);
parent.SetRedraw(true);
return true;
}
WS_CLIPCHILDREN is forced on in WinCe, you cannot toggle it. I dont know why, maybe it is done for performance reasons.
From my experience what i did in this situation.
1) If the parent window bacgkround is dynamic (for instance window that contains map, which can be moved), then it is painted to memory canvas first, then to the screen, and memory canvas is saved and used for painting transparent childs. Memory canvas would not contain holes in place of child windows, so it can be used for futher pixel merge. The disadvantage here is memory consumption to hold canvas in memory.
2) If parent window background is static (dialog box, menu, etc) then you can make non-window childs.
class CImageButton
{
public:
bool IsPointInside(POINT pt);
void OnPaint(HDC canvas);
void OnClick();
void SetRect(RECT& rc);
private:
RECT m_rc;
};
Your parent window will contain an array of such objects and redirect WM_PAINT and
mouse clicks to them.
The disavantage is additional code needed to be added to parent window, but you can make a base class for all your parent windows, which would handle issues with non-windowed controls.
I want to change the appearance of a window's caption bar, so I decided to override the OnNcPaint() method of CMainFrame. But when I did this, I found a problem. If there is another window covering my window, and I drag the window quickly, the content of the client area of my window disappeared, which came to sight only when I stopped the dragging.
My overridden OnNcPaint() is like below:
void CMainFrame::OnNcPaint()
{
CDC* pWinDC = GetWindowDC();
//do some drawing
ReleaseDC(pWinDC);
}
Is there something wrong with my approach?
Thank you!
Unless you use a clipping region set up to exclude the client area, you can paint over it from OnNcPaint(). So... if your drawing logic can't be modified to exclude the client in some other way, set up an appropriate clipping region first:
CRect rect;
GetWindowRect(&rect);
ScreenToClient(&rect);
CRect rectClient;
GetClientRect(&rectClient);
rectClient.OffsetRect(-rect.left, -rect.top);
rect.OffsetRect(-rect.left, -rect.top);
pWinDC->ExcludeClipRect(&rectClient);
// ...
// draw stuff here
// ...
pWinDC->SelectClipRgn(NULL);