[gdi] Erasing Window

[zorro59]

Hello everyone!
My problem is this:

case WM_PAINT:
		{
			PAINTSTRUCT ps;
			HDC hdc = BeginPaint(imagine_aux, &ps);

			
				
			        RestoreDC(hdc,-1);//reinitializez fereastra, cum era inainte de desenat
				
				HDC hdcMem = CreateCompatibleDC(hdc);
				SelectObject(hdcMem, imagine_bmp);

				GetObject(imagine_bmp, sizeof(bm), &bm);

				BitBlt(hdc, image_x, image_y, bm.bmWidth, bm.bmHeight, hdcMem, 0, 0, SRCCOPY);//redesenez imaginea

				//SelectObject(hdcMem, hbmOld);
				DeleteDC(hdcMem);
		
			EndPaint(hwnd, &ps);
			break;
		}

I am sending InvalidateRect from another function. What i want to do is this:
Erase the current window (imagine_aux), then send RestoreDc to get the initial image.
So after a HBITMAP was loaded, i save the dc, when it was moved, i simply want to delete everything and redraw the bitmap in the new position.
The bitmap loads, the image is moved, but the window isnt't reinitialised , so i get the trail.

[zorro59]

Edit now the window is erased, but i lose all the drawing =))
The problem is with savedc / restoredc. Save dc returns 0.

[hoxsiew]

Just looking at your code, everything looks OK except the RestoreDC. That should only be called when a corresponding SaveDC has been called first, but both calls should be within the BeginPaint and EndPaint block. In your example above, neither one is really needed.

[zorro59]

case WM_PAINT:
		{
			PAINTSTRUCT ps;
			HDC hdc = BeginPaint(hwnd, &ps);

			if (current_sel == 1) {
			
				if (saved == false)
				{
					reg = SaveDC(hdc);//salvez status, inainte de desenarea imaginii
					saved = true;
				}
				else
					RestoreDC(hdc,reg);//reinitializez fereastra, cum era inainte de desenat

				BITMAP bm;				
				HDC hdcMem = CreateCompatibleDC(hdc);
				SelectObject(hdcMem, imagine_bmp);

				GetObject(imagine_bmp, sizeof(bm), &bm);

				BitBlt(hdc, image_x+70, image_y, bm.bmWidth, bm.bmHeight, hdcMem, 0, 0, SRCCOPY);//redesenez imaginea
				

				DeleteDC(hdcMem);
			}
			//SetBkMode((HDC)hwnd,TRANSPARENT);
			EndPaint(hwnd, &ps);
			break;
		}

Still not beying able to restore the window initial state, then repaint the image. However saveDc now woks ok.

[hoxsiew]

What are you trying to do with SaveDC/RestoreDC? I don't think they do what you think they do:

http://msdn.microsoft.com/en-us/libr...45(VS.85).aspx

[zorro59]

I need to save the image, am a bmp for example. I dont want to use GetPixel.

[hoxsiew]

Get Pixel()? I'm not sure how that relates at all. I'm not sure, but I believe you want to sort-of cache a DC's contents (an already rendered screen) between paint cycles which is not what SaveDC() and RestoreDC() are for.

If you're trying to save a bitmap somehow, you'll need to go about that very differently.

[zorro59]

Yes,that is what i am trying. MSDN was very confuse, and i tought that the function saveDC it saves the capture of the window. An example of that different thing?

[hoxsiew]

Do you want to save a screen image to a file? There are tons of examples of that on the web.

[zorro59]

Without any other library like gdi+. The aplication is designed for windows mobile

[VladimirF]

Judging by the attempt to use SaveDC / RestoreDC, I guess saving to a file is not needed.
To cache content of your window, create compatible DC, select a properly sized bitmap into it and BitBlt the content of your DC into it.
When needed, you can BitBlt it back.

[zorro59]

Go it thanks!