Solved

transparent Backgrous Image

Posted on 2002-04-26
5
309 Views
Last Modified: 2013-12-03
I m using win32 (NOT MFC) and i have a 24bit color image (BMP) in my resource file.
i m trying to create its background transparent to put on a Dialog box (i do not want to see the backgoud).

i tried to change the BML in photoshop, but VC IDE doesn't allow me to load a 24bit image (only 256).

i have a code in MFC that creates transparent background, but when i tried to create the equivalent win32, it does something wrong...

all i need is a code to put in WM_PAINT to make it transparent..

thanks
Shay
0
Comment
Question by:Shay050799
  • 2
5 Comments
 
LVL 1

Expert Comment

by:hide_in
ID: 6972688
No, you are wrong.
you can load a bitmap of 24bit using the API - LoadBitmap()
or LoadImage(). It's true that the VC IDE can't display a
bitmap of 24bit, image, but you can use 24bit bitmap.
0
 
LVL 3

Author Comment

by:Shay050799
ID: 6973020
hide_in you didn't answer my question...i need the code to put in WM_PAIN to display this image !!!

Shay
0
 
LVL 1

Expert Comment

by:hide_in
ID: 6974603
ok, I'm sorry for my answer.
please give me your mail address, then I send a sample code to you ?
the project is developed by VC++ 6.0.




0
 
LVL 2

Accepted Solution

by:
manojbkumar earned 200 total points
ID: 6980041
Use the following function for Transparent Blitting
void DrawTransparentBitmap(HDC hdc, HBITMAP hBitmap, short xStart,
                          short yStart, COLORREF cTransparentColor)
{
   BITMAP     bm;
   COLORREF   cColor;
   HBITMAP    bmAndBack, bmAndObject, bmAndMem, bmSave;
   HBITMAP    bmBackOld, bmObjectOld, bmMemOld, bmSaveOld;
   HDC        hdcMem, hdcBack, hdcObject, hdcTemp, hdcSave;
   POINT      ptSize;

   hdcTemp = CreateCompatibleDC(hdc);
   SelectObject(hdcTemp, hBitmap);   // Select the bitmap

   GetObject(hBitmap, sizeof(BITMAP), (LPSTR)&bm);
   ptSize.x = bm.bmWidth;            // Get width of bitmap
   ptSize.y = bm.bmHeight;           // Get height of bitmap
   DPtoLP(hdcTemp, &ptSize, 1);      // Convert from device

                                     // to logical points

   // Create some DCs to hold temporary data.
   hdcBack   = CreateCompatibleDC(hdc);
   hdcObject = CreateCompatibleDC(hdc);
   hdcMem    = CreateCompatibleDC(hdc);
   hdcSave   = CreateCompatibleDC(hdc);

   // Create a bitmap for each DC. DCs are required for a number of
   // GDI functions.

   // Monochrome DC
   bmAndBack   = CreateBitmap(ptSize.x, ptSize.y, 1, 1, NULL);

   // Monochrome DC
   bmAndObject = CreateBitmap(ptSize.x, ptSize.y, 1, 1, NULL);

   bmAndMem    = CreateCompatibleBitmap(hdc, ptSize.x, ptSize.y);
   bmSave      = CreateCompatibleBitmap(hdc, ptSize.x, ptSize.y);

   // Each DC must select a bitmap object to store pixel data.
   bmBackOld   = (HBITMAP)SelectObject(hdcBack, bmAndBack);
   bmObjectOld = (HBITMAP)SelectObject(hdcObject, bmAndObject);
   bmMemOld    = (HBITMAP)SelectObject(hdcMem, bmAndMem);
   bmSaveOld   = (HBITMAP)SelectObject(hdcSave, bmSave);

   // Set proper mapping mode.
   SetMapMode(hdcTemp, GetMapMode(hdc));

   // Save the bitmap sent here, because it will be overwritten.
   BitBlt(hdcSave, 0, 0, ptSize.x, ptSize.y, hdcTemp, 0, 0, SRCCOPY);

   // Set the background color of the source DC to the color.
   // contained in the parts of the bitmap that should be transparent
   cColor = SetBkColor(hdcTemp, cTransparentColor);

   // Create the object mask for the bitmap by performing a BitBlt
   // from the source bitmap to a monochrome bitmap.
   BitBlt(hdcObject, 0, 0, ptSize.x, ptSize.y, hdcTemp, 0, 0,
          SRCCOPY);

   // Set the background color of the source DC back to the original
   // color.
   SetBkColor(hdcTemp, cColor);

   // Create the inverse of the object mask.
   BitBlt(hdcBack, 0, 0, ptSize.x, ptSize.y, hdcObject, 0, 0,
          NOTSRCCOPY);

   // Copy the background of the main DC to the destination.
   BitBlt(hdcMem, 0, 0, ptSize.x, ptSize.y, hdc, xStart, yStart,
          SRCCOPY);

   // Mask out the places where the bitmap will be placed.
   BitBlt(hdcMem, 0, 0, ptSize.x, ptSize.y, hdcObject, 0, 0, SRCAND);

   // Mask out the transparent colored pixels on the bitmap.
   BitBlt(hdcTemp, 0, 0, ptSize.x, ptSize.y, hdcBack, 0, 0, SRCAND);

   // XOR the bitmap with the background on the destination DC.
   BitBlt(hdcMem, 0, 0, ptSize.x, ptSize.y, hdcTemp, 0, 0, SRCPAINT);

   // Copy the destination to the screen.
   BitBlt(hdc, xStart, yStart, ptSize.x, ptSize.y, hdcMem, 0, 0,
          SRCCOPY);

   // Place the original bitmap back into the bitmap sent here.
   BitBlt(hdcTemp, 0, 0, ptSize.x, ptSize.y, hdcSave, 0, 0, SRCCOPY);

   // Delete the memory bitmaps.
   DeleteObject(SelectObject(hdcBack, bmBackOld));
   DeleteObject(SelectObject(hdcObject, bmObjectOld));
   DeleteObject(SelectObject(hdcMem, bmMemOld));
   DeleteObject(SelectObject(hdcSave, bmSaveOld));

   // Delete the memory DCs.
   DeleteDC(hdcMem);
   DeleteDC(hdcBack);
   DeleteDC(hdcObject);
   DeleteDC(hdcSave);
   DeleteDC(hdcTemp);
}
0

Featured Post

ScreenConnect 6.0 Free Trial

Check out the updates in one game-changing release, ScreenConnect 6.0, based on partner feedback. New features include a redesigned UI that improves session organization and overall user experience. See the enhancements for yourself!

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

This article describes how to programmatically preset the "Pages per Sheet" option that's available with most printer drivers.   This setting lets you do "n-Up" printing, where two, four, or more pages are printed on each sheet of paper. If your …
If you have ever found yourself doing a repetitive action with the mouse and keyboard, and if you have even a little programming experience, there is a good chance that you can use a text editor to whip together a sort of macro to automate the proce…
Along with being a a promotional video for my three-day Annielytics Dashboard Seminor, this Micro Tutorial is an intro to Google Analytics API data.
This is Part 3 in a 3-part series on Experts Exchange to discuss error handling in VBA code written for Excel. Part 1 of this series discussed basic error handling code using VBA. http://www.experts-exchange.com/videos/1478/Excel-Error-Handlin…

772 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question