I have a problem converting a character into a bitmap pixel array.
I work with Windows CE 6 and I have written an application in C++ to manage an OLED by serial interface.
To display the image on OLED I use the bitmap format, then if I want to display a text on OLED I have to convert the character to a bitmap array first, but I don't know how take a single character from a Windows CE font and convert it into a bitmap pixel array (bytes) to send it out via the serial interface.
Have you got an idea (standard functions, custom functions etc) how to solve this problem?
CreateDC to create a device context.
CreateCompatibleBitmap to create a bitmap of the right size.
SelectObject to select the bitmap into the DC.
CreateFontIndirect to create font.
SelectObject to select the font into the DC.
DrawText to draw the character on the DC.
SelectObject to select the previously selected bitmap back into the DC.
SelectObject to select the previously selected font back into the DC.
DeleteObject to delete the created font.
DeleteDC to delete the DC.
You now have a bitmap with the letter.
Related
I am trying to create a Gdiplus::Bitmap from a device context. The function I use is:
Bitmap bitmap((HBITMAP)myDC.GetCurrentBitmap(), (HPALETTE)myDC.GetCurrentPalette());
...but when I draw the bitmap on the screen, all I see is a black rectangle. I think I'm using the Bitmap constructor wrong, because in docs it's written:
Do not pass to the GDI+ Bitmap::Bitmap constructor a GDI bitmap or a
GDI palette that is currently (or was previously) selected into a
device context.
But I have no idea how to go around this. Another approach I tried is using:
To capture the preexisting image from a window, a Windows Graphics Device Interface (GDI) function such as BitBlt() or StretchBlt() would have to be used to copy the image from the screen to a memory bitmap. This memory bitmap could then be used in the overloaded Bitmap constructor, which takes an HBITMAP as a parameter.
But I couldn't achieve this either.
Someone can give me short explanation how to create bitmap runtime using GDI/GDI+ and to fill it with color ?
Thanks in advance.
CreateBitmap, CreateCompatibleBitmap or CreateDIBSection (in case you want access to raw underlying data bits)
CreateCompatibleDC
SelectObject the bitmap into created device context
FillRect or friends on the device context, and the painting takes place on your selected bitmap (there are options there: standard brushes for black and white, having RGB on hands instead of creating a brush you can do SetBkColor + ExtTextOut with an empty string and ETO_OPAQUE and the rectangle will be filled)
SelectObject back
The bitmap remains to hold the painting
Release the resources
Still it has something to do with "entire screen" in the title, and you need explain what you want there.
Query screen size
Create your drawable (or just manipulate the graphics object in your paint handler)
Fill it with color
:)
I am using visual c++ 6.0 and need to capture the image on the screen to memory. How do I do this? thx
Get the DC for the screen with GetDC(NULL)
Create a memory DC with CreateCompatibleDC.
Create a bitmap compatible with the screen DC and the same size as the screen.
Select the bitmap into the memory DC.
BitBlt from the screen DC to the memory DC.
Deselect the bitmap from the memory DC.
Use GetBitmapBits to copy the bitmap into memory.
I'm trying to do some double buffering in an MFC application and trying to draw on the memory DC with GDI+. However, although I called CreateCompatibleDC(), I'm only getting a monochrome image. Here is the code:
CDC bufferDC;
CBitmap bufferBitmap;
bufferDC.CreateCompatibleDC(&dc);
bufferBitmap.CreateCompatibleBitmap(&bufferDC, 300, 300);
bufferDC.SelectObject(bufferBitmap);
Graphics g(bufferDC);
g.Clear(Color::Green);
dc.BitBlt(0, 0, 300, 300, &bufferDC, 0, 0, SRCCOPY);
Instead of a green patch, I see a rectangle of dithered black and white dots. I even tried to save the bitmap to disk after the g.Clear() call. It is indeed a 1-bit depth file.
Any ideas what went wrong? Thanks.
A common mistake. A memory DC takes on the properties of the bitmap selected into it, no matter what compatibility it was created with. The default bitmap selected into a DC is monochrome. If you create a bitmap compatible with that DC, it will be monochrome too.
Create the bitmap to be compatible with the original DC, not the memory DC.
Both the bitnmap and the bufferDC should be compatible with dc (whatever device it refers to), not the bitmap compatible ... with its own DC.
Try to give &dc to CreateCopmpatibleBitmap.
Your code snippet does not show where the dc variable comes from. ThIs guy probably contains a monochrome bitmap, the default. You dont need it anyway. Instead, pass NULL to CreateCompatibleDC and it will be the same format as your display, which is probably color.
How to Convert a Bitmap-like struct into an HDC?
I am now writting image processing program in c++, gdi.
If I got a HDC.
I can draw whatever I like on the HDC in gdi by the following code.
// HDC is handy.
HDC dc;
dc.DrawXXX // I can draw using gdi method.
Graphics gr(dc); // now I can also draw on the dc using gdi+ method.
My Application is based on FreeImage.
I make of fipImage. ( use data struct like Bitmap )
However if I want to draw on fipWinImage, now I have to copy fipWinImageto Bitmap, then draw on the Bitmap, and finally convert the bitmap into fipImage again, which is time comsuming and memory comsuming.
Convert fipImage to Bitmap -> Draw on the bitmap -> convert bitmap to fipWinImage
fipWinImage imagefip;
Bitmap* tempImg = new Bitmap(imagefip->GetWidth(), imagefip.GetHeigt(), PixelFormat24bppRGB); // memory comsuming is image is large
Graphics *pGr = Graphics::FromImage(tempImg);
HDC dc = pGr->GetHDC();
RECT rec;
rec.left = 0;
rec.top = 0;
rec.right = imagefip.GetWidth();
rec.bottom = imagefip.GetHeight();
fipImage.draw(dc, rec); // using stretchdibits()
pGr->ReleaseHDC(dc);
Graphics gr(tempImg);
HDC dc = gr.GetHDC(); // Get an Hdc, draw using gdi method
gr.ReleaseHDC(tempDC); //
gr.drawXXX // Draw using gdi+ method.
fipWinImage fipImg; // final result fipWinImage.
HBITMAP temp;
Color color;
tempImg->GetHBITMAP(color, &temp);
fipImg->copyFromBitmap(temp);
I want to construct a HDC directly from fipImage. and draw directly on fipWinImage
How can I do this?
First a few clarifications:
A Device Context is basically a structure that remembers things like foreground and background colors, brushes, font info, and the physical drawing surface (bitmap).
This is a handy thing, so that you don't have to keep specifying all of these things when you're doing one graphics operation after another. You can also pass all of these settings around more easily this way. That's all that a DC really is - just a collection of drawing parameters, including the surface to draw upon.
An "HDC" is just a handle (reference) to one of these structs. Being a "Handle" lets window move the struct around in memory to manage free space without your pointers to it getting messed up.
If you have access to the source code for the library you're using, examine the fipWinImage::draw(...) method. If they're using StretchDIBits, then they must get their raw bitmap data into a compatible format at some point. It's also possible that the fipWinImage class is wrapping an underlying BITMAP or DIB, etc.
The final step to getting your own HDC...
A bitmap is "SELECTED" into a device context, and can only be selected into a single DC at one time. If you can get the internal HBITMAP from fipWinImage, you can select it into another DC (assuming that it isn't still selected into another HC).
When you create a DC, windows automatically creates a 1x1 bitmap for it (since a DC must have a selected bitmap at all times). When you select in a new bitmap, you get the handle to the previously selected bitmap returned to you. Hang on to that, because you're going to need to put it back when you're done.
Hope that helps.
I don't know FreeImage, but if you can get a pointer to the actual pixel data (DIB section) out of it, you could just create a HBITMAP that shares it without having to copy the data every time.