I'm trying to achieve what almost every application does, and that's to have an embedded icon which I can show in the title bar and taskbar.
The requirements are:
The icon must support transparency
The icon must be embedded, not a separate file on the disk
The icon file format doesn't matter; can be ico, bmp or anything else that works.
I tried to create a bmp in paint.net, but LoadImage kept returning NULL. I recreated it as a 32-bit png, then used
this tool to convert it to a 32-bit bmp, my reasoning for which being to get LoadImage working again, and this time with transparency. I'm using LoadImage because apparently LoadBitmap isn't so well-supported.
resources.rc:
100 BITMAP "icons\\icon.bmp"
code:
HBITMAP h_bmp = (HBITMAP)LoadImage(GetModuleHandle(NULL), MAKEINTRESOURCE(100), IMAGE_BITMAP, 0, 0, 0);
HDC dc = CreateCompatibleDC(NULL);
HBITMAP bmp_old = (HBITMAP)SelectObject(dc, h_bmp);
BITMAP bmp = {};
GetObject(h_bmp, sizeof(bmp), &bmp);
BITMAPINFO info;
info.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
info.bmiHeader.biWidth = bmp.bmWidth;
info.bmiHeader.biHeight = -bmp.bmHeight;
info.bmiHeader.biPlanes = 1;
info.bmiHeader.biBitCount = bmp.bmBitsPixel;
info.bmiHeader.biCompression = BI_RGB;
info.bmiHeader.biSizeImage = ((bmp.bmWidth * bmp.bmBitsPixel + 31) / 32) * 4 * bmp.bmHeight;
std::vector<unsigned char> pixels;
pixels.resize(info.bmiHeader.biSizeImage);
GetDIBits(dc, h_bmp, 0, bmp.bmHeight, &pixels[0], &info, DIB_RGB_COLORS);
SelectObject(dc, bmp_old);
DeleteDC(dc);
GLFWimage image = { bmp.bmWidth, bmp.bmHeight, &pixels[0] };
glfwSetWindowIcon(window, 1, &image);
There were two issues with the image; firstly it was displaying upside-down, hence the negation of the height above. Secondly, the RGB channels are flipped and I have no idea how to fix it.
So, is there a simpler way to do this, perhaps without having to suffer bmp formats and needing 3rd-party tools, and if not, how can I get the colours displaying properly?
Windows (HWNDs) uses HICONs. A HICON is a handle to an icon loaded from a .ico file or an icon resource. A .ico file consists of one or more bmp and/or png files in various sizes. You should use a real icon editor to create your icon. You can find several free editors if you look around.
Once you have the ico file in your resources, load it with LoadImage(hInst, ..., IMAGE_ICON, ..., LR_SHARED) and apply it with SetClassLongPtr or WM_SETICON.
Solved as per #user253751's comment;
SetClassLongPtr(glfwGetWin32Window(window), GCLP_HICON, (LONG_PTR)LoadIcon(GetModuleHandle(NULL), MAKEINTRESOURCE(100)));
Much simpler than I expected!
Related
I am using this code to add a toolbar to the window with one button having a custom image:
HWND hToolbar = CreateWindow(TOOLBARCLASSNAME, NULL,WS_CHILD |
TBSTYLE_FLAT|TBSTYLE_AUTOSIZE |TBSTYLE_LIST|CCS_BOTTOM, 0, 0, 0, 0,
hwnd, NULL, ghInstance, NULL); //create the toolbar
SendMessage(hToolbar, WM_SETFONT, (WPARAM)hFontBold,
static_cast<LPARAM>(MAKELONG(TRUE, 0))); //set the font. there cannot be the problem
//↓↓↓↓↓**ILC_COLOR32 is specificied here but 32bit bmp is still not showing**//
auto hImagelist = ImageList_Create(32, 32,ILC_COLOR32|ILC_MASK,1, 0);
//↑↑↑↑↑**ILC_COLOR32 is specificied here but 32bit bmp is still not showing**//
HBITMAP bitmap = static_cast<HBITMAP>(ghInstance,
MAKEINTRESOURCE(ID_IMG_SPAWN),// <- ID_IMG_SPAWN is my custom resource
IMAGE_BITMAP, 32, 32, NULL));
ImageList_Add(hImagelist, bitmap, nullptr);
SendMessage(hToolbar, TB_SETIMAGELIST,static_cast<WPARAM>(0),(LPARAM)hImagelist);
In the code above, ID_IMG_SPAWN is the resource bmp image I imported to Visual Studio. However, Visual Studio threw an error saying it didn't recognize my bmp, and the bmp showed up blank when running the application.
Visual Studio told me my bmp wasn't recognized, see the below error:
When the app runs it looks as below:
I learned that Visual Studio hereby recognizes ONLY 24bit bmp.
So, I converted the bmp to 24bit and imported it again, changed ILC_COLOR32 to ILC_COLOR24, that really worked. No error and my image were shown on the button.
However, I lost my alpha channel. Because 24bit bitmap does not support an alpha channel, my image ended up having an ugly square background.
Try something like this (Note I used a "BINARY" resource.. maybe it will work with others too but not sure.. This code works with 32-bit bitmaps, alpha-transparent PNGs, and JPEG):
#include <windows.h>
#include <gdiplus.h>
HBITMAP LoadBitmapFromResource(DWORD ResourceID, bool transparent = true)
{
HANDLE hGlobal = NULL;
ULONG_PTR GDIToken = 0;
Gdiplus::Image* Img = NULL;
Gdiplus::GdiplusStartupInput GDIStartInput = NULL;
Gdiplus::GdiplusStartup(&GDIToken, &GDIStartInput, NULL);
HRSRC hResource = FindResource(NULL, MAKEINTRESOURCE(ResourceID), "BINARY");
if (!hResource) {return NULL;}
HGLOBAL hFileResource = LoadResource(NULL, hResource);
if (!hFileResource) {return NULL;}
LPVOID lpFile = LockResource(hFileResource);
if (!lpFile) {return NULL;}
DWORD dwSize = SizeofResource(NULL, hResource);
if (!dwSize) {return NULL;}
void* data = LockResource(hFileResource);
if (!data) {return NULL;}
IStream* pStream = NULL;
hGlobal = GlobalAlloc(GMEM_FIXED, dwSize);
memcpy(hGlobal, data, dwSize);
UnlockResource(hFileResource);
FreeResource(hFileResource);
if (CreateStreamOnHGlobal(hGlobal, true, &pStream) == S_OK)
{
Img = new Gdiplus::Image(pStream, false);
pStream->Release();
GlobalFree(hGlobal);
hGlobal = NULL;
HBITMAP hBitmap = NULL;
static_cast<Gdiplus::Bitmap*>(Img)->GetHBITMAP(transparent ? Gdiplus::Color::Transparent : Gdiplus::Color(0, 0, 0), &hBitmap);
delete Img;
Gdiplus::GdiplusShutdown(GdiImage::GDIToken);
GDIStartInput = NULL;
GDIToken = 0;
return hBitmap;
}
GlobalFree(hGlobal);
hGlobal = NULL;
Gdiplus::GdiplusShutdown(GdiImage::GDIToken);
GDIStartInput = NULL;
GDIToken = 0;
return NULL;
}
You will have to link against GDIPlus. It's not very nice to constantly startup and shutdown GDIPlus for every image you load.. so it's best to move that somewhere.. but other than that, everything should work just fine.
There are other ways without GDIPlus but it makes for a long post..
I learned that Visual Studio hereby recognizes ONLY 24bit bmp.
No, that's wrong. Visual Studio supports alpha-premultiplied 32-bit bitmaps.
32-bit bitmap has 8 bits for ALPHA, it's capable to make a smooth effect.
To show a 32-bit bitmap properly, you have to:
specify ILC_COLOR32
change the resource of ID_IMG_SPAWN to a 32-bit bitmap with premultiplied alpha.
create a DIB section to your bitmap when loading
(Win32's format requirement is very strict)
Q: How to create a DIB section to the bitmap?
A: Specify LR_CREATEDIBSECTION in the last parameter of LoadImage.
Explanation:
LoadImage((HINSTANCE)GetWindowLong(hwnd,GWL_HINSTANCE),MAKEINTRESOURCE(ID_IMG_SPAWN), IMAGE_BITMAP,32, 32,NULL)
This is your code of the LoadImage function. See the MSDN document of LoadImage, to create the DIB section, all you need is to specify LR_CREATEDIBSECTION in the last parameter of LoadImage.
Q: How to get a BMP with premultiplied alpha?
A: Pixelformer can help you convert your alpha-channeled file to a premultiplied-alpha BMP.
The steps are
Open your image (any format) in Pixelformer and choose Export from the menu
Select A8:R8:G8: B8 (32bpp) and Premultiplied Alpha, then click Ok.
Then you can save your BMP file! Import this BMP file to Visual Studio resources, replacing your previous 24-bit BMP.
Then, you don't need to use the ImageList_AddMasked (which makes the image sharp) anymore, because you already have a recognizable ALPHA in your 32-bit BMP. So, straight use ImageList_Add.
Okay, after the manipulations explained above your code should be this:
// Create the toolbar
HWND hToolbar = CreateWindow(TOOLBARCLASSNAME,NULL,
WS_CHILD | TBSTYLE_FLAT | TBSTYLE_AUTOSIZE | TBSTYLE_LIST | CCS_BOTTOM,
0, 0, 0, 0, hwnd, NULL, ghInstance, NULL);
// Set the font (this cannot be the problem)
SendMessage(hToolbar, WM_SETFONT, (WPARAM)hFontBold,
static_cast<LPARAM>(MAKELONG(TRUE, 0)));
auto hImagelist =
ImageList_Create(32, 32,ILC_COLOR32 /*DON'T NEED THE MASK. CHANGED TO ILC_COLOR32.*/, 1, 0);
HBITMAP bitmap = static_cast<HBITMAP>(LoadImage((HINSTANCE)GetWindowLong(hwnd,
GWL_HINSTANCE), MAKEINTRESOURCE(ID_IMG_SPAWN), IMAGE_BITMAP,
32, 32, LR_CREATEDIBSECTION /*THIS IS IMPORTANT*/ ));
ImageList_Add(hImagelist, bitmap, NULL);
SendMessage(hToolbar, TB_SETIMAGELIST, static_cast<WPARAM>(0), (LPARAM)hImagelist);
This worked fine as below.
These I answered above is well enough to solve this problem. You may wonder "What means DIB bitmaps?" "What is Premultiplied Alpha?". Those are the deep topics.
To learn DIB bitmaps and Premultiplied Alpha, see the links.
If you are using Visual Studio 2010 or higher (i guess), you can use PNG files. As stated here.
I have inherited an old-school MFC Windows CE program, and am having to make some modifications to it. As part of this I have to create a monochrome image with text on it, and both display it on a screen as well as send each row of the image to a printer one at a time.
I originally used a bitmap, and had success using DrawText() and getting a test string (Hello World) to display on the screen (this code is in Figure 1). However, I hit a wall at the stage where I am looking to extract the wrap data from the bitmap. What I am trying to get is an array with 1s or 0s representing black or white. I had first thought I would use GetBitmapBits() but unfortunately the code I am working with is so old that function is not supported yet. I thought I could get around this issue by using GetBitmap() and then accessing the bmBits parameter. However this appears to always be null which was confirmed when I found the following link: Why does GetObject return an BITMAP with null bmBits?.
My next attempt was to follow the advice in the link and use CreateDIBSection() instead of CreateCompatibleBitmap(). This seems like the right path, and I should have access to the data I want, but unfortunately I cannot get the DIB to display (code is in Figure 2). I suspect I am doing something wrong in creating the header of the DIB, but I cannot figure out what my mistake is.
If anyone has suggestions for a way to access the data in the bitmap, or can see what I am doing wrong with the DIB, I would greatly appreciate the help!
*** FIGURE 1: Code to create and display a bitmap
void CRunPage::OnPaint()
{
CPaintDC dc(this); // property page device context for painting
CBitmap mBmp; // CBitmap object for displaying built-in bitmaps
CDC mDCMem; // CDC object to handle built-in bitmap
int iWidth, iHeight; // dimension to draw on the screen
int icurLabel, // current label index of open print file
iLabelNum; // number of labels in open print file
LPBITMAPINFOHEADER pBMIH; // bitmap header object for current label
LPBYTE pImage; // bitmap data for current label
CSize size; // size of label
int PreviewLeft,PreviewTop,PreviewWidth,PreviewHeight;
CRect Rect;
BITMAP bm;
LPVOID bmBits=NULL;
// Calculate the preview area
PreviewLeft=5;
PreviewTop=5;
GetDlgItem(IDC_RUN_NEXT)->GetWindowRect(&Rect);
ScreenToClient(&Rect);
PreviewWidth=Rect.left-PreviewLeft*2;
GetDlgItem(IDC_RUN_WRAPTEXT)->GetWindowRect(&Rect);
ScreenToClient(&Rect);
PreviewHeight=Rect.top-PreviewTop*2;
CRect textRect;
CString testText(_T("Hello World"));
CBitmap * pOldBitmap;
CBrush whiteBrush, *pOldBrush;
CPen blackPen, *pOldPen;
mDCMem.CreateCompatibleDC(&dc);
mBmp.CreateCompatibleBitmap(&dc, PreviewWidth+PreviewLeft*2, PreviewHeight+PreviewTop*2);
//mBmp.CreateCompatibleBitmap(&dc, PreviewWidth, PreviewHeight);
pOldBitmap = mDCMem.SelectObject(&mBmp);
blackPen.CreatePen(PS_SOLID, 2, RGB(0, 0, 0));
whiteBrush.CreateSolidBrush(RGB(255,255,255));
textRect.SetRect(0,0,PreviewWidth, PreviewHeight);
// this means behind the text will be a white box w/ a black boarder
pOldBrush = mDCMem.SelectObject(&whiteBrush);
pOldPen = mDCMem.SelectObject(&blackPen);
//these commands draw on the memory-only context (mDCMem)
mDCMem.Rectangle(&textRect);
mDCMem.DrawText((LPCTSTR)testText, 11, &textRect, DT_CENTER|DT_VCENTER);
mDCMem.SelectObject(pOldBrush);
mDCMem.SelectObject(pOldPen);
dc.StretchBlt(PreviewLeft,PreviewTop, PreviewWidth, PreviewHeight, & mDCMem, 0, 0, PreviewWidth, PreviewHeight, SRCCOPY);
mDCMem.SelectObject(pOldBitmap);
}
*** FIGURE 2: Trying to use a DIB instead of a bitmap
void CRunPage::OnPaint()
{
CPaintDC dc(this); // property page device context for painting
CBitmap mBmp; // CBitmap object for displaying built-in bitmaps
CDC mDCMem; // CDC object to handle built-in bitmap
int iWidth, iHeight; // dimension to draw on the screen
int icurLabel, // current label index of open print file
iLabelNum; // number of labels in open print file
LPBITMAPINFOHEADER pBMIH; // bitmap header object for current label
LPBYTE pImage; // bitmap data for current label
CSize size; // size of label
int PreviewLeft,PreviewTop,PreviewWidth,PreviewHeight;
CRect Rect;
BITMAP bm;
// Calculate the preview area
PreviewLeft=5;
PreviewTop=5;
GetDlgItem(IDC_RUN_NEXT)->GetWindowRect(&Rect);
ScreenToClient(&Rect);
PreviewWidth=Rect.left-PreviewLeft*2;
GetDlgItem(IDC_RUN_WRAPTEXT)->GetWindowRect(&Rect);
ScreenToClient(&Rect);
PreviewHeight=Rect.top-PreviewTop*2;
CRect textRect;
CString testText(_T("Hello World"));
CBitmap * pOldBitmap;
CBrush whiteBrush, *pOldBrush;
CPen blackPen, *pOldPen;
LPBYTE pFWandImageMem=NULL, pImageMem=NULL, pTemp=NULL;
int i=0,j=0, buffSize=0, numBytesPerRow=0, bitmapWidthPix,bitmapHeightPix;
char *numBytesPerRowString;
char temp;
void ** ppvBits;
BITMAPINFOHEADER bmif;
BITMAPINFO bmi;
HBITMAP myDIB, myOldDIB;
mDCMem.CreateCompatibleDC(&dc);
//this rect is the area in which I can draw (its x,y location is set by BitBlt or StretchBlt
//mBmp.CreateCompatibleBitmap(&dc, PreviewWidth+PreviewLeft*2, PreviewHeight+PreviewTop*2);
bmif.biSize = sizeof(BITMAPINFOHEADER);
bmif.biWidth = PreviewWidth+PreviewLeft*2;
bmif.biHeight = -(PreviewHeight+PreviewTop*2);//- means top down (I think? I tried both ways and neither worked)
bmif.biPlanes = 1;
bmif.biBitCount = 1;
bmif.biCompression = BI_RGB; // no compression
bmif.biSizeImage = 0; // Size (bytes) if image - this can be set to 0 for uncompressed images
bmif.biXPelsPerMeter = 0;
bmif.biYPelsPerMeter = 0;
bmif.biClrUsed =0;
bmif.biClrImportant = 0;
bmi.bmiColors[0].rgbBlue=0;
bmi.bmiColors[0].rgbGreen=0;
bmi.bmiColors[0].rgbRed=0;
bmi.bmiColors[0].rgbReserved=0;
bmi.bmiColors[1].rgbBlue=255;
bmi.bmiColors[1].rgbGreen=255;
bmi.bmiColors[1].rgbRed=255;
bmi.bmiColors[1].rgbReserved=0;
bmi.bmiHeader=bmif;
myDIB = CreateDIBSection(dc.GetSafeHdc(), &bmi, DIB_RGB_COLORS, ppvBits, NULL, 0);
myOldDIB = (HBITMAP)mDCMem.SelectObject(myDIB);//SelectObject(mDCMem, myDIB);
blackPen.CreatePen(PS_SOLID, 2, RGB(0, 0, 0));
whiteBrush.CreateSolidBrush(RGB(255,255,255));
textRect.SetRect(0,0,PreviewWidth, PreviewHeight);
// this means behind the text will be a white box w/ a black boarder
pOldBrush = mDCMem.SelectObject(&whiteBrush);
pOldPen = mDCMem.SelectObject(&blackPen);
//these commands draw on the memory-only context (mDCMem)
mDCMem.Rectangle(&textRect);
mDCMem.DrawText((LPCTSTR)testText, 11, &textRect, DT_CENTER|DT_VCENTER);
mDCMem.SelectObject(pOldBrush);
mDCMem.SelectObject(pOldPen);
dc.StretchBlt(PreviewLeft,PreviewTop, PreviewWidth, PreviewHeight, & mDCMem, 0, 0, PreviewWidth, PreviewHeight, SRCCOPY);
mDCMem.SelectObject(myOldDIB);
}
So I made two minor changes to the DIB code, and it is displaying the image correctly now.
First, I changed the way I passed in my pointer to the CreateDIBSection():
void ** ppvBits;
to
LPBYTE pBits;
And then I had to change how I passed that into CreateDIBSection. I also explicitly casted the return of CreateDIBSection() to an HBITMAP:
myDIB = CreateDIBSection(dc.GetSafeHdc(), &bmi, DIB_RGB_COLORS, (void**)&pBits, NULL, 0);
to
myDIB = (HBITMAP) CreateDIBSection(dc.GetSafeHdc(), &bmi, DIB_RGB_COLORS, ppvBits, NULL, 0);
I have not had a chance to see if I can access the image data, but I am past the initial issues now. Thanks to anyone who looked at this, and if people know how to do the first (device dependent bitmap) method I would be interested to know.
I have a two dimensional array of data that I want to display as an image.
The plan goes something like this -
Create a bitmap using CreateCompatibleBitmap (this results in a solid black bitmap and I can display this with no problems)
Edit the pixels of this bitmap to match my data
BitBlt the bitmap to the window
I think that I need a pointer to the place in memory where the pixel data begins. I've tried many different methods of doing this and googled it for 3 days and still haven't been able to even edit a single pixel.
Using a loop of SetPixel(HDC, x, y, Color) to set each pixel works but VERY slowly.
I have accomplished this in C# by locking the bitmap and editing the bits, but I am new to C++ and can't seem to figure out how to do something similar.
I have mostly been trying to use memset(p, value, length)
For "p" I have tried using the handle returned from CreateCompatibleBitmap, the DC for the bitmap, and the DC for the window. I have tried all sorts of values for the value and length.
I'm not sure if this is the right thing to use though.
I don't have to use a bitmap, that's just the only thing I know to do. Actually it would be awesome to find a way to directly change the main window's DC.
I do want to avoid libraries though. I am doing this purely for learning C++.
This took QUITE a bit of research so I'll post exactly how it is done for anyone else who may be looking.
This colors every pixel red.
hDC = BeginPaint(hWnd, &Ps);
const int
width = 400,
height = 400,
size = width * height * 3;
byte * data;
data = new byte[size];
for (int i = 0; i < size; i += 3)
{
data[i] = 0;
data[i + 1] = 0;
data[i + 2] = 255;
}
BITMAPINFOHEADER bmih;
bmih.biBitCount = 24;
bmih.biClrImportant = 0;
bmih.biClrUsed = 0;
bmih.biCompression = BI_RGB;
bmih.biWidth = width;
bmih.biHeight = height;
bmih.biPlanes = 1;
bmih.biSize = 40;
bmih.biSizeImage = size;
BITMAPINFO bmpi;
bmpi.bmiHeader = bmih;
SetDIBitsToDevice(hDC, 0, 0, width, height, 0, 0, 0, height, data, &bmpi, DIB_RGB_COLORS);
delete[] data;
memset can be used on the actually RGB information array (but you need to also know the format of the bitmap, if a pixel has 32 or 24 bits ).
From a bit of research on msdn, it seems that what you want to get is the BITMAP structure :
http://msdn.microsoft.com/en-us/library/k1sf4cx2.aspx
There you have the bmBits on which you can memset.
How to get there from your function ?
Well, CreateCompatibleBitmap returns a HBITMAP structure and it seems you can get BITMAP from HBITMAP with the following code :
BITMAP bmp;
GetObject(hBmp, sizeof(BITMAP), &bmp);
This however seems to get a you copy of the existing bitmap info, which only solves your memset problem (you can now set the bitmap information with memset, eventhou I don't see any other use for memeset besides making the bmp all white or black).
There should be a function that allows you to set the DC bites to a bitmap thou, so you should be able to use the new bitmap as a parameter.
Brief introduction to the problem:
I got the zip archive, where the set of files in the bmp format are placed.
I wan't to load bitmaps from that archive (create system objects) and pass their HBITMAP to a client method which will display it on the screen.
I tried 2 ways to solve my task:
1) using temporary file (this methods works fine, but I think that it is inefficient - as requires additional actions on file creation and requires that user posses some privileges that allows him to create files)
hBitmap = (HBITMAP)LoadImage(NULL, fullpath.c_str(), IMAGE_BITMAP, 0, 0, LR_LOADFROMFILE | LR_DEFAULTCOLOR | LR_CREATEDIBSECTION );
2) unzipping the needed file to the memory and using the memory buffer for bitmap creation
(My solution is based on the information from the similar questions on SO and other sources)
BITMAPFILEHEADER* bmfh = (BITMAPFILEHEADER*)ibuf;
BITMAPINFOHEADER* bmih = (BITMAPINFOHEADER*)(ibuf + sizeof(BITMAPFILEHEADER));
BITMAPINFO* bmi = (BITMAPINFO*)bmih;
void* pBMPdata = (void*)(ibuf + bmfh->bfOffBits);
hBitmap = CreateDIBitmap(NULL, bmih, CBM_INIT, pBMPdata, bmi, DIB_RGB_COLORS);
I need help on the 2-nd way.
When image is loaded from the HBITMAP obtained on the second method - black square is displayed/
UPDATE:
I tried 3-rd method:
BITMAPFILEHEADER* pBmfh = (BITMAPFILEHEADER*)ibuf;
BITMAPINFOHEADER* pBmih = (BITMAPINFOHEADER*)(ibuf + sizeof(BITMAPFILEHEADER));
BITMAPINFO* pBmi = (BITMAPINFO*)pBmih;
void* pBMPdata = (void*)(ibuf + pBmfh->bfOffBits);
void* pToFill = 0;
hBitmap = CreateDIBSection(NULL, pBmi, DIB_RGB_COLORS, &pToFill, NULL, NULL);
Result: is black square, which has dimensions of the picture I am trying to load.
Any ideas that might help are appreciated!
It might be helpful for others how may encounter this issue(black square which has dimensions of the image you are trying to load).
3-rd method works.
BITMAPFILEHEADER* pBmfh = (BITMAPFILEHEADER*)ibuf;
BITMAPINFOHEADER* pBmih = (BITMAPINFOHEADER*)(ibuf + sizeof(BITMAPFILEHEADER));
BITMAPINFO* pBmi = (BITMAPINFO*)pBmih;
void* pBMPdata = (void*)(ibuf + pBmfh->bfOffBits);
void* pToFill = 0;
hBitmap = CreateDIBSection(NULL, pBmi, DIB_RGB_COLORS, &pToFill, NULL, NULL);
memcpy(pToFill, pBMPdata, pBmfh->bfSize - pBmfh->bfOffBits); // this line should be added!!
My mistake was, that I was trying to pass pointer to pointer to the databits, instead of it
I should after invokage copy databits to the void (which is pToFill).**
I have an image data in a buffer(type - long) from a scanner which is 32 bit.
For example, buffer[0]'s corresponding pixel value is 952 which is [184, 3, 0, 0] <-[R,G,B,A];
I want to display/Paint/draw on to the screen; I am confused when i tried to read about displying bitmaps. I looked at win32 functions, CBitmap class, windows forms (picture box) etc I am hard to understand the general idea/appraoch for displaying this buffer data on to a application window.
I have constructed the BITMAPFILEHEADER AND BITMAPINFOHEADER; Has the pixel data in a buffer, (unsigned char *)vInBuff whose size is vImageSz;
//construct the BMP file Header
vBmfh.bfType = 19778;
vBmfh.bfSize = 54+vImageSz;//size of the whole image
vBmfh.bfReserved2 = 0;
vBmfh.bfReserved1 = 0;
vBmfh.bfOffBits = 54;//offset from where the pixel data can be found
//Construct the BMP info header
vBmih.biSize = 40;//size of header from this point
vBmih.biWidth = 1004;
vBmih.biHeight = 1002;
vBmih.biPlanes = 1;
vBmih.biCompression = BI_RGB;
vBmih.biSizeImage = vBmih.biWidth*vBmih.biHeight*4;
vBmih.biBitCount = 32;
vBmih.biClrUsed = 0;
vBmih.biClrUsed = 0;
1.What is that i should be doing next to display this?
2 What should i be using to display the 32bit bitmap? I see people using createwindows functions, windows forms, MFC etc;
3.I also understand that BitBlt,createDIBSection, OnPaint etc are being used? I am confused by these various functions and coding platforms? Please suggest me a simple approach.
4.How can i create a palette to display a 32 bit image?
Thanks
Raj
EDITED TRYING TO IMPLEMENT DAVE'S APPROACH, CAN SOMEBODY COMMENT ON MY IMPLEMTATION. I couldn't continue to the bitblt as i donot have two HDC, i donot know how to get this one? Any help please
DisplayDataToImageOnScreen(unsigned char* vInBuff, int vImageSz) // buffer with pixel data, Size of pixel data
{
unsigned char* vImageBuff = NULL;
HDC hdcMem=CreateCompatibleDC(NULL);
HBITMAP hBitmap = CreateDIBSection(hdcMem,
(BITMAPINFO*)&vBmih,
DIB_RGB_COLORS,
(void **)&vImageBuff,
NULL, 0);
GetDIBits(hdcMem,
hBitmap,
0,
1,
(void**)&vImageBuff,
(BITMAPINFO*)&vBmih,
DIB_RGB_COLORS);
memcpy(vImageBuff,vInBuff,vImageSz);
}
An alternative if you just want to plot it on screen is to use TinyPTC ( http://sourceforge.net/projects/tinyptc/files/ ). It's just 3 functions and very simple if you just want to plot some pixels.
EDIT: Seems like http://www.pixeltoaster.com is a continuation of TinyPTC, probably preffered.
If you have image's bytes already in a buffer you can use:
a CBitmap object (MFC) and the method CBitmap::CreateBitmapIndirect
or
win32 routine CreateBitmapIndirect.
Now you can use BitBlt to draw it on a DC. To get a window DC use GetDC.
There is no need to create a pallete for 32 bit images.
Here's a simplified approach you can try, broken down into steps:
BITMAPINFO bitmapinfo = { 0 };
bitmapinfo.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
bitmapinfo.bmiHeader.biWidth = 1004;
bitmapinfo.bmiHeader.biHeight = -1002;
bitmapinfo.bmiHeader.biPlanes = 1;
bitmapinfo.bmiHeader.biCompression = BI_RGB;
HBITMAP hBitmap = CreateDIBSection(NULL,
&bitmapinfo,
DIB_RGB_COLORS,
(void **)&vImageBuff,
NULL,
0);
Now party on vImageBuff and then cache hBitmap somewhere so that within your wndproc you can then in the WM_PAINT handler:
select hBitmap into temp compatible HDC
call BitBlt(..., SRCCOPY) from the compatible HDC to the window's HDC. the other parameters should be obvious. don't try to stretch or do anything fancy at first.
remember to select the original dummy bitmap into the temp HDC before destroying it.
If you aren't seeing results try looping through vImageBuff and just set every pixel to RGB(255, 0, 0), or something like that, just to sanity check the rest of the logic.
If nothing is drawing make sure that the alpha component for each pixel is 255.
If you're getting a garbled image then you need to double-check pixelformat, stride, etc.
Here's a strategy you might like:
Create a bitmap with the same size as your scanned data, and the same format (use CreateDIBSection).
Use GetDIBits to get the base address of the pixel data.
Copy your data (from the scanner) to the address GetDIBits returns.
Now render your bitmap! (use BitBlt, or somesuch).
Regarding palettes- a 32bit image does not, generally, have an explicit palette - you'd need 16.7million (assuming 8bits of alpha) values in the palette. Generally the palette is assumed to be 8bits red, 8bits green, 8bits blue, as you've described above.