Is it possible to load a PNG from a file into an HBITMAP using Win32 GDI functions? If not, what would be the lightest solution without using external libraries (like libpng)?
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2I'm just trying to keep everything as small and fast as possible. I've had bad experiences with GDI+'s speed in the past. I need an HBITMAP and GDI+ doesn't load directly into an HBITMAP, thus requiring another copy. GDI+ is an option, just not my favorite.– jnm2Commented Dec 31, 2010 at 14:21
5 Answers
You can use the Windows Imaging Component to load PNG files (on Windows XP SP2 and later). See MSDN Magazine (original in web archive - a bit better formatting) for an introduction on how to use the API and my blog post for a code sample that loads a PNG from an IStream and converts it to an HBITMAP.
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1Hi Bradley, It looks like the MSDN magazine link is down, could you update the link and maybe add some sample code into the answer from the article? Thanks!– jrhCommented Mar 7, 2017 at 21:49
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3@jrh Yes, it looks like Microsoft pulled that page down, but an archived copy is available: web.archive.org/web/20080507014245/http://msdn.microsoft.com/… Commented Mar 8, 2017 at 18:29
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1Note that Microsoft converted the older issues to chm format -- if you want I can suggest an edit that adds code into the answer.– jrhCommented Mar 8, 2017 at 19:34
There is no need to use Windows Imaging Component, GDI+ or PNG library. You can use Icon functionality.
Add new icon (ICO_PNG) to VC project resources with custom Width and Height (Resource Editor->Image->New Image Type). Copy Your png image here and use Fill Tool+transparent color to make icon transparent.
Add Picture Control (IDC_PNG) to Your dialog (Type = Owner draw).
Dialog procedure code:
switch (msg)
{
...
case WM_DRAWITEM:
{
LPDRAWITEMSTRUCT pDIS = (LPDRAWITEMSTRUCT)lParam;
if (pDIS->CtlID == IDC_PNG)
{
HICON hIcon = (HICON)LoadImage(GetModuleHandle(0), MAKEINTRESOURCE(ICO_LOGO), IMAGE_ICON, 0, 0, LR_LOADTRANSPARENT);
DrawIconEx(pDIS->hDC, 0, 0, hIcon, 0, 0, 0, NULL, DI_NORMAL);
DestroyIcon(hIcon);
return TRUE;
}
}
}
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Related: How would I draw a PNG image using LoadImage and StretchDIBits?. Note that this answer seems to only work if the png is a resource, I was not able to load a png straight from a standalone file (e.g., myimage.png). It seems that
LoadImage
only supports loading .ico icons from file.– jrhCommented Mar 10, 2017 at 20:06 -
2You sure LoadImage can load PNG resource? I did not create IDC, just need to load resource, but looks like its not loading. Commented Mar 20, 2018 at 13:16
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@SergKryvonos No,
LoadImage()
will not load a PNG image. The solution here simply cheats by first using a tool to convert the PNG to an ICO file and then loading that ICO file. That's quite literally not what the question is asking for. It also never produces anHBITMAP
as the question is asking for. This is down-vote material. Commented Dec 30, 2023 at 9:57 -
@IInspectable there is no win gdi API to load png natively. If you want to achieve transparency - you can use icons.– vadim_hrCommented Dec 31, 2023 at 11:17
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The question isn't demanding "no GDI". It's asking for "no external libraries". This answer outlines how to do so (the WIC is a system service that ships with Windows; it has native PNG support). If you request a DIB section, an
HBITMAP
can store an alpha channel just fine. Commented Dec 31, 2023 at 11:51
You can do it with StretchDIBits
API, but limited by OS/driver availability.
Consult MSDN documentation for details:
http://msdn.microsoft.com/en-us/library/dd145121(v=VS.85).aspx
http://msdn.microsoft.com/en-us/library/dd145107(VS.85).aspx
I sincerely apologize for misleading you guys interested in this issue.
Let me correct my mistake.
No StretchDIBits
for PNG drawing.
You'd better try WIC method or consider way to integrate GDI+ in your projects.
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+1... after banging my head on the wall numerous times before, I'm glad to finally see this answer! :) Commented Dec 31, 2010 at 3:59
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3Ooch! I did some research on this. It's seems like there is no working code actually drawing PNG image to GDI device context. Many pointing out StretchDIBits PNG support totally useless.– 9danCommented Dec 31, 2010 at 6:55
We can display png image via GDI, by the following two steps when creating your window(case WM_CREATE
in window procedure function):
- load png file (via libpng or stb image), pixel values saved in a variable, say
buffer
- create
HBITMAP
instance usingbuffer
inCreateBitmap()
function
Here's the runnable code, which is in pure C and main()
as entry point function (libpng and zlib are from my own opencv compilation)
#include <stdio.h>
#include <windows.h>
#include "png.h"
#define CRTDBG_MAP_ALLOC
#include <crtdbg.h>
// **NB**: You may use OpenCV prebuilt package's self contained libpng.lib file
// or, maybe, you can also compile it from source (which cost time and not necessary), see: `http://www.libpng.org` and `https://www.zlib.net`
#define LIBPNG_PTH "D:/opencv_249/build/x64/vc12/staticlib/libpng.lib"
#define ZLIB_PTH "D:/opencv_249/build/x64/vc12/staticlib/zlib.lib"
#pragma comment(lib, LIBPNG_PTH)
#pragma comment(lib, ZLIB_PTH)
typedef struct MyRect {
int x, y, width, height;
} MyRect;
char bitmap_im_pth[100];
typedef struct MyWindow {
HDC dc;
//HGDIOBJ image;
HBITMAP hBmp;
unsigned char* imdata;
} MyWindow;
MyWindow* my_window;
enum ImageType {BMP, PNG};
long ReadPngData(const char *szPath, int *pnWidth, int *pnHeight, unsigned char **cbData)
{
FILE *fp = NULL;
long file_size = 0, pos = 0, mPos = 0;
int color_type = 0, x = 0, y = 0, block_size = 0;
png_infop info_ptr;
png_structp png_ptr;
png_bytep *row_point = NULL;
fp = fopen(szPath, "rb");
if (!fp) return -1;
png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, 0, 0, 0);
info_ptr = png_create_info_struct(png_ptr);
png_init_io(png_ptr, fp);
png_read_png(png_ptr, info_ptr, PNG_TRANSFORM_EXPAND, 0);
*pnWidth = png_get_image_width(png_ptr, info_ptr);
*pnHeight = png_get_image_height(png_ptr, info_ptr);
color_type = png_get_color_type(png_ptr, info_ptr);
file_size = (*pnWidth) * (*pnHeight) * 4;
*cbData = (unsigned char *)malloc(file_size);
row_point = png_get_rows(png_ptr, info_ptr);
block_size = color_type == 6 ? 4 : 3;
for (x = 0; x < *pnHeight; x++)
for (y = 0; y < *pnWidth*block_size; y += block_size)
{
(*cbData)[pos++] = row_point[x][y + 2]; //B
(*cbData)[pos++] = row_point[x][y + 1]; //G
(*cbData)[pos++] = row_point[x][y + 0]; //R
(*cbData)[pos++] = row_point[x][y + 3]; //alpha
}
png_destroy_read_struct(&png_ptr, &info_ptr, 0);
fclose(fp);
return file_size;
}
LRESULT __stdcall WindowProcedure(HWND window, unsigned int msg, WPARAM wp, LPARAM lp)
{
int im_width, im_height;
int image_type = PNG;
switch (msg)
{
case WM_CREATE:
if (image_type == BMP) {
my_window->hBmp = (HBITMAP)LoadImage(NULL, "lena512.bmp", IMAGE_BITMAP, 0, 0, LR_LOADFROMFILE);
}
else if (image_type == PNG) {
ReadPngData("Lena.png", &im_width, &im_height, &my_window->imdata);
my_window->hBmp = CreateBitmap(im_width, im_height, 32, 1, my_window->imdata);
}
if (my_window->hBmp == NULL)
MessageBox(window, "Could not load image!", "Error", MB_OK | MB_ICONEXCLAMATION);
break;
case WM_PAINT:
{
BITMAP bm;
PAINTSTRUCT ps;
HDC hdc = BeginPaint(window, &ps);
SetStretchBltMode(hdc, COLORONCOLOR);
my_window->dc = CreateCompatibleDC(hdc);
HBITMAP hbmOld = SelectObject(my_window->dc, my_window->hBmp);
GetObject(my_window->hBmp, sizeof(bm), &bm);
#if 1
BitBlt(hdc, 0, 0, bm.bmWidth, bm.bmHeight, my_window->dc, 0, 0, SRCCOPY);
#else
RECT rcClient;
GetClientRect(window, &rcClient);
int nWidth = rcClient.right - rcClient.left;
int nHeight = rcClient.bottom - rcClient.top;
StretchBlt(hdc, 0, 0, nWidth, nHeight, hdcMem, 0, 0, bm.bmWidth, bm.bmHeight, SRCCOPY);
#endif
SelectObject(my_window->dc, hbmOld);
DeleteDC(my_window->dc);
EndPaint(window, &ps);
}
break;
case WM_DESTROY:
printf("\ndestroying window\n");
PostQuitMessage(0);
return 0L;
case WM_LBUTTONDOWN:
printf("\nmouse left button down at (%d, %d)\n", LOWORD(lp), HIWORD(lp));
// fall thru
default:
//printf(".");
return DefWindowProc(window, msg, wp, lp);
}
}
const char* szWindowClass = "myclass";
ATOM MyRegisterClass(HINSTANCE hInstance)
{
WNDCLASSEX wc;
wc.cbSize = sizeof(WNDCLASSEX);
/* Win 3.x */
wc.style = CS_DBLCLKS;
wc.lpfnWndProc = WindowProcedure;
wc.cbClsExtra = 0;
wc.cbWndExtra = 0;
wc.hInstance = GetModuleHandle(0);
wc.hIcon = LoadIcon(0, IDI_APPLICATION);
wc.hCursor = LoadCursor(0, IDC_ARROW);
wc.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);
wc.lpszMenuName = 0;
wc.lpszClassName = szWindowClass;
/* Win 4.0 */
wc.hIconSm = LoadIcon(0, IDI_APPLICATION);
return RegisterClassEx(&wc);
}
BOOL InitInstance(HINSTANCE hInstance, int nCmdShow)
{
MyRect rect;
rect.x = 300;
rect.y = 300;
rect.width = 640;
rect.height = 480;
DWORD defStyle = WS_VISIBLE | WS_MINIMIZEBOX | WS_MAXIMIZEBOX | WS_SYSMENU;
HWND hwnd = CreateWindowEx(0, szWindowClass, "title",
defStyle, rect.x, rect.y,
rect.width, rect.height, 0, 0, hInstance, 0);
if (!hwnd)
{
return FALSE;
}
ShowWindow(hwnd, nCmdShow);
UpdateWindow(hwnd);
return TRUE;
}
void create_my_window(MyWindow** _my_window) {
MyWindow* my_window = (MyWindow*)malloc(sizeof(MyWindow));
my_window->dc = NULL;
my_window->imdata = NULL;
my_window->hBmp = NULL;
*_my_window = my_window; // write back
}
void destroy_my_window(MyWindow* my_window) {
if (my_window) {
if (my_window->imdata) free(my_window->imdata);
free(my_window);
}
}
int main()
{
printf("hello world!\n");
HINSTANCE hInstance = GetModuleHandle(0);
int nCmdShow = SW_SHOWDEFAULT;
MyRegisterClass(hInstance);
create_my_window(&my_window);
if (!InitInstance(hInstance, nCmdShow))
{
return FALSE;
}
MSG msg;
while (GetMessage(&msg, 0, 0, 0)) {
DispatchMessage(&msg);
}
destroy_my_window(my_window);
return 0;
}
Reference: https://www.cnblogs.com/mr-wid/archive/2013/04/22/3034840.html
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Please don't use hardcoded paths. They won't work on other's PCs. Not all of us have "d:" ... #pragma comment(lib, "D:/opencv345/mybuild/libpng.lib") - I edited your answer accordingly Commented Aug 25, 2019 at 20:25
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@MichaelHaephrati Sorry, I'm not very agree with your opinion. I paste the specific path of libpng.lib as something like "F:\zhangzhuo\lib\opencv_249\build\x64\vc12\staticlib\libpng.lib", is to tell people that they can use the opencv 249 prebuild package self contained library. People would easily get that version of prebuilt opencv, thus they don't have to compile the zlib and libpng manually, which is time-consuming. People of course should modify that path since people may have different path.– ChrisZZCommented Aug 26, 2019 at 3:09
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2
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1The question is asking how to load a PNG image using only services provided by the OS (Win32/GDI). Suggesting to use some random 3rd party library does not answer that question. The question even explicitly says "without using external libraries (like libpng)". This isn't useful. Commented Apr 21, 2022 at 16:26
The answer by vladimir_hr is simplicity itself.
Simple steps to follow.
In the resources header file declare like: #define IDI_PNG 1000
In the resource file *.rc have: IDI_PNG ICON "protractor.ico"
The icon file. Convert your (transparent) png file into an icon file by using an icon editor that support custom size instead of the standard Windows' icon sizes, save this png image as an icon image.
The rest is just blitting between DC's.
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1If you are referring to another answer, please write a comment to that aswer.– EFrankCommented Dec 10, 2020 at 11:15
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1The question is asking how to load a PNG image. Recommending to use a different image format does not provide an answer to that question. Commented Apr 21, 2022 at 16:28