Windows API Rendering an Image From File (Beginner) - c++

Question

I am trying to understand how to load and render an image from a file using the Windows API, Direct2D, and Visual C++. I have been more or less attempting to follow an MSDN article on this topic. I am new to both C++ (experienced in C) and the Windows API.
I wrote 3 functions.
HRESULT imagefactorysetup(IWICImagingFactory * pImageFactory)
{
HRESULT hr = CoCreateInstance(CLSID_WICImagingFactory, NULL, CLSCTX_INPROC_SERVER, IID_IWICImagingFactory, (LPVOID *) &pImageFactory);
return hr;
}
HRESULT imageload(LPCWSTR filename, IWICImagingFactory * pImageFactory, IWICBitmapFrameDecode * pFrame)
{
IWICBitmapDecoder * pDecoder = NULL;
HRESULT hr = pImageFactory->CreateDecoderFromFilename(filename, NULL, GENERIC_READ, WICDecodeMetadataCacheOnLoad, &pDecoder);
if (SUCCEEDED(hr))
hr = pDecoder->GetFrame(0, &pFrame);
//Format convert the frame to 32bppPBGRA
IWICFormatConverter * pFormatConverter = NULL;
if (SUCCEEDED(hr))
{
SafeRelease(&pFormatConverter);
hr = pImageFactory->CreateFormatConverter(&pFormatConverter);
}
if (SUCCEEDED(hr))
hr = pFormatConverter->Initialize(pFrame, GUID_WICPixelFormat32bppPBGRA, WICBitmapDitherTypeNone, NULL, 0.f, WICBitmapPaletteTypeCustom);
return hr;
}
HRESULT imagerender(HWND hWnd, IWICBitmapFrameDecode * pFrame, int x, int y)
{
//Create a D2D render target properties
D2D1_RENDER_TARGET_PROPERTIES renderTargetProperties = D2D1::RenderTargetProperties();
//Set the DPI to be the default system DPI to allow direct mapping
//between image pixels and desktop pixels in different system DPI settings
renderTargetProperties.dpiX = DEFAULT_DPI;
renderTargetProperties.dpiY = DEFAULT_DPI;
//Create a D2D render target
D2D1_SIZE_U sz = D2D1::SizeU(MAINWINDOWWIDTH, MAINWINDOWHEIGHT); //Change size
ID2D1Factory * pD2DFactory;
HRESULT hr = D2D1CreateFactory(D2D1_FACTORY_TYPE_SINGLE_THREADED, __uuidof(ID2D1Factory1), NULL, (LPVOID *) &pD2DFactory);
ID2D1RenderTarget * pRenderTarget;
//renderTargetProperties, D2D1::HwndRenderTargetProperties(hWnd, sz), &pRenderTarget);
hr = pD2DFactory->CreateHwndRenderTarget(&renderTargetProperties, D2D1::HwndRenderTargetProperties(hWnd, sz), &pRenderTarget);
ID2D1Bitmap * pD2DBitmap = NULL;
pRenderTarget->CreateBitmapFromWicBitmap(pFrame, NULL, &pD2DBitmap);
D2D1_SIZE_F size = pD2DBitmap->GetSize();
D2D1_POINT_2F origin = D2D1::Point2F((float) x, (float) y);
if (pD2DBitmap)
pRenderTarget->DrawBitmap(pD2DBitmap, D2D1::RectF(origin.x, origin.y, origin.x + size.width, origin.y + size.height));
return hr;
}
Question:
1) The following line gives me an error. I tried reading some documentation on MSDN but am unsure what the issue is.
hr = pD2DFactory->CreateHwndRenderTarget(&renderTargetProperties, D2D1::HwndRenderTargetProperties(hWnd, sz), &pRenderTarget);
Error:
IntelliSense: no instance of overloaded function "ID2D1Factory::CreateHwndRenderTarget" matches the argument list
argument types are: (D2D1_RENDER_TARGET_PROPERTIES *, D2D1_HWND_RENDER_TARGET_PROPERTIES, ID2D1RenderTarget **)
object type is: ID2D1Factory 68 18
2) In general, is there a more idiomatic / efficient way of approaching the problem of rendering an image from a file onto a window than what I have attempted? My previous programming experience has been strictly in C.

Answer 1

No problem. You can use GDI+ to load any image that windows supports natively.
You can then use GDI to draw it.
Here's a short example of drawing a (transparent) PNG to the background of a dialog. I've built it using MinGW32 and Code::Blocks. You'll need to link the msimg32 and gdiplus libraries to make use of AlphaBlend and the Bitmap class (and the functions to init/shutdown GDI+).
Points that may be worth mentioning are:
mLoadImage will load anything that windows will show in Windows Photo
Viewer (// BMP, GIF, JPEG, PNG, TIFF, Exif, WMF, and EMF) - it uses
the Bitmap class, as found in Gdiplus.
The WM_ERASEBKGND message comes with wParam holding a device context
that you can draw straight into - that's why there's no need to get
one by usig BeginPaint, as we do in response to a WM_PAINT message.
You can use BitBlt or StretchBlt for images that dont contain transparent areas.
Main.cpp
#define WINVER 0x0500 // for AlphaBlend
#include <windows.h>
#include <commctrl.h>
#include <stdio.h>
#include <gdiplus.h>
#include "resource.h"
using namespace Gdiplus;
HINSTANCE hInst;
void setClientSize(HWND mHwnd, int width, int height)
{
RECT wndRect, clientRect, mRect;
int clientX, clientY, windowX, windowY, difX, difY;
GetWindowRect(mHwnd, &wndRect);
GetClientRect(mHwnd, &clientRect);
clientX = clientRect.right - clientRect.left;
clientY = clientRect.bottom - clientRect.top;
windowX = wndRect.right - wndRect.left;
windowY = wndRect.bottom - wndRect.top;
difX = windowX - clientX;
difY = windowY - clientY;
// GetWindowRect(mHwnd, &mRect);
POINT topLeft = {wndRect.left, wndRect.top};
// ScreenToClient(mParentHwnd, &topLeft);
SetWindowPos(mHwnd, HWND_TOP, topLeft.x, topLeft.y, width+difX, height+difY, SWP_NOZORDER);
}
HBITMAP mLoadImg(wchar_t *filename)
{
Bitmap mBitmap(filename,false);
HBITMAP result;
mBitmap.GetHBITMAP(0x00000000, &result);
return result;
}
void onPaint(HWND hwnd, HBITMAP bkg)
{
HDC memDC, hdc;
PAINTSTRUCT ps;
HBITMAP old;
RECT clientRect;
int width, height;
hdc = BeginPaint(hwnd, &ps);
GetClientRect(hwnd, &clientRect);
width = clientRect.right - clientRect.left;
height = clientRect.bottom - clientRect.top;
memDC = CreateCompatibleDC(NULL);
old = (HBITMAP)SelectObject(memDC, bkg);
byte alpha = 255;
BLENDFUNCTION bf = {AC_SRC_OVER,0,alpha,AC_SRC_ALPHA};
AlphaBlend(hdc, 0,0,width,height, memDC, 0,0, width,height, bf);
// try the below instead of AlphaBlend - they each rely on the fact I've resized the
// client area to the same size as the image I'll draw on it.
// BitBlt(hdc, 0,0, clientRect.right,clientRect.bottom, memDC, 0,0, SRCCOPY);
SelectObject(memDC, old);
DeleteDC(memDC);
EndPaint(hwnd, &ps);
}
BOOL CALLBACK DlgMain(HWND hwndDlg, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
static HBITMAP mBkg;
switch(uMsg)
{
case WM_INITDIALOG:
{
mBkg = mLoadImg(L"wiki.png");
BITMAP bm;
GetObject(mBkg, sizeof(bm), &bm);
setClientSize(hwndDlg, bm.bmWidth, bm.bmHeight);
}
return TRUE;
case WM_ERASEBKGND:
{
RECT clientRect;
HBRUSH bkgBrush = CreateSolidBrush( RGB(255,0,0) );
GetClientRect(hwndDlg, &clientRect);
FillRect( (HDC)wParam, &clientRect, bkgBrush);
DeleteObject(bkgBrush);
}
return 1;
case WM_PAINT:
onPaint(hwndDlg, mBkg);
return 0;
case WM_CLOSE:
{
EndDialog(hwndDlg, 0);
}
return TRUE;
case WM_COMMAND:
{
switch(LOWORD(wParam))
{
}
}
return TRUE;
}
return FALSE;
}
int APIENTRY WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nShowCmd)
{
GdiplusStartupInput gdiplusStartupInput;
ULONG_PTR gdiplusToken;
GdiplusStartup(&gdiplusToken, &gdiplusStartupInput, NULL);
hInst=hInstance;
InitCommonControls();
int retVal = DialogBox(hInst, MAKEINTRESOURCE(DLG_MAIN), NULL, (DLGPROC)DlgMain);
GdiplusShutdown(gdiplusToken);
return retVal;
}
resource.h
#ifndef IDC_STATIC
#define IDC_STATIC (-1)
#endif
#define DLG_MAIN 100
resource.rc
// Generated by ResEdit 1.6.2
// Copyright (C) 2006-2014
// http://www.resedit.net
#include <windows.h>
#include <commctrl.h>
#include <richedit.h>
#include "resource.h"
//
// Dialog resources
//
DLG_MAIN DIALOG 0, 0, 186, 95
STYLE DS_3DLOOK | DS_CENTER | DS_SHELLFONT | WS_CAPTION | WS_VISIBLE | WS_POPUP | WS_THICKFRAME | WS_SYSMENU
EXSTYLE WS_EX_WINDOWEDGE
CAPTION "Dialog"
FONT 8, "Ms Shell Dlg"
{
}
Wiki.png
Result