Windows API Rendering an Image From File (Beginner)

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