Direct2D窗口無法完全呈現

Question

我才剛剛開始嘗試學習Direct2D和Windows，並且已經遍歷了他們在MSDN上的教程。 我編寫的大多數代碼都是從他們的網站上手工復制的。 我在一個教程模塊中，它是對用戶輸入的介紹，其代碼與先前的模塊基本相同，但是該程序啟動了，窗口從未完全渲染。 它只是一個白色區域，包括非客戶區域應渲染的位置（頂部欄，側面和底部）。 下面是main.cpp文件的代碼：

#ifndef UNICODE
#define UNICODE
#endif // !UNICODE

#include <windowsx.h>
#include <Windows.h>
#include <d2d1.h>
#pragma comment (lib, "d2d1")

#include "BaseWindow.h"

template <class T> void SafeRelease(T **ppT)
{
if(*ppT)
{
    (*ppT)->Release();
    *ppT = NULL;
}
}

class DPIScale
{
static float scaleX;
static float scaleY;

public:
static void Intitialize(ID2D1Factory *pFactory)
{
    FLOAT   dpiX, dpiY;
    pFactory->GetDesktopDpi(&dpiX, &dpiY);
    scaleX = dpiX/96.0f;
    scaleY = dpiY/96.0f;
}

template <typename T>
static D2D1_POINT_2F Pixels_To_DIPs(T x, T y)
{
    return D2D1::Point2F(static_cast<float>(x) / scaleX, static_cast<float>(y)     
 / scaleY);
}
};

float DPIScale::scaleX = 1.0F;
float DPIScale::scaleY = 1.0F;

class MainWindow : public BaseWindow<MainWindow>
{
ID2D1Factory            *pFactory;
ID2D1HwndRenderTarget   *pRenderTarget;
ID2D1SolidColorBrush    *pBrush;
D2D1_ELLIPSE            ellipse;
D2D1_POINT_2F           ptMouse;

HRESULT CreateGraphicsResources();
void    DiscardGraphicsResources();
void    Resize();
void    OnPaint();
void    OnLButtonDown(int pixelX, int pixelY, DWORD flags);
void    OnLButtonUp();
void    OnMouseMove(int pixelX, int pixelY, DWORD flags);

public:

MainWindow() : pFactory(NULL), pRenderTarget(NULL), pBrush(NULL),   
ellipse(D2D1::Ellipse(D2D1::Point2F(), 0, 0)), 
    ptMouse(D2D1::Point2F()) {}

PCWSTR ClassName() const { return L"D2D Drawing Program Class"; }
LRESULT HandleMessage(UINT uMsg, WPARAM wParam, LPARAM lParam);
};

HRESULT MainWindow::CreateGraphicsResources()
{
HRESULT hr = S_OK;
if( pRenderTarget == NULL )
{
    RECT rc;
    GetClientRect(m_hwnd, &rc);

    D2D_SIZE_U size = D2D1::SizeU(rc.right, rc.bottom);

    hr = pFactory->CreateHwndRenderTarget(
        D2D1::RenderTargetProperties(),
        D2D1::HwndRenderTargetProperties(m_hwnd, size),
        &pRenderTarget
        );

    if(SUCCEEDED(hr))
    {
        const D2D1_COLOR_F color = D2D1::ColorF(0.0f, 0.0f, 0.0f, 1.0f);
        hr = pRenderTarget->CreateSolidColorBrush(color, &pBrush);
    }
}

return hr;
}

void MainWindow::DiscardGraphicsResources()
{
SafeRelease(&pRenderTarget);
SafeRelease(&pBrush);
}

void MainWindow::OnPaint()
{
HRESULT hr = CreateGraphicsResources();
if(SUCCEEDED(hr))
{
    PAINTSTRUCT ps;
    BeginPaint(m_hwnd, &ps);

    pRenderTarget->BeginDraw();

    pRenderTarget->Clear(D2D1::ColorF(D2D1::ColorF::White));
    pRenderTarget->FillEllipse(ellipse, pBrush);

    hr = pRenderTarget->EndDraw();
    if(FAILED(hr) || hr == D2DERR_RECREATE_TARGET)
    {
        DiscardGraphicsResources();
    }
    EndPaint(m_hwnd, &ps);
}
}

void MainWindow::Resize()
{
    if (pRenderTarget != NULL)
    {
        RECT rc;
        GetClientRect(m_hwnd, &rc);

        D2D1_SIZE_U size = D2D1::SizeU(rc.right, rc.bottom);

        pRenderTarget->Resize(size);
        InvalidateRect(m_hwnd, NULL, FALSE);
    }
 }

void MainWindow::OnLButtonDown(int pixelX, int pixelY, DWORD flags)
{
SetCapture(m_hwnd);
ellipse.point = ptMouse = DPIScale::Pixels_To_DIPs(pixelX, pixelY);
ellipse.radiusX = ellipse.radiusY = 1.0f;
InvalidateRect(m_hwnd, NULL, FALSE);
}

void MainWindow::OnLButtonUp()
{
ReleaseCapture();
}

void MainWindow::OnMouseMove(int pixelX, int pixelY, DWORD flags)
{
const D2D1_POINT_2F DIPs = DPIScale::Pixels_To_DIPs(pixelX, pixelY);

const float width = (DIPs.x - ptMouse.x) / 2;
const float height = (DIPs.y - ptMouse.y) / 2;
const float x1 = ptMouse.x + width;
const float y1 = ptMouse.y + height;

ellipse = D2D1::Ellipse(D2D1::Point2F(x1, y1), width, height);

InvalidateRect(m_hwnd, NULL, FALSE);
}

int WINAPI wWinMain(HINSTANCE hInstance, HINSTANCE, PWSTR, int nCmdShow)
{
MainWindow win;

if( !win.Create(L"D2D Drawing Program", WS_OVERLAPPEDWINDOW) )
{
    return 0;
}

ShowWindow(win.Window(), nCmdShow);

MSG msg = {};

while(GetMessage(&msg, NULL, 0, 0))
{
    TranslateMessage(&msg);
    DispatchMessage(&msg);
}

return 0;
}

LRESULT MainWindow::HandleMessage(UINT uMsg, WPARAM wParam, LPARAM lParam)
{
switch(uMsg)
{
    case WM_CREATE:
        if(FAILED(D2D1CreateFactory(D2D1_FACTORY_TYPE_SINGLE_THREADED,  
                         &pFactory)))
        {
            return -1;
        }

        // DPIScale::Intitialize(pFactory);
        return 0;

    case WM_DESTROY:
        DiscardGraphicsResources();
        SafeRelease(&pFactory);
        PostQuitMessage(0);
        return 0;

    case WM_PAINT:
        OnPaint();
        return 0;

    case WM_SIZE:
        Resize();
        return 0;

    case WM_LBUTTONDOWN:
        OnLButtonDown(GET_X_LPARAM(lParam), GET_Y_LPARAM(lParam), 
                           (DWORD)wParam);
        return 0;

    case WM_LBUTTONUP:
        OnLButtonUp();
        return  0;

    case WM_MOUSEMOVE:
        OnMouseMove(GET_X_LPARAM(lParam), GET_Y_LPARAM(lParam   
                           (DWORD)wParam);
        return 0;
}
}

如果可以的話請幫忙！ 我已經經歷了大約一個半小時的時間，找不到任何不一致之處。

頭文件中包含一個BaseWindow模板類，該代碼用於創建和注冊窗口類以及所有其他類，但是頭文件是另一個程序的直接副本，可以正常工作，因此我認為不需要被包括。

Answer 1

我自己想通了。 原來我忘了在HandleMessage方法末尾返回默認的Windows過程。