Memory DC PaintCanvas Projectv12 COMPLETE

#include <vector>
#include <windows.h>
#include <fstream>
#include <string>
#include <commdlg.h>
#include <codecvt>
#include <algorithm>

using namespace std;

struct Brushstroke;
struct Eraserstroke;
HWND hWnd;
HINSTANCE hInst;
bool IsPointInClientRect(HWND hwnd, int x, int y) {
    RECT rect;
    GetClientRect(hwnd, &rect);
    return (x >= 0 && x < rect.right&& y >= 0 && y < rect.bottom);
}

struct Brushstroke {
    int x;
    int y;
    int size;
    COLORREF color;
    void serialize(ofstream& outFile) const {
        outFile << "B " << x << " " << y << " " << size << " "
            << (int)GetRValue(color) << " "
            << (int)GetGValue(color) << " "
            << (int)GetBValue(color) << endl;
    }
};

struct Eraserstroke {
    int x;
    int y;
    int size;
    COLORREF color;
    void serialize(ofstream& outFile) const {
        outFile << "E " << x << " " << y << " " << size << endl;
    }
};

std::vector<Brushstroke> storedBrushstrokes;
std::vector<Eraserstroke> storedEraserstrokes;

void RedrawStrokes();
void SaveDrawing(const string& filename);
void LoadDrawing(const string& filename);

POINT previousPoint;
HDC hdc, memDC;
HBITMAP memBitmap;

bool isPaintbrushSelected = true;
bool isDrawing = false;
bool isErasing = false;
bool isClearing = false;
bool isEraserSelected = false;
int brushSize = 10;

void DrawBrush(HDC hdc, int x, int y) {
    if (!IsPointInClientRect(hWnd, x, y)) return;
    HGDIOBJ originalBrush = SelectObject(hdc, CreateSolidBrush(RGB(255, 0, 0)));
    HGDIOBJ originalPen = SelectObject(hdc, GetStockObject(NULL_PEN));
    Ellipse(hdc, x - brushSize, y - brushSize, x + brushSize, y + brushSize);
    DeleteObject(SelectObject(hdc, originalBrush));
    DeleteObject(SelectObject(hdc, originalPen));
}

void Erase(HDC hdc, int x, int y, int eraserSize) {
    if (!IsPointInClientRect(hWnd, x, y)) return;
    HBRUSH hBrush = CreateSolidBrush(RGB(255, 255, 255));
    SelectObject(hdc, GetStockObject(NULL_PEN));
    SelectObject(hdc, hBrush);
    Ellipse(hdc, x - eraserSize, y - eraserSize, x + eraserSize, y + eraserSize);
    DeleteObject(hBrush);

    // Remove brushstrokes that intersect with the eraser
    storedBrushstrokes.erase(
        std::remove_if(storedBrushstrokes.begin(), storedBrushstrokes.end(),
            [x, y, eraserSize](const Brushstroke& stroke) {
                int dx = stroke.x - x;
                int dy = stroke.y - y;
                return (dx * dx + dy * dy) <= (eraserSize + stroke.size) * (eraserSize + stroke.size);
            }),
        storedBrushstrokes.end()
                );
}

// Update the ClearDrawing function
void ClearDrawing(HWND hwnd) {
    RECT rect;
    GetClientRect(hwnd, &rect);
    HBRUSH hBrush = CreateSolidBrush(RGB(255, 255, 255));

    // Clear both hdc AND memDC
    HDC hdc = GetDC(hwnd);
    FillRect(hdc, &rect, hBrush);
    FillRect(memDC, &rect, hBrush);
    ReleaseDC(hwnd, hdc);

    DeleteObject(hBrush);
    storedBrushstrokes.clear();

    InvalidateRect(hwnd, NULL, FALSE);
    UpdateWindow(hwnd);
}

void DrawSmoothBrush(HDC hdc, int x, int y) {
    if (isDrawing && (isPaintbrushSelected || isEraserSelected)) {
        int numPoints = 3;
        POINT currentPoint = { x, y };
        for (int i = 1; i <= numPoints; i++) {
            float t = (float)i / (float)numPoints;
            int smoothX = (int)(previousPoint.x + t * (currentPoint.x - previousPoint.x));
            int smoothY = (int)(previousPoint.y + t * (currentPoint.y - previousPoint.y));
            if (isPaintbrushSelected) {
                DrawBrush(hdc, smoothX, smoothY);
                Brushstroke newBrushstroke;
                newBrushstroke.x = smoothX;
                newBrushstroke.y = smoothY;
                newBrushstroke.size = brushSize;
                newBrushstroke.color = RGB(255, 0, 0);
                storedBrushstrokes.push_back(newBrushstroke);
            }
            else if (isEraserSelected) {
                Erase(hdc, smoothX, smoothY, brushSize);
                Eraserstroke newEraserstroke;
                newEraserstroke.x = smoothX;
                newEraserstroke.y = smoothY;
                newEraserstroke.size = brushSize;
                newEraserstroke.color = RGB(255, 255, 255);
                storedEraserstrokes.push_back(newEraserstroke);
            }
        }
        previousPoint = currentPoint;
    }
}

void RedrawStrokes() {
    // Clear the entire drawing area
    RECT rect;
    GetClientRect(hWnd, &rect);
    HBRUSH hBrush = CreateSolidBrush(RGB(255, 255, 255));
    FillRect(memDC, &rect, hBrush);
    DeleteObject(hBrush);

    // Redraw all brushstrokes
    for (const auto& brushstroke : storedBrushstrokes) {
        HGDIOBJ originalBrush = SelectObject(memDC, CreateSolidBrush(brushstroke.color));
        HGDIOBJ originalPen = SelectObject(memDC, GetStockObject(NULL_PEN));
        Ellipse(memDC, brushstroke.x - brushstroke.size, brushstroke.y - brushstroke.size,
            brushstroke.x + brushstroke.size, brushstroke.y + brushstroke.size);
        DeleteObject(SelectObject(memDC, originalBrush));
        DeleteObject(SelectObject(memDC, originalPen));
    }

    // Update the window
    InvalidateRect(hWnd, NULL, FALSE);
    UpdateWindow(hWnd);
}

void SaveDrawing(const string& filename) {
    ofstream outFile(filename);
    if (outFile.is_open()) {
        outFile << storedBrushstrokes.size() << endl;
        for (const auto& brushstroke : storedBrushstrokes) {
            brushstroke.serialize(outFile);
        }
        outFile.close();
    }
}

void LoadDrawing(const string& filename) {
    ifstream inFile(filename);
    if (inFile.is_open()) {
        int numBrushstrokes;
        inFile >> numBrushstrokes;
        storedBrushstrokes.clear();
        storedBrushstrokes.reserve(numBrushstrokes);
        for (int i = 0; i < numBrushstrokes; ++i) {
            char type;
            Brushstroke brushstroke;
            int r, g, b;
            inFile >> type >> brushstroke.x >> brushstroke.y >> brushstroke.size >> r >> g >> b;
            brushstroke.color = RGB(r, g, b);
            storedBrushstrokes.push_back(brushstroke);
        }
        inFile.close();
        RedrawStrokes();
    }
}

void SaveDrawingDialog(HWND hwnd) {
    OPENFILENAME ofn;
    wchar_t szFileName[MAX_PATH] = L"";

    ZeroMemory(&ofn, sizeof(ofn));
    ofn.lStructSize = sizeof(ofn);
    ofn.hwndOwner = hwnd;
    ofn.lpstrFilter = L"Text Files (*.txt)\0*.txt\0All Files (*.*)\0*.*\0";
    ofn.lpstrFile = szFileName;
    ofn.nMaxFile = MAX_PATH;
    ofn.Flags = OFN_EXPLORER | OFN_OVERWRITEPROMPT;
    ofn.lpstrDefExt = L"txt";

    if (GetSaveFileName(&ofn)) {
        std::wstring_convert < std::codecvt_utf8 < wchar_t>> converter;
        std::string filenameStr = converter.to_bytes(szFileName);
        SaveDrawing(filenameStr);
        MessageBox(hwnd, L"Save Complete", L"Doodle App", MB_OK | MB_ICONINFORMATION);
    }
}

void LoadDrawingDialog(HWND hwnd) {
    OPENFILENAME ofn;
    wchar_t szFileName[MAX_PATH] = L"";

    ZeroMemory(&ofn, sizeof(ofn));
    ofn.lStructSize = sizeof(ofn);
    ofn.hwndOwner = hwnd;
    ofn.lpstrFilter = L"Text Files (*.txt)\0*.txt\0All Files (*.*)\0*.*\0";
    ofn.lpstrFile = szFileName;
    ofn.nMaxFile = MAX_PATH;
    ofn.Flags = OFN_EXPLORER | OFN_FILEMUSTEXIST;

    if (GetOpenFileName(&ofn)) {
        std::wstring_convert<std::codecvt_utf8<wchar_t>> converter;
        std::string filenameStr = converter.to_bytes(szFileName);
        LoadDrawing(filenameStr);
    }
}

void SanitizeAndSaveDrawing(const string& filename) {
    ofstream outFile(filename);
    if (outFile.is_open()) {
        RECT rect;
        GetClientRect(hWnd, &rect);

        vector<Brushstroke> validBrushstrokes;
        for (const auto& brushstroke : storedBrushstrokes) {
            if (IsPointInClientRect(hWnd, brushstroke.x, brushstroke.y)) {
                validBrushstrokes.push_back(brushstroke);
            }
        }

        outFile << validBrushstrokes.size() << endl;
        for (const auto& brushstroke : validBrushstrokes) {
            brushstroke.serialize(outFile);
        }
        outFile.close();
    }
}
LRESULT CALLBACK WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam) {
    switch (uMsg) {
    case WM_CREATE:
    {
        hWnd = hwnd;
        RECT rect;
        GetClientRect(hwnd, &rect);
        HDC hdc = GetDC(hwnd);
        memDC = CreateCompatibleDC(hdc);
        memBitmap = CreateCompatibleBitmap(hdc, rect.right - rect.left, rect.bottom - rect.top);
        SelectObject(memDC, memBitmap);
        ReleaseDC(hwnd, hdc);
        HBRUSH hBrush = CreateSolidBrush(RGB(255, 255, 255));
        FillRect(memDC, &rect, hBrush);
        DeleteObject(hBrush);
        isPaintbrushSelected = true;
        LoadDrawing("drawing.txt");
    }
    break;
    case WM_KEYDOWN:
        if (wParam == VK_ADD) {
            brushSize += 5;
        }
        else if (wParam == VK_SUBTRACT) {
            if (brushSize > 5) {
                brushSize -= 5;
            }
        }
        else if (wParam == 0x43) { // 'C' key
            if (!(GetKeyState(VK_CONTROL) & 0x8000)) {
                ClearDrawing(hwnd);
            }
        }
        else if (wParam == 0x50) {
            isPaintbrushSelected = true;
            isEraserSelected = false;
        }
        else if (wParam == 0x45) {
            isEraserSelected = true;
            isPaintbrushSelected = false;
        }
        else if (wParam == 'S' && (GetKeyState(VK_CONTROL) & 0x8000)) {
            SaveDrawingDialog(hwnd);
        }
        else if (wParam == 'O' && (GetKeyState(VK_CONTROL) & 0x8000)) {
            LoadDrawingDialog(hwnd);
        }
        break;
    case WM_LBUTTONDOWN:
        if (isPaintbrushSelected || isEraserSelected) {
            previousPoint.x = LOWORD(lParam);
            previousPoint.y = HIWORD(lParam);
        }
        isDrawing = true;
        break;
    case WM_LBUTTONUP:
        isDrawing = false;
        break;
    case WM_MOUSEMOVE:
        if (isDrawing && isPaintbrushSelected) {
            int x = LOWORD(lParam);
            int y = HIWORD(lParam);
            DrawSmoothBrush(memDC, x, y);
            InvalidateRect(hwnd, NULL, FALSE);
            if (IsPointInClientRect(hWnd, x, y)) {
                Brushstroke newBrushstroke;
                newBrushstroke.x = x;
                newBrushstroke.y = y;
                newBrushstroke.size = brushSize;
                newBrushstroke.color = RGB(255, 0, 0);
                storedBrushstrokes.push_back(newBrushstroke);
            }
        }
        else if (isDrawing && isEraserSelected) {
            int x = LOWORD(lParam);
            int y = HIWORD(lParam);
            Erase(memDC, x, y, brushSize);
            InvalidateRect(hwnd, NULL, FALSE);
        }
        break;
    case WM_SIZE:
    {
        static bool isMinimized = false;
        if (wParam == SIZE_MINIMIZED)
        {
            isMinimized = true;
        }
        else if (wParam == SIZE_MAXIMIZED || wParam == SIZE_RESTORED)
        {
            if (isMinimized)
            {
                isMinimized = false;
            }
            InvalidateRect(hwnd, NULL, TRUE);
        }
        RECT rect;
        GetClientRect(hwnd, &rect);
        if (memDC)
        {
            DeleteDC(memDC);
            DeleteObject(memBitmap);
        }
        HDC hdc = GetDC(hwnd);
        memDC = CreateCompatibleDC(hdc);
        memBitmap = CreateCompatibleBitmap(hdc, rect.right - rect.left, rect.bottom - rect.top);
        SelectObject(memDC, memBitmap);
        ReleaseDC(hwnd, hdc);
        HBRUSH hBrush = CreateSolidBrush(RGB(255, 255, 255));
        FillRect(memDC, &rect, hBrush);
        DeleteObject(hBrush);
        RedrawStrokes();
    }
    break;
    case WM_PAINT:
    {
        PAINTSTRUCT ps;
        HDC hdc = BeginPaint(hwnd, &ps);
        BitBlt(hdc, 0, 0, ps.rcPaint.right, ps.rcPaint.bottom, memDC, 0, 0, SRCCOPY);
        EndPaint(hwnd, &ps);
    }
    break;
    case WM_SETCURSOR:
        if (LOWORD(lParam) == HTCLIENT) {
            SetCursor(LoadCursor(NULL, IDC_ARROW));
            return TRUE;
        }
        break;
    case WM_CLOSE:
        // Sanitize and save before closing
        SanitizeAndSaveDrawing("drawing.txt");
        DestroyWindow(hwnd);
        break;
    case WM_DESTROY:
        DeleteDC(memDC);
        DeleteObject(memBitmap);
        PostQuitMessage(0);
        break;
    default:
        return DefWindowProc(hwnd, uMsg, wParam, lParam);
    }
}

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow) {
    const wchar_t CLASS_NAME[] = L"PaintCanvasWindowClass";
    WNDCLASS wc = { };

    wc.lpfnWndProc = WindowProc;
    wc.hInstance = hInstance;
    wc.lpszClassName = CLASS_NAME;

    RegisterClass(&wc);
    HWND hwnd = CreateWindowEx(
        0,                              // Optional window styles
        CLASS_NAME,                     // Window class
        L"Paint Canvas (P=Brush E=Eraser C=Clear +-=BrushSize Ctrl+S=Save Ctrl+O=Load)",            // Window text
        WS_OVERLAPPEDWINDOW | WS_MAXIMIZE,            // Window style

        // Size and position
        CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT,

        NULL,       // Parent window
        NULL,       // Menu
        hInstance,  // Instance handle
        NULL        // Additional application data
    );

    if (hwnd == NULL) {
        return 0;
    }

    ShowWindow(hwnd, SW_SHOWMAXIMIZED);
    // Run the message loop
    MSG msg = { };
    while (GetMessage(&msg, NULL, 0, 0)) {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }

    return 0;
}