Question

我在这段代码中搜索内存泄漏。我是GDI +的新手，我不确定我做错了什么。您在下面看到的类在我的main函数中循环调用。每次循环迭代我将另一个向量推送到函数。一切都工作正常，除了内存泄漏。我尝试了程序cppCheck来查找泄漏但发现没有内存泄漏：/ 我解决问题的最后机会是问一个比GDI +有更多经验的人

非常感谢你的帮助和对不起长代码：）

#include "helper.h"

Gui::Gui(const TCHAR* fileName) {
    this->fileName = fileName;
}

void Gui::drawGui(Gdiplus::Bitmap* image, std::vector<std::wstring> &vec) {

    // Init graphics
    Gdiplus::Graphics* graphics = Gdiplus::Graphics::FromImage(image);

    Gdiplus::Pen penWhite (Gdiplus::Color::White);
    Gdiplus::Pen penRed   (Gdiplus::Color::Red);
    Gdiplus::SolidBrush redBrush(Gdiplus::Color(255, 255, 0, 0));
    penRed.SetWidth(8);

    unsigned short marginTop = 15;
    unsigned short marginLeft = 5;
    unsigned short horizontalBarsizeStart = marginLeft + 60;


    for (unsigned short iter = 0; iter < 8; iter++) {
        // Draw text
        std::wstring coreLabel = L"Core " + std::to_wstring(iter) + L':';
        Gdiplus::Font myFont(L"Arial", 12);
        Gdiplus::PointF origin(marginLeft, marginTop - 10);
        graphics->DrawString(coreLabel.c_str(), coreLabel.length(), &myFont, origin, &redBrush);

        // Draw CPU lines
        unsigned short horizontalBarsizeEnd = horizontalBarsizeStart + std::stoi(vec.at(iter)); // 100 == Max cpu load
        graphics->DrawLine(&penRed, horizontalBarsizeStart, marginTop, horizontalBarsizeEnd, marginTop);

        // Draw border
        Gdiplus::Rect rect(horizontalBarsizeStart, marginTop - 5, 100, 8);
        graphics->DrawRectangle(&penWhite, rect);

        // Next element
        marginTop += 17;
    }
}


bool Gui::SetColorBackgroundFromFile(std::vector<std::wstring> &vec) {

    Gdiplus::GdiplusStartupInput gdiplusStartupInput;
    ULONG_PTR gdiplusToken;
    // Initialize GDI+.
    Gdiplus::GdiplusStartup(&gdiplusToken, &gdiplusStartupInput, NULL);

    HDC hdc = GetDC(NULL);

    // Load the image. Any of the following formats are supported: BMP, GIF, JPEG, PNG, TIFF, Exif, WMF, and EMF
    Gdiplus::Bitmap* image = Gdiplus::Bitmap::FromFile(this->fileName, false);

    if (image == NULL) {
        return false;
    }

    // Draw the gui
    this->drawGui(image, vec);

    // Get the bitmap handle
    HBITMAP hBitmap = NULL;
    Gdiplus::Status status = image->GetHBITMAP(RGB(0, 0, 0), &hBitmap);
    if (status != Gdiplus::Ok) {
        return false;
    }

    BITMAPINFO bitmapInfo = { 0 };
    bitmapInfo.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);

    // Check what we got
    int ret = GetDIBits(hdc, hBitmap, 0, 0, NULL, &bitmapInfo, DIB_RGB_COLORS);

    if (LOGI_LCD_COLOR_WIDTH != bitmapInfo.bmiHeader.biWidth || LOGI_LCD_COLOR_HEIGHT != bitmapInfo.bmiHeader.biHeight) {
        std::cout << "Oooops. Make sure to use a 320 by 240 image for color background." << std::endl;
        return false;
    }

    bitmapInfo.bmiHeader.biCompression = BI_RGB;
    bitmapInfo.bmiHeader.biHeight = -bitmapInfo.bmiHeader.biHeight; // this value needs to be inverted, or else image will show up upside/down

    BYTE byteBitmap[LOGI_LCD_COLOR_WIDTH * LOGI_LCD_COLOR_HEIGHT * 4]; // we have 32 bits per pixel, or 4 bytes

    // Gets the "bits" from the bitmap and copies them into a buffer 
    // which is pointed to by byteBitmap.
    ret = GetDIBits(hdc, hBitmap, 0,
    -bitmapInfo.bmiHeader.biHeight, // height here needs to be positive. Since we made it negative previously, let's reverse it again.
    &byteBitmap,
    (BITMAPINFO *)&bitmapInfo, DIB_RGB_COLORS);

    LogiLcdColorSetBackground(byteBitmap); // Send image to LCD

    // delete the image when done 
    if (image) {
        delete image;
        image = NULL;
        Gdiplus::GdiplusShutdown(gdiplusToken); // Shutdown GDI+
    }
return true;
}

Answer 1

在drawGui()中，您泄漏了graphics个对象。此行创建一个新的Gdiplus::Graphics对象：

Gdiplus::Graphics* graphics = Gdiplus::Graphics::FromImage(image);

但是，一旦你完成它，你就无处打电话给delete graphics删除它。

在SetColorBackgroundFromFile中，你正在泄漏DC。

HDC hdc = GetDC(NULL);

这会为屏幕显示DC，但您无法调用ReleaseDC(NULL, hdc);来释放它。

在同一个功能中，您使用以下调用创建HBITMAP：

Gdiplus::Status status = image->GetHBITMAP(RGB(0, 0, 0), &hBitmap);

但是你无处致电DeleteObject(hBitmap);来释放它。

您还遇到的问题是，如果出现错误，您的代码可以返回而无需进行必要的清理。例如。如果GetHBITMAP调用失败，则会立即返回并泄漏您在上面创建几行的image对象。

C ++ GDI +本类中的内存泄漏

1 个答案: