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MeshLab调试问题

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MeshLab调试时加载的dll版本不对

从MeshLab 2023.12下载安装的2023.12版本，我在本地clone了一份源码编译，发现在C:\Users\Administrator\AppData\Roaming\VCG\MeshLab_64bit_fp\MeshLabExtraPlugins\2023.12位置存放了一套插件的dll文件，也就是这一套dll文件影响了源码的调试，也即调试时加载的这个目录下的dll文件，不是生成路径下的dll文件。

根据调用栈加载dll的路径就是这个路径：

MeshLabApplication::extraPluginsLocation看出，appVer也出了力。但是核心路径还是来自于QStandardPaths::standardLocations(QStandardPaths::AppDataLocation).first()。 

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const QString MeshLabApplication::extraPluginsLocation()
{
	QDir appDir(QStandardPaths::standardLocations(QStandardPaths::AppDataLocation).first());
	appDir.mkpath(appDir.absolutePath());
	
	appDir.mkdir("MeshLabExtraPlugins");
	appDir.cd("MeshLabExtraPlugins");
	
	//QString major = appVer().left(4);
	//appDir.mkdir(major);
	//appDir.cd(major);

	//just for first versions, compatibility of plugins is fixed for same version of meshlab
	appDir.mkdir(appVer());
	appDir.cd(appVer());

	return appDir.absolutePath();
}

可以看一下QStandardPaths::standardLocations的内容，可以添加上： 

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   #include <QDebug>
   #include <Windows.h>
   #include <shlobj_core.h>
QStringList allAppDataLocations =
	QStandardPaths::standardLocations(QStandardPaths::AppDataLocation);
// QString loc = QStandardPaths::writableLocation(QStandardPaths::AppDataLocation);
foreach (QString path, allAppDataLocations) {
	qInfo() << path;
}
auto s = appDir.absolutePath();
LPWSTR  path;
SHGetKnownFolderPath(FOLDERID_RoamingAppData, KF_FLAG_DONT_VERIFY, 0, &path);

QStandardPaths::standardLocations(QStandardPaths::AppDataLocation)是个啥

QStandardPaths::standardLocations(QStandardPaths::AppDataLocation)返回的是QStringList类型，本地测试如下，有5个路径，extraPluginsLocation用的就是第一个路径。

路径来源

deepseek了解了一下，setOrganizationName和setApplicationName会影响到这个路径，细节就没有了，也没有chat到为啥多个路径。setOrganizationName和setApplicationName在meshlab/main.cpp中都调用到了。 

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QCoreApplication::setOrganizationName(MeshLabApplication::organization());

QString tmp = MeshLabApplication::appArchitecturalName(MeshLabApplication::HW_ARCHITECTURE(QSysInfo::WordSize));
QCoreApplication::setApplicationName(MeshLabApplication::appArchitecturalName(MeshLabApplication::HW_ARCHITECTURE(QSysInfo::WordSize)));

具体原因只能看具体实现了，源码面前，了无秘密。来看一看QStandardPaths::standardLocations的定义，在qstandardpaths_win.cpp中。 

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QStringList QStandardPaths::standardLocations(StandardLocation type)
{
    QStringList dirs;
    const QString localDir = writableLocation(type);
    if (!localDir.isEmpty())
        dirs.append(localDir);

    // type-specific handling goes here
    if (isConfigLocation(type)) {
        QString programData = sHGetKnownFolderPath(FOLDERID_ProgramData);
        if (!programData.isEmpty()) {
            if (!isGenericConfigLocation(type))
                appendOrganizationAndApp(programData);
            dirs.append(programData);
        }
#ifndef QT_BOOTSTRAPPED
        // Note: QCoreApplication::applicationDirPath(), while static, requires
        // an application instance. But we might need to resolve the standard
        // locations earlier than that, so we fall back to qAppFileName().
        QString applicationDirPath = qApp ? QCoreApplication::applicationDirPath()
            : QFileInfo(qAppFileName()).path();
        dirs.append(applicationDirPath);
        const QString dataDir = applicationDirPath + "/data"_L1;
        dirs.append(dataDir);

        if (!isGenericConfigLocation(type)) {
            QString appDataDir = dataDir;
            appendOrganizationAndApp(appDataDir);
            if (appDataDir != dataDir)
                dirs.append(appDataDir);
        }
#endif // !QT_BOOTSTRAPPED
    } // isConfigLocation()

    return dirs;
}

可以看到，QStandardPaths::standardLocations正好有5个append操作，正对着QStandardPaths::standardLocations(QStandardPaths::AppDataLocation)返回的5条路径，其中第一条来自于writableLocation设置，并附加了appendOrganizationAndApp名称。递归一下，writableLocation的实现基本如下：

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#include <Windows.h>
#include <shlobj_core.h>
LPWSTR  path;
// FOLDERID_Programs,      // ApplicationsLocation
SHGetKnownFolderPath(FOLDERID_RoamingAppData, KF_FLAG_DONT_VERIFY, 0, &path);

path结果，不出所料，正是：

调试方法

如果修改的dll恰巧也在C:\Users\Administrator\AppData\Roaming\VCG\MeshLab_64bit_fp\MeshLabExtraPlugins\2023.12目录下，把生成结果copy到该目录下，就可以正常调试了。