Question

Am Creating this function to return the Font Family Name but obviously it seems to be pointing on different results every time:

unsigned int len = txtFormat->GetFontFamilyNameLength();
WCHAR fontFamilyName[64];
txtFormat->GetFontFamilyName(fontFamilyName, len+1);
//fontFamilyName[len] = '\0'; not needed because the function "GetFontFamilyName" returns a null terminated pointer.
return fontFamilyName;

Answer 1

Change:

txtFormat->GetFontFamilyName(fontFamilyName, len+1);

to:

txtFormat->GetFontFamilyName(fontFamilyName, sizeof(fontFamilyName)/sizeof(fontFamilyName[0]));

This will make sure that GetFontFamilyName doesn't overrun the buffer that you're passing in.

Answer 2

它比我需要的时间长了一点但我现在就明白了。

原因是用[]创建数组不会返回正确的地址。所以我们可以有两个解决方案：

解决方案1：动态定位要在函数内返回的数组。记得用它完成后删除返回的文本。

inline WCHAR *GetFontFamilyName(IDWriteTextFormat *txtFormat)
{
    WCHAR *fontFamilyName = new WCHAR[64];
    unsigned int len = txtFormat->GetFontFamilyNameLength();
    txtFormat->GetFontFamilyName(fontFamilyName, len+1);
    //fontFamilyName[len] = L'\0'; not really needed but it can be used as confirmation
    return fontFamilyName;
}

解决方案2：将静态数组传递给函数。在这种情况下，您不必删除它，因为它不是动态分配的。

在这种情况下，您可以将名称[64]等数组传递给该函数，您不必担心删除该文本。

inline void GetFontFamilyName(IDWriteTextFormat *txtFormat, WCHAR fontFamilyName [])
{
    unsigned int len = txtFormat->GetFontFamilyNameLength();
    txtFormat->GetFontFamilyName(fontFamilyName, len+1);
//fontFamilyName[len] = L'\0'; not really needed but it can be used as confirmation.
}

Direct Write: GetFontFamilyName returning different results every time

2 个答案: