C++ 方法对 C 函数的引用

Question

我有一个用 C 语言定义的结构，它需要一个指向函数的指针。我在 C++ 中定义的函数/方法。如何将对 C++ 方法的引用传递给 C 结构？

这是我得到的错误:“类型为“void (Ili9341::)(void , int16_t, int16_t, uint16_t)”的值不能用于初始化类型为“void ()( void , int16_t, int16_t, uint16_t) C"

这是C文件

typedef struct Graphics_Display
{
    int32_t  size;              //!< The size of this structure.
    void *displayData;          //!< A pointer to display driver-specific data.
    uint16_t width;             //!< The width of this display.
    uint16_t heigth;            //!< The height of this display.
    void (*callPixelDraw)(void *displayData, int16_t x, int16_t y,
            uint16_t value);    //!< A pointer to the function to draw a pixel on this display.
    void (*callPixelDrawMultiple)(void *displayData, int16_t x, int16_t y,
            int16_t x0, int16_t count, int16_t bPP, const uint8_t *data,
            const uint32_t *pucPalette);    //!< A pointer to the function to draw multiple pixels on this display.
    void (*callLineDrawH)(void *displayData, int16_t x1, int16_t x2, int16_t y,
            uint16_t value);    //!< A pointer to the function to draw a horizontal line on this display.
    void (*callLineDrawV)(void *displayData, int16_t x, int16_t y1,
            int16_t y2, uint16_t value); //!< A pointer to the function to draw a vertical line on this display.
    void (*callRectFill)(void *displayData, const Graphics_Rectangle *rect,
            uint16_t value);    //!< A pointer to the function to draw a filled rectangle on this display.
    uint32_t (*callColorTranslate)(void *displayData, uint32_t  value); //!< A pointer to the function to translate 24-bit RGB colors to display-specific colors.
    void (*callFlush)(void *displayData); //!< A pointer to the function to flush any cached drawing operations on this display.
    void (*callClearDisplay)(void *displayData, uint16_t value); //!<  A pointer to the function to clears Display. Contents of display buffer unmodified
} Graphics_Display;

这是 C++ 文件

    Ili9341::Ili9341(void){

    }

Graphics_Display Ili9341::ili9341_GetDisplay(){
    Graphics_Display g_sDriver =
    {
        sizeof(tDisplay),
        ili9341_Memory,
    #if defined(PORTRAIT) || defined(PORTRAIT_FLIP)
        LCD_Y_SIZE,
        LCD_X_SIZE,
    #else
        LCD_X_SIZE,
        LCD_Y_SIZE,
    #endif
        ili9341_PixelDraw,
        ili9341_PixelDrawMultiple,
        ili9341_LineDrawH,
        ili9341_LineDrawV,
        ili9341_RectFill,
        ili9341_ColorTranslate,
        ili9341_Flush,
        ili9341_ClearScreen
    };
    return g_sDriver;
}

void Ili9341::ili9341_PixelDraw(void *displayData, int16_t x, int16_t y, uint16_t value){

}

void Ili9341::ili9341_PixelDrawMultiple(void *displayData, int16_t x, int16_t y, int16_t x0, int16_t count, int16_t bPP, const uint8_t *data, const uint32_t *pucPalette){

}

void Ili9341::ili9341_LineDrawH(void *displayData, int16_t x1, int16_t x2, int16_t y, uint16_t value){

}

void Ili9341::ili9341_LineDrawV(void *displayData, int16_t x, int16_t y1, int16_t y2, uint16_t value){

}

void Ili9341::ili9341_RectFill(void *displayData, const Graphics_Rectangle *rect, uint16_t value){

}

uint32_t Ili9341::ili9341_ColorTranslate(void *displayData, uint32_t  value){
    return 0;
}

void Ili9341::ili9341_Flush(void *displayData){

}

void Ili9341::ili9341_ClearScreen(void *displayData, uint16_t value){

}

Answer 1

您无法获得指向非静态成员函数的常规函数​​指针，因为通过指针调用它的代码将无法指定要调用它的对象(基本上是 的值)这个)。

但是，您可以使用静态或非成员函数，并使用 displayData 字段来存储指向该对象的指针。像这样的事情:

void ili9341_PixelDrawStatic(void *displayData, int x, int y, int value) {
    static_cast<Ili9341*>(displayData)->ili9341_PixelDraw(x, y, value);
}
void ili9341_PixelDrawMultipleStatic(void *displayData, int x, int y, int16_t count, int16_t bPP, const uint8_t *data, const uint32_t *pucPalette) {
    static_cast<Ili9341*>(displayData)->ili9341_PixelDrawMultiple(x, y, count, bPP, data, pucPalette);
}
// ... and so on

Graphics_Display g_sDriver =
{
    sizeof(tDisplay),
    this,
    // ...
    ili9341_PixelDrawStatic,
    ili9341_PixelDrawMultipleStatic,
    // ... and so on
};

请注意，您现在无法使用 displayData 指向 ili9341_Memory - 但如果 ili9341_Memory 是 Ili9341 的成员变量 已经有了，那么你就不需要它了。