Question

我正在尝试将Qt库与SDL应用程序集成。我想将QPixmap转换为SDL_Surface，然后显示该表面。我怎样才能做到这一点？我找不到任何好的例子。

到目前为止，我已经管理了以下代码：

Uint32 rmask = 0x000000ff;
Uint32 gmask = 0x0000ff00;
Uint32 bmask = 0x00ff0000;
Uint32 amask = 0xff000000;

SDL_FillRect(screen, NULL, SDL_MapRGBA(screen->format, 255, 255, 255, 255));

const QImage *qsurf = ...;

SDL_Surface *surf = SDL_CreateRGBSurfaceFrom((void*)qsurf->constBits(), qsurf->width(), qsurf->height(), 32, qsurf->width() * 4, rmask, gmask, bmask, amask);
SDL_BlitSurface(surf, NULL, screen, NULL);
SDL_FreeSurface(surf);
SDL_Flip(screen);

这是有效的，但唯一的问题是，每次我的基于QImage的表面都被绘制时，底层区域不会被清除，透明部分会在几帧的过程中“淡化”为实体。

我确实有SDL_FillRect我会想象清除屏幕，但它似乎没有这样做。 screen是主要的SDL表面。

Answer 1

我最初的重绘问题是因为我的源图像实际上没有得到正确清理。哎呀。一旦我修好了，我的口罩就错了;没有让我在脑海中点击SDL如何使用这些。最终的工作代码如下：

这是将QImage转换为SDL_Surface的函数：

/*!
 * Converts a QImage to an SDL_Surface.
 * The source image is converted to ARGB32 format if it is not already.
 * The caller is responsible for deallocating the returned pointer.
 */
SDL_Surface* QImage_toSDLSurface(const QImage &sourceImage)
{
    // Ensure that the source image is in the correct pixel format
    QImage image = sourceImage;
    if (image.format() != QImage::Format_ARGB32)
        image = image.convertToFormat(QImage::Format_ARGB32);

    // QImage stores each pixel in ARGB format
    // Mask appropriately for the endianness
#if SDL_BYTEORDER == SDL_BIG_ENDIAN
    Uint32 amask = 0x000000ff;
    Uint32 rmask = 0x0000ff00;
    Uint32 gmask = 0x00ff0000;
    Uint32 bmask = 0xff000000;
#else
    Uint32 amask = 0xff000000;
    Uint32 rmask = 0x00ff0000;
    Uint32 gmask = 0x0000ff00;
    Uint32 bmask = 0x000000ff;
#endif

    return SDL_CreateRGBSurfaceFrom((void*)image.constBits(),
        image.width(), image.height(), image.depth(), image.bytesPerLine(),
        rmask, gmask, bmask, amask);
}

我绘图功能的核心：

// screen == SDL_GetVideoSurface()
// finalComposite == my QImage that SDL will convert and display
SDL_FillRect(screen, NULL, SDL_MapRGBA(screen->format, 255, 255, 255, 255));
SDL_Surface *surf = QImage_toSDLSurface(finalComposite);
SDL_BlitSurface(surf, NULL, screen, NULL);
SDL_FreeSurface(surf);
SDL_Flip(screen);

将QPixmap转换为SDL_Surface并将其显示在屏幕上

1 个答案: