Function DrawBitmapImage

LibLemon/src/gfx/image.cpp:260–302

    }

    int DrawBitmapImage(int x, int y, int w, int h, uint8_t *data, surface_t* surface, bool preserveAspectRatio) {
        bitmap_file_header_t bmpHeader = *(bitmap_file_header_t*)data;
        bitmap_info_header_t bmpInfoHeader = *(bitmap_info_header_t*)(data + sizeof(bitmap_file_header_t));
        data += bmpHeader.offset;

        int originalWidth = bmpInfoHeader.width;
        int originalHeight = bmpInfoHeader.height;

        double xScale = ((double)w) / originalWidth;
        double yScale = (((double)h) / originalHeight);
        double xOffset = 0;

        if(preserveAspectRatio){
            xScale = ((double)h * (((double)originalWidth) / originalHeight)) / originalWidth;
        // if((xScale * originalWidth) < originalWidth) xOffset = (originalWidth - (xScale * originalWidth)) / 2;
        }


        uint8_t bmpBpp = 24;
        uint32_t rowSize = (int)floor((bmpBpp*bmpInfoHeader.width + 31) / 32) * 4;
        uint32_t bmp_offset = rowSize * (originalHeight - 1);

        uint32_t pixelSize = 4;
        for (int i = 0; i < h && i + y < surface->height; i++) {
            double _yval = ((double)i) / yScale;
            if(ceil(_yval) >= originalHeight) break;
            for (int j = 0; j < w && j + x < surface->width; j++) {
                double _xval = xOffset + ((double) + j) / xScale;
                if(ceil(_xval) >= originalWidth) break;

                uint8_t r = Interpolate(data[bmp_offset - ((int)floor(_yval) * rowSize) + (int)floor(_xval) * (bmpBpp / 8) + 0], data[bmp_offset - ((int)floor(_yval) * rowSize) + (int)ceil(_xval) * (bmpBpp / 8) + 0], data[bmp_offset - ((int)ceil(_yval) * rowSize) + (int)floor(_xval) * (bmpBpp / 8) + 0], data[bmp_offset - ((int)ceil(_yval) * rowSize) + (int)ceil(_xval) * (bmpBpp / 8) + 0], _xval, _yval);
                uint8_t g = Interpolate(data[bmp_offset - ((int)floor(_yval) * rowSize) + (int)floor(_xval) * (bmpBpp / 8) + 1], data[bmp_offset - ((int)floor(_yval) * rowSize) + (int)ceil(_xval) * (bmpBpp / 8) + 1], data[bmp_offset - ((int)ceil(_yval) * rowSize) + (int)floor(_xval) * (bmpBpp / 8) + 1], data[bmp_offset - ((int)ceil(_yval) * rowSize) + (int)ceil(_xval) * (bmpBpp / 8) + 1], _xval, _yval);
                uint8_t b = Interpolate(data[bmp_offset - ((int)floor(_yval) * rowSize) + (int)floor(_xval) * (bmpBpp / 8) + 2], data[bmp_offset - ((int)floor(_yval) * rowSize) + (int)ceil(_xval) * (bmpBpp / 8) + 2], data[bmp_offset - ((int)ceil(_yval) * rowSize) + (int)floor(_xval) * (bmpBpp / 8) + 2], data[bmp_offset - ((int)ceil(_yval) * rowSize) + (int)ceil(_xval) * (bmpBpp / 8) + 2], _xval, _yval);
                
                uint32_t offset = (y + i)*(surface->width*pixelSize) + (x + j) * pixelSize;
                surface->buffer[offset] = r;
                surface->buffer[offset + 1] = g;
                surface->buffer[offset + 2] = b;
            }
        }

        return 0;
    }
}