Question

我在使用freetype2渲染文本时遇到了一些问题，使其不能使用SDL_ttf。

以下代码会产生以下图像：

显然不是它所设置的DejaVu Sans字体，但不幸的是我不知道出了什么问题。

我认为代码大多是不言自明的 - blit_rect.address是目标缓冲区

/**
 * Blit text to the screen.
 * @param text Text to display.
 * @param colour Colour of the text.
 * @param xpos Absolute horizontal position at the display.
 * @param ypos Absolute vertical position at the display.
 * @param width Available width of the text (in pixels).
 * @param align Horizontal alignment of the string.
 */
void VideoSystem::BlitText(const uint8 *text, uint32 colour, int xpos, int ypos, int width, Alignment align)
{
    this->blit_rect.ValidateAddress();

    int w, h;
    this->GetTextSize(text, &w, &h);
    ypos += h;
    int real_w = std::min(w, width);
    switch (align) {
        case ALG_LEFT:
            break;

        case ALG_CENTER:
            xpos += (width - real_w) / 2;
            break;

        case ALG_RIGHT:
            xpos += width - real_w;
            break;

        default: NOT_REACHED();
    }

    bool use_kerning = FT_HAS_KERNING(this->face);
    uint previous = 0;
    FT_GlyphSlot slot = this->face->glyph;

    for (const uint8 *pt = text; *pt != '\0';) {
        uint32 u32;
        int len = DecodeUtf8Char(pt, strlen((const char *)pt), &u32);
        if (len == 0) break;
        pt += len;

        uint glyph = FT_Get_Char_Index(this->face, u32);

        if (use_kerning && previous && glyph) {
            FT_Vector delta;
            FT_Get_Kerning(this->face, previous, glyph, FT_KERNING_DEFAULT, &delta);
            xpos += delta.x >> 6;
        }

        if (FT_Load_Glyph(this->face, glyph, FT_LOAD_RENDER) != 0) {
        }

        uint32 *dest = this->blit_rect.address + (xpos + slot->bitmap_left) + (ypos - slot->bitmap_top) * this->blit_rect.pitch;
        for (int i = 0; i < slot->bitmap.rows; i++) {
            if (ypos - slot->bitmap_top + i < 0) continue;
            for (int j = 0; j < slot->bitmap.pitch; j++) {
                if (xpos + slot->bitmap_left + j < 0) continue;
                if (slot->bitmap.buffer[i * slot->bitmap.pitch + j] > 0) {
                    dest[i * this->blit_rect.pitch + j] = slot->bitmap.buffer[i * slot->bitmap.pitch + j];
                }
            }
        }

        previous = glyph;
        xpos += slot->advance.x >> 6;
        ypos += slot->advance.y >> 6;
    }
}

编辑：字体加载：

/* Freetype init */
if (FT_Init_FreeType(&this->library) != 0) {
}

if (FT_New_Face(this->library, font_name, 0, &this->face) != 0) {
}

/** @todo use actual screen dpi? */
if (FT_Set_Char_Size(this->face, 0, font_size * 64, 0, 0) != 0) {
}

EDIT2：在FT_Load_Glyph不执行任何操作后添加FT_Render_Glyph(slot, FT_RENDER_MODE_NORMAL);（或FT_RENDER_MODE_MONO）。

关于质量的任何其他评论，当然

Freetype2无法正确呈现字体

0 个答案: