Method GetLetterPosXY

Source/Graphics/text.cpp:384–447

Get the coordinates of the cursor after a given letter in an edit field

// Get the coordinates of the cursor after a given letter in an edit field
void TextCanvasTexture::GetLetterPosXY(const char* str, const CanvasTextStyle& style, int letter, int coords[2]) {
    std::vector<uint32_t> utf32_string;
    try {
        utf8::utf8to32(str, str + strlen(str), std::back_inserter(utf32_string));
    } catch (const utf8::not_enough_room& ner) {
        LOGE << "Got utf8 exception \"" << ner.what() << "\" this might indicate invalid utf-8 data" << std::endl;
    }

    FontRenderer* font_renderer = FontRenderer::Instance();
    FT_Matrix matrix;
    FTMatrixFromAngle(&matrix, 0.0f);
    int line_height = font_renderer->GetFontInfo(style.font_face_id, FontRenderer::INFO_HEIGHT);
    int line_start = 0;
    FT_Vector zero_vec = {0};
    TextMetrics metrics;
    ClearTextMetrics(&metrics);
    for (int i = 0; i <= (int)utf32_string.size(); ++i) {
        if (str[i] == '\n' || i == (int)utf32_string.size()) {  // Find line endings to draw entire lines at once
            TextMetrics line_metrics;
            ClearTextMetrics(&line_metrics);
            for (int j = line_start; j < i; ++j) {
                font_renderer->SetTransform(style.font_face_id, &matrix, &zero_vec);
                FT_GlyphSlot slot = font_renderer->RenderCharacterBitmap(style.font_face_id, str[j], FontRenderer::RCB_METRIC);
                ApplyGlyphSlotToTextMetrics(&line_metrics, slot);
            }
            switch (style.alignment) {
                case CanvasTextStyle::RIGHT:
                    metrics.advance[0] = -line_metrics.bounds[1];
                    break;
                default:
                    LOGD << "Unhandled style.alignment " << CanvasTextStyle::GetAlignmentString(style.alignment) << std::endl;
                    ;
                    break;
            }
            for (int j = line_start; j < i; ++j) {
                font_renderer->SetTransform(style.font_face_id, &matrix, &zero_vec);
                FT_GlyphSlot slot = font_renderer->RenderCharacterBitmap(style.font_face_id, str[j], FontRenderer::RCB_METRIC);
                if (j == letter) {
                    coords[0] = metrics.advance[0] / 64;
                    coords[1] = metrics.advance[1] / 64;
                }
                ApplyGlyphSlotToTextMetrics(&metrics, slot);
                if (j + 1 == letter) {
                    coords[0] = metrics.advance[0] / 64;
                    coords[1] = metrics.advance[1] / 64;
                }
            }
            if (str[i] == '\n') {
                metrics.advance[1] += line_height;
                metrics.advance[0] = 0;
            }
            line_start = i + 1;
        }
    }
    switch (style.alignment) {
        case CanvasTextStyle::RIGHT:
            coords[0] -= metrics.bounds[0] / 64;
            break;