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创建具有属性定义的块表记录

2024-5-18 18:49| 发布者: admin| 查看: 293| 评论: 0|原作者: admin|来自: AutoCAD

创建具有属性定义的块表记录

AutoCAD 块是存储在块表记录中的图元集合。每个块都有一个对象，后跟一个或多个对象，并以一个对象结尾（请参阅“实体所有权”下的插图）。AcDbBlockBeginAcDbEntityAcDbBlockEnd

块可以包含属性定义，这些定义是用于创建属性的模板。属性是与块关联的信息文本。根据用户提供的设置，在将块插入到图形中时，可能会也可能不会复制属性值。通常，应用程序会在运行时提示用户输入属性值。

创建块表记录

创建新的块表记录。
将块表记录添加到块表中。
创建实体并将其添加到块表记录中。
创建属性定义，设置其值，并将其添加到块表记录中。

当您关闭块表记录时，块开始和块结束对象会自动添加到块中。

以下示例创建一个名为

ASDK-BLOCK-WITH-ATTR并将其添加到块表中。接下来，它创建一个圆形实体并将其添加到新的块表记录中。它创建两个属性定义实体（第二个是第一个实体的克隆），并将它们附加到同一个块表记录

void
defineBlockWithAttributes(
    AcDbObjectId& blockId, // This is a returned value.
    const AcGePoint3d& basePoint,
    double textHeight,
    double textAngle)
{
    int retCode = 0;
    AcDbBlockTable *pBlockTable = NULL;
    AcDbBlockTableRecord* pBlockRecord = new AcDbBlockTableRecord;
    AcDbObjectId entityId;
    // Step 1: Set the block name and base point of the 
    // block definition.
    //
    pBlockRecord->setName("ASDK-BLOCK-WITH-ATTR");
    pBlockRecord->setOrigin(basePoint);
    // Open the block table for write.
    //
    acdbHostApplicationServices()->workingDatabase()
        ->getSymbolTable(pBlockTable, AcDb::kForWrite);
    // Step 2: Add the block table record to block table.
    //
    pBlockTable->add(blockId, pBlockRecord);
    // Step 3: Create a circle entity.
    //
    AcDbCircle *pCircle = new AcDbCircle;
    pCircle->setCenter(basePoint);
    pCircle->setRadius(textHeight * 4.0);
    pCircle->setColorIndex(3);
    // Append the circle entity to the block record.
    //
    pBlockRecord->appendAcDbEntity(entityId, pCircle);
    pCircle->close();
    // Step 4: Create an attribute definition entity.
    //
    AcDbAttributeDefinition *pAttdef
        = new AcDbAttributeDefinition;
    // Set the attribute definition values.
    //
    pAttdef->setPosition(basePoint);
    pAttdef->setHeight(textHeight);
    pAttdef->setRotation(textAngle);
    // For horizontal modes other than AcDb::kTextLeft
    // and vertical modes other than AcDb::kTextBase,
    // you may need to call setAlignmentPoint(). See the
    // AcDbText::setAlignmentPoint() documentation for details.
    pAttdef->setHorizontalMode(AcDb::kTextLeft);
    pAttdef->setVerticalMode(AcDb::kTextBase);
    pAttdef->setPrompt("Prompt");
    pAttdef->setTextString("DEFAULT");
    pAttdef->setTag("Tag");
    pAttdef->setInvisible(Adesk::kFalse);
    pAttdef->setVerifiable(Adesk::kFalse);
    pAttdef->setPreset(Adesk::kFalse);
    pAttdef->setConstant(Adesk::kFalse);
    pAttdef->setFieldLength(25);
    // Append the attribute definition to the block.
    //
    pBlockRecord->appendAcDbEntity(entityId, pAttdef);
    // The second attribute definition is a little easier
    // because we are cloning the first one.
    //
    AcDbAttributeDefinition *pAttdef2
        = AcDbAttributeDefinition::cast(pAttdef->clone());
    // Set the values that are specific to the
    // second attribute definition.
    //
    AcGePoint3d tempPt(basePoint);
    tempPt.y -= pAttdef2->height();
    pAttdef2->setPosition(tempPt);
    pAttdef2->setColorIndex(1); // Red
    pAttdef2->setConstant(Adesk::kTrue);
    // Append the second attribute definition to the block.
    //
    pBlockRecord->appendAcDbEntity(entityId, pAttdef2);
    pAttdef->close();
    pAttdef2->close();
    pBlockRecord->close();
    pBlockTable->close();
    return;
}