检索对象属性，选择新对象

应用程序可以通过调用 GetCurrentObject 和 GetObject 函数来检索笔、画笔、调色板、字体或位图的属性。 GetCurrentObject 函数返回一个句柄，标识当前选定到 DC 中的对象;GetObject 函数返回一个结构，该结构描述对象的属性。

以下示例演示应用程序如何检索当前画笔属性，并使用检索到的数据来确定是否需要选择新的画笔。

    HDC hdc;                     // display DC handle  
    HBRUSH hbrushNew, hbrushOld; // brush handles  
    HBRUSH hbrush;               // brush handle  
    LOGBRUSH lb;                 // logical-brush structure  
 
    // Retrieve a handle identifying the current brush.  
 
    hbrush = GetCurrentObject(hdc, OBJ_BRUSH); 
 
    // Retrieve a LOGBRUSH structure that contains the  
    // current brush attributes.  
 
    GetObject(hbrush, sizeof(LOGBRUSH), &lb); 
 
    // If the current brush is not a solid-black brush,  
    // replace it with the solid-black stock brush.  
 
    if ((lb.lbStyle != BS_SOLID) 
           || (lb.lbColor != 0x000000)) 
    { 
        hbrushNew = GetStockObject(BLACK_BRUSH); 
        hbrushOld = SelectObject(hdc, hbrushNew); 
    } 
 
    // Perform painting operations with the solid-black brush.  
 
 
    // After completing the last painting operation with the new  
    // brush, the application should select the original brush back  
    // into the device context and delete the new brush.  
    // In this example, hbrushNew contains a handle to a stock object.  
    // It is not necessary (but it is not harmful) to call  
    // DeleteObject on a stock object. If hbrushNew contained a handle  
    // to a brush created by a function such as CreateBrushIndirect,  
    // it would be necessary to call DeleteObject.  
 
    SelectObject(hdc, hbrushOld); 
    DeleteObject(hbrushNew); 

注意

应用程序在首次调用 SelectObject 函数时保存了原始画笔句柄。 保存此句柄，以便在使用新画笔完成最后一次绘制操作后，可以将原始画笔选回 DC。 将原始画笔选回 DC 后，将删除新画笔，从而释放 GDI 堆中的内存。