Changing Many Attributes (XForms (Forms Library) - Version 1.2 (Rev. 4) A Graphical User Interface Toolkit for X)

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#### 3.11.6 Changing Many Attributes

Whenever you change an attribute of an object in a visible form the object is redrawn immediately to make the change visible. This can be undesirable when you change a number of attributes of the same object. You only want the changed object to be drawn after the last change. Drawing it after each change will give a flickering effect on the screen. This gets even worse when you, for example, just want to hide a few objects. After each object you hide the entire form is redrawn. In addition to the flickering, it is also time consuming. Thus it is more efficient to tell the library to temporarily not redraw the form while changes are being made. This can be done by "freezing" the form. While a form is being frozen it is not redrawn, all changes made are instead buffered internally. Only when you unfreeze the form, all changes made in the meantime are drawn at once. For freezing and unfreezing two calls exist:

    void fl_freeze_form(FL_FORM *form);

and

    void fl_unfreeze_form(FL_FORM *form);

It is a good practice to place multiple changes to the contents of a form always between calls to these two procedures. Further, it is better to complete modifying the attributes of one object before starting work on the next.