PLabel.cxx

//==============================================================================
// File:        PLabel.cxx
//
// Description: A wrapper to avoid unnecessary screen updates if the label doesn't
//              change
//
// Created:     PH 10/15/99
//
// Copyright (c) 2017, Phil Harvey, Queen's University
//==============================================================================

#include <string.h>
#include <Xm/Label.h>
#include "PLabel.h"
#include "PUtils.h"

PLabel::PLabel(Widget aLabel)
{
    mString = NULL;
    mLabel = aLabel;
}

PLabel::~PLabel()
{
    FreeString();
}

// CreateLabel - create XmLabel widget
// - if managed is 0, the widget is created but not managed
void PLabel::CreateLabel(char *name, Widget parent, ArgList args, Cardinal num_args, int managed)
{
    if (managed) {
        mLabel = XtCreateManagedWidget(name,xmLabelWidgetClass,parent,args,num_args);
    } else {
        mLabel = XtCreateWidget(name,xmLabelWidgetClass,parent,args,num_args);
    }
    // the widget name is the initial string, so save it
    SaveString(name);
}

// DestroyLabel - destroy the label widget
void PLabel::DestroyLabel()
{
    if (mLabel) {
        XtDestroyWidget(mLabel);
        mLabel = NULL;
    }
    FreeString();
}

// CreateString - create string and save length of allocated string
void PLabel::CreateString(int len)
{
    mStringLen = len;
    mString = XtMalloc(mStringLen + 1); // need extra character for NULL terminator
}

// FreeString - free our copy of the string
void PLabel::FreeString()
{
    if (mString) {
        XtFree(mString);
        mString = NULL;
    }
}

// SaveString - save string to our local copy
// - returns zero if string has not changed
int PLabel::SaveString(char *str)
{
    int     len;
    
    if (mString) {
        if (!strcmp(mString, str)) return(0);   // text is the same
        len = strlen(str);
        if (len > mStringLen) {
            // only reallocate string memory if new string is larger
            FreeString();
            CreateString(len);
        }
    } else {
        CreateString(strlen(str));
    }
    if (mString) {
        strcpy(mString, str);
    }
    return(1);
}

// SetString - set the label string (must create a label before this is called!)
void PLabel::SetString(char *str)
{
    if (SaveString(str)) {
        setLabelString(mLabel, str);    // set the XmLabel string
    }
}

// SetStringNow - set the label and draw immediately
// - call SetString() instead of this routine unless you specifically need
//   to update the string before the next time through the event loop
void PLabel::SetStringNow(char *str)
{
    if (SaveString(str)) {
        setLabelString(mLabel, str);
        XmUpdateDisplay(mLabel);
    }
}