qwt_utils.h 文件参考

Qwt plot utility classes collection and compatibility functions 更多...

#include "qwt_global.h"
#include <qsize.h>
#include "qwt_plot_factory.h"
#include "qwt_plot_item_info.h"
#include "qwt_plot_data_access.h"
#include "qwt_plot_transform.h"
#include "qwt_plot_styling.h"
#include "qwt_pyplot.h"

浏览源代码.

函数
QSize QWT_EXPORT	qwtExpandedToGlobalStrut (const QSize &size)
	Expand a size to the global strut (Qt5/Qt6 compatibility function)

详细描述

Qwt plot utility classes collection and compatibility functions

This file provides two main features:

1. Forward includes for plot utility classes: Including this file gives access to all Qwt plot utility classes at once. These utility classes replace the deprecated Qwt::plotItemColor() function with more powerful and type-safe functionality.
2. Qt version compatibility function: qwtExpandedToGlobalStrut() handles the globalStrut API difference between Qt 5 and Qt 6, primarily used internally by Qwt widget classes.

Plot Utility Classes

Since Qwt 7.x, the following 5 dedicated utility classes are recommended for working with plot items:

• QwtPlotFactory: Factory methods for creating plot items (curves, bars, markers, etc.)
• QwtPlotItemInfo: Type queries for determining item types and basic information
• QwtPlotDataAccess: Data access for reading and writing plot item data
• QwtPlotTransform: Coordinate transformations between pixel and data coordinates
• QwtPlotStyling: Style operations for getting/setting colors, pens, brushes, etc.

All classes are in the Qwt namespace and provide type-safe, rtti-dispatched APIs that are safer and more efficient than the old dynamic_cast approach.

Example

#include <qwt_utils.h>
 
// Create a plot
QwtPlot* plot = new QwtPlot();
 
// Create a curve using factory method
QVector<QPointF> points = {{0,0}, {1,1}, {2,4}};
QwtPlotCurve* curve = QwtPlotFactory::createCurve(plot, "Temperature", points);
 
// Query type
if (QwtPlotItemInfo::isSeriesItem(item)) {
    // Handle series item
}
 
// Read data
QVector<QPointF> data = QwtPlotDataAccess::xySamples(curve);
 
// Set style
QwtPlotStyling::setColor(curve, Qt::blue);
QwtPlotStyling::setPenWidth(curve, 2.0);
 
// Coordinate transformation
QPointF plotPos = QwtPlotTransform::toPlotCoordinates(plot, screenPos);

Guide

If you were using Qwt::plotItemColor(), you should now use QwtPlotStyling::color():

// Old way (deprecated)
QColor color = Qwt::plotItemColor(item);
 
// New way (recommended)
QColor color = QwtPlotStyling::color(item);

The new approach supports more plot item types and uses rtti dispatch instead of dynamic_cast for better performance.

注解

The qwtExpandedToGlobalStrut() function is retained for internal Qwt use only. Application code should not call this function directly.

函数说明

qwtExpandedToGlobalStrut()

QSize QWT_EXPORT qwtExpandedToGlobalStrut

(

const QSize &

size

)

Expand a size to the global strut (Qt5/Qt6 compatibility function)

In Qt 5.0-5.14, QApplication::globalStrut() returns the application-defined minimum widget size. This function expands the given size to at least that minimum size.

In Qt 5.15+ and Qt 6, globalStrut() has been removed and this function returns the original size unchanged.

参数

size	Original size

返回

Size expanded to the global strut, or the original size on Qt 5.15+/Qt 6