QT chart案例

examples-zoomlinechart.qdoc

Zoom Line Example | Qt Charts 5.15.2

Qt 5.15

Qt Charts

Zoom Line Example

Qt Charts | Commercial or GPLv3

Contents

Running the Example

Customizing Zooming Effects

Zoom Line Example

$zoomlinechart-brief The example shows how to create your own custom zooming effect. @@@zoomlinechart $$$zoomlinechart-description The example shows how to create your own custom zooming effect with QRubberBand by using a mouse and how to use touch gestures for paning and zooming. Running the Example To run the example from Qt Creator, open the Welcome mode and select the example from Examples. For more information, visit Building and Running an Example. Customizing Zooming Effects Let's first create a line series with some example data. **QLineSeries \*series = new QLineSeries(); for (int i = 0; i \< 500; i++) { QPointF p((qreal) i, qSin(M_PI / 50 \* i) \* 100); p.ry() += QRandomGenerator::global()-\>bounded(20); \*series \<\< p; }** Then we create a custom chart view by deriving from QChartView: class ChartView : public QChartView We override mouse and key event handling **protected: bool viewportEvent(QEvent \*event); void mousePressEvent(QMouseEvent \*event); void mouseMoveEvent(QMouseEvent \*event); void mouseReleaseEvent(QMouseEvent \*event); void keyPressEvent(QKeyEvent \*event);** Then we implement a custom logic for mouse and key events. For example pressing the '+' key will zoom in and pressing the '-' key will zoom out. **void ChartView::keyPressEvent(QKeyEvent \*event) { switch (event-\>key()) { case Qt::Key_Plus: chart()-\>zoomIn(); break; case Qt::Key_Minus: chart()-\>zoomOut(); break;** We also create our own QChart: **class Chart : public QChart** **Where we can handle the gestures: bool Chart::sceneEvent(QEvent \*event) { if (event-\>type() == QEvent::Gesture) return gestureEvent(static_cast\(event)); return QChart::event(event); }** **bool Chart::gestureEvent(QGestureEvent \*event) { if (QGesture \*gesture = event-\>gesture(Qt::PanGesture)) { QPanGesture \*pan = static_cast\(gesture); QChart::scroll(-(pan-\>delta().x()), pan-\>delta().y()); }** **if (QGesture \*gesture = event-\>gesture(Qt::PinchGesture)) { QPinchGesture \*pinch = static_cast\(gesture); if (pinch-\>changeFlags() \& QPinchGesture::ScaleFactorChanged) QChart::zoom(pinch-\>scaleFactor()); }** **return true; }** Note that you will need to call grabGesture() to both QMainWindow and QChart. Example project @ code.qt.io @@@zoomlinechart © 2020 The Qt Company Ltd. Documentation contributions included herein are the copyrights of their respective owners. The documentation provided herein is licensed under the terms of the GNU Free Documentation License version 1.3 as published by the Free Software Foundation. Qt and respective logos are trademarks of The Qt Company Ltd. in Finland and/or other countries worldwide. All other trademarks are property of their respective owners.

相关推荐
Sylvia-girl2 小时前
Java——抽象类
java·开发语言
Yana.nice4 小时前
Bash函数详解
开发语言·chrome·bash
tomorrow.hello5 小时前
Java并发测试工具
java·开发语言·测试工具
晓13136 小时前
JavaScript加强篇——第四章 日期对象与DOM节点(基础)
开发语言·前端·javascript
老胖闲聊6 小时前
Python I/O 库【输入输出】全面详解
开发语言·python
她说人狗殊途7 小时前
java.net.InetAddress
java·开发语言
天使day7 小时前
Cursor的使用
java·开发语言·ai
Dxy12393102167 小时前
Python ExcelWriter详解:从基础到高级的完整指南
开发语言·python
源代码•宸9 小时前
C++高频知识点(十三)
开发语言·c++·经验分享·面经
wa的一声哭了9 小时前
python基础知识pip配置pip.conf文件
java·服务器·开发语言·python·pip·risc-v·os