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Accelerating lineseries with OpenGL...
Accelerating lineseries with OpenGL Added support for QAbstractSeries::useOpenGL property. When true, the series in question is drawn on a separate offscreen buffer using OpenGL and then superimposed on the chart. Currently this property is only supported for line and scatter series. Change-Id: I174fec541f9f3c23464270c1fe08f824af16a0fb Reviewed-by: Titta Heikkala <titta.heikkala@theqtcompany.com> Reviewed-by: Tomi Korpipää <tomi.korpipaa@theqtcompany.com>

File last commit:

r2820:79a856530b69
r2820:79a856530b69
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glwidget.cpp
222 lines | 6.5 KiB | text/x-c | CppLexer
/****************************************************************************
**
** Copyright (C) 2015 The Qt Company Ltd
** All rights reserved.
** For any questions to The Qt Company, please use contact form at http://qt.io
**
** This file is part of the Qt Charts module.
**
** Licensees holding valid commercial license for Qt may use this file in
** accordance with the Qt License Agreement provided with the Software
** or, alternatively, in accordance with the terms contained in a written
** agreement between you and The Qt Company.
**
** If you have questions regarding the use of this file, please use
** contact form at http://qt.io
**
****************************************************************************/
#ifndef QT_NO_OPENGL
#include "private/glwidget_p.h"
#include "private/glxyseriesdata_p.h"
#include <QtGui/QOpenGLShaderProgram>
#include <QtGui/QOpenGLContext>
#include <QtGui/QOpenGLBuffer>
//#define QDEBUG_TRACE_GL_FPS
#ifdef QDEBUG_TRACE_GL_FPS
# include <QElapsedTimer>
#endif
QT_CHARTS_BEGIN_NAMESPACE
GLWidget::GLWidget(GLXYSeriesDataManager *xyDataManager, QWidget *parent)
: QOpenGLWidget(parent),
m_program(0),
m_shaderAttribLoc(-1),
m_colorUniformLoc(-1),
m_minUniformLoc(-1),
m_deltaUniformLoc(-1),
m_pointSizeUniformLoc(-1),
m_xyDataManager(xyDataManager)
{
setAttribute(Qt::WA_TranslucentBackground);
setAttribute(Qt::WA_AlwaysStackOnTop);
setAttribute(Qt::WA_TransparentForMouseEvents);
QSurfaceFormat surfaceFormat;
surfaceFormat.setDepthBufferSize(0);
surfaceFormat.setStencilBufferSize(0);
surfaceFormat.setRedBufferSize(8);
surfaceFormat.setGreenBufferSize(8);
surfaceFormat.setBlueBufferSize(8);
surfaceFormat.setAlphaBufferSize(8);
surfaceFormat.setSwapBehavior(QSurfaceFormat::DoubleBuffer);
surfaceFormat.setRenderableType(QSurfaceFormat::DefaultRenderableType);
setFormat(surfaceFormat);
connect(xyDataManager, &GLXYSeriesDataManager::seriesRemoved,
this, &GLWidget::cleanXYSeriesResources);
}
GLWidget::~GLWidget()
{
cleanup();
}
void GLWidget::cleanup()
{
makeCurrent();
delete m_program;
m_program = 0;
foreach (QOpenGLBuffer *buffer, m_seriesBufferMap.values())
delete buffer;
m_seriesBufferMap.clear();
doneCurrent();
}
void GLWidget::cleanXYSeriesResources(const QXYSeries *series)
{
makeCurrent();
if (series) {
delete m_seriesBufferMap.take(series);
} else {
// Null series means all series were removed
foreach (QOpenGLBuffer *buffer, m_seriesBufferMap.values())
delete buffer;
m_seriesBufferMap.clear();
}
doneCurrent();
}
static const char *vertexSource =
"attribute highp vec2 points;\n"
"uniform highp vec2 min;\n"
"uniform highp vec2 delta;\n"
"uniform highp float pointSize;\n"
"void main() {\n"
" vec2 normalPoint = vec2(-1, -1) + ((points - min) / delta);\n"
" gl_Position = vec4(normalPoint, 0, 1);\n"
" gl_PointSize = pointSize;\n"
"}";
static const char *fragmentSource =
"uniform highp vec3 color;\n"
"void main() {\n"
" gl_FragColor = vec4(color,1);\n"
"}\n";
void GLWidget::initializeGL()
{
connect(context(), &QOpenGLContext::aboutToBeDestroyed, this, &GLWidget::cleanup);
initializeOpenGLFunctions();
glClearColor(0, 0, 0, 0);
m_program = new QOpenGLShaderProgram;
m_program->addShaderFromSourceCode(QOpenGLShader::Vertex, vertexSource);
m_program->addShaderFromSourceCode(QOpenGLShader::Fragment, fragmentSource);
m_program->bindAttributeLocation("points", 0);
m_program->link();
m_program->bind();
m_colorUniformLoc = m_program->uniformLocation("color");
m_minUniformLoc = m_program->uniformLocation("min");
m_deltaUniformLoc = m_program->uniformLocation("delta");
m_pointSizeUniformLoc = m_program->uniformLocation("pointSize");
// Create a vertex array object. In OpenGL ES 2.0 and OpenGL 2.x
// implementations this is optional and support may not be present
// at all. Nonetheless the below code works in all cases and makes
// sure there is a VAO when one is needed.
m_vao.create();
QOpenGLVertexArrayObject::Binder vaoBinder(&m_vao);
glEnableVertexAttribArray(0);
glDisable(GL_DEPTH_TEST);
glDisable(GL_STENCIL_TEST);
#if !defined(QT_OPENGL_ES_2)
if (!QOpenGLContext::currentContext()->isOpenGLES()) {
// Make it possible to change point primitive size and use textures with them in
// the shaders. These are implicitly enabled in ES2.
glEnable(GL_PROGRAM_POINT_SIZE);
}
#endif
m_program->release();
}
void GLWidget::paintGL()
{
glClear(GL_COLOR_BUFFER_BIT);
QOpenGLVertexArrayObject::Binder vaoBinder(&m_vao);
m_program->bind();
GLXYDataMapIterator i(m_xyDataManager->dataMap());
while (i.hasNext()) {
i.next();
QOpenGLBuffer *vbo = m_seriesBufferMap.value(i.key());
GLXYSeriesData *data = i.value();
m_program->setUniformValue(m_colorUniformLoc, data->color);
m_program->setUniformValue(m_minUniformLoc, data->min);
m_program->setUniformValue(m_deltaUniformLoc, data->delta);
if (!vbo) {
vbo = new QOpenGLBuffer;
m_seriesBufferMap.insert(i.key(), vbo);
vbo->create();
}
vbo->bind();
if (data->dirty) {
vbo->allocate(data->array.constData(), data->array.count() * sizeof(GLfloat));
data->dirty = false;
}
glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 0, 0);
if (data->type == QAbstractSeries::SeriesTypeLine) {
glLineWidth(data->width);
glDrawArrays(GL_LINE_STRIP, 0, data->array.size() / 2);
} else { // Scatter
m_program->setUniformValue(m_pointSizeUniformLoc, data->width);
glDrawArrays(GL_POINTS, 0, data->array.size() / 2);
}
vbo->release();
}
#ifdef QDEBUG_TRACE_GL_FPS
static QElapsedTimer stopWatch;
static int frameCount = -1;
if (frameCount == -1) {
stopWatch.start();
frameCount = 0;
}
frameCount++;
int elapsed = stopWatch.elapsed();
if (elapsed >= 1000) {
elapsed = stopWatch.restart();
qreal fps = qreal(0.1 * int(10000.0 * (qreal(frameCount) / qreal(elapsed))));
qDebug() << "FPS:" << fps;
frameCount = 0;
}
#endif
m_program->release();
}
void GLWidget::resizeGL(int w, int h)
{
Q_UNUSED(w)
Q_UNUSED(h)
}
QT_CHARTS_END_NAMESPACE
#endif