chatterino2
Code Issues

Scroll Using Click-and-Drag with Middle Mouse Button (#1559)

Browse Source 
* ChannelView: Rename mouse event related members

This is more in line with the naming of the other members as well as
future members.

* ChannelView: Add ability to scroll with middle mouse button

* Add scrolling resources

* Use custom icons for scroll cursor

* Slightly refactor scrolling logic

* Respect screen scaling when calculating scroll offset

* Nicer scrolling UX

This change allows scrolling to be feel smoother when close to the
starting point.

* Add scrolling with keeping middle mouse pressed

This mimics the behavior of browsers as well.

* Refactor ChannelView::enableScrolling

* Disable drag-scrolling on left or right click
This commit is contained in:
Leon Richardt
2020-04-18 11:09:22 +02:00
committed by GitHub
parent 2076715e23
commit b4a2ced180
11 changed files with 448 additions and 13 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/widgets/helper/ChannelView.cpp
+98 -7
View File
@@ -6,6 +6,7 @@
#include <QGraphicsBlurEffect>
#include <QMessageBox>
#include <QPainter>
#include <QScreen>
#include <algorithm>
#include <chrono>
#include <cmath>
@@ -25,6 +26,7 @@
#include "messages/layouts/MessageLayoutElement.hpp"
#include "providers/twitch/TwitchChannel.hpp"
#include "providers/twitch/TwitchIrcServer.hpp"
#include "singletons/Resources.hpp"
#include "singletons/Settings.hpp"
#include "singletons/Theme.hpp"
#include "singletons/TooltipPreviewImage.hpp"
@@ -114,6 +116,10 @@ ChannelView::ChannelView(BaseWidget *parent)
this->initializeScrollbar();
this->initializeSignals();
this->cursors_.neutral = QCursor(getResources().scrolling.neutralScroll);
this->cursors_.up = QCursor(getResources().scrolling.upScroll);
this->cursors_.down = QCursor(getResources().scrolling.downScroll);
this->pauseTimer_.setSingleShot(true);
QObject::connect(&this->pauseTimer_, &QTimer::timeout, this, [this] {
/// remove elements that are finite
@@ -131,6 +137,10 @@ ChannelView::ChannelView(BaseWidget *parent)
this->clickTimer_->setSingleShot(true);
this->clickTimer_->setInterval(500);
this->scrollTimer_.setInterval(20);
QObject::connect(&this->scrollTimer_, &QTimer::timeout, this,
&ChannelView::scrollUpdateRequested);
this->setFocusPolicy(Qt::FocusPolicy::StrongFocus);
}
@@ -1060,8 +1070,13 @@ void ChannelView::mouseMoveEvent(QMouseEvent *event)
return;
}
if (this->isScrolling_)
{
this->currentMousePosition_ = event->screenPos();
}
// is selecting
if (this->isMouseDown_)
if (this->isLeftMouseDown_)
{
// this->pause(PauseReason::Selecting, 300);
int index = layout->getSelectionIndex(relativePos);
@@ -1326,8 +1341,11 @@ void ChannelView::mousePressEvent(QMouseEvent *event)
switch (event->button())
{
case Qt::LeftButton: {
this->lastPressPosition_ = event->screenPos();
this->isMouseDown_ = true;
if (this->isScrolling_)
this->disableScrolling();
this->lastLeftPressPosition_ = event->screenPos();
this->isLeftMouseDown_ = true;
if (layout->flags.has(MessageLayoutFlag::Collapsed))
return;
@@ -1344,11 +1362,22 @@ void ChannelView::mousePressEvent(QMouseEvent *event)
break;
case Qt::RightButton: {
if (this->isScrolling_)
this->disableScrolling();
this->lastRightPressPosition_ = event->screenPos();
this->isRightMouseDown_ = true;
}
break;
case Qt::MiddleButton: {
if (this->isScrolling_)
this->disableScrolling();
else
this->enableScrolling(event->screenPos());
}
break;
default:;
}
@@ -1373,11 +1402,11 @@ void ChannelView::mouseReleaseEvent(QMouseEvent *event)
return;
}
}
else if (this->isMouseDown_)
else if (this->isLeftMouseDown_)
{
this->isMouseDown_ = false;
this->isLeftMouseDown_ = false;
if (fabsf(distanceBetweenPoints(this->lastPressPosition_,
if (fabsf(distanceBetweenPoints(this->lastLeftPressPosition_,
event->screenPos())) > 15.f)
{
return;
@@ -1405,6 +1434,13 @@ void ChannelView::mouseReleaseEvent(QMouseEvent *event)
return;
}
}
else if (event->button() == Qt::MiddleButton)
{
if (event->screenPos() == this->lastMiddlePressPosition_)
this->enableScrolling(event->screenPos());
else
this->disableScrolling();
}
else
{
// not left or right button
@@ -1638,7 +1674,7 @@ void ChannelView::mouseDoubleClickEvent(QMouseEvent *event)
return;
}
if (!this->isMouseDown_)
if (!this->isLeftMouseDown_)
{
this->isDoubleClick_ = true;
@@ -1803,4 +1839,59 @@ void ChannelView::getWordBounds(MessageLayout *layout,
wordEnd = wordStart + length;
}
void ChannelView::enableScrolling(const QPointF &scrollStart)
{
this->isScrolling_ = true;
this->lastMiddlePressPosition_ = scrollStart;
// The line below prevents a sudden jerk at the beginning
this->currentMousePosition_ = scrollStart;
this->scrollTimer_.start();
if (!QGuiApplication::overrideCursor())
QGuiApplication::setOverrideCursor(this->cursors_.neutral);
}
void ChannelView::disableScrolling()
{
this->isScrolling_ = false;
this->scrollTimer_.stop();
QGuiApplication::restoreOverrideCursor();
}
void ChannelView::scrollUpdateRequested()
{
const qreal dpi =
QGuiApplication::screenAt(this->pos())->devicePixelRatio();
const qreal delta = dpi * (this->currentMousePosition_.y() -
this->lastMiddlePressPosition_.y());
const int cursorHeight = this->cursors_.neutral.pixmap().height();
if (fabs(delta) <= cursorHeight * dpi)
{
/*
* If within an area close to the initial position, don't do any
* scrolling at all.
*/
QGuiApplication::changeOverrideCursor(this->cursors_.neutral);
return;
}
qreal offset;
if (delta > 0)
{
QGuiApplication::changeOverrideCursor(this->cursors_.down);
offset = delta - cursorHeight;
}
else
{
QGuiApplication::changeOverrideCursor(this->cursors_.up);
offset = delta + cursorHeight;
}
// "Good" feeling multiplier found by trial-and-error
const qreal multiplier = qreal(0.02);
this->scrollBar_->offset(multiplier * offset);
}
} // namespace chatterino