MainWindow: Fix session error slot declaration

[pulseview.git] / pv / view / decodetrace.cpp

/*
 * This file is part of the PulseView project.
 *
 * Copyright (C) 2012 Joel Holdsworth <joel@airwebreathe.org.uk>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
 */

extern "C" {
#include <libsigrokdecode/libsigrokdecode.h>
}

#include <mutex>

#include <extdef.h>

#include <tuple>

#include <boost/functional/hash.hpp>
#include <boost/thread/locks.hpp>
#include <boost/thread/shared_mutex.hpp>

#include <QAction>
#include <QApplication>
#include <QComboBox>
#include <QFormLayout>
#include <QLabel>
#include <QMenu>
#include <QPushButton>
#include <QToolTip>

#include "decodetrace.hpp"

#include <pv/session.hpp>
#include <pv/strnatcmp.hpp>
#include <pv/data/decoderstack.hpp>
#include <pv/data/decode/decoder.hpp>
#include <pv/data/logic.hpp>
#include <pv/data/logicsegment.hpp>
#include <pv/data/decode/annotation.hpp>
#include <pv/view/view.hpp>
#include <pv/view/viewport.hpp>
#include <pv/widgets/decodergroupbox.hpp>
#include <pv/widgets/decodermenu.hpp>

using boost::shared_lock;
using boost::shared_mutex;
using std::dynamic_pointer_cast;
using std::list;
using std::lock_guard;
using std::make_pair;
using std::max;
using std::make_pair;
using std::map;
using std::min;
using std::pair;
using std::shared_ptr;
using std::tie;
using std::unordered_set;
using std::vector;

namespace pv {
namespace views {
namespace TraceView {

const QColor DecodeTrace::DecodeColours[4] = {
	QColor(0xEF, 0x29, 0x29),	// Red
	QColor(0xFC, 0xE9, 0x4F),	// Yellow
	QColor(0x8A, 0xE2, 0x34),	// Green
	QColor(0x72, 0x9F, 0xCF)	// Blue
};

const QColor DecodeTrace::ErrorBgColour = QColor(0xEF, 0x29, 0x29);
const QColor DecodeTrace::NoDecodeColour = QColor(0x88, 0x8A, 0x85);

const int DecodeTrace::ArrowSize = 4;
const double DecodeTrace::EndCapWidth = 5;
const int DecodeTrace::RowTitleMargin = 10;
const int DecodeTrace::DrawPadding = 100;

const QColor DecodeTrace::Colours[16] = {
	QColor(0xEF, 0x29, 0x29),
	QColor(0xF6, 0x6A, 0x32),
	QColor(0xFC, 0xAE, 0x3E),
	QColor(0xFB, 0xCA, 0x47),
	QColor(0xFC, 0xE9, 0x4F),
	QColor(0xCD, 0xF0, 0x40),
	QColor(0x8A, 0xE2, 0x34),
	QColor(0x4E, 0xDC, 0x44),
	QColor(0x55, 0xD7, 0x95),
	QColor(0x64, 0xD1, 0xD2),
	QColor(0x72, 0x9F, 0xCF),
	QColor(0xD4, 0x76, 0xC4),
	QColor(0x9D, 0x79, 0xB9),
	QColor(0xAD, 0x7F, 0xA8),
	QColor(0xC2, 0x62, 0x9B),
	QColor(0xD7, 0x47, 0x6F)
};

const QColor DecodeTrace::OutlineColours[16] = {
	QColor(0x77, 0x14, 0x14),
	QColor(0x7B, 0x35, 0x19),
	QColor(0x7E, 0x57, 0x1F),
	QColor(0x7D, 0x65, 0x23),
	QColor(0x7E, 0x74, 0x27),
	QColor(0x66, 0x78, 0x20),
	QColor(0x45, 0x71, 0x1A),
	QColor(0x27, 0x6E, 0x22),
	QColor(0x2A, 0x6B, 0x4A),
	QColor(0x32, 0x68, 0x69),
	QColor(0x39, 0x4F, 0x67),
	QColor(0x6A, 0x3B, 0x62),
	QColor(0x4E, 0x3C, 0x5C),
	QColor(0x56, 0x3F, 0x54),
	QColor(0x61, 0x31, 0x4D),
	QColor(0x6B, 0x23, 0x37)
};

DecodeTrace::DecodeTrace(pv::Session &session,
	shared_ptr<data::SignalBase> signalbase, int index) :
	Trace(signalbase),
	session_(session),
	signalbase_(signalbase),
	row_height_(0),
	max_visible_rows_(0),
	delete_mapper_(this),
	show_hide_mapper_(this)
{
	std::shared_ptr<pv::data::DecoderStack> decoder_stack =
		signalbase_->decoder_stack();

	// Determine shortest string we want to see displayed in full
	QFontMetrics m(QApplication::font());
	min_useful_label_width_ = m.width("XX"); // e.g. two hex characters

	signalbase_->set_name(QString::fromUtf8(decoder_stack->stack().front()->decoder()->name));
	signalbase_->set_colour(DecodeColours[index % countof(DecodeColours)]);

	connect(decoder_stack.get(), SIGNAL(new_decode_data()),
		this, SLOT(on_new_decode_data()));
	connect(&delete_mapper_, SIGNAL(mapped(int)),
		this, SLOT(on_delete_decoder(int)));
	connect(&show_hide_mapper_, SIGNAL(mapped(int)),
		this, SLOT(on_show_hide_decoder(int)));
}

bool DecodeTrace::enabled() const
{
	return true;
}

std::shared_ptr<data::SignalBase> DecodeTrace::base() const
{
	return base_;
}

pair<int, int> DecodeTrace::v_extents() const
{
	const int row_height = (ViewItemPaintParams::text_height() * 6) / 4;

	// Make an empty decode trace appear symmetrical
	const int row_count = max(1, max_visible_rows_);

	return make_pair(-row_height, row_height * row_count);
}

void DecodeTrace::paint_back(QPainter &p, const ViewItemPaintParams &pp)
{
	Trace::paint_back(p, pp);
	paint_axis(p, pp, get_visual_y());
}

void DecodeTrace::paint_mid(QPainter &p, const ViewItemPaintParams &pp)
{
	using namespace pv::data::decode;

	std::shared_ptr<pv::data::DecoderStack> decoder_stack =
		signalbase_->decoder_stack();

	const int text_height = ViewItemPaintParams::text_height();
	row_height_ = (text_height * 6) / 4;
	const int annotation_height = (text_height * 5) / 4;

	assert(decoder_stack);
	const QString err = decoder_stack->error_message();
	if (!err.isEmpty()) {
		draw_unresolved_period(
			p, annotation_height, pp.left(), pp.right());
		draw_error(p, err, pp);
		return;
	}

	// Set default pen to allow for text width calculation
	p.setPen(Qt::black);

	// Iterate through the rows
	int y = get_visual_y();
	pair<uint64_t, uint64_t> sample_range = get_sample_range(
		pp.left(), pp.right());

	const vector<Row> rows(decoder_stack->get_visible_rows());

	visible_rows_.clear();
	for (const Row& row : rows) {
		// Cache the row title widths
		int row_title_width;
		try {
			row_title_width = row_title_widths_.at(row);
		} catch (std::out_of_range) {
			const int w = p.boundingRect(QRectF(), 0, row.title()).width() +
				RowTitleMargin;
			row_title_widths_[row] = w;
			row_title_width = w;
		}

		// Determine the row's color
		size_t base_colour = 0x13579BDF;
		boost::hash_combine(base_colour, this);
		boost::hash_combine(base_colour, row.decoder());
		boost::hash_combine(base_colour, row.row());
		base_colour >>= 16;

		vector<Annotation> annotations;
		decoder_stack->get_annotation_subset(annotations, row,
			sample_range.first, sample_range.second);
		if (!annotations.empty()) {
			draw_annotations(annotations, p, annotation_height, pp, y,
				base_colour, row_title_width);

			y += row_height_;

			visible_rows_.push_back(row);
		}
	}

	// Draw the hatching
	draw_unresolved_period(p, annotation_height, pp.left(), pp.right());

	if ((int)visible_rows_.size() > max_visible_rows_)
		owner_->extents_changed(false, true);

	// Update the maximum row count if needed
	max_visible_rows_ = std::max(max_visible_rows_, (int)visible_rows_.size());
}

void DecodeTrace::paint_fore(QPainter &p, const ViewItemPaintParams &pp)
{
	using namespace pv::data::decode;

	assert(row_height_);

	for (size_t i = 0; i < visible_rows_.size(); i++) {
		const int y = i * row_height_ + get_visual_y();

		p.setPen(QPen(Qt::NoPen));
		p.setBrush(QApplication::palette().brush(QPalette::WindowText));

		if (i != 0) {
			const QPointF points[] = {
				QPointF(pp.left(), y - ArrowSize),
				QPointF(pp.left() + ArrowSize, y),
				QPointF(pp.left(), y + ArrowSize)
			};
			p.drawPolygon(points, countof(points));
		}

		const QRect r(pp.left() + ArrowSize * 2, y - row_height_ / 2,
			pp.right() - pp.left(), row_height_);
		const QString h(visible_rows_[i].title());
		const int f = Qt::AlignLeft | Qt::AlignVCenter |
			Qt::TextDontClip;

		// Draw the outline
		p.setPen(QApplication::palette().color(QPalette::Base));
		for (int dx = -1; dx <= 1; dx++)
			for (int dy = -1; dy <= 1; dy++)
				if (dx != 0 && dy != 0)
					p.drawText(r.translated(dx, dy), f, h);

		// Draw the text
		p.setPen(QApplication::palette().color(QPalette::WindowText));
		p.drawText(r, f, h);
	}
}

void DecodeTrace::populate_popup_form(QWidget *parent, QFormLayout *form)
{
	using pv::data::decode::Decoder;

	std::shared_ptr<pv::data::DecoderStack> decoder_stack =
		signalbase_->decoder_stack();

	assert(form);
	assert(parent);
	assert(decoder_stack);

	// Add the standard options
	Trace::populate_popup_form(parent, form);

	// Add the decoder options
	bindings_.clear();
	channel_selectors_.clear();
	decoder_forms_.clear();

	const list< shared_ptr<Decoder> >& stack = decoder_stack->stack();

	if (stack.empty()) {
		QLabel *const l = new QLabel(
			tr("<p><i>No decoders in the stack</i></p>"));
		l->setAlignment(Qt::AlignCenter);
		form->addRow(l);
	} else {
		auto iter = stack.cbegin();
		for (int i = 0; i < (int)stack.size(); i++, iter++) {
			shared_ptr<Decoder> dec(*iter);
			create_decoder_form(i, dec, parent, form);
		}

		form->addRow(new QLabel(
			tr("<i>* Required channels</i>"), parent));
	}

	// Add stacking button
	pv::widgets::DecoderMenu *const decoder_menu =
		new pv::widgets::DecoderMenu(parent);
	connect(decoder_menu, SIGNAL(decoder_selected(srd_decoder*)),
		this, SLOT(on_stack_decoder(srd_decoder*)));

	QPushButton *const stack_button =
		new QPushButton(tr("Stack Decoder"), parent);
	stack_button->setMenu(decoder_menu);

	QHBoxLayout *stack_button_box = new QHBoxLayout;
	stack_button_box->addWidget(stack_button, 0, Qt::AlignRight);
	form->addRow(stack_button_box);
}

QMenu* DecodeTrace::create_context_menu(QWidget *parent)
{
	QMenu *const menu = Trace::create_context_menu(parent);

	menu->addSeparator();

	QAction *const del = new QAction(tr("Delete"), this);
	del->setShortcuts(QKeySequence::Delete);
	connect(del, SIGNAL(triggered()), this, SLOT(on_delete()));
	menu->addAction(del);

	return menu;
}

void DecodeTrace::draw_annotations(vector<pv::data::decode::Annotation> annotations,
		QPainter &p, int h, const ViewItemPaintParams &pp, int y,
		size_t base_colour, int row_title_width)
{
	using namespace pv::data::decode;

	vector<Annotation> a_block;
	int p_end = INT_MIN;

	double samples_per_pixel, pixels_offset;
	tie(pixels_offset, samples_per_pixel) =
		get_pixels_offset_samples_per_pixel();

	// Sort the annotations by start sample so that decoders
	// can't confuse us by creating annotations out of order
	stable_sort(annotations.begin(), annotations.end(),
		[](const Annotation &a, const Annotation &b) {
			return a.start_sample() < b.start_sample(); });

	// Gather all annotations that form a visual "block" and draw them as such
	for (const Annotation &a : annotations) {

		const int a_start = a.start_sample() / samples_per_pixel - pixels_offset;
		const int a_end = a.end_sample() / samples_per_pixel - pixels_offset;
		const int a_width = a_end - a_start;

		const int delta = a_end - p_end;

		bool a_is_separate = false;

		// Annotation wider than the threshold for a useful label width?
		if (a_width >= min_useful_label_width_) {
			for (const QString &ann_text : a.annotations()) {
				const int w = p.boundingRect(QRectF(), 0, ann_text).width();
				// Annotation wide enough to fit a label? Don't put it in a block then
				if (w <= a_width) {
					a_is_separate = true;
					break;
				}
			}
		}

		// Were the previous and this annotation more than a pixel apart?
		if ((abs(delta) > 1) || a_is_separate) {
			// Block was broken, draw annotations that form the current block
			if (a_block.size() == 1) {
				draw_annotation(a_block.front(), p, h, pp, y, base_colour,
					row_title_width);
			}
			else
				draw_annotation_block(a_block, p, h, y, base_colour);

			a_block.clear();
		}

		if (a_is_separate) {
			draw_annotation(a, p, h, pp, y, base_colour, row_title_width);
			// Next annotation must start a new block. delta will be > 1
			// because we set p_end to INT_MIN but that's okay since
			// a_block will be empty, so nothing will be drawn
			p_end = INT_MIN;
		} else {
			a_block.push_back(a);
			p_end = a_end;
		}
	}

	if (a_block.size() == 1)
		draw_annotation(a_block.front(), p, h, pp, y, base_colour,
			row_title_width);
	else
		draw_annotation_block(a_block, p, h, y, base_colour);
}

void DecodeTrace::draw_annotation(const pv::data::decode::Annotation &a,
	QPainter &p, int h, const ViewItemPaintParams &pp, int y,
	size_t base_colour, int row_title_width) const
{
	double samples_per_pixel, pixels_offset;
	tie(pixels_offset, samples_per_pixel) =
		get_pixels_offset_samples_per_pixel();

	const double start = a.start_sample() / samples_per_pixel -
		pixels_offset;
	const double end = a.end_sample() / samples_per_pixel -
		pixels_offset;

	const size_t colour = (base_colour + a.format()) % countof(Colours);
	p.setPen(OutlineColours[colour]);
	p.setBrush(Colours[colour]);

	if (start > pp.right() + DrawPadding || end < pp.left() - DrawPadding)
		return;

	if (a.start_sample() == a.end_sample())
		draw_instant(a, p, h, start, y);
	else
		draw_range(a, p, h, start, end, y, pp,
			row_title_width);
}

void DecodeTrace::draw_annotation_block(
	vector<pv::data::decode::Annotation> annotations, QPainter &p, int h,
	int y, size_t base_colour) const
{
	using namespace pv::data::decode;

	if (annotations.empty())
		return;

	double samples_per_pixel, pixels_offset;
	tie(pixels_offset, samples_per_pixel) =
		get_pixels_offset_samples_per_pixel();

	const double start = annotations.front().start_sample() /
		samples_per_pixel - pixels_offset;
	const double end = annotations.back().end_sample() /
		samples_per_pixel - pixels_offset;

	const double top = y + .5 - h / 2;
	const double bottom = y + .5 + h / 2;

	const size_t colour = (base_colour + annotations.front().format()) %
		countof(Colours);

	// Check if all annotations are of the same type (i.e. we can use one color)
	// or if we should use a neutral color (i.e. gray)
	const int format = annotations.front().format();
	const bool single_format = std::all_of(
		annotations.begin(), annotations.end(),
		[&](const Annotation &a) { return a.format() == format; });

	p.setPen((single_format ? OutlineColours[colour] : Qt::gray));
	p.setBrush(QBrush((single_format ? Colours[colour] : Qt::gray),
		Qt::Dense4Pattern));
	p.drawRoundedRect(
		QRectF(start, top, end - start, bottom - top), h/4, h/4);
}

void DecodeTrace::draw_instant(const pv::data::decode::Annotation &a, QPainter &p,
	int h, double x, int y) const
{
	const QString text = a.annotations().empty() ?
		QString() : a.annotations().back();
	const double w = min((double)p.boundingRect(QRectF(), 0, text).width(),
		0.0) + h;
	const QRectF rect(x - w / 2, y - h / 2, w, h);

	p.drawRoundedRect(rect, h / 2, h / 2);

	p.setPen(Qt::black);
	p.drawText(rect, Qt::AlignCenter | Qt::AlignVCenter, text);
}

void DecodeTrace::draw_range(const pv::data::decode::Annotation &a, QPainter &p,
	int h, double start, double end, int y, const ViewItemPaintParams &pp,
	int row_title_width) const
{
	const double top = y + .5 - h / 2;
	const double bottom = y + .5 + h / 2;
	const vector<QString> annotations = a.annotations();

	// If the two ends are within 1 pixel, draw a vertical line
	if (start + 1.0 > end) {
		p.drawLine(QPointF(start, top), QPointF(start, bottom));
		return;
	}

	const double cap_width = min((end - start) / 4, EndCapWidth);

	QPointF pts[] = {
		QPointF(start, y + .5f),
		QPointF(start + cap_width, top),
		QPointF(end - cap_width, top),
		QPointF(end, y + .5f),
		QPointF(end - cap_width, bottom),
		QPointF(start + cap_width, bottom)
	};

	p.drawConvexPolygon(pts, countof(pts));

	if (annotations.empty())
		return;

	const int ann_start = start + cap_width;
	const int ann_end = end - cap_width;

	const int real_start = std::max(ann_start, pp.left() + row_title_width);
	const int real_end = std::min(ann_end, pp.right());
	const int real_width = real_end - real_start;

	QRectF rect(real_start, y - h / 2, real_width, h);
	if (rect.width() <= 4)
		return;

	p.setPen(Qt::black);

	// Try to find an annotation that will fit
	QString best_annotation;
	int best_width = 0;

	for (const QString &a : annotations) {
		const int w = p.boundingRect(QRectF(), 0, a).width();
		if (w <= rect.width() && w > best_width)
			best_annotation = a, best_width = w;
	}

	if (best_annotation.isEmpty())
		best_annotation = annotations.back();

	// If not ellide the last in the list
	p.drawText(rect, Qt::AlignCenter, p.fontMetrics().elidedText(
		best_annotation, Qt::ElideRight, rect.width()));
}

void DecodeTrace::draw_error(QPainter &p, const QString &message,
	const ViewItemPaintParams &pp)
{
	const int y = get_visual_y();

	p.setPen(ErrorBgColour.darker());
	p.setBrush(ErrorBgColour);

	const QRectF bounding_rect =
		QRectF(pp.width(), INT_MIN / 2 + y, pp.width(), INT_MAX);
	const QRectF text_rect = p.boundingRect(bounding_rect,
		Qt::AlignCenter, message);
	const float r = text_rect.height() / 4;

	p.drawRoundedRect(text_rect.adjusted(-r, -r, r, r), r, r,
		Qt::AbsoluteSize);

	p.setPen(Qt::black);
	p.drawText(text_rect, message);
}

void DecodeTrace::draw_unresolved_period(QPainter &p, int h, int left,
	int right) const
{
	using namespace pv::data;
	using pv::data::decode::Decoder;

	double samples_per_pixel, pixels_offset;

	std::shared_ptr<pv::data::DecoderStack> decoder_stack =
		signalbase_->decoder_stack();

	assert(decoder_stack);

	shared_ptr<Logic> data;
	shared_ptr<data::SignalBase> signalbase;

	const list< shared_ptr<Decoder> > &stack = decoder_stack->stack();

	// We get the logic data of the first channel in the list.
	// This works because we are currently assuming all
	// LogicSignals have the same data/segment
	for (const shared_ptr<Decoder> &dec : stack)
		if (dec && !dec->channels().empty() &&
			((signalbase = (*dec->channels().begin()).second)) &&
			((data = signalbase->logic_data())))
			break;

	if (!data || data->logic_segments().empty())
		return;

	const shared_ptr<LogicSegment> segment =
		data->logic_segments().front();
	assert(segment);
	const int64_t sample_count = (int64_t)segment->get_sample_count();
	if (sample_count == 0)
		return;

	const int64_t samples_decoded = decoder_stack->samples_decoded();
	if (sample_count == samples_decoded)
		return;

	const int y = get_visual_y();

	tie(pixels_offset, samples_per_pixel) =
		get_pixels_offset_samples_per_pixel();

	const double start = max(samples_decoded /
		samples_per_pixel - pixels_offset, left - 1.0);
	const double end = min(sample_count / samples_per_pixel -
		pixels_offset, right + 1.0);
	const QRectF no_decode_rect(start, y - h/2 + 0.5, end - start, h);

	p.setPen(QPen(Qt::NoPen));
	p.setBrush(Qt::white);
	p.drawRect(no_decode_rect);

	p.setPen(NoDecodeColour);
	p.setBrush(QBrush(NoDecodeColour, Qt::Dense6Pattern));
	p.drawRect(no_decode_rect);
}

pair<double, double> DecodeTrace::get_pixels_offset_samples_per_pixel() const
{
	std::shared_ptr<pv::data::DecoderStack> decoder_stack =
		signalbase_->decoder_stack();

	assert(owner_);
	assert(decoder_stack);

	const View *view = owner_->view();
	assert(view);

	const double scale = view->scale();
	assert(scale > 0);

	const double pixels_offset =
		((view->offset() - decoder_stack->start_time()) / scale).convert_to<double>();

	double samplerate = decoder_stack->samplerate();

	// Show sample rate as 1Hz when it is unknown
	if (samplerate == 0.0)
		samplerate = 1.0;

	return make_pair(pixels_offset, samplerate * scale);
}

pair<uint64_t, uint64_t> DecodeTrace::get_sample_range(
	int x_start, int x_end) const
{
	double samples_per_pixel, pixels_offset;
	tie(pixels_offset, samples_per_pixel) =
		get_pixels_offset_samples_per_pixel();

	const uint64_t start = (uint64_t)max(
		(x_start + pixels_offset) * samples_per_pixel, 0.0);
	const uint64_t end = (uint64_t)max(
		(x_end + pixels_offset) * samples_per_pixel, 0.0);

	return make_pair(start, end);
}

int DecodeTrace::get_row_at_point(const QPoint &point)
{
	if (!row_height_)
		return -1;

	const int y = (point.y() - get_visual_y() + row_height_ / 2);

	/* Integer divison of (x-1)/x would yield 0, so we check for this. */
	if (y < 0)
		return -1;

	const int row = y / row_height_;

	if (row >= (int)visible_rows_.size())
		return -1;

	return row;
}

const QString DecodeTrace::get_annotation_at_point(const QPoint &point)
{
	using namespace pv::data::decode;

	if (!enabled())
		return QString();

	const pair<uint64_t, uint64_t> sample_range =
		get_sample_range(point.x(), point.x() + 1);
	const int row = get_row_at_point(point);
	if (row < 0)
		return QString();

	vector<pv::data::decode::Annotation> annotations;

	std::shared_ptr<pv::data::DecoderStack> decoder_stack =
		signalbase_->decoder_stack();

	assert(decoder_stack);
	decoder_stack->get_annotation_subset(annotations, visible_rows_[row],
		sample_range.first, sample_range.second);

	return (annotations.empty()) ?
		QString() : annotations[0].annotations().front();
}

void DecodeTrace::hover_point_changed()
{
	assert(owner_);

	const View *const view = owner_->view();
	assert(view);

	QPoint hp = view->hover_point();
	QString ann = get_annotation_at_point(hp);

	assert(view);

	if (!row_height_ || ann.isEmpty()) {
		QToolTip::hideText();
		return;
	}

	const int hover_row = get_row_at_point(hp);

	QFontMetrics m(QToolTip::font());
	const QRect text_size = m.boundingRect(QRect(), 0, ann);

	// This is OS-specific and unfortunately we can't query it, so
	// use an approximation to at least try to minimize the error.
	const int padding = 8;

	// Make sure the tool tip doesn't overlap with the mouse cursor.
	// If it did, the tool tip would constantly hide and re-appear.
	// We also push it up by one row so that it appears above the
	// decode trace, not below.
	hp.setX(hp.x() - (text_size.width() / 2) - padding);

	hp.setY(get_visual_y() - (row_height_ / 2) +
		(hover_row * row_height_) -
		row_height_ - text_size.height() - padding);

	QToolTip::showText(view->viewport()->mapToGlobal(hp), ann);
}

void DecodeTrace::create_decoder_form(int index,
	shared_ptr<data::decode::Decoder> &dec, QWidget *parent,
	QFormLayout *form)
{
	const GSList *l;

	assert(dec);
	const srd_decoder *const decoder = dec->decoder();
	assert(decoder);

	const bool decoder_deletable = index > 0;

	pv::widgets::DecoderGroupBox *const group =
		new pv::widgets::DecoderGroupBox(
			QString::fromUtf8(decoder->name), nullptr, decoder_deletable);
	group->set_decoder_visible(dec->shown());

	if (decoder_deletable) {
		delete_mapper_.setMapping(group, index);
		connect(group, SIGNAL(delete_decoder()), &delete_mapper_, SLOT(map()));
	}

	show_hide_mapper_.setMapping(group, index);
	connect(group, SIGNAL(show_hide_decoder()),
		&show_hide_mapper_, SLOT(map()));

	QFormLayout *const decoder_form = new QFormLayout;
	group->add_layout(decoder_form);

	// Add the mandatory channels
	for (l = decoder->channels; l; l = l->next) {
		const struct srd_channel *const pdch =
			(struct srd_channel *)l->data;
		QComboBox *const combo = create_channel_selector(parent, dec, pdch);
		connect(combo, SIGNAL(currentIndexChanged(int)),
			this, SLOT(on_channel_selected(int)));
		decoder_form->addRow(tr("<b>%1</b> (%2) *")
			.arg(QString::fromUtf8(pdch->name),
			     QString::fromUtf8(pdch->desc)), combo);

		const ChannelSelector s = {combo, dec, pdch};
		channel_selectors_.push_back(s);
	}

	// Add the optional channels
	for (l = decoder->opt_channels; l; l = l->next) {
		const struct srd_channel *const pdch =
			(struct srd_channel *)l->data;
		QComboBox *const combo = create_channel_selector(parent, dec, pdch);
		connect(combo, SIGNAL(currentIndexChanged(int)),
			this, SLOT(on_channel_selected(int)));
		decoder_form->addRow(tr("<b>%1</b> (%2)")
			.arg(QString::fromUtf8(pdch->name),
			     QString::fromUtf8(pdch->desc)), combo);

		const ChannelSelector s = {combo, dec, pdch};
		channel_selectors_.push_back(s);
	}

	std::shared_ptr<pv::data::DecoderStack> decoder_stack =
		signalbase_->decoder_stack();

	// Add the options
	shared_ptr<binding::Decoder> binding(
		new binding::Decoder(decoder_stack, dec));
	binding->add_properties_to_form(decoder_form, true);

	bindings_.push_back(binding);

	form->addRow(group);
	decoder_forms_.push_back(group);
}

QComboBox* DecodeTrace::create_channel_selector(
	QWidget *parent, const shared_ptr<data::decode::Decoder> &dec,
	const srd_channel *const pdch)
{
	assert(dec);

	const auto sigs(session_.signalbases());

	vector< shared_ptr<data::SignalBase> > sig_list(sigs.begin(), sigs.end());
	std::sort(sig_list.begin(), sig_list.end(),
		[](const shared_ptr<data::SignalBase> &a,
		const shared_ptr<data::SignalBase> &b) {
			return strnatcasecmp(a->name().toStdString(),
				b->name().toStdString()) < 0; });

	const auto channel_iter = dec->channels().find(pdch);

	QComboBox *selector = new QComboBox(parent);

	selector->addItem("-", qVariantFromValue((void*)nullptr));

	if (channel_iter == dec->channels().end())
		selector->setCurrentIndex(0);

	for (const shared_ptr<data::SignalBase> &b : sig_list) {
		assert(b);
		if (b->type() == sigrok::ChannelType::LOGIC && b->enabled()) {
			selector->addItem(b->name(),
				qVariantFromValue((void*)b.get()));

			if (channel_iter != dec->channels().end() &&
				(*channel_iter).second == b)
				selector->setCurrentIndex(
					selector->count() - 1);
		}
	}

	return selector;
}

void DecodeTrace::commit_decoder_channels(shared_ptr<data::decode::Decoder> &dec)
{
	assert(dec);

	map<const srd_channel*, shared_ptr<data::SignalBase> > channel_map;

	const unordered_set< shared_ptr<data::SignalBase> >
		sigs(session_.signalbases());

	for (const ChannelSelector &s : channel_selectors_) {
		if (s.decoder_ != dec)
			break;

		const data::SignalBase *const selection =
			(data::SignalBase*)s.combo_->itemData(
				s.combo_->currentIndex()).value<void*>();

		for (shared_ptr<data::SignalBase> sig : sigs)
			if (sig.get() == selection) {
				channel_map[s.pdch_] = sig;
				break;
			}
	}

	dec->set_channels(channel_map);
}

void DecodeTrace::commit_channels()
{
	std::shared_ptr<pv::data::DecoderStack> decoder_stack =
		signalbase_->decoder_stack();

	assert(decoder_stack);
	for (shared_ptr<data::decode::Decoder> dec : decoder_stack->stack())
		commit_decoder_channels(dec);

	decoder_stack->begin_decode();
}

void DecodeTrace::on_new_decode_data()
{
	if (owner_)
		owner_->row_item_appearance_changed(false, true);
}

void DecodeTrace::delete_pressed()
{
	on_delete();
}

void DecodeTrace::on_delete()
{
	session_.remove_decode_signal(base_);
}

void DecodeTrace::on_channel_selected(int)
{
	commit_channels();
}

void DecodeTrace::on_stack_decoder(srd_decoder *decoder)
{
	std::shared_ptr<pv::data::DecoderStack> decoder_stack =
		signalbase_->decoder_stack();

	assert(decoder);
	assert(decoder_stack);
	decoder_stack->push(shared_ptr<data::decode::Decoder>(
		new data::decode::Decoder(decoder)));
	decoder_stack->begin_decode();

	create_popup_form();
}

void DecodeTrace::on_delete_decoder(int index)
{
	std::shared_ptr<pv::data::DecoderStack> decoder_stack =
		signalbase_->decoder_stack();

	decoder_stack->remove(index);

	// Update the popup
	create_popup_form();	

	decoder_stack->begin_decode();
}

void DecodeTrace::on_show_hide_decoder(int index)
{
	using pv::data::decode::Decoder;

	std::shared_ptr<pv::data::DecoderStack> decoder_stack =
		signalbase_->decoder_stack();

	const list< shared_ptr<Decoder> > stack(decoder_stack->stack());

	// Find the decoder in the stack
	auto iter = stack.cbegin();
	for (int i = 0; i < index; i++, iter++)
		assert(iter != stack.end());

	shared_ptr<Decoder> dec = *iter;
	assert(dec);

	const bool show = !dec->shown();
	dec->show(show);

	assert(index < (int)decoder_forms_.size());
	decoder_forms_[index]->set_decoder_visible(show);

	if (owner_)
		owner_->row_item_appearance_changed(false, true);
}

} // namespace TraceView
} // namespace views
} // namespace pv