84 lines
3.3 KiB
C++
84 lines
3.3 KiB
C++
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#include "axistag.h"
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AxisTag::AxisTag(QCPAxis* parentAxis) :
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QObject(parentAxis),
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mAxis(parentAxis)
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{
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// The dummy tracer serves here as an invisible anchor which always sticks to the right side of
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// the axis rect
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mDummyTracer = new QCPItemTracer(mAxis->parentPlot());
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mDummyTracer->setVisible(false);
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mDummyTracer->position->setTypeX(QCPItemPosition::ptAxisRectRatio);
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mDummyTracer->position->setTypeY(QCPItemPosition::ptPlotCoords);
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mDummyTracer->position->setAxisRect(mAxis->axisRect());
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mDummyTracer->position->setAxes(0, mAxis);
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mDummyTracer->position->setCoords(1, 0);
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// the arrow end (head) is set to move along with the dummy tracer by setting it as its parent
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// anchor. Its coordinate system (setCoords) is thus pixels, and this is how the needed horizontal
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// offset for the tag of the second y axis is achieved. This horizontal offset gets dynamically
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// updated in AxisTag::updatePosition. the arrow "start" is simply set to have the "end" as parent
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// anchor. It is given a horizontal offset to the right, which results in a 15 pixel long arrow.
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mArrow = new QCPItemLine(mAxis->parentPlot());
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mArrow->setLayer("overlay");
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mArrow->setClipToAxisRect(false);
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mArrow->setHead(QCPLineEnding::esSpikeArrow);
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mArrow->end->setParentAnchor(mDummyTracer->position);
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mArrow->start->setParentAnchor(mArrow->end);
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mArrow->start->setCoords(15, 0);
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// The text label is anchored at the arrow start (tail) and has its "position" aligned at the
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// left, and vertically centered to the text label box.
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mLabel = new QCPItemText(mAxis->parentPlot());
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mLabel->setLayer("overlay");
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mLabel->setClipToAxisRect(false);
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mLabel->setPadding(QMargins(3, 0, 3, 0));
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mLabel->setBrush(QBrush(Qt::white));
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mLabel->setPen(QPen(Qt::blue));
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mLabel->setPositionAlignment(Qt::AlignLeft | Qt::AlignVCenter);
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mLabel->position->setParentAnchor(mArrow->start);
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}
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AxisTag::~AxisTag()
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{
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if (mDummyTracer)
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mDummyTracer->parentPlot()->removeItem(mDummyTracer);
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if (mArrow)
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mArrow->parentPlot()->removeItem(mArrow);
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if (mLabel)
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mLabel->parentPlot()->removeItem(mLabel);
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}
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void AxisTag::setPen(const QPen& pen)
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{
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mArrow->setPen(pen);
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mLabel->setPen(pen);
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}
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void AxisTag::setBrush(const QBrush& brush)
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{
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mLabel->setBrush(brush);
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}
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void AxisTag::setText(const QString& text)
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{
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mLabel->setText(text);
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}
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void AxisTag::updatePosition(double value)
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{
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// since both the arrow and the text label are chained to the dummy tracer (via anchor
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// parent-child relationships) it is sufficient to update the dummy tracer coordinates. The
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// Horizontal coordinate type was set to ptAxisRectRatio so to keep it aligned at the right side
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// of the axis rect, it is always kept at 1. The vertical coordinate type was set to
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// ptPlotCoordinates of the passed parent axis, so the vertical coordinate is set to the new
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// value.
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mDummyTracer->position->setCoords(1, value);
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// We want the arrow head to be at the same horizontal position as the axis backbone, even if
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// the axis has a certain offset from the axis rect border (like the added second y axis). Thus we
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// set the horizontal pixel position of the arrow end (head) to the axis offset (the pixel
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// distance to the axis rect border). This works because the parent anchor of the arrow end is
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// the dummy tracer, which, as described earlier, is tied to the right axis rect border.
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mArrow->end->setCoords(mAxis->offset(), 0);
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}
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