mirror of
https://github.com/qelectrotech/qelectrotech-source-mirror.git
synced 2026-09-29 22:24:13 +02:00
Andre Rummler
6b577ee757
Shapes and images can now be resized, rotated, and skewed directly on the canvas, not just moved. Both share one small transform struct (rotation, then skew, then scale, anchored on a movable pivot) and one handle widget, so a corner drag, an edge skew, or grabbing the rotate handle behaves the same way and runs through the same matrix math everywhere, instead of every item type reinventing its own. Shapes also gained a proper pen tool (bezier paths, corner/smooth/ symmetric nodes), arc support, and mirroring. Images gained non-destructive cropping and colour-keyed transparency, both remember their own settings, so reopening the dialog picks up where you left off instead of starting over. Properties dialogs for both were extended to match (position, size, angle, skew), with undo/redo wired through for every handle drag. Old XML files can read easily as the transformation is only added if needed and the old syntax is still used and understood if it is not needed.
91 lines
3.7 KiB
C
91 lines
3.7 KiB
C
/*
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Copyright 2006-2026 The QElectroTech Team
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This file is part of QElectroTech.
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QElectroTech is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 2 of the License, or
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(at your option) any later version.
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QElectroTech is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with QElectroTech. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef SHAPETRANSFORM_H
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#define SHAPETRANSFORM_H
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#include <QPointF>
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#include <QTransform>
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/**
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@brief The ShapeTransform struct
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Rotation, skew and scale applied to a shape's local geometry around an
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arbitrary local pivot point.
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These five scalars plus a pivot are a convenient, directly-editable
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basis for 2D affine transforms: every handle in the UI changes exactly
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one field, which is what makes per-handle drag math simple. Note that
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a plain 2x2 linear map only has 4 true degrees of freedom, one fewer
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than (rotation, skewX, skewY, scaleX, scaleY) -- so this is not a
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*unique* representation of a matrix, only a convenient one. That
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redundancy is harmless for editing (nothing here ever needs to invert
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the forward direction) and only matters to decomposeLinear() below,
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which exists for later consumers (flattening a group transform onto
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its children, importing a foreign matrix) rather than everyday use.
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The resulting matrix is meant to be handed directly to
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QGraphicsItem::setTransform(). QGraphicsItem::transformOriginPoint()
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is deliberately NOT used anywhere in this design: it only centers
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QGraphicsItem's own rotation()/scale() convenience properties, and has
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no effect on a custom transform() matrix -- the pivot has to be baked
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into the matrix itself, as toMatrix() does. QGraphicsItem::pos()
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supplies the translation on top, unchanged from how shapes are
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already positioned and moved today.
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*/
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struct ShapeTransform
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{
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qreal rotation = 0; // degrees
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qreal skewX = 0; // degrees
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qreal skewY = 0; // degrees
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qreal scaleX = 1;
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qreal scaleY = 1;
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QPointF pivot; // local coordinates; caller decides the default (usually local bbox center)
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bool isIdentity() const;
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// Rotate+shear+scale about the origin, ignoring pivot -- this is the
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// "linear part" used by compensatedPositionForNewPivot() and by
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// anything that needs to map a direction/offset rather than a point.
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QTransform linearPart() const;
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// The pivot-centered matrix to pass to QGraphicsItem::setTransform().
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QTransform toMatrix() const;
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bool operator==(const ShapeTransform &other) const;
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bool operator!=(const ShapeTransform &other) const { return !(*this == other); }
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};
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// Canonical decomposition of an arbitrary 2x2 linear map into the five
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// scalars above, always returning skewY == 0 (all shear folded into
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// skewX -- matching how most authoring tools represent shear on export).
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// Rebuilding via ShapeTransform::linearPart() from the result reproduces
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// the input matrix exactly; the individual scalar values are not
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// guaranteed to match whatever scalars (if any) originally produced that
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// matrix, only the matrix itself is guaranteed to match.
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ShapeTransform decomposeLinear(const QTransform &linear);
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// Position adjustment needed when the pivot moves, so the shape does not
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// visibly jump on screen: call once, at the end of a pivot-handle drag,
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// alongside setting the new pivot.
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QPointF compensatedPositionForNewPivot(
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const QPointF &position,
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const QPointF &oldPivot,
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const QPointF &newPivot,
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const QTransform &linearPart);
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#endif // SHAPETRANSFORM_H
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