Copyright (C) 2012-2020 Rudolf Cardinal (email@example.com).
This file is part of CamCOPS.
CamCOPS 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 3 of the License, or
(at your option) any later version.
CamCOPS 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 CamCOPS. If not, see <http://www.gnu.org/licenses/>.
class LabelWordWrapWide : public QLabel
// Label that word-wraps its text, and prefers to be wide rather than tall.
// This is a surprisingly tricky thing to do.
// Construct with text.
// The default size policy is preferredPreferredHFWPolicy().
explicit LabelWordWrapWide(const QString& text, QWidget* parent = nullptr);
// Default constructor.
explicit LabelWordWrapWide(QWidget* parent = nullptr);
virtual QSize sizeHint() const override;
// Returns the size of non-word-wrapped (unwrapped) text.
// ... "I would like to be very wide and not very tall."
// - QLabel::heightForWidth() gives a sensible answer; no need to override.
// But sometimes helpful to see when it's being used:
virtual bool hasHeightForWidth() const override;
virtual int heightForWidth(int width) const override;
// - QLabel::minimumSizeHint() gives a sensible answer (the size of the
// smallest individual word); no need to override.
// ... "I need to be big enough to contain my smallest word."
// ... EXCEPT that once resizeEvent() has used setFixedHeight(), it
// returns that as the minimum.
// ... and then it caches that.
virtual QSize minimumSizeHint() const override;
// - However, even with a size policy of Maximum/Fixed/hasHeightForWidth,
// the label's height does not increase as its width is decreased, unless
// you override resizeEvent().
virtual void resizeEvent(QResizeEvent* event) override;
// - resizeEvent() does the trick, but it isn't normally called when, for
// example, we set our text. So catch other events:
bool event(QEvent* e) override;
// Set the text of the label.
void setText(const QString& text);
// Returns the height of our text, given a width.
int qlabelHeightForWidth(int width) const;
// If we weren't word-wrapping (i.e. if we were using a single line of
// text), how big would we be?
QSize sizeOfTextWithoutWrap() const;
// Set our height to an appropriate fixed value, given our width.
// How much extra space do we need to allocate for CSS features like
QSize extraSizeForCssOrLayout() const;
// Clear our cached information.
// - Widgets shouldn't need to cache their size hints; that's done by layouts
// for them. See
// - However, for performance... we'll cache some things.
// In particular, word-wrapping labels can get asked to calculate their
// width for a great many heights (sometimes repeatedly).
// - Moreover, the application of stylesheets varies with time (so calls
// can be made prior to, and then after, application of
// stylesheets). So the caches must be cleared whenever things like that
mutable QSize m_cached_unwrapped_text_size; // cached "single-line" text size
mutable QSize m_cached_extra_for_css_or_layout; // cached "extra size for CSS"
mutable QMap<int, int> m_cached_qlabel_height_for_width; // cached map of width -> height