87 lines
2.5 KiB
Markdown
87 lines
2.5 KiB
Markdown
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# Coding Conventions
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This document describes some of the recommended coding conventions that should be followed in KWin.
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For KWin, it is recommended to follow the KDE Frameworks Coding Style.
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## `auto` Keyword
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Optionally, you can use the `auto` keyword in the following cases. If in doubt, for example if using
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`auto` could make the code less readable, do not use `auto`. Keep in mind that code is read much more
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often than written.
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* When it avoids repetition of a type in the same statement.
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```
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auto something = new MyCustomType;
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auto keyEvent = static_cast<QKeyEvent *>(event);
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auto myList = QStringList({ "FooThing", "BarThing" });
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```
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* When assigning iterator types.
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```
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auto it = myList.const_iterator();
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```
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## `QRect::right()` and `QRect::bottom()`
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For historical reasons, the `QRect::right()` and `QRect::bottom()` functions deviate from the true
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bottom-right corner of the rectangle. Note that this is not the case for the `QRectF` class.
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As a general rule, avoid using `QRect::right()` and `QRect::bottom()` as well methods that operate
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on them. There are exceptions, though.
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Exception 1: you can use `QRect::moveRight()` and `QRect::moveBottom()` to snap a `QRect` to
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another `QRect` as long as the corresponding borders match, for example
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```
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// Ok
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rect.moveRight(anotherRect.right());
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rect.moveBottom(anotherRect.bottom());
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rect.moveBottomRight(anotherRect.bottomRight());
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// Bad
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rect.moveRight(anotherRect.left() - 1); // must be rect.moveLeft(anotherRect.left() - rect.width());
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rect.moveBottom(anotherRect.top() - 1); // must be rect.moveTop(anotherRect.top() - rect.height());
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rect.moveBottomRight(anotherRect.topLeft() - QPoint(1, 1));
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```
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Exception 2: you can use `QRect::setRight()` and `QRect::setBottom()` to clip a `QRect` by another
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`QRect` as long as the corresponding borders match, for example
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```
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// Ok
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rect.setRight(anotherRect.right());
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rect.setBottom(anotherRect.bottom());
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rect.setBottomRight(anotherRect.bottomRight());
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// Bad
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rect.setRight(anotherRect.left());
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rect.setBottom(anotherRect.top());
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rect.setBottomRight(anotherRect.topLeft());
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```
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Exception 3: you can use `QRect::right()` and `QRect::bottom()` in conditional statements as long
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as the compared borders are the same, for example
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```
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// Ok
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if (rect.right() > anotherRect.right()) {
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return;
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}
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if (rect.bottom() > anotherRect.bottom()) {
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return;
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}
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// Bad
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if (rect.right() > anotherRect.left()) {
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return;
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}
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if (rect.bottom() > anotherRect.top()) {
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return;
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}
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```
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