Here you’ll discover why traditional layouts in QML often lead to dead ends and what mechanism developers use instead. You’ll find out how you can abandon complex coordinate calculations, simplify code, and at the same time get more predictable interface behavior when resizing windows. The result — cleaner QML, less JavaScript, and noticeably higher performance.
Anchors will be shown, grouped properties, filling areas with a single line of code, and techniques that allow you to control element sizes between neighbors. Also, 5 types of traditional layouts are compared, demonstrating where they’re truly appropriate and where they lose to anchoring.
This chapter is a turning point: after it, your approach to designing interfaces in QML will never be the same. Skipping it means continuing to make life harder for yourself.
This chapter includes ready-to-use code examples.
Chapter Self-Check
Why is it recommended to use anchors instead of traditional layouts for positioning elements in QML?Answer
Correct answer: Anchors allow easy application of animation effects and overlapping elements on top of each other, which is difficult to implement with traditional layouts. They’re also more efficient because they’re implemented in C++.
What’s the difference between parent.horizontalCenter and parent.anchors.horizontalCenter?Answer
Correct answer: Anchors of referenced elements have direct reflection, so the short form parent.horizontalCenter is used. The full form with anchors is not required and is redundant.
What happens when binding the anchors.fill: parent property? What four lines of code does it replace?Answer
Correct answer: The fill property replaces four separate bindings: anchors.left, anchors.right, anchors.top, and anchors.bottom to the corresponding edges of the parent element, forcing the element to completely fill the parent’s area.
Why does the green rectangle remain filled across the entire area when resizing the window, despite its size not being explicitly set?Answer
Correct answer: Because properties aren’t assigned a specific value, but rather bound together. When property values change, the values of properties bound to them automatically change as well.
How can you create an element that will automatically fill the space between two fixed-width elements?Answer
Correct answer: You need to bind the left edge of the middle element to the right edge of the left element (anchors.left: leftElement.right), and the right edge to the left edge of the right element (anchors.right: rightElement.left).
What’s the difference between leftMargin and verticalCenterOffset?Answer
Correct answer: leftMargin creates an absolute offset in pixels from the edge, while verticalCenterOffset creates a relative offset from the centerline, working together with the verticalCenter binding.
What are grouped properties and how can they be written in compact form?Answer
Correct answer: Grouped properties are properties combined into a separate group (for example, anchors). In compact form, they’re written as anchors { left: parent.left; right: parent.right } instead of repeating anchors. before each property.
What’s the key difference between Row and RowLayout layout elements?Answer
Correct answer: RowLayout is contained in the QtQuick.Layouts module and has an additional Layout property that allows setting minimum, maximum, and preferred element sizes, as well as controlling space filling.
What will happen if in a RowLayout element you set Layout.fillWidth: true for the middle rectangle, and Layout.fillHeight: true for the edge elements?Answer
Correct answer: The middle element will stretch horizontally, filling the space between the edge elements, and the edge elements will stretch vertically, filling the entire height of the container.
How does the Flow layout work and how does it differ from Row?Answer
Correct answer: Flow automatically wraps elements to a new line when reaching the container boundary, trying to place the maximum number of elements in the available area. Row places elements strictly in one line without wrapping.
Why is the opacity: 0.5 property set for the green rectangle in the overlap example?Answer
Correct answer: To make the green rectangle semi-transparent and visually see the overlap area with the red rectangle underneath it.
What happens to elements in a Flow layout when the window width decreases?Answer
Correct answer: Elements automatically rearrange in a “snake” pattern, moving to the next line to fit in the reduced area. The number of elements in each line will decrease.
Why are anchors considered more efficient than calculating positions through JavaScript?Answer
Correct answer: Anchors are implemented in C++, which provides better performance. They also have better readability and automatically handle size changes without additional code.
Practical Assignments
Easy Level
Adaptive Photo Gallery
Create an application with three images (use Rectangles of different colors) arranged horizontally using anchors. The first and last images should have a fixed width of 100 pixels, and the middle one should automatically fill the remaining space. All images should occupy the entire window height with a 10-pixel margin on all sides.
Hints: Use three Rectangle elements with different colors. Give identifiers to the edge elements. For the middle element, bind anchors.left to the right of the first element, and anchors.right to the left of the third element. Don’t forget about anchors.top and anchors.bottom for all elements, as well as margins.
Medium Level
Adaptive Card Panel
Create an application using Flow that displays 12 card-rectangles sized 80×80 pixels. Each card should contain a number (use the Text element). Cards with even numbers should be blue, with odd numbers — orange. When resizing the window, cards should automatically rearrange. Add the ability to change the corner radius of the cards.
Hints: Use a Flow element with Repeater. The model should generate an array with 12 elements. Determine color through checking index % 2. For rounded corners, use the radius property. To display the number, place Text inside Rectangle with anchors.centerIn: parent.
Hard Level
Complex Layout with Dynamic Positioning
Create a complex interface: top panel (height 60px, red) anchored at the top across the full width, bottom panel (height 40px, green) — at the bottom. Between them, place a RowLayout with three areas: left sidebar (minimum width 150px, blue, fillHeight: true), center area (fills remaining space, yellow, with text “Content”), right sidebar (minimum width 120px, purple, fillHeight: true). All panels should have 5-pixel margins. When resizing the window, the layout should adapt while maintaining minimum sizes.
Hints: Use a combination of anchors and RowLayout. Top panel: anchors.top and anchors.left/right to parent. Bottom panel: anchors.bottom and anchors.left/right to parent. RowLayout: anchors.top to bottom of top panel, anchors.bottom to top of bottom panel, anchors.left/right to parent. Import QtQuick.Layouts. Use Layout.minimumWidth, Layout.fillWidth, and Layout.fillHeight.
💬 Join the Discussion!
Mastered the anchoring mechanism in QML? Have questions about when it’s better to use anchors versus traditional layouts?
Which approach to element positioning seemed most convenient to you? Share your experience creating adaptive interfaces!