Groups in Programming

Groups in Programming

• Groups allow treating multiple shapes as a single entity.
• A group is created using the Group function, including shapes separated by commas, e.g., Group(Circle(...), Rect(...)).
• Crucially, the closing parenthesis must be present after all shapes.
• Group Properties: Changing position properties (e.g., centerX) affects all shapes within the group. This change affects the group's position, not individual shape positions. Non-position properties (e.g., fill, opacity) can be set for the whole group.
• Shape-specific Properties: Group cannot access or change shape-specific properties of shapes within it.
• Child-specific Properties: Shapes within a group are considered children of the group. To change properties of individual shapes, access them as variables before adding them to the group.

Group Methods

• Groups use similar methods (toFront, toBack, hitsShape) as individual shapes.
• add method adds a new shape to a group.
• clear method removes all shapes from a group.
• remove method removes a specific shape from a group, given its name/reference.

Shape Visibility

• Shapes can be removed from a group by setting their visible property to False.
• Shapes not explicitly in a group are automatically added to the application's default group (app.group).

Step Events and Motion

• Step Events: The onStep function runs repeatedly (30 times per second by default) without user interaction. This is useful for animations.
• app.stepsPerSecond: Adjusts the animation speed by changing the number of times onStep is called per second.
• Horizontal Motion:
  • Straight Motion: Changes the centerX of a shape on each call to onStep using the dx property. Positive dx moves right; negative dx moves left.
  • Reversing Motion: Changes the sign of the dx property.
  • Standing Still: Sets dx to 0.
  • Bounded Motion: Shape stops at the edge of the canvas.
  • Wraparound Motion: Shape reappears on the opposite edge of the canvas after reaching its boundary.
  • Bouncing Motion: Reverses direction (dx) when reaching the boundary.
• Vertical Motion: Similar to horizontal, but uses centerY, dy, top, and bottom properties.
• Diagonal Motion: Combines horizontal and vertical motion using dx and dy.
• Smooth Motion: Higher dx values lead to faster but less smooth motion. Increasing app.stepsPerSecond can result in faster but potentially less smooth animations.

This quiz covers the concepts of groups in programming, focusing on how multiple shapes can be treated as a single entity. Learn about the properties and methods associated with groups, including how to manipulate position properties and access specific shape attributes within a group.