Codechange: Add some Rect helpers.

Shrink/Expand/Translate are marked nodiscard as they provide a new Rect
rather than modifying the original Rect.

(cherry picked from commit d8e01f8aa5)

src/core/geometry_type.hpp

@@ -49,6 +49,112 @@ struct Rect {
 	int top;
 	int right;
 	int bottom;
+
+	/**
+	 * Get width of Rect.
+	 * @return width of Rect.
+	 */
+	inline int Width() const { return this->right - this->left + 1; }
+
+	/**
+	 * Get height of Rect.
+	 * @return height of Rect.
+	 */
+	inline int Height() const { return this->bottom - this->top + 1; }
+
+	/**
+	 * Copy and shrink Rect by s pixels.
+	 * @param s number of pixels to remove from each side of Rect.
+	 * @return the new smaller Rect.
+	 */
+	[[nodiscard]] inline Rect Shrink(int s) const
+	{
+		return {this->left + s, this->top + s, this->right - s, this->bottom - s};
+	}
+
+	/**
+	 * Copy and shrink Rect by h horizontal and v vertical pixels.
+	 * @param h number of pixels to remove from left and right sides.
+	 * @param v number of pixels to remove from top and bottom sides.
+	 * @return the new smaller Rect.
+	 */
+	[[nodiscard]] inline Rect Shrink(int h, int v) const
+	{
+		return {this->left + h, this->top + v, this->right - h, this->bottom - v};
+	}
+
+	/**
+	 * Copy and shrink Rect by pixels.
+	 * @param left number of pixels to remove from left side.
+	 * @param top number of pixels to remove from top side.
+	 * @param right number of pixels to remove from right side.
+	 * @param bottom number of pixels to remove from bottom side.
+	 * @return the new smaller Rect.
+	 */
+	[[nodiscard]] inline Rect Shrink(int left, int top, int right, int bottom) const
+	{
+		return {this->left + left, this->top + top, this->right - right, this->bottom - bottom};
+	}
+
+	/**
+	 * Copy and expand Rect by s pixels.
+	 * @param s number of pixels to add to each side of Rect.
+	 * @return the new larger Rect.
+	 */
+	[[nodiscard]] inline Rect Expand(int s) const
+	{
+		return this->Shrink(-s);
+	}
+
+	/**
+	 * Copy and translate Rect by x,y pixels.
+	 * @param x number of pixels to move horizontally.
+	 * @param y number of pixels to move vertically.
+	 * @return the new translated Rect.
+	 */
+	[[nodiscard]] inline Rect Translate(int x, int y) const
+	{
+		return {this->left + x, this->top + y, this->right + x, this->bottom + y};
+	}
+
+	/**
+	 * Copy Rect and set its width.
+	 * @param width width in pixels for new Rect.
+	 * @param end   if set, set width at end of Rect, i.e. on right.
+	 * @return the new resized Rect.
+	 */
+	[[nodiscard]] inline Rect WithWidth(int width, bool end) const
+	{
+		return end
+			? Rect {this->right - width + 1, this->top, this->right,            this->bottom}
+			: Rect {this->left,              this->top, this->left + width - 1, this->bottom};
+	}
+
+	/**
+	 * Copy Rect and indent it from its position.
+	 * @param indent offset in pixels for new Rect.
+	 * @param end   if set, set indent at end of Rect, i.e. on right.
+	 * @return the new resized Rect.
+	 */
+	[[nodiscard]] inline Rect Indent(int indent, bool end) const
+	{
+		return end
+			? Rect {this->left,          this->top, this->right - indent, this->bottom}
+			: Rect {this->left + indent, this->top, this->right,          this->bottom};
+	}
+
+	/**
+	 * Copy Rect and set its height.
+	 * @param width height in pixels for new Rect.
+	 * @param end   if set, set height at end of Rect, i.e. at bottom.
+	 * @return the new resized Rect.
+	 */
+	[[nodiscard]] inline Rect WithHeight(int height, bool end = false) const
+	{
+		return end
+			? Rect {this->left, this->bottom - height + 1, this->right, this->bottom}
+			: Rect {this->left, this->top,                 this->right, this->top + height - 1};
+	}
 };
 
 struct Rect16 {