Brush tool with a pen mode

Currently, i can use the brush tool to either free hand draw texture onto the foreground/background. Or I can use the rectangle , ellipse, or polygon mode to apply a texture within a selection of those shapes. There should be a pen mode that lets you create a custom shape using the pen tool which you can then use to apply a texture. Would make life so much easier when trying to apply a texture across a large, yet specific, plot of land. Bonus points if i can select an existing line , such as the outer wall of a city, and then apply the texture to everything within that line.