"""
Demonstrates how clipping of objects occurs with the view_bounds parameter to draw().
"""

from enthought.enable.example_support import DemoFrame, demo_main

from enthought.enable.api import Container, Component, Scrolled, Window
from enthought.enable.base import empty_rectangle, intersect_bounds


class Box(Component):
    def _draw_mainlayer(self, gc, view_bounds=None, mode="default"):
        gc.save_state()
        gc.set_fill_color((1.0, 0.0, 0.0, 1.0))
        dx, dy = self.bounds
        x, y = self.position
        gc.rect(x, y, dx, dy)
        gc.fill_path()
        gc.restore_state()
        return

class VerboseContainer(Container):
    """
    By default a container just doesn't draw contained components if they are
    outside its view_bounds.  This subclass modifies the behavior to report
    what components are not being drawn and what their bounds are.
    """
    
    fit_window = False
    
    def _draw_container_mainlayer(self, gc, view_bounds, mode="default"):
        gc.save_state()
        gc.set_fill_color((1.0, 1.0, 1.0, 1.0))
        gc.set_stroke_color((1.0, 1.0, 1.0, 1.0))
        gc.rect(self.x, self.y, self.width, self.height)
        gc.fill_path()
        gc.restore_state()

        if view_bounds:
            v = view_bounds
            new_bounds = (v[0]-self.x, v[1]-self.y, v[2], v[3])
        else:
            new_bounds = None
        
        gc.save_state()
        try:
            gc.translate_ctm(*self.position)
            gc.set_stroke_color((0.0, 0.0, 0.0, 1.0))
            for component in self._components:
                # See if the component is visible:
                tmp = intersect_bounds(component.position + component.bounds, 
                                       new_bounds)
                if tmp == empty_rectangle:
                    print "skipping component:", component.__class__.__name__,
                    print "\tbounds:", component.position, component.bounds
                    continue
                    
                gc.save_state()
                try:
                    component.draw(gc, new_bounds, mode)
                finally:
                    gc.restore_state()
        finally:
            gc.restore_state()


class MyFrame(DemoFrame):
    def _create_window(self):

        container = VerboseContainer(auto_size=False, bounds = [800,800])
        a = Box(bounds=[50.0,50.0], position=[50.0,50.0])
        b = Box(bounds=[50.0,50.0], position=[200.0,50.0])
        c = Box(bounds=[50.0,50.0], position=[50.0,200.0])
        d = Box(bounds=[50.0,50.0], position=[200.0,200.0])
        container.add(a)
        container.add(b)
        container.add(c)
        container.add(d)
        scr = Scrolled(container, bounds=[300,300], position=[50,50], 
                       fit_window=False)
        return Window(self, -1, component=scr)


if __name__ == "__main__":
    demo_main(MyFrame, title="Use the scroll bars to show and hide components")


# EOF