New Visual: Bar

examples/scene/bar_plot.py

@@ -0,0 +1,32 @@
+import numpy as np
+from vispy import scene, app
+
+if __name__ == "__main__":
+
+    canvas = scene.SceneCanvas(keys='interactive', vsync=False)
+    canvas.size = 800, 600
+    canvas.show()
+
+    grid = canvas.central_widget.add_grid()
+    grid.padding = 10
+
+    vb1 = grid.add_view(row=0, col=1, camera='panzoom')
+
+    x_axis1 = scene.AxisWidget(orientation='bottom')
+    x_axis1.stretch = (1, 0.1)
+    grid.add_widget(x_axis1, row=1, col=1)
+    x_axis1.link_view(vb1)
+    y_axis1 = scene.AxisWidget(orientation='left')
+    y_axis1.stretch = (0.1, 1)
+    grid.add_widget(y_axis1, row=0, col=0)
+    y_axis1.link_view(vb1)
+
+    grid_lines1 = scene.visuals.GridLines(parent=vb1.scene)
+
+    bar1 = scene.Bar(height=np.arange(0, 250, 0.5), bottom=np.arange(0, 125, 0.25), width=0.8, shift=0.5, 
+                     color=(0.25, 0.8, 0.), parent=vb1.scene)
+
+    vb1.camera.set_range()
+
+    canvas.measure_fps()
+    app.run()

vispy/scene/visuals.py

@@ -232,6 +232,7 @@ def generate_docstring(subclass, clsname):
 
 Arrow = create_visual_node(visuals.ArrowVisual)
 Axis = create_visual_node(visuals.AxisVisual)
+Bar = create_visual_node(visuals.BarVisual)
 Box = create_visual_node(visuals.BoxVisual)
 ColorBar = create_visual_node(visuals.ColorBarVisual)
 Compound = create_visual_node(visuals.CompoundVisual)

vispy/visuals/__init__.py

@@ -12,6 +12,7 @@
 """
 
 from .axis import AxisVisual  # noqa
+from .bar import BarVisual  # noqa
 from .box import BoxVisual  # noqa
 from .cube import CubeVisual  # noqa
 from .ellipse import EllipseVisual  # noqa

vispy/visuals/bar.py

@@ -0,0 +1,74 @@
+# -*- coding: utf-8 -*-
+# -----------------------------------------------------------------------------
+# Copyright (c) Vispy Development Team. All Rights Reserved.
+# Distributed under the (new) BSD License. See LICENSE.txt for more info.
+# -----------------------------------------------------------------------------
+
+import numpy as np
+from .mesh import MeshVisual
+
+
+class BarVisual(MeshVisual):
+    """Visual that calculates and displays a bar graph
+
+    Parameters
+    ----------
+    data : array-like
+        1st column is the height, optional 2nd column is bottom
+    height : array-like
+        Height of the bars
+    bottom : array-like
+        Bottom of the bars
+    width : int | float
+        Width of all bars
+    shift : int | float
+        Shift of all bars along the x-axis
+    color : instance of Color
+        Color of the bar.
+    """
+
+    def __init__(self, height, bottom=None, width=0.8, shift=0.0, color='w'):
+        if bottom is None:
+            bottom = np.zeros(height.shape[0])
+        rr, tris = calc_vertices(height, bottom, width, shift)
+
+        MeshVisual.__init__(self, rr, tris, color=color)
+
+    def update_data(self, height, bottom=None, width=0.8, shift=0.0, color='w'):
+        if bottom is None:
+            bottom = np.zeros(height.shape[0])
+        rr, tris = calc_vertices(height, bottom, width, shift=shift)
+
+        MeshVisual.set_data(self, rr, tris, color=color)
+
+
+def calc_vertices(height, bottom, width, shift):
+
+    y_position = np.zeros((height.shape[0], 2))
+    y_position[:, 0] = height
+    y_position[:, 1] = bottom
+
+    y_position = y_position.flatten().repeat(2)
+
+    stack_n_x2 = np.arange(0, height.shape[0], dtype=int) 
+    stack_n_x2 = np.expand_dims(stack_n_x2, axis=1)
+    stack_n_x2 = np.repeat(stack_n_x2, 1, axis=1)
+    stack_n_x2 = np.repeat(stack_n_x2, 2, axis=0)
+
+    vertices = np.array([
+        [-width/2 + shift, 1, 0],
+        [width/2 + shift, 1, 0],
+        [width/2 + shift, 0, 0],
+        [-width/2 + shift, 0, 0]])
+
+    vertices = np.tile(vertices, (height.shape[0], 1))
+    vertices[:, 0] = vertices[:, 0] + stack_n_x2[:, 0].repeat(2)
+    vertices[:, 1] = y_position
+
+    base_faces = np.array([[0, 1, 2], [0, 2, 3]])
+
+    base_faces = np.tile(base_faces, (height.shape[0], 1))
+
+    faces = stack_n_x2*4 + base_faces
+
+    return vertices, faces