add slider widget (#10)

example.jl

@@ -138,6 +138,7 @@ function start()
 
     hot_widget = NULL_WIDGET_ID
     active_widget = NULL_WIDGET_ID
+    slider_value = 1
 
     while !GLFW.WindowShouldClose(window)
         drawing_time_start = time_ns()
@@ -159,6 +160,16 @@ function start()
         end
         SD.draw!(image, button2_shape, 0x0000aa00)
 
+        slider_shape = SD.FilledRectangle(SD.Point(600, 600), 50, 100)
+        slider_id = WidgetID(@__LINE__, @__FILE__)
+        hot_widget, active_widget, slider_value = widget(hot_widget, active_widget, slider_id, UI_SLIDER, SD.get_i_min(slider_shape), SD.get_j_min(slider_shape), SD.get_i_max(slider_shape), SD.get_j_max(slider_shape), cursor.i, cursor.j, mouse_left.ended_down, mouse_left.half_transition_count, slider_value)
+        # if slider_value
+            # text_color = 0x0000aa00
+        # end
+        SD.draw!(image, slider_shape, 0x00000000)
+        slider_value_shape = SD.FilledRectangle(SD.Point(600, 600), 50, slider_value)
+        SD.draw!(image, slider_value_shape, 0x000000aa)
+
         empty!(lines)
         push!(lines, "previous frame number: $(i)")
         push!(lines, "average time spent per frame (averaged over previous $(length(time_stamp_buffer)) frames): $(round((last(time_stamp_buffer) - first(time_stamp_buffer)) / (1e6 * length(time_stamp_buffer)), digits = 2)) ms")
@@ -176,6 +187,7 @@ function start()
         push!(lines, "button1_id: $(button1_id)")
         push!(lines, "button2_id: $(button2_id)")
         push!(lines, "text_color: $(repr(text_color))")
+        push!(lines, "slider_value: $(slider_value)")
         push!(lines, "hot_widget: $(hot_widget)")
         push!(lines, "active_widget: $(active_widget)")
 

ui.jl

@@ -10,6 +10,9 @@ abstract type AbstractWidget end
 struct UIButton <: AbstractWidget end
 const UI_BUTTON = UIButton()
 
+struct UISlider <: AbstractWidget end
+const UI_SLIDER = UISlider()
+
 went_down(ended_down, half_transition_count) = (half_transition_count >= 2) || ((half_transition_count == 1) && ended_down)
 went_up(ended_down, half_transition_count) = (half_transition_count >= 2) || ((half_transition_count == 1) && !ended_down)
 
@@ -70,3 +73,30 @@ function widget(hot_widget, active_widget, widget, widget_type::UIButton, i_min,
 
     return hot_widget, active_widget, value
 end
+
+function get_widget_value(hot_widget, active_widget, widget, ::UISlider, active_value, last_value)
+    if (active_widget == widget) && (hot_widget == widget)
+        return active_value
+    else
+        return last_value
+    end
+end
+
+function widget(hot_widget, active_widget, widget, widget_type::UISlider, i_min, j_min, i_max, j_max, i_mouse, j_mouse, ended_down, half_transition_count, last_value)
+    mouse_over_slider = (i_min <= i_mouse <= i_max) && (j_min <= j_mouse <= j_max)
+    mouse_went_down = went_down(ended_down, half_transition_count)
+    mouse_went_up = went_up(ended_down, half_transition_count)
+
+    hot_widget = try_set_hot_widget(hot_widget, active_widget, widget, mouse_over_slider)
+
+    active_widget = try_set_active_widget(hot_widget, active_widget, widget, mouse_over_slider && mouse_went_down)
+
+    # value = get_widget_value(hot_widget, active_widget, widget, widget_type, mouse_over_slider && mouse_went_up)
+    value = get_widget_value(hot_widget, active_widget, widget, widget_type, clamp(j_mouse - j_min + one(j_min), one(j_min), j_max - j_min + one(j_min)), last_value)
+
+    active_widget = try_reset_active_widget(hot_widget, active_widget, widget, mouse_went_up)
+
+    hot_widget = try_reset_hot_widget(hot_widget, active_widget, widget, !mouse_over_slider)
+
+    return hot_widget, active_widget, value
+end