Add a color picker UI element

Replace sliders in the color_write_enable sample with a color picker
element.

framework/gui.cpp

@@ -1245,4 +1245,26 @@ void Drawer::text(const char *formatstr, ...)
 	va_end(args);
 }
 
+bool Drawer::color_picker(const char *caption, const char channel_count, float *color, uint16_t width, ImGuiColorEditFlags flags)
+{
+	assert((channel_count == 3 || channel_count == 4) && "Channel count value must be 3 or 4");
+	bool res;
+	if (width)
+		ImGui::PushItemWidth(width);
+	switch (channel_count)
+	{
+		case 3:
+			res = ImGui::ColorPicker3(caption, color, flags);
+			break;
+		case 4:
+			res = ImGui::ColorPicker4(caption, color, flags);
+			break;
+	}
+	if (res)
+	{
+		dirty = true;
+	};
+	return res;
+}
+
 }        // namespace vkb

framework/gui.h

@@ -173,6 +173,16 @@ class Drawer
 	 */
 	void text(const char *formatstr, ...);
 
+	/**
+	 * @brief Adds a color picker to the gui
+	 * @param caption The text to display
+	 * @param channel_count Number of channels. Must be 3 or 4.
+	 * @param color Color channel array on which the picker works. It contains values ranging from 0 to 1.
+	 * @param width Element width.
+	 * @param flags Flags to modify the appearance and behavior of the element.
+	 */
+	bool color_picker(const char *caption, const char channel_count, float *color, uint16_t width = 0, ImGuiColorEditFlags flags = 0);
+
   private:
 	bool dirty{false};
 };

samples/extensions/color_write_enable/color_write_enable.cpp

@@ -469,9 +469,9 @@ void ColorWriteEnable::build_command_buffers()
 	// Clear color values.
 	std::array<VkClearValue, 4> clear_values = {};
 	clear_values[0].color                    = {0.0f, 0.0f, 0.0f, 0.0f};
-	clear_values[1].color                    = {background_r_value, 0.0f, 0.0f, 0.0f};
-	clear_values[2].color                    = {0.0f, background_g_value, 0.0f, 0.0f};
-	clear_values[3].color                    = {0.0f, 0.0f, background_b_value, 0.0f};
+	clear_values[1].color                    = {background_color[0], 0.0f, 0.0f, 0.0f};
+	clear_values[2].color                    = {0.0f, background_color[1], 0.0f, 0.0f};
+	clear_values[3].color                    = {0.0f, 0.0f, background_color[2], 0.0f};
 
 	// Begin the render pass.
 	VkRenderPassBeginInfo render_pass_begin_info    = vkb::initializers::render_pass_begin_info();
@@ -539,15 +539,11 @@ void ColorWriteEnable::on_update_ui_overlay(vkb::Drawer &drawer)
 {
 	if (drawer.header("Background color"))
 	{
-		if (drawer.slider_float("Red", &background_r_value, 0.0f, 1.0f))
-		{
-			build_command_buffers();
-		}
-		if (drawer.slider_float("Green", &background_g_value, 0.0f, 1.0f))
-		{
-			build_command_buffers();
-		}
-		if (drawer.slider_float("Blue", &background_b_value, 0.0f, 1.0f))
+		if (drawer.color_picker("", 3, background_color.data(), 200,
+		                        ImGuiColorEditFlags_NoSidePreview |
+		                            ImGuiColorEditFlags_NoSmallPreview |
+		                            ImGuiColorEditFlags_Float |
+		                            ImGuiColorEditFlags_RGB))
 		{
 			build_command_buffers();
 		}

samples/extensions/color_write_enable/color_write_enable.h

@@ -94,12 +94,11 @@ class ColorWriteEnable : public ApiVulkanSample
 	void setup_descriptor_set_layout();
 	void setup_descriptor_set();
 
-	bool  r_bit_enabled      = true;
-	bool  g_bit_enabled      = true;
-	bool  b_bit_enabled      = true;
-	float background_r_value = 0.5f;
-	float background_g_value = 0.5f;
-	float background_b_value = 0.5f;
+	bool r_bit_enabled = true;
+	bool g_bit_enabled = true;
+	bool b_bit_enabled = true;
+
+	std::array<float, 3> background_color = {0.5f, 0.5f, 0.5f};
 };
 
 std::unique_ptr<vkb::Application> create_color_write_enable();